Characterisation of reused osmotic solution as ingredient in new product formulation

Abstract

Osmotic dehydration (OD) with sugar solutions has been used in fruit preservation but part of the process's economic viability depends on the possibility of reusing the osmotic solution (OS) in successive dehydration cycles. Despite the increase in water content, OD promotes OS enrichment in certain water-soluble natural components extracted from fruits, such as vitamins and minerals. For this reason, to recycle it for new food formulation seems to be an attractive alternative. In this paper, changes in soluble solids, a w, pH, electrical conductivity, density, viscosity and colour in osmotic solution used for kiwifruit dehydration in function of the ratio osmotic solution/fruit (20:1, 10:1 and 5:1) and the number of cycles (up to 10) have been studied. Microbiological analysis of OS and fruit compositional changes were also studied. The results show that during OD likewise water interchange between fruit and OS, a flow of mineral salts and sugar from the fruit to the OS, is produced. Nevertheless OS changes associated to the OD of kiwifruit under the conditions of this study allow OS reuse for at least 10 cycles without any problems related to fruit dehydration level, colour fruit changes, or considerable microbiological contamination.