Composição fenólica, atividade antioxidante e estabilidade química de kombuchas contendo casca e polpa de pitaya (Hylocereus polyrhizus)

Abstract

Kombucha is a drink of Asian origin, which has been growing popularly in the West for its possible health-beneficial properties. Despite growing studies regarding this drink, there is still no consensus on the best conditions for fermentation, something that aims to increase or maintain the phenolic composition of the drink. The objective of this work was to evaluate the influence of red Pitaya (skin and pulp) added in the second fermentation of Kombucha on the phenolic composition, antioxidant activity and chemical stability (sugar content and pH) of the beverage. The results showed a reduction in the phenolic composition of 8.4% in Kombucha base of first fermentation, compensated by the addition of the skin and pulp increasing approximately by 9% and 5%, respectively. In relation to anthocyanins, Kombucha base did not show significant change in the first fermentation, as with the addition of substrates, the anthocyanin values increased 55 and 91 times in the skin and pulp compared to Kombucha base, respectively. It was observed an increase in the antioxidant activity with the addition of Pitaya, both the peel and the pulp, increasing by 6 and 4%, respectively. The evaluation of stability over a period of 7 to 35 days resulted in an average pH variation of 5, 7 and 1% for Kombucha base, peel and pulp, respectively, with the pulp presenting the greatest stability in this parameter and the shell, the smallest. For the sugar content, the variations in the Brix degree were 2.34; 1.76 and 0.44 for Kombucha base, peel and pulp, respectively, again showing greater stability for the beverage added with pulp. Although more studies are needed, the results demonstrate that Pitaya can be an excellent source of phenolic compounds to be incorporated in the second fermentation of Kombucha, aiming to increase its antioxidant activity. [resumo fornecido pelo autor]