ABSTRACT

   The close association between consumption of fruit and health stems from the presence therein of a number of nutrients and other non-nutritious but with a key role in preventing certain diseases. However, its processing and storage affects these compounds, so it is interesting to consider this effect when selecting treatments. The stated goal in this work was the study of the influence of processing conditions and storage stability of major macro and micronutrients present in the grape, with a view to recommending those that provide products with the maximum sensory and nutritional quality, and healthier. This study has been focused on various processes applied to the preparation of partially dehydrated fruit, fruit in syrup and dried fruit. Conventional treatments were applied by air drying and alternative processes such as osmotic dehydration and microwave assisted drying or only microwave assisted drying were applied to obtain partially dried grapes and raisins, respectively. We also studied the effect of blanching (conventional and microwave) as a pretreatment for the production of grapes in syrup. Milder treatments (applied to obtain partially dehydrated fruit and fruit in syrup) do not involve significant changes in the compounds of the grape, except for tartaric acid that decreases in all cases. However, the dehydration to obtain raisins caused, in general, a decrease of all compounds studied except for total phenols. Also, the application of microwave in short processes involves no differences with respect to conventional processed products obtained, whereas in the case of raisins greater losses of ascorbic acid and increased solubilization of pectins, related to the texture, were observed. However samples provided more antioxidant activity. The observed changes during storage were important only in the case of fruit in syrup and in the early days, where there is an exchange of solutes between the grapes and syrup.