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ESEM micrographs from surface of exocarp plantain, 200X magnification. (a) treated to 29 °Brix 40°C (b) treated to 29°Brix 80°C (c) treated to 45°Brix 80°C
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This work studies the structural properties of plantain (Musa paradisiaca AAB) during osmotic dehydration (OD) and its role in the phenomena of mass transfer. Drying temperatures of 40, 60 and 80°C and sucrose solutions of 29 and 45°Brix were used in OD. Apparent and true volume, were measured using volumetric displacement and gas stereopycnometer...
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Citations
... The osmotic dehydration of ripe plantain using sucrose as the osmotic agent has been reported by several researchers [20][21][22][23]. The resulting product may not be good for consumption by people with certain ailments especially diabetics because the use of sucrose coupled with the high sugar content of ripe plantain (10.42 %) [24] may contribute to a rise in the blood sugar levels and the glycemic index of the concerned. ...
... On their part,) [42] working on osmotic dehydration of carrot slices associated increase moisture loss at higher temperatures to rise in fruit membrane permeability which promotes swelling and plasticization of cell membrane, and better water transfer characteristics on the product surface due to lower viscosity of the osmotic medium. Regarding the decreased moisture loss observed at 50 °C, [20] made similar observation on the influence of OD on the structural properties of plantain. The authors attributed this decrease in WL at higher temperature (above 40°C) to increased density (reduced porosity) of samples, due to rapid solute impregnation and starch gelatinization. ...
Plantain is consumed as a stable food in most sub-Saharan countries and to some extent in southern America and Asia. To avoid deterioration of the plantain after harvest and to provide food variety, a reasonable quantity of plantain is now being transformed into flour. Osmotic dehydration (OD) is a critical step in the flour production process because it enhances the nutritional and sensory quality of the flour. There are concerns to use alternative osmotic agents to sucrose and salts to avoid their high content in the final product which have an adverse effect on the health of consumers. Suitable alternatives are low-calorie sugars (LCS) because they have low glycemic indices but which unfortunately have not been tested for the OD of plantain. The aim of this work was to study the osmotic dehydration of unripe plantain using a commonly consumed commercial LCS (Sussli) as an osmotic agent. The influence of process variables (thickness, concentration, sample/solution ratio and temperature) on mass transfer parameters; water loss (WL) and solute gain (SG) on osmotic dehydration of plantain (Musa paradisiaca) were evaluated. All parameters studied had a significant influence on weight loss and solid gain. The kinetics of the osmotic dehydration was modeled using the Azuara, Peleg and Page models. Plantain slice of thickness 5 mm, LCS solution concentration of 50% at ambient temperature (25 ± 2°C), and a sample/solution ratio of 1:10 (w/v) was judged best for osmotic treatment of plantains in LCS. Under these conditions the weight loss and solid gain were 20% and 1.73% respectively. The Peleg model best described the dehydration kinetics with the highest R² (0.999) and the least RMSE.
... Table 2 presents the values for the diffusion exponent (n) and the diffusion coefficient (D) for water release during tortilla chip frying, and these values were in agreement with those reported by Soppirnath and Aminabhavi, (2002), who suggested that the D w and n values decreased when the crosslinking of the network polymer increased. Gallegos-Marin et al., (2016) mentioned that water diffusion coefficients are related to the increase or decrease of pores in the matrix material due to changes in the starch granule. It has been very often pointed out that the properties of water molecules in polymer gels are different from those of free water, and that the degree of the differences is dependent upon the degree of cross-linking. ...
Simple equation Mt/M∞ = Ktn is evaluated to describe the Fickian mechanism of oil absorption and water release during the frying of tortilla chips in nixtamalized samples with lime and without lime where Mt/M∞ is the fractional solute absorption or release, and n is the diffusional exponent characteristic of the Fickian mechanism that changes with food physical and chemical properties. For the Fickian mechanism, the exponent (n) is ≤0.50, and non-Fickian is 0.5<n<1 for slabs. Moisture releases showed a Fickian mechanism form tortilla chips with lime (n = 0.5) due to water interaction with matrix components and non-Fickian for tortilla chips without lime (n = 0.6). Oil absorption showed a Fickian mechanism for nixtamalization with lime n = 0.4 and for nixtamalization without lime, one of n = 0.3. The larger water diffusion coefficient in the tortilla chip compared to that of oil diffusion indicates that water release and oil absorption during frying is not a simultaneous event. The behavior of the water and oil diffusion is an interesting topic that, in this study, was investigated using a practical equation with potential application in food processing.
The study was aimed at evaluating the influence of process variableon mass transfer parameters; water loss (WL) and solute gain (SG) on osmotic dehydration of plantain ( Musa paradisiaca ) in low calorie sugar solution. Fully matured unripe plantain fruits of the ´´False Horn´´ cultivar were peeled and sliced into thicknesses of 2.5, 5 and 10mm. The slices were immersed in the commercial low-calorie sugar solutionsof concentrations 12.5, 25 and 50% and varying sample /solution ratio (1:5, 1:10 and 1:20) at room temperature (27 ± 2). To investigate the effect of temperature, plantain slices of thickness 5mm were immersed in low calorie sugar solution of concentration 12.5 and sample/solution ratio 1:20 at temperatures 30, 40 and 50°C. The water WL and SG of the slices under the different experimental conditions were measured at various time intervals (10, 20, 40, 60, 80, 100, 120 and 140min). The kinetics of the osmotic dehydration was modeled using the Azuara, Peleg and Page models.Plantain slice of thickness 5mm, low-calorie sugar solution concentration of 50% at temperature 40°C, and a sample/solution ratio of 1:20 was judged best for osmotic treatment of plantains in low-calorie sugar solution.The Peleg model best described the dehydration kinetics with the highest R ² (> 0.999) and the least RMSE.
Plantains are termed as ‘culinary bananas’ due to the fact that they are only consumed after cooking or other forms of processing. Providing good nutritional value and versatility in diet, it is considered an important commercial crop and an efficient dietary staple in Africa. However, irrespective of geographical locations and economic status of diverse ethnic groups, plantains are consumed extensively due to their easy availability and preparation. They are prepared and consumed in numerous forms between the green and yellow stages of maturity and ripeness. The nutritional composition of plantains provides several health benefits and therapeutic applications, making it preferable for consumption. They are processed for the further development of a variety of products like biscuits, baby foods, bread, etc. The present review aims to enlist various traditional dishes and the value-added products prepared from plantains after processing. It also highlights other diverse uses of plantain where all the parts of the crop are functional and demonstrate its potential in future scope.
Osmotic dehydration (OD) is a coupled mass transfer operation where foods are partially dewatered while simultaneously impregnated with solute from the solution. Nonetheless, water loss (WL) and solute gain (SG) are treated as independent processes for modeling purposes and the effect of their coupling on the estimation of water/solute diffusivities (Dw, Ds) and equilibrium dehydration/impregnation levels (WLe, SGe) has not been elucidated yet. The objective of this study was to develop a new model considering the coupled mass transport of water and solute occurring during OD of foods and to evaluate the contribution of this coupling on the estimation of Dw, Ds, WLe, and SGe in comparison with the rigid/shrinking solid assumption. Experimental WL, SG, and volume kinetics were obtained during OD of papaya cubes in sucrose solutions (50°Bx; 45, 55 and 65 °C) and further analyzed with the proposed model solved under different assumptions: coupled and partially coupled mass transfer equations (MTEs) in a shrinking solid and uncoupled MTEs in a rigid solid (no shrinkage) with uncorrected and corrected lengths for diffusion. Properties Dw, Ds, WLe, and SGe with coupled MTEs and shrinkage were estimated in the ranges of (2.52–5.48) × 10⁻¹⁰ m²/s, (3.91–5.43) × 10⁻¹⁰ m²/s, 0.47–0.53 g/g and 0.18–0.30 g/g, respectively, with partially coupled and uncoupled MTEs leading to a significant overestimation of diffusivities under the tested experimental conditions (up to 281% for water and 75% for solute), even when shrinkage was considered in the 3D model solution. Current findings demonstrate that, like shrinkage, coupling of WL and SG is of upmost importance for a reliable estimation of mass transfer properties during OD.
Modification of the surface properties of materials is a promising approach to reduce the uptake of oils during frying. In this work, the quality characteristics of plantain chips subjected to a pretreatment consisting of osmotic drying in sugar solutions (29 and 45° Brix; 40 and 80 °C) were evaluated. True density, apparent density, porosity and moisture content were measured in pretreated samples (PS) before frying. Image ESEM was used to evaluate microstructural changes on the surface and in cross-sections at different depths. Global oil absorption (GOA) and fatty acid profile were monitored in surface and deep cross-sections (DCS). The color parameters of chips (L*, a*, b*, ΔE), browning index, crispness, crunchiness and hardness were evaluated during frying. Oil absorption in the crust was lower in samples subjected to pretreatments with a higher temperature. PS showed high gelatinization in both the surface and DCS, thus changing crust physical properties, total oil uptake and fatty acid profile. An exponential correlation between porosity (ε) and GOA was found, while a second order correlation was found between ε and the fatty acid profile. The characteristics of texture and color, as desired by the consumer, were reached more quickly in the PS at 29° Brix and 40 °C.
While various mechanisms have been proposed for the water transfer during osmotic dehydration (OD), little progress has been made to understand the mechanisms of solute transfer during osmotic dehydration. The transfer of solutes has been often described only by the diffusion mechanism; however, numerous evidences suggest the participation of a variety of mechanisms. This review deals with the main issues of solute transfer in the OD of vegetables. In this context, several studies suggest that during OD of fruits and vegetables, the migration of solutes is not influenced by diffusion. Thus, new theories that may explain the solute transport are analyzed, considering the influence of the plant microstructure and its interaction with the physicochemical properties of osmotic liquid media. In particular, the surface adhesion phenomenon is analyzed and discussed, as a possible mechanism present during the transfer of solutes in OD.
