Anisotropic diffusion during osmotic dehydration of celery stalks in salt solution

Mass transfer characteristics during ultrasound-assisted osmotic dehydration of button mushroom (Agaricus bisporus)

Button mushroom (Agaricus bisporus) slices were dehydrated using ultrasound-assisted osmotic dehydration (UOD), and three osmotic agents including sucrose, glucose and sodium chloride were investigated for their effects on the mass transfer characteristics, average density and microstructure. Different mathematical models were selected to describe the osmotic behaviours, and the effective moisture (D _m) as well as solid diffusivities (D _s) during UOD were also calculated. The results showed that, during UOD, button mushrooms had the highest D _m values in the sodium chloride solutions, and they had the highest D _s values in the glucose solutions, which indicated that faster moisture and solid transfers could occur in these two osmotic solutions, respectively. Moreover, the Weibull model provided the best fit for the UOD curves of button mushrooms under the study's operating conditions, which showed good predictability for the moisture and solid contents of the button mushrooms during UOD. In addition, sucrose agents were suggested for use in the UOD of button mushrooms due to the better microstructure of the products as well as the appropriate rates of effective moisture and solid diffusivities during UOD. This study provides a theoretical basis for the deep processing of mushrooms and other food products.

Study of osmotic dehydration of kiwi fruit using sucrose solution

Abstract Osmotic dehydration of kiwi was evaluated using 45, 55 and 65 °Brix sucrose solutions. Free moisture, water activity and solutes gain decreased in fruit during the process. Water loss rates were higher in the beginning of drying. Water activity decrease was higher when the product was in 65 °Brix solution. The equilibrium moisture content estimated by the Peleg model decreased significantly with increasing concentration of the osmotic solution, and the diffusivity values of water loss were in the range from 1.5 × 10-9 to 1.9 × 10-9 m2 s-1. The osmotic pressures of the solutions were also predicted.

The Influence of the Osmotic Dehydration Process on Physicochemical Properties of Osmotic Solution

The osmotic dehydration (OD) process consists of the removal of water from a material during which the solids from the osmotic solution are transported to the material by osmosis. This process is commonly performed in sucrose and salt solutions. Taking into account that a relatively high consumption of those substances might have a negative effect on human health, attempts have been made to search for alternatives that can be used for osmotic dehydration. One of these is an application of chokeberry juice with proven beneficial properties to human health. This study aimed to evaluate the physicochemical properties of the OD solution (chokeberry juice concentrate) before and after the osmotic dehydration of carrot and zucchini. The total polyphenolics content, antioxidant capacity (ABTS, FRAP), dynamic viscosity, density, and water activity were examined in relation to the juice concentration used for the osmotic solution before and after the OD process. During the osmotic dehydration process, the concentration of the chokeberry juice decreased. Compounds with lower molecular weight and lower antioxidant capacity present in concentrated chokeberry juice had a stronger influence on the exchange of compounds during the OD process in carrot and zucchini. The water activity of the osmotic solution increased after the osmotic dehydration process. It was concluded that the osmotic solution after the OD process might be successfully re-used as a product with high quality for i.e. juice production.

Analysis of Operating Conditions on Osmotic Dehydration of Plums (Prunus Domestica L.) and 3D-Numerical Determination of Effective Diffusion Coefficients

The objective of this work was to analyze the relevant process conditions on osmotic dehydration of plums and to determine the diffusion coefficients related to this process. The influence of solution (type and concentration of solute, temperature, fruit/solution ratio) and process time on water loss, water content and solutes gain were studied. Process analysis was performed experimentally by means of a set of 16 duplicate tests and numerically by mathematical modeling of the unsteady-state mass transfer phenomena. Experiments were carried out with glucose and sorbitol solutions (40–60 % w/w), dehydrating plum pieces during 2 h at temperatures of 25 and 40ºC, with fruit/solution ratios of 1/4 and 1/10. For calculating effective diffusion coefficients, a novelty inverse-method was applied, the approximate shape of food-pieces was considered using Finite Elements Method. Calculated diffusion coefficients ranged from 1.13 × 10−09to 4.71 × 10−09m2s−1and 0.44 × 10−09to 3.46 × 10−09m2s−1, for water and solutes, respectively.

Modelling and Optimization of Process Parameters for Strawberry Osmotic Dehydration Using Central Composite Rotatable Design

Osmotic dehydration conditions for strawberry were optimized using central composite rotatable design. The optimal conditions included osmotic dehydration temperature of 59.5°C, osmotic dehydration time of 245.6 min, and sorbitol concentration of 66.8%. Water loss (WL) exhibited a response value of 52.5% and was mainly influenced by sorbitol concentration (p≤0.01), followed by osmotic dehydration temperature (p≤0.01) and time (p≤0.01). The optimal condition was validated and found to be fitted well with the experimental data. The osmotic dehydration of strawberry was significantly influenced by osmotic dehydration temperature and time and sorbitol concentration. Based on the parameters of ANOVA, the predicted model for WL rate established by response surface quadratic regression provided an adequate mathematical description of the osmotic dehydration of strawberry.