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Polyphenol oxidase, alpha-amylase and beta-amylase activities of Triticum monococcum, Triticum turgidum and Triticum aestivum: A two-year study
Abstract
Enzymatic activity often reduces the nutritional value of wheat flour during food manufacturing, causing compound degradation and/or heat damage. The choice of wheat varieties with low enzymatic activity could therefore help to preserve the nutritional quality of food. The aim of this research was to evaluate polyphenol oxidase, alpha-amylase and beta-amylase activities in whole meal flours of 59 accessions belonging to different wheat species and subspecies, cropped in two years. The extraction pH (7.0), reaction pH (5.5) and reaction temperature (45 °C) were determined by preliminary trials. The ANOVA highlighted significant differences for all enzymes among species/subspecies and, for amylases, between cropping years; however, the year influence was overwhelming only for alpha-amylase. Einkorn showed the highest polyphenol oxidase (362.1 ± 9.46 U/g DM) as well as the lowest alpha-amylase (0.20 ± 0.006 CU/g DM) and beta-amylase (12.0 ± 0.36 B3U/g DM) activities. The embryo/scutellum had the highest polyphenol oxidase and alpha-amylase values, followed by the bran and the endosperm; in contrast, beta-amylase was evenly distributed in the bran and the endosperm, and was absent in the embryo/scutellum.
... Cereal products containing wholemeal flour or bran are susceptible to enzymatic browning over time (Hidalgo et al., 2013;Niu et al., 2014). Bran possesses high polyphenol oxidase (PPO) activity (Habuš et al., 2021), which catalyses the formation reaction of o-quinons in the presence of molecular oxygen, resulting in undesirable browning (Fan et al., 2020;Niu et al., 2014;Pathare et al., 2013;Pellicer et al., 2018;Zhang et al., 2019). ...
... Dough for bread, noodles or pasta tend to darken undesirably over time due to the presence of PPO (Hidalgo et al., 2013;Niu et al., 2014). A commonly used indicator of darkening in carbohydrate-rich foods is BI (Pathare et al., 2013). ...
... Both enzymatic and non-enzymatic oxidation of phenolic compounds can lead to the browning process. In contrast to moderate non-enzymatic browning, which occurs at temperatures above 100 °C, enzymatic darkening of cereal-based food occurring at temperatures ranging from ambient temperature to about 90 °C is undesirable (Hidalgo et al., 2013;Niu et al., 2014). Enzymatic browning occurs as an indirect outcome of PPO activity (Pathare et al., 2013;Yadav et al., 2010). ...
3D printing is an emerging technology that offers the ability to produce tailor-made foods. This work addresses the physical properties of 3D-printed snacks enriched with wheat bran as a function of flour type (oat, barley), addition of acidity regulators (citric acid, sodium bicarbonate), printing temperature (20 °C, 30 °C, 40 °C), and bran pre-processing (high-intensity ultrasound, vacuum microwave and pulsed light). Polyphenol oxidase activity, total phenolic content, antioxidant activity of bran, the viscosity profile of the flour-bran blend, the precision of 3D printing and browning kinetics of the physical properties of the dough and of baked snacks were investigated. During 1 h required to print ten pieces, the dough became very distinctly darker. Adjusting the printing temperature to 20 °C and adding sodium bicarbonate resulted in a dough, which changed colour less, but still very distinctly. Bran pre-processing inactivated polyphenol oxidase activity by 77–92%, which stopped browning of the dough within 50 min without affecting the printing precision. The use of ultrasound, vacuum microwave and pulsed light could be extended to other food components to achieve a greater inactivation of undesirable enzymes. Pre-processing techniques resulted in minor differences in the baked snack, so their future choice depends mainly on the amount of water that can be added to the recipe.
... Sound einkorn seeds display low alpha-amylase (0.14-0.29 CU/g DM) and beta-amylase (8.2-15.9 B3U/g DM) activities (Hidalgo et al., 2013), thus limiting the formation of reducing sugars (in particular, maltose) and the development of heat damage during processing, but show greater polyphenol oxidase (PPO) activity (252.1-478.5 U/g DM) than the polyploid wheats. A high PPO activity in the kernels and in the flour is responsible for the darkening of many end-products. ...
... A high PPO activity in the kernels and in the flour is responsible for the darkening of many end-products. The embryo/scutellum has the highest polyphenol oxidase and alpha-amylase values, followed by the bran and the endosperm; in contrast, beta-amylase is evenly distributed in the bran and the endosperm, and is absent in the embryo/scutellum (Hidalgo et al., 2013). Einkorn also shows low lipoxygenase activity (0.45 ± 0.072 μmol/min/g DM), unlike most polyploid wheats (T. ...
... 1989-2021 [114,115] Effects of storage conditions and duration on nutritional and technological properties of grain and semolina; [116][117][118] Effects of debranning on the technological and health properties of grain and pasta; [119][120][121] Effects of micronisation and air-classification on the technological and health properties of grain and pasta; [122][123][124] Effects of milling and pasta-making on the nutritional, technological, and health properties; [117,[125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141] Effects of germination in reducing gluten peptides associated with CD and on technological features; [142] Effects of drying conditions on the protein denaturation, aggregation and digestibility of pasta; [143][144][145][146] Pasta formulation ...
... In line with them, Hidalgo and Brandolini 2012 [129] stressed the need to select genotypes with high yellow pigment colour and low enzymatic activity, to maintain higher antioxidant features and a better appearance in the final products. Utilising species/subspecies/accessions differing in their enzymatic activity or their esterification ability could be useful for producing foods with improved technological and nutritional quality features [43,131]. However, other approaches to increase carotenoids and tocols stability were also proposed, such as the enrichment of pasta with encapsulated carrot waste extracts in oil [177]. ...
Durum wheat is one of the most important food sources in the world, playing a key role in human nutrition, as well as in the economy of the different countries in which its production areas are concentrated. Its grain also represents a staple and highly versatile ingredient in the development of health foods. Nonetheless, the aspects determining durum wheat’s health quality and their interactions are many, complex, and not entirely known. Therefore, the present systematic literature review aims at advancing the understanding of the relationships among nutritional, health, and technological properties of durum wheat grain, semolina, and pasta, by evaluating the factors that, either positively or negatively, can affect the quality of the products. Scopus, Science Direct, and Web of Science databases were systematically searched utilising sets of keywords following the PRISMA guidelines, and the relevant results of the definitive 154 eligible studies were presented and discussed. Thus, the review identified the most promising strategies to improve durum wheat quality and highlighted the importance of adopting multidisciplinary approaches for such purposes.
... g/100 g DM, respectively), with the exception of the pregerminated sample (0.115 and 0.125 g/100 g DM, respectively), whose enzymes (in particular, α-amylases) were activated by the sprouting; interestingly, no superior maltose content was detected, indicating that the β-amylase was still inactive. The higher maltose concentration found in durum wheat semolina (0.135 g/100 g DM) was probably a consequence of the higher β-amylase activity observed in polyploid wheats (Hidalgo, Brusco, Plizzari, & Brandolini, 2013). Sucrose was present in all flours, particularly in the sample from decorticated kernels, where the removal of the pericarp increased its concentration. ...
... Reducing sugar content increased significantly in pasta samples (Table 4) with respect to the flours (Table 2), mainly because the amylase activity was triggered by the addition of water to the flour/ mixtures, thus causing the release of sugars during kneading . Interestingly, maltose was abundant only in durum wheat pasta, because T. turgidum has a higher β-amylase activity than T. monococcum (Hidalgo et al., 2013). Fructose and glucose were generally scarce, except in EPG (0.465 and 0.553 g/100 g DM, respectively). ...
The increasing interest of consumers for foods with enhanced nutritional characteristics has spurred the industry to look for unconventional raw materials and novel products. Aim of this research was to evaluate pasta prepared from different T. monococcum flours and mixtures: refined flour (EF), refined flour from pregerminated kernels (EPG), whole meal flour from decorticated kernels (EDK), refined flour plus egg albumen (EA) and refined flour plus whole egg (EW); pasta from durum wheat semolina (DS) was the control. Pasta colour was not modified by the addition of egg white or pregerminated flour, while decorticated flour decreased brightness and whole egg increased brightness and yellow component. All einkorn samples showed higher protein and carotenoid content, and lower heat damage than DS. The EDK pasta had more carotenoid, lipid and furosine than EF pasta; EPG instead had slightly less proteins, more reducing sugars and higher heat damage. The addition of egg products increased protein content and, for whole egg, lipids and carotenoids concentration, while maintaining within acceptable levels the heat damage. All einkorn pastas had good cooking characteristics; compared to whole egg, the albumen gave an optimal texture pasta, while delivering a cholesterol-free product with low lipid content.
... As Hidalgo et al., [37] indicate, grains of mature kamut wheat contain many enzymes such as amylases, proteases, oxidases and lipases that exert essential and specific functions As Hidalgo et al., [37] indicate, grains of mature kamut wheat contain many enzymes such as amylases, proteases, oxidases and lipases that exert essential and specific functions during the early stages of sprouting that aid the development of the seedlings and that influence their quality and nutritional properties of the germinate. In this study, these authors also report that amylases are of great importance in pseudocereals because they catalyze the degradation of starch, considered the basis of most food processing pathways. ...
... As Hidalgo et al., [37] indicate, grains of mature kamut wheat contain many enzymes such as amylases, proteases, oxidases and lipases that exert essential and specific functions As Hidalgo et al., [37] indicate, grains of mature kamut wheat contain many enzymes such as amylases, proteases, oxidases and lipases that exert essential and specific functions during the early stages of sprouting that aid the development of the seedlings and that influence their quality and nutritional properties of the germinate. In this study, these authors also report that amylases are of great importance in pseudocereals because they catalyze the degradation of starch, considered the basis of most food processing pathways. ...
The establishment of colonies of Atta cephalotes cutter ants under laboratory conditions has been proposed for the study and development of plague control products. However, few laboratories in Colombia have colonies of Atta cephalotes cutter ants, with food being a limiting factor given their sensitivity, selectivity and voracity. In this study, the use of wheat germinated kamut (Triticum turgidum), quinoa (Chenopodium quinoa) and mung bean (Vigna radiata) as an alternative for the feeding of colonies under laboratory conditions y mango leaves like control, using mini-colonies was evaluated. In the study, mung bean sprouts and kamut wheat were preferred (100% load, 24 hours), compared to quinoa (89 ± 10% load, 24 hours). The determination of the effect of the sprouts on the growth rate of the mini-colonies was evaluated during 8 weeks, showing that the germinated kamut wheat and control treatment generated the best growth rates of fungus in the exponential phase (3.19 and 3.73 g / week respectively) compared with mung beans and quinoa (1 g / wk), supporting the potential of kamut wheat for the maintenance of colonies under laboratory conditions.
... behavior of raw materials during processing (Hidalgo et al 2013). Also, these enzymes play critical roles in cereal processability (Basinskiene et al 2011). ...
... In fact, the higher the activity of αamylase, the lower the value of falling number and the more the reduction in viscosity. Moreover, αamylase activity is often assessed to deduce the manufacturing quality of flours (Hidalgo et al 2013). In addition, amylases can reduce the firming rate of bread crumb, have an anti-staling action which has been ascribed to the modification of retrogradation behavior for the hydrolyzed starch (Miguel et al 2013). ...
... Brandolini et al. (2010) reported that a-amylase activity was decreased while FN was increased during storage of whole wheat flour. In general, FN should be in the range of 250e350 s to maintain functionality of wheat flour (Hidalgo, Brusco, Plizzari, & Brandolini, 2013). WFIW stored at 0 or 25 C for 24 wk were within the range of 250e350 s for FN, indicating that WFIW should be kept below 25 C to maintain the quality of flour during storage. ...
... In contrast, FN of WFIW stored at 45 C was over 350 s after 4 wk storage. A high FN (>350 s) indicates insufficient formation of oligosaccharides, maltotriose, glucose, and maltose with low a-amylase activities, resulting in decreased quality of wheat flour (Hidalgo et al., 2013). ...
The objectives of this study were to investigate quality changes in whole flour of immature wheat (WFIW) stored during 24 wk at different temperatures (0, 25, 35 or 45 °C) and to develop Arrhenius models to predict its quality. Color coordinates a* and b*, α-amylase activity, falling number (FN), setback, and final viscosity as quality attributes of WFIW during storage were measured every 4 wk for 24 wk and the changes were kinetically modeled using the Arrhenius equation. The activation energy (Ea) of quality attributes was in the range of 23,000–70,000 kJ/mol and that for FN was the highest, which was 70,000 kJ/mol. Additionally, volatile compounds in WFIW and consumer acceptance of cookies baked with WFIW as an end-product were measured. Among the volatile compounds, the propan-2-one and hexanal dramatically increased in WFIW stored at relative high temperature (35 or 45 °C) for prolonged period. Consumer acceptance of cookies showed that consumers prefer cookies made with WFIW stored relatively low temperature (0–25 °C).
... With compared to numerous investigations (agronomic traits, resistance to abiotic and biotic stress) on synthetic hexaploid wheat, researches on quality traits are less (van Ginkel and Ogbonnaya, 2007 ). The PPO activity in several subspecies of Triticum monococcum, T. turgidum and T. aestivum had been investigated (Hidalgo et al., 2013 ), yet there is no literature evaluating PPO activity in synthetic hexaploid wheat. Although Mares and Mrva (2008) surveyed the PPO activity of primary and derived synthetic hexaploid wheat lines, the female parents of most of the primary synthetics (from CIMMYT) in that study were T. turgidum ssp. ...
... \, represents maternal; _, represents paternal, and synthetics represents synthetic hexaploid wheat, S 7 eS 8 generation. large variations among different species/subspecies (Hidalgo et al., 2013). Mares and Mrva (2008) reported that more than 30% of the primary synthetics (mostly from CIMMYT) surveyed had very low or near zero PPO activity (Mares and Mrva, 2008). ...
... The high b-amylase activity of T. urartu could have been expected due to the medium to high values observed in emmer, spelt, durum and bread wheat (Hidalgo et al., 2013), while the low bamylase activity reported for domesticated einkorn (Hidalgo et al., 2013) finds its confirmation here and is parallel to the low values found in feral and wild einkorn. Despite the observed low bamylase concentration of wild, feral and domesticated einkorn, the use of this cereal for making ethanol-enriched products cannot be excluded. ...
... The high b-amylase activity of T. urartu could have been expected due to the medium to high values observed in emmer, spelt, durum and bread wheat (Hidalgo et al., 2013), while the low bamylase activity reported for domesticated einkorn (Hidalgo et al., 2013) finds its confirmation here and is parallel to the low values found in feral and wild einkorn. Despite the observed low bamylase concentration of wild, feral and domesticated einkorn, the use of this cereal for making ethanol-enriched products cannot be excluded. ...
... 55 A recent study analyzing wholemeal flours of 59 accessions belonging to different wheat species and subspecies and cropped in two years evidenced lower α-amylase activity in wholemeal flours of einkorn (0.20 ± 0.006 Ceralpha U g −1 DM) than in those of T. turgidum (0.24 ± 0.030 Ceralpha U g −1 DM) and T. aestivum (0.29 ± 0.032 Ceralpha U g −1 DM). 56 The β-amylases are exo-hydrolases that release β-maltose from the non-reducing ends of α(1-4)-linked poly-and oligoglucans until the first α(1-6) branching point along the substrate molecule is encountered. The result is the complete hydrolysis of amylose to maltose, while amylopectin gives maltose (∼60%) and dextrines (∼40%). ...
... 40,42 In fact, the limited heat damage reported in einkorn bread 40 and water biscuits 42 can be attributed to the lower β-amylase activity of T. monococcum (12.0 ± 0.36 Betamyl-3 U g −1 DM) compared with T. turgidum (48.6 ± 1.44 Betamyl-3 U g −1 DM) and T. aestivum (58.5 ± 2.29 Betamyl-3 U g −1 DM). 56 The enzyme lipoxygenase (LOX, linoleate:oxygen oxidoreductase) catalyzes the oxidation of polyunsaturated fatty acids (mainly linoleic and linolenic acids), leading to the formation of fatty acid radicals, which are responsible for the oxidative degradation of carotenoids and tocols. From a technological point of view, LOX activity is useful for whitening bread or for improving the rheological characteristics of the dough; 58 however, a high LOX activity is detrimental to the nutritional value of the end-products, because the enzyme is responsible for the majority of antioxidant degradation. ...
The hulled wheat einkorn (Triticum monococcum L. ssp. monococcum), staple food of early farmers for many thousand years, today is cropped only in small areas of the Mediterranean region and continental Europe. The increasing attention for the nutritional quality of foods has fostered a renewed interest for this low-impact crop. The reappraisal of einkorn quality evidenced that this ancient wheat has some dietary advantages over polyploid wheats. Einkorn whole meal is poor in dietary fibre, but rich in proteins, lipids (mostly unsaturated fatty acids), fructans and trace elements, including Zn and Fe. The good concentration of several antioxidant compounds (carotenoids, tocols, conjugated polyphenols, alkylresorcinols and phytosterols) and the low beta-amylase and lipoxygenase activities (which limit antioxidants degradation during food processing) contribute to the excellent nutritional properties of its flour, superior to those of other wheats. Conversely, einkorn has relatively low bound polyphenols content and high polyphenol oxidase activity. In spite of eliciting weaker toxic reactions than other Triticum ssp., einkorn is not suitable for coeliacs. Current trends towards the consumption of functional foods suggest that this cereal may still play a significant role in human consumption, especially in the development of new or special foods with superior nutritional quality.
... Crust shape and colour are similar to those of wheat loaves, but the crumb shows an enticing yellow tinge [11] for the high carotenoids content [5]. Furthermore, the lower endogenous enzymatic activity [12,13] allows for be er preservation of antioxidants during storage [14,15] and processing [16,17], and limits heat damage [18], thus safeguarding the favourable nutritional characteristics of einkorn-derived products. ...
Einkorn flour, rich in proteins, carotenoids, and other antioxidants, generally has poor breadmaking value. In this research, the composition and technological characteristics of the flours and breads of two elite einkorns (Monlis and ID331) and a bread wheat (Blasco), cropped in four different environments, were evaluated. The einkorns confirmed better flour composition than bread wheat for proteins (on average, 16.5 vs. 10.5 g/100 g), soluble pentosans (1.03 vs. 0.85 g/100 g), and yellow pigment (10.0 vs. 1.0 mg/kg). Technologically, they had better SDS sedimentation values (89 vs. 66 mL), lower farinographic water absorption (52.6 vs. 58.8%), and a similar development time, stability, and degree of softening. Viscoelasticity tests showed lower storage and loss moduli and more prevalent elastic behaviour for Blasco, while rheofermentographic tests showed an anticipated development time (120.8 vs. 175.0 min), higher maximum height (73.0 vs. 63.0 mm), and superior retention coefficient (99.1 vs. 88.7%), but a lower CO2 total (1152 vs. 1713 mL) for einkorn doughs. Einkorn breads were bigger than the control (736 vs. 671 cm3); crumb pores percentage was similar, but medium-size pores were scarcer. Finally, a 52-h shelf-life trial demonstrated that einkorn bread had a softer texture, maintained for a longer time, and a slower retrogradation than the control. Therefore, choice of appropriate varieties and process optimisation allows the production of excellent einkorn breads with a superior nutritional value and longer shelf life.
... The revival of the interest in the ancient wheats has increased the number of surveys carried out on cultivated einkorn, mainly with respect to the nutritional and health aspects of this ancestral crop [19][20][21][22][23][24][25]. As the decline in this crop began in antiquity [26][27][28], the variation retained from domestication until the present day could be relatively scarce. ...
Wild einkorn (Triticum monococcum L. ssp. aegilopoides (Link) Thell.) is a diploid wheat species from the Near East that has been classified as an ancestor of the first cultivated wheat (ein-korn; T. monococcum L. ssp. monococcum). Its genome (A m), although it is not the donor of the A genome in polyploid wheat, shows high similarity to the A u genome. An important characteristic for wheat improvement is grain quality, which is associated with three components of the wheat grain: endosperm storage proteins (gluten properties), starch synthases (starch characteristics) and puroindolines (grain hardness). In the current study, these grain quality traits were studied in one collection of wild einkorn with the objective of evaluating its variability with respect to these three traits. The combined use of protein and DNA analyses allows detecting numerous variants for each one of the following genes: six for Ax, seven for Ay, eight for Wx, four for Gsp-1, two for Pina and three for Pinb. The high variability presence in this species suggests its potential as a source of novel alleles that could be used in modern wheat breeding.
... composed of amylose and amylopectin, and possesses high amylolytic activity which leads to redundant reduction of paste viscosity(Hidalgo et al., 2013). Gelatinization and swelling of wheat starch have an important effect on the quality of end-use products, especially on the quality of white salted noodles(AACC, 2000). ...
Wheat bran is a by‐product rich in bioactive compounds, but possess a strong polyphenol oxidase (PPO) activity, which can act undesirably on product quality. This study aimed to optimize the particle size (500, 255, 10 µm) of wheat bran and time and amplitude of high‐intensity ultrasound (HIU) treatment on the PPO activity, total phenolics, antioxidant activity, and water swelling using response surface methodology. The PPO activity decreased depending on the particle size and HIU treatment time. Phenolic content, antioxidant activity and swelling were dependent on bran particle size. Temperature rise, depending on the HIU time and amplitude, affected PPO, phenolics and antioxidants. In optimized conditions (particle size 10 µm, HIU 15 min), 93% of bran PPO was inactivated while phenolic content increased for 11%. Wheat flour combined with micronized and ultrasonically treated bran (at 20% w/w) had improved gluten formation and pasting properties compared with flour containing native bran.
... It should be noted that addition of raw TT and S flour had a higher influence on pasting properties compared to G and T. The highest values of the maximum torque during heating (C3) were 1.99 and 2.20 Nm in case of the samples with raw G and T flour addition. Weaker starch gel stability (C4) was registered for dough samples with S and TT, most probably because of the high amylase activity in these samples, compared to G and T. Triticale and spelt tend to have higher α-amylase activity compared to wheat, depending on the cropping environment [28,29]. ...
Common cereal processing through germination and fermentation usually has an important impact on the technological performance of the flours, mainly because of the activation of endogenous enzymes acting on macromolecules. The aim of the present study is to estimate the effect of germination and fermentation, using a mixture of Lactobacillus casei and Kluyveromyces marxianus subsp. marxianus, on the rheological properties of different wheat and triticale varieties. Moreover, the thermo-mechanical behaviour of the white wheat flour-based dough, including germinated grain flour or sourdough was also tested. Grains germination and sourdough fermentation exerted a high influence on the rheological behaviour of the flour-based suspensions. Germination affected the structure and stability of the suspensions, resulting in samples with viscous behaviour prevailing over the elastic one. The temperature ramp tests revealed that germination together with fermentation lead to higher resistance to temperature changes. In agreement with the results of the rheological investigations on rheometer, the Mixolab test performed on flour obtained from germinated grains revealed lower dough stability and protein weakening at temperature increase. On the other hand, a significant improvement of the pasting properties of the dough was obtained when adding sourdoughs to the wheat flour.
... An adequate level of α-amylase activity in wheat flour is essential to F I G U R E 2 Response surfaces of falling number (a-c) of wheat flour stored at 12% and 15% (w.b.) grain moisture at different temperatures (14, 26, and 38°C) over a 12-month period F I G U R E 3 Response surfaces of wet gluten (a) and gluten strength (b) of wheat flour stored at 12% and 15%, 18% (w.b.) moisture content at different temperatures (14, 26, and 38°C) over a 12 month-period hydrolyze starch and provide yeast with fermentable sugars. A high FN suggests a low α-amylase activity, which thus causes the insufficient formation of oligosaccharides, maltotriose, glucose, and maltose, and results in decreased wheat flour quality (Hidalgo, Brusco, Plizzari, & Brandolini, 2013) due to slow dough fermentation. In contrast, an excess leads to sticky crumbs and problems in slicing bread (González-Torralba et al., 2013;McCleary, McNally, Monaghan, & Mugford, 2002). ...
To maintain grain quality and prevent loss, effective storage systems are required. To
enable wheat flour of a certain quality to be extracted from grain, stored dry wheat
must be humidified prior to milling. With the aim of reducing post‐harvest drying
stage costs for subsequent grain rehydration, the objective of this study was to opti‐
mize the wheat grain storage steps while maintaining the protein quality and baking
performance using response surface methodology. A mixed 2 and 3 level design (3
factors) was used to optimize the independent variable (factors) values of grain mois‐
ture content (12% and 15%), temperature (14, 26, and 38°C) and storage time (4, 8,
and 12‐months). The quality of grain, flour, and baking performance were evaluated.
It was possible to maintain the gluten protein quality at a low temperature and grain
moisture. All of the flour evaluated provided a good baking performance, and there
were no significant differences in specific volumes of treatments.
... Among studies included in the review, Abdel-Aal el and Rabalski (2008) reported a higher concentration of total phenolics in KAMUT V R wheat than in 10 common wheat cultivars. This could be due to the low polyphenol oxidase found in KAMUT V R flour compared to other 59 whole meal flours (Hidalgo et al. 2013). In addition, a higher content of total carotenoids in KAMUT V R wheat compared with common wheat was reported (Abdel-Aal el et al. 2007). ...
After WWII, the industrialized agriculture selected modern varieties of Triticum turgidum spp. durum and spp. aestivum (durum wheat and common wheat) based on higher yields and technological characteristics. Nowadays, the use of whole ancient grains and pseudo cereals is considered nutritionally important. How ancient grains have positive effects is not entirely known, the fragmentation of the scientific knowledge being also related to the fact that ancient grains are not a homogeneous category. The KAMUT® trademark indicates a specific and ancient variety of grain (Triticum turgidum ssp. turanicum, commonly khorasan wheat), and guarantees certain attributes making studies sufficiently comparable. In this work, studies on KAMUT® khorasan wheat have been systematically reviewed, evidencing different aspects supporting its benefits. Although it is not possible to establish whether all ancient grains share these positive characteristics, in total or in part, this review provides further evidences supporting the consumption of ancient grains.
... The average levels of alpha-amylase activity in T. monococcum kernels were similar to those noted in wheat cultivated in Italy [2], whereas the results reported for spring spelt correspond to the values noted in winter spelt [31]. The activity of alpha-amylase in five winter spelt cultivars was significantly lower than in common winter wheat [4]. Due to a general scarcity of data regarding hulled wheat, our results cannot be fully compared with the findings of other authors. ...
http://www.ejpau.media.pl/volume16/issue4/art-06.html
... Os resultados encontrados foram de 86,2 a 201,7 UB/g, a menor variação encontrada para as enzimas estudadas. Estudo de caracterização enzimática com 59 genótipos de diferentes espécies e subespécies de trigo em duas safras, os autores encontraram um CV% de 30% para a atividade de -amilase (HIDALGO et al., 2013). Em aveia e cevada malteadas em condições de temperatura que variaram de 10 a 20 ºC e períodos de germinação de 48 a 144 horas, a atividade de -amilase pouco variou (HÜBNER et al., 2010). ...
During harvest, wheat is exposed to damage from rain, which may lead to changes in quality and loss of commercial value. The aim of this study was to characterize the changes in different varieties of wheat from the
south of Brazil, damaged by rain as detected with the falling number method. Thirteen samples were evaluated for hectoliter weight, thousand-seed weight, protein, reducing sugars, soluble nitrogen, free amino nitrogen and enzyme
activity (alpha and beta-amylase, beta-glucanase and protease).
... It have been assessed the polifenoloxidase, alpha-amylase and betaamylase activity of flours at wheat species and subspecies (A. HIDALGO & al. [4]). The analysis of the chemical composition of bran cereal has revealed high levels of dry matter and low in fat, which makes them useful as value-added products (R. BENNETT & al. [1]). ...
Sprouted grain flour (sprouted grains) is rich in many active principles (oligosaccharides, vitamins, antioxidants, enzymes, microelements), making it a very valuable raw material for food, pharmaceuticals, diets, etc. The aim of our study was the biochemical characterization of flour obtained from germinated cereals (wheat, barley and oats) carried out for the glucose content, the content of total polyphenols and total antioxidant activity. There were performed two-dimensional diagram for biochemical characteristics from germinated cereals flours. The flour obtained from IPZ 807 barley genotype had the highest content of glucose (5.33 mg/g flour). A significantly lower content of glucose was found in the flour obtained from the varieties of oats (Jeremy and Lovrin 1) and the doubled haploid DH 295-3 barley line. These flours can be used in hypoglucidic diets. Flour from IPZ 807 germinated barley variety had the highest content of polyphenols (3.305 μM/ml gallic acid) and flour made from Hyproly barley genotype had highest total antioxidant capacity (20.52 μMTrolox/g) to all other studied genotypes. These flours may be used in food and in pharmaceutical preparations.
... During the WB mixing step (Fig. 1), a decrease was detected only for soluble conjugated p-hydroxybenzoic acid (on average 23 %), syringic acid (12 %) and syringaldehyde (20 %). Significant reductions of all the compounds were instead recorded for bound phenolic acids (Fig. 3), possibly because of enzymatic activity (Hidalgo et al. 2013); the average losses were 13 % for ferulic acid, 17 % for p-coumaric acid, 32 % for caffeic acid, 9 % for vanillic acid, 17 % for syringic acid, and 35 % for p-hydroxybenzoic acid. These results are consistent with the observations of Moore et al. (2009), which reported that fermentation significantly decreased either soluble conjugated or insoluble bound ferulic acid, and of Boskov Hansen et al. (2002), which observed an 8.6 % reduction of the total bound phenolic acids, due to ferulic acid decrease, during the preparation of rye bread acid dough. ...
The whole meal flour of wheat is rich in phenolic acids, which provide a relevant antioxidant activity to food products. Aim of this research was to assess the influence of processing on phenolic acid content and antioxidant activity of whole meal flour water biscuits and puffed kernels of einkorn and bread wheat. To this end, the evolution of syringaldehyde, ferulic, vanillic, syringic, p-coumaric, p-hydroxybenzoic, and caffeic acids was studied during manufacturing. Overall, from flour to water biscuit, the total soluble conjugated phenolic acids increased slightly in einkorn, while the insoluble bound phenolic acids decreased in all the accessions as a consequence of losses during the mixing step. In the puffed kernels, instead, the total soluble conjugated phenolic acids increased markedly, while the bound phenolics did not show any clear change, evidencing their high thermal stability. The antioxidant activity, measured by FRAP and ABTS, increased during processing and was highest under the most drastic puffing conditions.
... Os resultados encontrados foram de 86,2 a 201,7 UB/g, a menor variação encontrada para as enzimas estudadas. Estudo de caracterização enzimática com 59 genótipos de diferentes espécies e subespécies de trigo em duas safras, os autores encontraram um CV% de 30% para a atividade de -amilase (HIDALGO et al., 2013). Em aveia e cevada malteadas em condições de temperatura que variaram de 10 a 20 ºC e períodos de germinação de 48 a 144 horas, a atividade de -amilase pouco variou (HÜBNER et al., 2010). ...
During harvest, wheat is exposed to damage from rain, which may lead to changes in quality and loss of commercial value. The aim of this study was to characterize the changes in different varieties of wheat from the south of Brazil, damaged by rain as detected with the falling number method. Thirteen samples were evaluated for hectoliter weight, thousand-seed weight, protein, reducing sugars, soluble nitrogen, free amino nitrogen and enzyme activity (α and β-amylase, β-glucanase and protease). Changes in the gliadin fraction were evaluated by SDS-PAGE electrophoresis. The variables, reducing sugars, soluble nitrogen, free amino nitrogen, the activity of α-amylase, β- glucanase and protease all showed significant correlation with the falling number test. As the falling number values were reduced, the gliadins displayed changes to the 40 and 30 KDa bands, which become more intense.
... Possibly the acetate buffer solubilised not only phenols and hydrosoluble antioxidants but also additional compounds able to inactivate the DMPD radical. Other hydrophilic antioxidants not considered in this research are, for example, flavonoids and phytic acid (Gani et al., 2012); furthermore, it has to be remembered that buffers are commonly utilized for enzymes extraction (Hidalgo et al., 2013) and that some enzymes possess a certain antioxidant activity (Singh and Singh, 2008). Because of the known incompatibility of the DMPD method with extraction solvents such as ethanol and methanol (RodríguezNogales et al., 2011), which was verified and confirmed by us in preliminary trials (data not presented), the DMPD test was also performed on samples extracted with MeOH:acetone:H 2 O and EtOH, evaporated by Rotavapor and dissolved in acetate buffer (pH 5.3). ...
... The quantity of endogenous enzymes varies among different species, genotypes, times, and possibly environments. Hidalgo et al (2013) evaluated polyphenol oxidase, α-amylase, and β-amylase in wholemeal flour of different wheat species. Einkorn possessed the highest level of polyphenol oxidase but the lowest αand β-amylase levels. ...
There is renewed interest in adopting hulled wheats (emmer, einkorn, and spelt) into our food system, because of their nutritional qualities and improved organoleptic properties. Current research findings have been concisely put together in this review to show the extent of the current and past work in this area and suggest additional research areas. Breeding programs for hulled wheats have received a great deal of attention, and their research findings have shown potential to generate genotypes with improved qualities. More work is required to investigate the changes in nutritional and structural composition of hulled wheats during and after processing and to develop suitable processing methods.
In cadmium (Cd) contaminated farmland soil, antagonism between elements can be used to control the absorption and accumulation of Cd in crops through the external application of zinc (Zn) and manganese (Mn). Dithiocarbamates (DTCs) are highly effective fungicides commonly used in farmlands, and DTCs are rich in Zn and Mn. We selected three representative DTCs (propineb, mancozeb, and zineb) for a field experiment in Henan province, China. The effects of DTC on Cd absorption and accumulation in wheat and the interaction of Zn, Mn, and Cd in wheat after spraying of DTC were studied using different application times at the heading stage. The results showed that after foliar spraying of DTCs according to pesticide application requirements, wheat yield was not affected. The Zn and Mn contents in grains increased, with the highest increases being 19.2% and 12.4%, respectively. Zn and Cd as well as Mn and Cd were antagonistic in wheat, and the transport of Cd from soil to root and from husk to grain was inhibited. The bioconcentration factor (grains/soil) decreased from 1.3 to 0.68 and the translocation factor (grains/husks) decreased from 0.76 to 0.35. The Cd content in grains decreased by 60.4%, 52.8%, and 25.6% with mancozeb, propineb, and zineb applications, respectively, and the Cd reduction effect of spraying DTCs twice was better than that of spraying DTCs once and thrice. The results show that DTCs application could reduce the Cd content in wheat grains and realize the dual effects of crop disease prevention and Cd reduction.
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International license (https://creativecommons.org/licenses/by-nc/4.0/). Non-commercial uses of the work are permitted, provided the original work is properly cited. Producing high-quality gluten-free products by some pseudo-cereals like Quinoa and Amaranth, which have a high nutritional value has been proved, but their enzymatic activity hasn't been completely known. Considering the effect and importance of enzymes in bakery products, this study, investigated the activity of alpha amylase, protease, lipase, lipoxygenase and Phytase in amaranth, quinoa and wheat. Quinoa and wheat have the highest and the lowest alpha amylase activity, respectively. The lipoxygenase activity in quinoa and amaranth is significantly (p < 0.05) greater than its activity in wheat. The activity of lipase and protease enzymes in wheat is significantly (p < 0.05) higher than amaranth and quinoa enzymes. Consequently, it seems that using lipase and protease in the production of Quinoa and Amaranth products, could increase the quality of these products. Phytase enzyme activity in amaranth is significantly (p < 0.05) higher than this enzyme activity in quinoa and wheat. Citation: Azizi S, Azizi MH, Rajaei P. Investigating and comparing the enzymatic activity of wheat, Quinoa and Amaranth. J food safe & hyg 2021; 7(2):110-120.
The role of amylase is often neglected in the separation of starch by protease despite the fact that it likely impacts the properties of starch. This study aimed to explore the effects of endogenous alpha-amylase on the pasting properties of starch during isolation using protease. A strategy is developed according to prevent the influence of alpha-amylase on starch pasting properties. Decreased pasting viscosity was observed in the presence of endogenous alpha-amylase while an increase in reducing sugar during incubation decrease viscosity due to starch degradation. The addition of acarbose effectively inhibits starch degradation due to endogenous alpha-amylase. However, acarbose does not appear to affect protease activity. Thus, a combination of protease and acarbose can effectively prevent interference from endogenous alpha-amylase without affecting the gelatinization properties of starch.
A comparative evaluation of the rheological properties of ancient wheat flours (emmer, spelt and khorasan), cultivated under the same conditions, was conducted. They were evaluated for chemical composition, wet gluten quantity, quality, aggregation and disruption kinetics (GlutoPeak), dough proofing (Rheofermentometer), as well as mixing and thermal behavior (Mixolab). High wet gluten content of spelt flour led to formation of strong gluten network with the highest water absorption and maximum dough height during proofing in comparison to other varieties. Khorasan flour, although having very low wet gluten content, exhibited the highest dough stability both during mixing and fermentation due to high gluten index. Despite being characterized with high wet gluten, very low gluten index of emmer flour affected dough development process, resulting in the lowest dough height and pronounced loss in dough height during fermentation as well as the lowest percentage of gas retained in the dough compared to other species.
To overcome the limited surface area of starch and improve the adsorption capacity of starch, porous starch has been widely produced in various fields. In this study, the different enzyme activities of α-amylase (AM), glucoamylase (GAM), and mixed enzyme (ME) were used to prepare different types of porous maize starch, and the microstructure, particle morphology, adsorption, and gelatinization characteristics of the porous starch were studied. Scanning electron microscopy showed porous structures with diverse pore size distribution and pore area depending on the enzyme type and its activities; AM produced the largest holes, GAM produced the deepest holes, and ME produced large and deep holes. Adsorptive capacity was significantly affected by enzymatic modification being greater influenced by GAM. The porous starches had higher relative crystallinity as deduced from X-ray diffraction and Fourier transform infrared spectroscopy. The MA-treated starch had higher solubility whereas swelling capacity, peak viscosity, final viscosity, breakdown, and setback of both treatments were decreased compared to the native starch. The results indicate porous maize starch can provide different functions according to the action pattern of enzymes. The type of enzyme and its enzyme activity can be used to produce the ideal cavity and pore size starch granules, which expands its application scope.
Knowledge of the biochemical processes responsible for the release of phenolic acids (precursors of vinyl aromatics) during malting is important to find mitigation strategies for the toxicologically relevant styrene (formed from cinnamic acid) in wheat beer. Therefore, grain and malts of four barley and three wheat varieties were screened for the activities of various enzymes and the amounts of nonstarch polysaccharides (to which the phenolic acids are bound to a certain extent). During malting, a very strong degradation of β-glucan, synonymous to a depletion of the cell walls, was found, suggesting that a partial degradation of cell walls cannot have an effect on the release of phenolic acids. In barley malts, water-extractable arabinoxylan contents were between 0.59 and 0.79 g/100 g dm and in wheat malts between 0.93 and 1.51 g/100 g dm. Additionally, higher soluble ferulic acid contents in wheat wort compared to barley wort indicated that the degradation of nonstarch polysaccharides has an impact on the release of phenolic acids. For the feruloyl esterase, higher activities were found in malts of the barley varieties. However, this fact was not reflected by the free phenolic acid contents in those malts. Correlation coefficients between the protease activity and the feruloyl esterase, α- and β-amylase, and β-glucanase activities were proven to be insignificant, highlighting that the protease activity had no effect on the activities of these other enzymes.
Wet-milled glutinous rice flour (WMF) and dry milled glutinous rice flour (DMF) have different pasting and rheological properties but the underlying mechanism has not been defined. Dry milling methods can result in glutinous rice flour (GRF) with higher residual alpha-amylase activity and damaged starch content compared to flours prepared by wet milling methods. The addition of alpha-amylase significantly increased starch hydrolysis and reduced the peak, trough, and final viscosity of GRF gels. The pasting viscosity and dynamic modules of WMF-Water gels were significantly higher than those of DMF-Water gels. Inhibiting amylase activity significantly reduced the differences in paste viscosity and dynamic modules between WMF and DMF. Scanning electron microscopy (SEM) showed that alpha-amylase affected the microstructure of the DMF. FT-IR spectra results indicated no new formation of covalent bonds in GRF-Water or GRF-Ag gels. These results suggested that endogenous alpha-amylase influenced starch hydrolysis and subsequently the viscoelastic property of GRF gels, indicating that residual endogenous alpha-amylase explains the differences in pasting and rheological properties between WMF and DMF.
This study investigated insecticidal activity of Artemisia herba-alba essential oil (EO) against Tribolium castaneum adults and its impacts on wheat flour quality. GC/MS analysis of the EOs of A. herba-alba showed a predominance of β-thujone (27.79%), camphor (22.65%), chrysanthenone (17.97%) and α-thujone (13.56%). Therefore, the median effective concentrations (LC50 value) of Artemisia herba-alba essential oil used for preliminary screening tests were evaluated. Insect mortalities, occupation space conditions and wheat flour quality were investigated after 30 and 60 days of storage period. The results showed that mortality varies depending on occupation space and storage duration, which reached 42.15% and 59.8% after 30 and 60 days of storage, respectively. Furthermore, moisture, ash, gluten, falling number contents were examined according to international standards. Indeed, rheological dough parameters were examined using a Chopin alveograph and according to ISO standards. Results indicated that A. herba-alba essential oil changed wheat flour physicochemical parameters but did not affect dough rheological parameters which correspond to international ISO standards.
Various enzymes are added to dough to improve the quality. Two enzymes are α-amylase and hemicellulase (bakery enzymes), whose substrates are damaged starch and insoluble dietary fiber, respectively. They improve the formation of gluten networks in the dough, resulting in a higher specific loaf volume (SLV). The use of high-pressure treatment has also increased as a substitute for heat treatment and various products are being processed utilizing high-pressure treatment. This study investigated the effect of combing bakery enzyme and high-pressure treatment on dough qualities. The optimal concentration of bakery enzymes and high-pressure level were determined using response surface methodology and optimization technique. Bread dough was prepared by the optimal condition, 0.20% of bakery enzyme and 43 MPa of high-pressure treatment, and the bread dough was then baked. Optimal combining bakery enzyme and high-pressure treatment drastically improved bread making qualities such as increased SLV, higher concentrations of reducing sugar, and lower concentrations of damaged starch and insoluble dietary fiber compared to the control and to those that were only treated with bakery enzymes or high-pressure treatment, respectively. In addition, the bread with both bakery enzymes and high-pressure treatment showed improved micro structure in the crumb and maintained freshness longer.
For centuries, ancient grains fed populations, but due to their low yield, they were abandoned and replaced by high-yielding species. However, currently, there is a renewed interest in ancient wheat and pseudocereal grains from consumers, farmers, and manufacturers. Ancient wheat such as einkorn, emmer, spelt, and Kamut®, are being reintegrated because of their low fertilizer input, high adaptability and important genetic diversity. New trends in pseudocereal products are also emerging, and they are mostly appreciated for their nutritional outcomes, particularly by the gluten-free market. Toward healthier lifestyle, ancient grains-based foodstuffs are a growing business and their industrialization is taking 2 pathways, either as a raw ingredient or a functional ingredient. This paper deals with these grain characteristics by focusing on the compositional profile and the technological potential.
The purpose of the present study is to compare the effects of four different breads (one commercial par-baked wheat bread, three sourdough breads prepared with commercial wheat flour, organic wheat flour, organic einkorn flour) in 16 healthy subjects. The primary outcome of this randomized cross-over trial was evaluating intra-individual changes in glycemic areas-under-the-curve (AUCs) after 50 g carbohydrate portions of each bread; secondary outcomes were changes in insulin, fatty free acids (FFA), triglyceride, acylated ghrelin and satiety AUCs. Blood samples and satiety ratings were collected every 30-min for 2-h after the consumption of each bread. The einkorn flour showed the lowest amylase activity, the commercial flour the highest; commercial bread had the highest carbohydrate content and the lowest dietary fiber content.
Glucose AUCs were significantly lower after the consumption of sourdough breads made with organic (12,754 ± 1433 mg/dL × h) and einkorn flour (12,216 ± 1210 mg/dL × h), with respect to the commercial bread (13,849 ± 2193 mg/dL × h). Insulin AUCs decreased after the consumption of all sourdough breads when compared to commercial bread. FFA and triglyceride AUCs did not differ by kind of breads. Median ghrelin AUC was significantly lower and satiety higher after the einkorn bread (3710 pg/mL × h; 3225 ± 2414, respectively) than after commercial bread consumption (4140 pg/mL × h; 1706 ± 1766, respectively), but not with other sourdough breads.
In conclusion, the use of sourdough may improve the nutritional features of breads; einkorn bread induced the least disturbance in carbohydrate homeostasis and the greater satiety. If confirmed by further research, these results might have implications in the approach towards chronic dysmetabolic diseases.
Polyphenol oxidase (PPO) activity and yellow pigment content (YPC) are two important quality traits determining the color of wheat end-products. Synthetic hexaploid wheat (SHW) has been largely synthesized and widely used in wheat breeding. In this study, we investigated PPO activity and YPC of 118 accessions consist of Aegilops tauschii, Triticum turgidum, Triticum aestivum and synthetic hexaploid wheat. Irrespective of PPO activity or YPC, T. aestivum tended to a lower value and a more concentrated range. As for PPO activity, synthetic hexaploid wheat showed a large number of genetic variation comparable to T. turgidum. Each T. turgidum - SHW - Ae. tauschii combination represents an independent wheat hexaploidization process. By comparing 29 synthetic hexaploid wheats with their corresponding parents (maternal, T. turgidum, BBAuAu; paternal, Ae. tauschii, DD),our report highlighted different performances for PPO activity and YPC during wheat hexaploidization processes: the PPO activity of SHW can be higher, lower than both parents, or in the middle; in contrast, all the combinations showed a relative stable YPC trend. Besides, take these two traits we tested as an example, from an evolutionary perspective, the uniqueness of traits and their potential functions on polyploidy adaption or stress responses were also discussed.
Sunsik has been popular as well-being and healthy food to some Asian people, but it still has a limit to other foreigners because of its taste and appearance. This study tried to modify Sunsik into smoothie type for foreigners and investigate its physicochemical characteristics. Germinated black and brown rice was prepared. The germination condition of two cereals was steeping for 24 hr at room temperature, and then germinating for 24 hr at 30^{\circ}C. After germination, the {\alpha}-amylase activity of germinated grains was 13~15 times higher than before germination. The enzyme activity of brown rice was 9.16 CU/g, but germinated brown rice was 152.63 CU/g. In case of black rice, enzyme activity before germination was 7.47 CU/g, and enzyme activity after germination was 97.96 CU/g. The lactic acid bacteria was grown in 50 g germinated brown rice powder with 100 ml malt solution, 30 g tomato juice, and 1.5 g rice bran. After manufacturing beverage using milk and Sunsik and the cell count of lactic acid bacteria was 1.3{\times}10^5CFU/ml enough to use starter. According to sensory test, the optimal concentration of Sunsik smoothie was 30 g Sunsik in 200 ml of milk. The viscosity was 5.97?1.2 centipoise. The color of Sunsik beverage was evaluated as L value : 63.50?0.41, a value: -0.35?0.06, and b value: 8.85?0.19.
The distribution of alpha -amylase, protease, lipoxygenase, polyphenol oxidase and peroxidase in wheat roller flour mill streams was studied. Break flours had relatively less alpha -amylase and protease activity than reduction flours both on flour weight and a protein basis. Among the different flour streams, the 5thand 6threduction passage had the highest alpha -amylase activity, while the 4threduction passage had the highest protease activity. The lipoxygenase activity was concentrated mostly in the last break and the reduction streams, whereas polyphenol oxidase activity was highest in break flour streams. Peroxidase activity was distributed unevenly among the different mill streams. The lipoxygenase, polyphenol oxidase and peroxidase were highly concentrated in different bran fractions. Except for protease, the other enzymes were concentrated in the «atta», a milling by-product comprising refined flour, bran and shorts; and are least active in semolina (farina).
Late maturity α-amylase (LMA), or prematurity α-amylase (PMAA) as it has been termed in the UK, in wheat involves the untimely synthesis of high pI α-amylase during the middle to later stages of grain development and ripening. The enzyme activity is retained in the grain at harvest ripeness, resulting in low falling number and failure to meet receival standards and customer specifications. This phenomenon, which is restricted to specific genotypes, appears to be controlled by 1 or 2 recessive genes acting alone or in combination and in most cases appears to be triggered by a temperature shock. This shock is only effective if it occurs during a window of sensitivity around 25–30 days postanthesis. Expression of LMA is reduced in the presence of dwarfing genes such as Rht1, Rht2 and Rht3 that confer insensitivity to gibberellin. Screening technologies, including molecular markers and high pI-specific ELISA, have been developed to assist wheat breeders and will be required to meet new challenges posed by novel germplasm such as primary synthetic wheats.
In the earlier edition of this monograph, a chapter (Kruger and Reed 1988) was devoted to cereal enzymes and color. From the title of that chapter alone, one is tempted to believe that, at the time of writing, enzymes were considered to be of only minor importance and did not deserve a chapter of their own. While this may be overstated, it is clear that in the past two decades a lot of progress has been made and that there is increased awareness that wheat endogenous enzymes and wheat endogenous enzyme inhibitors can have an important impact on cereal functionality. These developments have gone hand in hand with increased insights into the functionality of added enzyme systems in cereal processing, be it to facilitate processing, increase yields, or improve final product quality (Goesaert et al 2005, Trogh et al 2005, Van der Borght et al 2005).
The above-cited chapter discussed carbohydrate-degrading enzymes, proteolytic enzymes, esterases, oxidases, and other enzymes. The present chapter does the same, focusing on novel developments. However, we considered it useful to deal not only with enzyme systems but also with their proteinaceous inhibitors. Indeed, a lot of progress has been made in this area and, more specifically, in the area of endoxylanase inhibition, a novel protein functionality first described in 1997 and hence unknown at the time the earlier version of this monograph was written.
It is not possible in the present chapter to discuss every protein characterized from wheat. We focus on the major groups that have been characterized in most detail and, in most cases, are present at levels sufficient to contribute to the functional properties of the grain.
The influence of the environment and genotype on the concentration of some semolina components involved in the Maillard Reaction (MR) during high temperature (HT) drying of pasta was determined in six varieties of durum wheat grown at two contrasting locations for two consecutive years. The extent of MR in HT dried pasta as determined by furosine level was found to be significantly related (r = 0.68; p < 0.05) with the amount of reducing sugars. Moreover, the susceptibility to MR appeared to be strictly dependent on α-amylase activity in both kernel (r = 0.70; p < 0.01) and semolina (r = 0.62; p < 0.01). The extent of MR showed a high heritability value, suggesting that genetic manipulation can be used to reduce the susceptibility to MR and preserve the nutritional value of wheat in HT dried pasta.
Polyphenol oxidase was purified to homogeneity from Japanese wheat (Triticum aestivum cv. Tohoku 198) bran, using 4-methylcatechol as a substrate. The enzyme was purified 1670-fold with a recovery of 0.175% by alkalization, ammonium sulfate precipitation, anion exchange chromatography, hydrophobic chromatography and gel filtration chromatography. The molecular mass was estimated to be 35kDa and 40kDa by gel filtration chromatography and SDS-PAGE, respectively. The N-terminal amino acid sequence matched well with the internal sequences of other plant PPOs. The pH optima for the purified enzyme and the crude enzyme were 4.5 and 5.3, respectively. The purified enzyme was stable in the range of pH 6.5-7.5 at 4 degrees C for 24hr. The purified enzyme was stable after heat treatment at 60 degrees C for 10 min. The purified enzyme oxidized L-tyrosine, pyrocatechol, 4-methyleatechol, L-DOPA, chlorogenic acid, (+)-catechin and (-) -epicatechin. The K(m) values of the purified enzyme for 4-methylcatechol and L-DOPA were 3.3 mM and 8.3 mM, respectively. The purified enzyme was strongly inhibited by dietyldithiocarbamate, thiourea, sodium azide, cystein, idoacetic acid, sodium fluoride, trans-cinnamic acid, p-coumaric acid, ferulic acid and vanillic acid. The K(I) value of the purified enzyme for ferulic acid was 108 mu M.
Polyphenol oxidase (PPO) is a major cause of time-dependent discoloration in raw wheat (Triticum aestivum) flour dough. The PPO-A1 and PPO-D1 genes have previously been implicated in dough discoloration. However, wheat contains multiple PPO genes. The goal of this study was to identify and quantify expression levels for PPO genes relevant to wheat quality. Three novel sequences were identified and found to be orthologous to one another and paralogous to the previously described PPO-A1/PPO-D1 group. The new genes localized to homeologous group 2 chromosomes. We propose naming these new genes PPO-A2, PPO-B2, and PPO-D2. Real-time PCR analysis determined that in the wheat cultivar ‘Alpowa’, PPO-A1a, PPO-A2b, PPO-D1b and PPO-D2b were all expressed to substantial levels in developing wheat kernels, while PPO-B2b was not. Transcript levels varied over the course of grain development, with peak levels observed at 9–16 days post-anthesis. These results show that wheat kernel PPO activity is the result of at least two orthologous families of two paralogous genes and that some of these genes are expressed to several-fold greater levels than others. The novel PPO-2 genes described here together account for 72% of PPO transcripts in developing kernels of the wheat cultivar Alpowa.
Polyphenol oxidase (PPO) activity is a factor in time-dependent discoloration of Asian noodles. At least two major genes Ppo-A1 and Ppo-D1 control kernel PPO activity in wheat. The goal was to determine the relative importance of allelic variation for Ppo-A1 and Ppo-D1 on Chinese raw noodle color profile and kernel and flour characteristics using a winter wheat recombinant inbred population segregating for Ppo-A1 and Ppo-D1. Ppo-A1 allelic variation explained 80% and Ppo-D1 allelic variation explained 2% of the variation in kernel PPO activity. The low PPO allele at each locus gave noodles that were brighter (greater L*), more yellow (greater b*) and more red (greater a*) at 24 h, and noodles with less change in L* but more change in a* and b* with time (0–24 h). The two loci combined explained 27, 35, and 17% of variation in L*, a*, and b* at 24 h, and 51, 55, and 58% of the variation in change in L*, a*, and b* with time, respectively. Allelic variation at Ppo-D1 explained a larger percentage of variation than did Ppo-A1 in each case except b* at 24 h where the two loci explained equal amounts.
To limit nutritional losses and optimise bread processing, heat damage indices (furosine, glucosylisomaltol, hydroxymethylfurfural), sugars, α-amylase, β-amylase and colour were monitored during bread manufacturing from refined flour of three einkorn, three bread and one durum wheat samples. The heat damage indices increased only during the baking step. Furosine was significantly lower in einkorn (on average, 9.3 ± 5.33 and 25.3 ± 10.70 mg/100 g protein in crumb and crust, respectively) than in bread wheat (31.6 ± 3.05 and 115.6 ± 13.53) and durum wheat (36.2 ± 2.82 and 165.0 ± 3.17). Glucosylisomaltol and hydroxymethylfurfural were detected only in the crust, with lower levels in einkorn (on average, 2.3 ± 1.78 and 10.0 ± 7.79 mg/kg DM, respectively) than in bread wheat (13.1 ± 5.57 and 42.8 ± 10.64) and durum wheat (18.9 ± 1.11 and 57.2 ± 0.80). The different behaviour of einkorn was probably related to its moderate β-amylase activity, and thus the low maltose content of its dough. Colour was correlated with heat damage, as einkorn breads were lighter than the others.The results show that einkorn bread undergoes lower heat damage than analogous products from durum and bread wheat, thus probably better preserving its nutritional value.
Polyphenol oxidase (PPO) has been related to an undesirable brown discoloration of wheat-based end products. Consumer acceptance and product quality are generally decreased by the darkening phenomena. Two sets of wheat samples (Triticum aestivum L.) were investigated for variation in grain and flour PPO levels. Samples included 40 advanced experimental hard white winter wheat lines grown at two Kansas locations and 10 hard red winter wheat genotypes grown at three Nebraska locations. The variability in grain and flour PPO activities was influenced by growing location and population for the hard white wheat samples. There also was a significant influence of population by growing location interactions on PPO activity in both grain and flour. Genotype and growing location both contributed to variability in flour PPO activity among the hard red wheat samples. The variation in flour PPO activities among growing locations appeared larger than variation produced by genotypes tested for the hard red wheat samples. Quality parameters, such as wheat physical properties, flour protein and ash contents, grain color, and milling yield significantly correlated with grain and flour PPO activities. Among red wheat samples, flour PPO activity was related to 100 kernel weight, first reduction flour yield, and flour ash content. Grain PPO activity was related to variation in grain color observed among hard white samples. The relationship of quality characteristics with grain and flour PPO activities varied among white and red wheat samples.
Analysis of aneuploid stocks of Chinese Spring wheat showed that some of the seed protein bands separated by two-step SDS—PAGE (Mr 65, 63, 60 and 45k) are controlled by genes on the chromosome arms 4DL, 4AL, 5AL and 5DL. The extractability characteristics of these bands indicated that they are albumins. One-dimensional SDS—PAGE analysis of protein fractions separated by size exclusion HPLC showed that these albumin bands are part of the polymeric protein fraction in bread wheat. Fractionation of total seed-proteins by diagonal electrophoresis (unreduced x reduced) revealed that the high molecular weight albumin bands occur in both polymeric (disulphide-linked aggregates) and monomeric forms in their native state. These proteins were rapidly degraded during seed germination like the storage proteins of wheat. They were found not to be present in the protein bodies from developing wheat endosperm, however. Subsequent analysis of these albumins using immunoblotting revealed that the bands controlled by chromosome arm 4DL, 4AL and 5AL are beta-amylases of wheat grain, and are probably encoded at the β-Amy-1 loci on these arms. A limited amount of allelic variation in these bands was observed by two-step SDS—PAGE of different bread wheat cultivars.
Flours milled from heat- and moisture-treated hard white wheat (KS-196) contained reduced levels of polyphenol oxidase (PPO), but not peroxidase (PO). With a 12-min heating period, the PPO activity decreased with increasing moisture content (MC) from 13 to 15%, whereas with 4- and 8-min heating periods, the PPO activity was insensitive to moisture level. When the tempering period was increased from 1 to 4 hr at 19% MC, PPO activity in the heat-treated wheat was unaffected. Three other wheat cultivars, tempered to 15% MC for 1 hr and then heat-treated for 8 min at 100°C, yielded flours with ≃50% reduction in PPO activity. Heating the KS-196 wheat for 12 min at 100°C reduced PPO activity in flour by as much as 76%, but destroyed the elasticity of gluten as determined by mixograms. White noodles and yellow alkaline noodles, made from heat-treated (15% MC, 8 min, 100°c) KS-196 wheat, had improved brightness in the raw state and showed little change in cooking quality and cooked texture, except for reduced firmness. When KS-196 wheat was pearled to remove 28% of its weight, and the pearled kernels were heat- and moisture-treated at 15% MC for g min at 100°C, the straight-grade flour contained 75% less PPO activity than the untreated wheat flour. White noodles made from pearled, heat- and moisture-treated wheat were brighter than those made from pearled untreated wheat. A white noodle dough, made from heat- and moisture-treated wheat with aminoguanidine bicarbonate added, had the brightest dough (L* = 75) after 24 hr at 25°C.
Polyphenol oxidase (PPO) activities of wheats from various classes and cultivars (grown both in the U.S.A. and in Australia), of some U.S. and Australian wheats, of wheat flours at various extraction rates and of kernels separated by size from various cultivars were measured by the oxygen electrode method. PPO activity of wheats was affected by both cultivar and growing location. Wheat flour contained on the average 3% of the PPO of the wheat grain. PPO activities of the flours increased as the flour extraction rates increased. Contrary to expectation, for a single cultivar, small kernels contained less PPO (on a weight basis and especially on a kernel basis) than did large kernels. Differences among kernels of various sizes for a single cultivar were smaller than differences in PPO among kernels of comparable sizes among various cultivars.
Studies were conducted to evaluate the effect of microwave (900 W, 2450 MHz) heating of wheat grains conditioned to different moisture levels on the activity of polyphenol oxidase (PPO) and subsequent colour changes during storage of wheat dough. The results showed that microwave heating of wheat grains for 80 s decreased the PPO activity significantly (P ≤ 0.05) with an increase in moisture level from 12 to 18%. Whole wheat flour milled from microwave treated wheat grains (80 s, 18% MC) had 93.39% less activity of PPO. The dough balls (40 g), pressed and rolled into circular form (150.00 mm diameter and 2.00 mm thickness) and stored at 5–6 °C for 72 h. The colour of flattened circular dough was measured using Hunter Colour Meter and it was found that L-value (lightness) decreased from 64.21 to 60.23 in treated and from 64.79 to 47.93 in control samples after 72 h of storage. The results showed that the microwave heating effectively controlled the enzymatic browning in dough and improved the consumer acceptability of chapattis prepared from the same during refrigerated (5–6 °C) storage for 72 h.
To limit heat damage and improve the nutritional properties of bakery products, furosine, glucosylisomaltol, hydroxymethylfurfural, furfural, sugars, α-amylase, β-amylase and colour were assessed during the production of water biscuits from three einkorn, three bread and one durum wheat flours. Heat damage indices, colour and aw development during baking (from 25 to 75 min duration) of water biscuits from one bread wheat were also studied.Furosine was more abundant in durum (86.0 ± 6.29 mg/100 g protein) and bread wheat (42.5 ± 6.93) than in einkorn (15.7 ± 3.92) water biscuits, while GLI was detected only in durum (10.0 ± 2.02 mg/kg DM) and bread wheat (5.2 ± 1.52) products; hydroxymethylfurfural and furfural were always absent. The limited heat damage of Triticum monococcum products was probably due to the moderate β-amylase activity of einkorn, and hence to the low maltose content of its mixes. The colour was correlated to heat damage, as einkorn water biscuits were lighter than those from other wheats.Highlights► Heat damage was monitored during water biscuits processing from three wheat species. ► Heat damage, colour and water activity were also studied at different baking times. ► Einkorn dough showed lower maltose content, because of the lower β-amylase activity. ► Einkorn products were lighter and showed more limited heat damage than other wheats.
Cerealbeta-amylases are perhaps best known in terms of the vital role they play in releasing easily fermentable sugars from cereal grain starch to fuel the production of alcohol by yeast in brewing. The extent to which they have been investigated is indeed largely due to their significance in this economically important industry. However, cerealbeta-amylases are also, or could be, employed in many other aspects of the food industry and the analysis of starch, and they constitute valuable markers in cereal assessment and breeding studies. Quite apart from their practical significance, they are rewarding objects of biochemical and physiological research. They are interesting models for the study of enzyme polymorphism, post-translational modification and the differential expression of isoenzymes. In spite of their often high activitiesin situand all that is known about their generation, they are an enigma in that their physiological function, or even necessity, remains unclear. It has been recently recognised that there are two different categories of cerealbeta-amylases which exhibit different tissue and taxonomic specificities and physiological developmental patterns. The «classical»beta-amylases present at high activities in cereal seeds appear to be limited to the endosperm of the species of the Triticeae tribe of the Festucoideae subfamily of the Gramineae (wheat, barley and rye), whereas all cereals exhibit a different, tissue-«ubiquitous» form of the enzyme which is present at much lower activity levels. The physiological phenomenology and the usage of cerealbeta-amylases are discussed in relation to these two categories of enzyme.
Cereal Chem. 83(1):62–68 Millstream flours, bran, pollard, and germ fractions were prepared from two Australian and two New Zealand wheat cultivars using a pilot-scale roller mill. The distribution of six redox enzymes in milling frac-tions and the relationship of the enzymes to baking parameters were investigated. Lipoxygenase (LOX), dehydroascorbate reductase (DAR), and protein disulfide isomerase (PDI) tended to be higher in the tail-end fractions of break and reduction flour streams, but the highest levels were in the bran, pollard, and germ fractions. These enzymes had moderate to strong correlations with ash content of flour. These results indicated that a considerable amount of these enzymes in the tail-end flour streams were likely to be derived from contamination with bran, aleurone, or germ components of grain. Peroxidase (POX) tended to be higher in the break flours, but polyphenol oxidase (PPO) and ascorbate oxidase (AOX) tended to be evenly distributed in the millstream flours. These three enzymes generally had poor correlations with ash and baking parameters. LOX and DAR had a negative correlation with the baking quality of bread made in the absence of ascorbic acid (AA) but a poor correlation with improvement of bread quality made with AA. The negative correlation probably reflects the high content of ash (hence trichomes), glutathione, and protein thiols in those fractions that have high LOX and DAR, and these high-reducing-power components and trichomes in flour may be the actual cause of poor quality bread. PDI generally had a poor correlation with bread quality in the absence of AA but a significant positive corre-lation with improvement in the quality of bread made with AA. It thus seems that the endogenous levels of these six enzymes were not a limiting factor in the breadmaking process, except for PDI, the levels of which may have positively influenced breadmaking in the presence of AA.
Wheat of two strong high-protein and two weak low-protein cultivars from New Zealand and Australia were milled to commercial
specifications. All millstreams were tested for α-amylase, β-amylase, falling number, protein, starch, damaged starch, amylose,
amylopectin, pentosan and ash. The distribution of β-amylase in millstream flours was more variable among cultivars than α-amylase.
Generally, both enzymes had lowest activity in sizing and early reduction flours. α-Amylase was very high in the bran, pollard
and germ fractions, in which ash content was very high, whereas β-amylase was low in these fractions. These observations,
together with the moderate correlation of α-amylase and poor correlation of β-amylase to ash content, suggest that most α-amylasein
flour derives from contamination with bran, pollard and germ, whereas most β-amylase derives from the endosperm. Falling numbers
varied between the cultivars, but variation amongst millstreams for each cultivar was low, except for cv. Frame, which had
particularly high falling number values (834 and 1197) in second and third break flours. These two flours had some of the
highest α-amylase levels and lowest starch levels. However, they also had very high protein content (22 and 26%) and very
low starch damage (3.2 and 4.5%), which may contribute to the high falling numbers. When endogenous α-amylase in the flour
with the highest falling number was supplemented with high levels of barleyα-amylase, the flour withstood the detrimental
effects of α-amylasein baking (sticky crumb, poor crumb texture and loaf volume) better than flours of lower falling number,
but did not withstand the effects ofα-amylase on falling number.
Polyphenol oxidase was extracted and partially purified from wheat leaves by a procedure that included ammonium sulfate fractionation followed by dialysis and gel filtration chromatography. These procedures led to 35.21-fold purification with 17.65% recovery. Optimum pH, temperature, and ionic strength were determined with six substrates. Some kinetic properties of the enzyme such as V
max,K
M, and k
cat were calculated for the substrates. The k
cat/K
M values of the PPO for catechol, catechin, pyrogallol, l-dopa, dopamine, and 4-methyl catechol were 31408, 31167, 28404, 15378, 4865, and 4967 mM/min, respectively. The best substrate of wheat PPO was found to be catechol. The native molecular weight of the PPO was estimated to be 243 kDa based on its mobility in gel filtration column. The inhibitory effects of glutathione, sodium azide, ascorbic acid, oxalic acid, l-cysteine, and thiourea on the reaction catalyzed by the enzyme were tested, and I
50 values were estimated to be 8.0 mM, 10.12 mM, 11.18 mM, 77.33 mM, 183 mM, and 413 mM, and K
i constants were also calculated as 0.416 ± 0.244 mM, 0.317 ± 0.208 mM, 0.820 ± 0.111 mM, 13.80 ± 1.179 mM, 14.10 ± 5.069 mM, and 130 ± 62.45 mM, respectively, by means of Lineweaver–Burk graphs. The most effective inhibitor was glutathione. Glutathione, sodium azide, oxalic acid, and thiourea were competitive inhibitors, whereas ascorbic acid and l-cysteine were also noncompetitive inhibitors.
Polyphenol oxidase (PPO) activity causes undesirable darkening of raw Asian noodles and other wheat products. In this study we investigate the genetic origins and diversity of wheat kernel PPO. PPO was characterized via activity assays, antigenic staining, and Southern blots in Triticum aestivum, Triticum dicoccoides, Triticum durum, Triticum dicoccum, Triticum monococcum, Triticum urartu, Aegilops speltoides, and Aegilops tauschii. Among these species, PPO activity was well-correlated with antigenic staining intensity toward a wheat kernel-type PPO antibody. High PPO activity was observed in all three T. monococcum accessions (Am genome), one Ae. speltoides accession, one T. durum accession, and two hexaploid wheat cultivars. Southern blots suggested the presence of two or more kernel-type PPO genes in diploid progenitors of the hexaploid A, B, and D genomes. Whole-kernel PPO activity was evaluated in disomic substitution lines derived from three T. dicoccoides accessions in the background of T. durum ‘Langdon’. PPO activity was primarily associated with chromosome 2A and to a much lower degree with chromosome 2B. DNA sequence comparisons showed that the intron associated with the high PPO allele on chromosome 2AL of hexaploid wheat had 94% nucleotide identity with the homeologous intron found in T. monococcum, a species with high kernel PPO activity. This implies that the ancestral PPO allele on the A genome is one of the high activity, and the low PPO allele found in hexaploid wheat represents a relatively recent genetic alteration. Results confirm the presence of multiple kernel-type PPO genes in the diploid and tetraploid progenitors and relatives of hexaploid wheat. However, it is likely that relatively few of the many kernel-type PPO genes present in wheat contribute substantially to kernel PPO activity. A single genetic locus on homeologous group 2 chromosomes may be the primary cause of high PPO activity in wheat kernels.
Genetic variability of polyphenol oxidase (PPO) activity was evaluated in hexaploid, tetraploid, and aneuploid wheat (Triticum spp.). A DNA probe to kernel-specific PPO hybridized to PPO clones from an immature wheat kernel cDNA library but not to clones from a seedling cDNA library. Recombinant protein and antibody were developed from the kernel-specific PPO. PPO transcript and antigenic proteins were most abundant during kernel development and decreased rapidly at physiological maturity. PPO proteins were more abundant in immature kernels, but PPO activity was greater in mature kernels. Wheat kernel antigenic protein bands of ∼58, 60, 62, and 75 kD were identified; immunoprecipitated proteins of ∼60 and ∼62 kD were confirmed to be PPOs by LC-MS/MS. The 2D chromosome was implicated as a major locus of PPO activity in cultivar (cv.) ‘Chinese Spring’ based on antigenic staining intensity of ∼60–62 kD proteins and kernel PPO activity in aneuploid lines. The ∼58 kD protein was not well-correlated with kernel PPO activity, while the ∼75 kD protein was likely a PPO precursor. Tropolone completely inhibited PPO activity extracted from mature kernels but not from immature kernels. Total PPO activity in mature kernels is thus a function of specific PPO isoforms present, their abundance, and activation levels.
Polyphenol oxidase (PPO) activity in finely milled wholewheat and milling fractions has been studied by measuring O2 consumption of aqueous suspensions after addition of catechol as substrate. Wheat bran contained higher levels of PPO than did wholemeal; white flour contained relatively low levels, and no PPO activity was detected in a germ-rich milling fraction. In wholemeal, 72% of the total PPO activity remained in a washed, insoluble residue after extraction with aqueous buffer solutions. Although treatment of wholemeal with solutions containing sodium dodecylsulphate, Triton X-100 or lactic acid caused substantial increases in the total PPO activity measured, most of this remained in the insoluble residue. The results are discussed in relation to a widely used alternative assay for PPO activity based on spectrophotometric measurements with aqueous extracts of ground wholewheat.
Phenolic content, o-diphenol oxidase activity and bread crumb colour have been compared for flour streams from a local mill and for flours and wholemeals from six New Zealand wheat cultivars. Phenolic content and o-diphenol oxidase activity varied significantly betwen milling flour streams and between cultivars. Flour and bread crumb colour correlated significantly with phenolic content and o-diphenol oxidase activity in the milling flour streams. A similar relationship was observed also between o-diphenol oxidase activity and the colour of flour and bread prepared from the different cultivars. These observations suggest an involvement of o-diphenol oxidase and phenolics in the pigmentation of both wheat flour and bread.
Polyphenol oxidase (PPO), known to induce browning in wheat-based products, has been shown to be activatable in wheat (Triticum aestivum) bran extracts by chemical compounds. The activity in the extracts could be increased to varying degrees with acetone, methanol, ethanol, 2-propanol, and n-butanol as additives in the extraction buffer. The most potent alcoholic activator was n-butanol (about a 3-fold increase), followed by 2-propanol and ethanol, whereas methanol had the least effect. Ionic detergents in the extraction buffer were also good activators, with sodium dodecyl sulfate (SDS) being more potent (3-fold increase) than cetyltrimethylammonium bromide (CTAB) that had only half as much effect, whereas the nonionic detergent, Triton X-114, was ineffective. The chaotropes, urea and guanidine x HCl (GND), were the most potent activators of all, increasing the activity over 4-fold. Of the two chaotropes, GND was more effective at lower concentrations (<6 M) than urea. However, the enzyme activity lessened at a higher concentration of GND (6 M), while there was a further increase in the activity with 6 M urea treatment. The activity lessened with higher concentration of GND presumably as a result of extensive denaturation of the enzyme, as GND is known to be a more potent denaturant than urea. It is hypothesized that in wheat PPO exists in an inactive form which may be activated by the presence of activators, hitherto unknown, similar in effect to that elicited by the chemical denaturants in this study.
Wheat: Chemistry and Technology. American Association of Cereal Chemists
- J E Kruger
- G Reed
Kruger, J.E., Reed, G., 1988. Enzymes and color. In: Pomeranz, Y. (Ed.), Wheat:
Chemistry and Technology. American Association of Cereal Chemists, St. Paul,
Minnesota, pp. 441e500.
Latent b-amylase of wheat: its mode of attachment to glutenin and its release
- E V Rowsell
- L G Goad
Rowsell, E.V., Goad, L.G., 1962. Latent b-amylase of wheat: its mode of attachment to
glutenin and its release. Biochemical Journal 84, 73e74.
Activation of polyphenol oxidase in extracts of bran from several wheat (Triticum aestivum) cultivars using organic solvents, detergents, and chaotropes
- J A Mccallum
- J R L Walker
- M Okot-Kotber
- A Liavoga
- K Yong
- K Bagorogoza
- W J Park
- D R Shelton
- C J Peterson
- T J Martin
- S D Kachman
- R L Wehling
McCallum, J.A., Walker, J.R.L., 1990. O-Diphenol oxidase activity, phenolic content
and colour of New Zealand wheats, flours and milling streams. Journal of Cereal
Science 12, 83e96.
Okot-Kotber, M., Liavoga, A., Yong, K., Bagorogoza, K., 2002. Activation of polyphenol oxidase in extracts of bran from several wheat (Triticum aestivum)
cultivars using organic solvents, detergents, and chaotropes. Journal of Agricultural and Food Chemistry 50, 2410e2417.
Park, W.J., Shelton, D.R., Peterson, C.J., Martin, T.J., Kachman, S.D., Wehling, R.L.,
1997. Variation in polyphenol oxidase activity and quality characteristics
among hard white wheat and hard red winter wheat samples. Cereal Chemistry
74, 7e11.