Sucrose syrup reuse during one‐ and multi‐stage osmotic dehydration of pineapple

Multi‐stage osmotic dehydration of pineapple with sucrose syrups in gradually increasing concentration was experimentally evaluated and compared to the single‐stage dehydration process. Also, osmotic solutions were reused for five osmotic dehydration cycles, without syrup reconditioning treatment. Single‐ and multi‐stage osmotic treatments were carried out for 2 hr at 40°C. Changes in pH, total acidity, and content of soluble solids, water, and ascorbic acid, in fruit and osmotic solutions, were analyzed. Water loss decreased with cycles of syrup reuse in one‐stage treatments and remained almost unchanged in multi‐stage treatments. Dry matter content of pineapple fruit during four‐stage osmotic dehydration cascade (40, 50, 55, and 60 °Bx) was increased respect to one‐stage dehydration at 40 and 60 °Bx. With regard to retention of syrup characteristics, multi‐stage dehydration reached a better performance as compared with the single‐stage dehydration and through the syrup reuse could become a more economical, environmentally friendly process. Practical applications Osmotic dehydration allows to reduce the fruit water content with energy saving and conservation of fruit characteristics, but also involves some negative aspects. Syrup management is usually the most important technological problem in the osmotic dehydration process on an industrial scale. Osmotic solution recycling could contribute to the solution of this problem. In this study, the effectiveness of pineapple osmotic dehydration in multi‐stage and single‐stage, with syrup reuse, were compared. The research show: (1) multi‐stage treatment was the most effective for the retention of syrup properties; (2) syrup reuse did not affect the dehydrated pineapple characteristics through multi‐stage dehydration. Thus, results indicated the proposed dehydration operation is of easy implementation, economically and environmentally friendly.