Effects of Alginate and Glycerol Concentrations Combined with Calcium Chloride as Edible Coatings on Mass Transfer During Osmotic Dehydration of Ginger Slices

Fresh ginger has a high moisture content, and improper storage makes it susceptible to microbial contamination, leading to product deterioration. Thus, drying is a pivotal step. Osmotic dehydration is widely used as a pre-treatment in the drying process due to its simplicity and potential for reducing energy consumption. During this process, samples are immersed in a hypertonic solution, utilizing osmosis to facilitate two main mass transfer mechanisms: water loss and solute gain. However, excessive solute gain can negatively impact the final product's texture and organoleptic qualities, thus limiting its application in the food industry. To mitigate this, extensive research has explored the use of edible coatings before osmotic dehydration to minimize solute gain. This study employed the central composite design technique to examine the effects of alginate and glycerol concentrations, mixed with calcium chloride, on water loss and solute gain during the osmotic dehydration of ginger slices. Alginate and glycerol concentrations were tested at levels ranging from 1% to 3%. The influence of these variables was evaluated using a second-order polynomial multiple regression model. Analysis of variance (ANOVA) showed high coefficients of determination (R²) values of 0.9 for both water loss and solute gain. Alginate significantly increased water loss (p < 0.05), indicating that alginate's hydrophilic properties improve the barrier, facilitating greater water loss during osmotic dehydration. For solute gain, glycerol significantly reduced solute gain (p < 0.05), suggesting that glycerol enhances the barrier properties of the coating, preventing excessive solute absorption. Interaction effects between alginate and glycerol were not significant for water loss but were significant for solute gain, indicating that the combined effect is crucial for controlling solute absorption during dehydration. Thus, optimizing alginate and glycerol concentrations is essential to improve mass transfer efficiency during the osmotic dehydration of ginger slices.