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Effect of press construction on yield of pressing and selected quality characteristics of apple juice
Abstract and Figures
Abstract. The process of fruit juices production should be characterised by a high efficiency, while the final
product should have a high content of soluble solids, low acidity and a high content of health-promoting
components. Currently, screw presses are becoming increasingly popular especially on small farms and
households. Their construction has a great impact on yield pressing and quality characteristics of juice. The
primary objective of this study was to determine the effect of the press type on juice extraction efficiency and on
the total amount of released polyphenols. The scope of the study included also the determination of the juice
quality parameters such as the content of soluble solids, pH, viscosity and density. Apple fruits were pressed
using two types of machines: a single-screw press and a twin gear juice extractor. Study results demonstrate that
the pressing efficiency depends on the press construction. The highest yield of extraction was obtained for the
twin-screw press. Under the experimental conditions, there was no influence of the press type on the quality
properties of the juice, except for its viscosity. However, the quality characteristics of the juice depended on the
apple variety. Higher contents of the extract and polyphenols were obtained in juice from the apple var. Jonagold
juice and viscosity in juice from the apple var. Ligol juice. The use of the press offers the possibility of
producing juices with desirable quality traits.
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... According to the literature, acidity (pH) of the apple juice varies from 3.37 to 4.24 [34]. Kobus et al. [14] found that the pH of the apple juice obtained on the screw press was in the range of 3.66 ± 0.09. The press construction had a significant effect on the pH of the tested apple juice. ...
... The TPC in juices produced in Europe varies within a broad range from 10 to 300 mg GAE 100 mL -1 [43]. Kobus et al. [14] showed that the content of polyphenols in juices obtained on the screw press ranged from 44.2 to 58.3 mg GAE 100 mL -1 . ...
... Since the apples were disintegrated directly in the screw press, the entire process of juice extraction was faster and the rate of mash oxidation was lower than The TPC in juices produced in Europe varies within a broad range from 10 to 300 mg GAE 100 mL −1 [43]. Kobus et al. [14] showed that the content of polyphenols in juices obtained on the screw press ranged from 44.2 to 58.3 mg GAE 100 mL −1 . ...
The paper presents the possibility of applying different press constructions for juice extraction in small farms. The research was carried out with three different varieties of apples, namely, Rubin, Mutsu, and Jonaprince. Two types of presses were tested: a basket press and a screw press. Generally, application of the screw press makes it possible to obtain a higher yield of extraction compared to the basket press. In our study, the differences in the pressing yield among press machines also depended on the apple variety used. The juices obtained on the screw press were found to be of a higher quality characterized by a higher content of soluble solids, higher viscosity, higher total content of polyphenols, higher antioxidant activity, and lower acidity. Thus, the selection of an appropriate press is the key to producing high-quality apple juice with health-promoting properties for manufacturers of apple juice at the local marketplace.
... Citrus depressa processed by screw press had a 42.5% higher juice yield compared to that of belt-pressing (Takenaka et al., 2007). Similarly, screw pressing produced higher apple juice yields than basket pressing (Kobus, Nadulski, Anifantis, & Santoro, 2018). Belt-pressing and basket pressing are similar to hydraulic pressing in that they all use compressive force to extract liquid from solids. ...
Carrot processors produce approximately 175,000 tons of waste annually in the United State of America. Carrot waste conversion is important to the carrot processing industry as this waste is rich in bioactive compounds and dietary fiber. We evaluated the effects of hydraulic press and expeller press on liquid and bioactive compound extractions. Mechanical separation of carrot mash by expeller pressing improved liquid extraction over the hydraulic press while simultaneously increasing the total solid, carotenoid, and polyphenol contents. Compared to untreated control mash, mechanically treated mash had higher fat-binding capacity. Our study indicates that further conversion of carrot mash could lead to better value streams for this byproduct.
... A considerable impact of variety characteristics on the efficiencies and the course of the pressing process in twin-screw press was also observed in the study by Kobus et al. [19]. ...
The paper presents the possibility of applying a twin-screw press for juice extraction from apples with different textural properties. The research was carried out with six different varieties; namely, Granny Smith, Modi, Ligol, Lobo, Boscop and Szampion. During the experiment, the following properties were measured: texture properties, pressing yield and polyphenolic content; and ascorbic acid content and antioxidant activity both in raw apples and apple juice. Based on the analysis, three hardness levels of apples can be distinguished, impacting the course of juice pressing in a twin-screw press (low hardness below 30 N, medium hardness 30–50 N and high hardness 50 N). The study showed that only high hardness apples are suitable for pressing on a twin-screw press. The mechanism by which texture properties influence the juice pressing process in the studied press was explained. It was further demonstrated that the hardness of apples has a positive impact on the degree of extraction of polyphenols and ascorbic acid into apple juice. This is caused by the different fracture patterns of tissues with different mechanical properties. High hardness apples (Granny Smith and Modi) were characterized by a considerably greater degree of bioactive substance extraction into juice than medium hardness apples.
Nowadays, the traditional energy sources used for greenhouse heating are fossil fuels such as LPG, diesel and natural gas. The global energy demand will continue to grow and alternative technologies need to be developed in order to improve the sustainability of crop production in protected environments. Innovative solutions are represented by renewable energy plants such as photovoltaic, wind and geothermal integrated systems, however, these technologies need to be connected to the power grid in order to store the energy produced. On agricultural land, power grids are not widespread and stand-alone renewable energy systems should be investigated especially for greenhouse applications. The aim of this research is to analyze, by means of a mathematical model,
the energy efficiency of a photovoltaic (8.2 kW), hydrogen (2.5 kW) and ground source gas heat pump (2.2 kW) integrated in a stand-alone system used for heating an experimental greenhouse tunnel (48 m2 ) during the winter season. A yearlong energy performance analysis was conducted for three different types of greenhouse cover materials, a single layer polyethylene film, an air inflated-double layer polyethylene film, and a double acrylic or polycarbonate. The results of one year showed that the integrated system had a total energy efficiency of 14.6%. Starting from the electric energy supplied by the photovoltaic array, the total efficiency of the hydrogen and ground source gas heat pump system was 112% if the coefficient of the performance of the heat pump is equal to 5.
The heating system increased the greenhouse air temperatures by 3–9 ◦C with respect to the external air temperatures, depending on the greenhouse cover material used.
Apulia (Southern Italy) is the leading Italian region for the production of olive oil (115 × 106 kg of oil/year), and the olive oil chain is really important from a business point of view. Currently, the extraction of olive oil is essentially performed by using a mechanical pressing process (traditional olive oil mills), or by the centrifugation process (modern olive oil mills). The aim of this paper is to evaluate in detail the noise levels within a typical olive oil mill located in the northern part of the Apulia region during olive oil extraction. The feasibility of this study focusing on the assessment of workers’ exposure to noise was tested in compliance with the Italian-European Regulations and US standards and criteria. Several measurements of the noise emission produced by each machine belonging to the productive cycle were carried out during olive oil production. The results obtained were then used to evaluate possible improvements to carry out in order to achieve better working conditions. An effective reduction in noise could probably be achieved through a combination of different solutions, which obviously have to be assessed not only from a technical point of view but also an economic one. A significant reduction in noise levels could be achieved by increasing the area of the room allotted to the olive oil extraction cycle by removing all the unnecessary partition walls that might be present.
The electromagnetic field (EMF) levels generated by mobile telephone radio base stations (RBS) situated on rural-agricultural lands were assessed in order to evaluate the exposure of farm workers in the surrounding area. The expected EMF at various distances from a mobile telephone RBS was calculated using an ad hoc numerical forecast model. Subsequently, the electric fields around some RBS on agricultural lands were measured, in order to obtain a good approximation of the effective conditions at the investigated sites. The viability of this study was tested according to the Italian Regulations concerning general and occupational public exposure to time-varying EMFs. The calculated E-field values were obtained with the RBS working constantly at full power, but during the in situ measurements the actual power emitted by RBS antennas was lower than the maximum level, and the E-field values actually registered were much lower than the calculated values.
The effect of ascorbic acid and N2 usage in large-scale cloudy apple juice production was investigated. Samples were stored at 5 and 20C for 6 months. The quality of the initial cloudy apple juice samples was evaluated by characteristic properties (pH, total titratable acidity, total dry matter, soluble solids and total phenolic content) and storage stability was evaluated by turbidity and color parameters, which were analyzed on a monthly basis. According to the results, change in total phenolic content of the samples was considerable (minimal values were recorded in N2-treated groups). However, ascorbic acid and N2 usage alone or in combination was not enough to prevent turbidity loss during storage. Only the lower temperature (5C) chosen was effective to decelerate this loss. In terms of color stability, the most stable group was the N2 and ascorbic acid-treated one (ΔE: 3.59 at 5C).
Color and cloud stability are important attributes of cloudy apple juice during storage. Many laboratory studies have been conducted to improve these quality parameters. However, there is no large-scale study about the storage stability of cloudy apple treated by N2 and ascorbic acid during the production stages. Therefore, in this study, a large-scale cloudy apple juice production was performed using N2 and ascorbic acid during the juice processing stage and the storage stability of the final products was investigated for 6 months. The results of this large-scale study could be useful for fruit juice processors and retailers.
en The paper presents the results of the research on the impact of enzymatic liquefaction, freezing and thawing on the efficiency of juice pressure extraction from apple pulp and quality of the obtained juices. The research was conducted using three types of pretreatment prior the pressing: crushing and enzymatic liquefaction in temperature of 25 °C, crushing and enzymatic liquefaction in temperature of 45 °C and crushing followed by freezing and thawing of the pulp. The study included three varieties of apples. The juice was obtained using a laboratory basket press. It was determined that the pretreatment of the pulp as well as the varietal characteristics of the fruits have a significant impact on the efficiency of the pressure extraction process. The enzymatic treatment of the pulp, irrespective of the temperature at which it was conducted, significantly increased the efficiency of the process. No effect of the temperature (25 or 45 °C) of enzymatic treatment on the efficiency of the pressure extraction process was found. Pretreatment of the pulp based on freezing and thawing contributes to the increase of efficiency of pressing in the case of two apple cultivars, that is, Idared and Red Delicious. It was showed that total phenolic content, antioxidant activity, the soluble solids content and juice acidity (pH) depend on the pretreatment of the pulp and the varietal characteristics of apples. Following the application of pretreatment of the pulp, an increase was observed in the content of polyphenols and in the antioxidant activity of the juices obtained.
Practical Application
pt Freezing and thawing as a pretreatment allows to eliminate enzymatic liquefaction of mash before press extraction. The suggested new method of the use of freezing and thawing techniques enables development of the production of juice with a very good sensory and prohealth properties.
Four technologies of clear and cloudy juice production according to typical Polish and French procedures were investigated with six apple cultivars. Clear juices were produced using technologies similar to those used by the processing industry, while cloudy juices were processed according to simple protocols used in small-scale processing. In order to best evaluate the effects of the processing technology and cultivar on juice quality, the production of juices was carried out both in Poland and France on the same raw material. The technology, unlike the cultivar, did not affect the soluble solids content of the juice, or the levels of most of the sugars, malic acid or potassium. However, the antioxidant activity measured by the ABTS+ method and the levels of monomeric phenolics and procyanidins strongly depended on the apple cultivar and production technology. For cloudy juices, the selection of appropriate cultivars and production without centrifugation are the key to substantially increasing the amounts of healthy compounds in apple juice.
Publisher Summary This chapter discusses the analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Analyses of the Folin-Ciocalteu (FC) type are convenient, simple, and require only common equipment and have produced a large body of comparable data. Under proper conditions, the assay is inclusive of monophenols and gives predictable reactions with the types of phenols found in nature. Because different phenols react to different degrees, expression of the results as a single number—such as milligrams per liter gallic acid equivalence—is necessarily arbitrary. Because the reaction is independent, quantitative, and predictable, analysis of a mixture of phenols can be recalculated in terms of any other standard. The assay measures all compounds readily oxidizable under the reaction conditions and its very inclusiveness allows certain substances to also react that are either not phenols or seldom thought of as phenols (e.g., proteins). Judicious use of the assay—with consideration of potential interferences in particular samples and prior study if necessary—can lead to very informative results. Aggregate analysis of this type is an important supplement to and often more informative than reems of data difficult to summarize from various techniques, such as high-performance liquid chromatography (HPLC) that separate a large number of individual compounds .The predictable reaction of components in a mixture makes it possible to determine a single reactant by other means and to calculate its contribution to the total FC phenol content. Relative insensitivity of the FC analysis to many adsorbents and precipitants makes differential assay—before and after several different treatments—informative.
The partial compositional characteristics were determined for apple juice from 175 non-commercial varieties of apples developed from scion wood collected from approximately 12 countries and several USA geographical areas. Juices from many of the varieties were high in malic acid and potassium. Mean values for many of the attributes did not match existing compositional database value means. However, some of the overall minimum and maximum values for the various attributes (i.e., Brix°, pH, ash, TA, sucrose, glucose, fructose, sorbitol, malic, citric, fumaric, sodium, and calcium) in this study compared reasonably well with existing compositional database values. Distribution of phenolics between the various varieties was highly variable with some juices containing little if any phenolic compounds. Chlorogenic acid and phloridzin were detected in all varietal samples while arbutin and HMF were not measurable. The data developed should be useful with other databases in describing authentic apple juice and in the development of future apple commercial varieties to target specific consumer requirements.