During the drying process, fruit pulps may undergo changes in their quality. This study aimed to select the optimal drying conditions for acerola–ciriguela mixed pulps using spouted bed drying and freeze-drying methods. For spouted bed drying, the influence of drying temperature, feed rate, and maltodextrin concentration was investigated using a 23 central composite experimental design. A similar design was applied to freeze-drying, but drying temperature, vacuum chamber pressure, and maltodextrin concentration were selected as the independent variables. In both cases, moisture content, water activity, hygroscopicity, and ascorbic acid retention were used as response variables. Optimisation of both processes was performed according to the desirability function. Higher temperatures and maltodextrin concentrations resulted in lower moisture content in the final product obtained through spouted bed drying. Furthermore, increasing these variables significantly reduced the water activity of both products. Ascorbic acid retention was maximised in the spouted bed-dried product when combining low drying temperatures with a slow suspension feed rate, whereas in the freeze-dried product, higher temperature and chamber pressure achieved the best results. These findings highlight the great potential of freeze-dried mixed acerola–ciriguela powder as an ingredient for vitamin C enrichment in foods.
Júnior et al. (Thu,) studied this question.