Mass transfer during osmotic dehydrationand its effect on anthocyanin retention of microwave vacuum‐dried blackberries

Abstract

BACKGROUND: The combination of sugar osmotic dehydration and microwave vacuum drying is an effective method for the dehydration of blackberries, the retention of their antioxidant properties, and the extension of their shelf life. Mass transfer during the osmotic dehydration of blackberries in sugar solution was investigated together with its influence on microwave vacuum drying characteristics, and the retention rate of anthocyanins in dried frozen blackberries. RESULTS:The concentrations of the osmotic solutions that were tested contained 40%, 50%, and 60% sugar, and the osmotic solution temperatures were 30 ∘ C, 40 ∘ C, and 50 ∘ C. The solution-to-blackberry mass ratio was 10:1 (w/w) and the process duration varied from 0 to 5 h. A two-parameter mathematical model was used to describe mass transfer in the osmotic dehydration of blackberry samples and estimate moisture loss and solid gain in the final equilibrium. The results showed that the dehydration rate and solid gain rate of the blackberries increased with an increase in osmotic concentration, osmotic time, and the temperature of the solution under certain experimental conditions. The effective diffusivity of moisture and solute were estimated using the analytical solution of Fick's second law of diffusion. The moisture and effective diffusivities of sugar in the above osmotic dehydration conditions were in the range of 1.77 × 10 −9 -2.10 × 10 −9 and 1.36 × 10 −9 -1.60 × 10 −9 m 2 .s −1 , respectively. CONCLUSION: The pretreatment of sugar osmosis greatly reduced the microwave vacuum drying time in the latter part of the dehydration period and increased anthocyanin retention. Estimation of moisture and solute diffusion coefficients during osmotic dehydration in blackberriesThe solution of Fick's second law for diffusion from a finite cylinder of model with a diameter of 2R and a height of 2 L during osmotic J Sci Food Agric 2020; 100: 102-109

Surface modification via alginate-based edible coating for enhanced osmotic dehydration mass transfer of ginger slices

“…Moreover, it is also described as a quality improvement and an energy-saving process. Previously, it was reported that applying osmotic pre-treatment prior to microwaveassisted vacuum drying of blackberries results in reduced drying time and increased anthocyanin retention (6). In a study conducted, it was shown that osmotic dehydration improved the colour of apricots after hot air drying (7).…”

Physical and chemical properties of purple cabbage as affected by drying conditions

“…[44] Previous research indicated that the antioxidant activity of fruit and vegetables might be ascribed to the presence of specific antioxidant groups, such as ascorbic acid, carotenoids, flavonoids, and phenolic acids . [45][46][47] In this study, the scavenging ability of DPPH, hydroxyl radicals, ABTS, and FRAP, as well as the TFC, TPC, and TAC values, were used to analyze the influence of drying methods on the antioxidant activity of purple cabbage. The scavenging ability of DPPH, hydroxyl radicals, ABTS, and FRAP for cabbage dried using different methods are presented in Table 2.…”

Influence of microwave vacuum drying on the effective moisture diffusivity of seedless white grapes

“…Effective moisture diffusivity (D eff ) is a critical parameter in the modeling, design, and optimization of the drying process. D eff describes the possible mechanisms of movement of water molecules within foodstuff (Dutta et al, 2020;Ozcan-Sinir et al, 2019;Song et al, 2020;Zielinska et al, 2019). The mechanisms include liquid diffusion, vapor diffusion, surface diffusion, capillary flow, hydrodynamic flow, and osmotic dehydration.…”