Study on the quality and stability of minimally processed apples impregnated with green tea polyphenols during storage

In the present study, a green tea extract (GTE) was used to enrich minimally processed apples by vacuum impregnation VI in order to obtain a nutritionally fortified product. Apples were impregnated with isotonic sucrose solutions containing 1% GTE and/or 1% ascorbic acid (AA). The impact of GTE enrichment on quality characteristics of the product, stability of the antioxidant compounds and activity during refrigerated storage were assessed. Results showed that a satisfactory impregnation of minimally processed apples was achieved and resulted in a strong increase of the antioxidant compounds content and activity. While other qualitative parameters were only slightly affected, colour of samples was influenced just after the VI treatment with an increase of the yellow/orange colour components but also during storage with a higher degree of browning development. However, the addition of 1% of AA allowed to better preserve colour and antioxidant properties during storage limiting oxidative phenomena. Industrial relevance The demand for functional foods characterized by a high nutritional value is constantly increasing. Vacuum impregnation (VI) is a technology that allows the replacement of the gas into the porous food structure with an aqueous solution, promoting compositional changes in short treatment times thus permitting the direct formulation of a porous food matrix, hence representing a promising technology for product innovation for the fruit and vegetable industry. Green tea (GT) is a high source of flavanoids, known to have strong antioxidant properties which has been widely studied both in in-vitro and in-vivo trials. According to the results obtained in this study, the enrichment of apples with GT catechins and AA seemed to be promising in order to obtain a nutritionally fortified fruit product.