Avaliação das propriedades antioxidantes, fisico-química e perfil microbiológico de kombucha saborizada com maracujá

Abstract

Kombucha is a fermented drink of Chinese origin. It is obtained by adding of sweet Camellia sinensis tea and a symbiotic culture of bacteria and yeast. The drink has become prominent for the variety of benefits it can provide to human health. The objective of this work was to evaluate the microbiological, antioxidante, and physicalchemical properties of the drink during the fermentation and storage period, for 75 days, until the product's final expiration date. The green tea and passion fruit pulp used to prepare the drink were evaluated for the content of phenolic compounds and antioxidant activity. Lactic acid, acetic, and yeast bacteria were counted in the kombucha throughout the storage period. The antioxidant activity was evaluated usingthe DPPH and ABTS methods, while the content of total phenolic compounds was assessed using the Folin-Ciocalteau method. The results of the antioxidant activity of kombucha, by the ABTS method, ranged between 9.47 and 11.56 mmol TEmL-1 (ET:Trolox equivalent), and by the DPPH method it ranged between 6.60 and 7.57 mmol TE mL- 1. Green tea had a high antioxidant capacity, being 28,850 mmol TE g-1 by the ABTS method and 1,899.39 mmol TE g-1 by the DPPH method, while passion fruit pulp was 404.70 mmol TE g-1 and 126.92 mmol TE g-1. The content of total phenolic compounds in kombucha varied between 1.58 and 1.68 mg GAE mL-1. For green tea and passion fruit pulp, the content of total phenolic compounds was 158.00 mg GAE g-1 and 6.05 mg GAE g-1. Acetic bacteria counts ranged from 1.6x106 CFU mL-1 to 1.6x1019 CFU mL-1. For lactic acid bacteria, it was possible to count from the 12th day, determining 5.5x103 to 2.6x105 CFU mL-1. Lactic acid bacteria increased up to the 45th day, decreasing after this period, reaching 7.1x103 CFU mL-1 at the end of the testing period. The yeast count started from the 7th day, the values varied between 3.2x103 to 3.4x105 CFU mL-1, and from the 30th day onwards, the yeasts decreased, reaching the end of the study with 3.2x103 CFU mL-1. The total acidity of the kombucha increased, ranging from 0.10 to 0.57% acetic acid, while the pH decreased from 3.93 to 3.12. Acetic bacteria were predominant in kombucha throughout the period evaluated, while there was a gradual decrease in lactic acid bacteria and yeasts throughout the storage period. The pH of the drink remained by current legislation and the total acidity stabilized at the end of the study. The presence of total phenolic compounds with antioxidant activity and a high concentration of probiotic microorganisms such as acetic and lactic acid bacteria and yeast make kombucha an excellent functional food.