Índice de polifenóis, antocianinas totais e atividade antioxidante de um sistema modelo de geléia de uvas

Abstract

Anthocyanins are phenolic pigments with a potential for replacing synthetic red dyes. However, their stability is affected by food processing, and temperature is one of the main factors involved in these pigments' color degradation. The aim of this work was to evaluate the concentration of phenolic compounds and the antioxidant capacity of a grape jelly model system (JMS). The grape varieties used here were Isabel (Vitis labrusca) and Refosco (Vitis vinifera L.) and the jelly was cooked at 45 °C, using a mixture of xanthan gum and locust bean gum as the thickening agent. Two JMSs were prepared and analyzed to determine their anthocyanin stability, total polyphenol index (TPI) and total anthocyanin content (TA). The antioxidant activity was measured by the DPPH and ABTS radical-scavenging methods. The TA concentration was also determined in the grape extracts used in the preparation of the JMSs. The best results in terms of TPI, TA and antioxidant activity were obtained for the JMS produced with Refosco grapes. A high correlation coefficient was found between the TA and TPI in the JMSs and the antioxidant activity. The method used in the production of the JMSs was effective in preserving the color of anthocyanins and the antioxidant properties of the total phenolic compounds evaluated here.