The impact of using vacuum and isomaltulose as an osmotic agent on mass exchange during osmotic dehydration and their effects on qualitative parameters of strawberries

Abstract

The impregnation of isomaltulose is an interesting strategy for the enrichment of strawberries since it is a carbohydrate with low glycemic and cariogenic indexes. The osmotic enrichment of strawberries with isomaltulose was performed considering the vacuum pulse in the first 0, 10, and 20 min in a total process time of 300 min, at 25°C. The tested solution concentrations were 25% and 35% (w w−1) of isomaltulose. The kinetics of solid gain, water loss, moisture content, and weight reduction were obtained. The fresh and final products had some physical and nutritional parameters evaluated. Osmotic processes resulted in a reduction of moisture content, water activity (aw), acidity, total anthocyanins and phenolic contents and antioxidant capacity, increased pH, influenced colorimetric parameters and caused shrinkage of the samples. The higher impregnation of isomaltulose was obtained with the vacuum pulse, which was 82% higher than the osmotic process without the vacuum pulse. The atmospheric process resulted in higher bioactive compounds levels and lower shrinkage and lower total color difference. Therefore, the 35% solution and use of vacuum were recommended when the objective was to maximize mass exchanges, while the 25% solution and without vacuum pulse were indicated for higher retention of strawberry bioactive compounds. The time of vacuum application at the beginning of the osmotic dehydration process and the use of osmotic solutions of different concentrations can result in different rates of dehydration and impregnation of isomaltulose in the strawberry and can influence important qualitative parameters. The evaluation of these factors helps in the optimization of the production of osmo-dehydrated strawberries, increasing the process efficiency and the preservation of product quality.

Practical applications: the time of vacuum application at the beginning of the osmotic dehydration process and the use of osmotic solutions of different concentrations can result in different rates of dehydration and impregnation of isomaltulose in the strawberry and can influence important qualitative parameters. The evaluation of these factors helps in the optimization of the production of osmo-dehydrated strawberries, increasing the process efficiency and the preservation of product quality.