Produção de bebidas fermentadas do tipo kombucha: estabilização da cultura starter e uso de matérias-primas alternativas

Abstract

The growing consumer awareness of the relationship between diet and health has increased the demand for functional foods that provide bioactive compounds besides nutritional ingredients. In this context, kombucha, a beverage produced by fermenting sweetened teas by a microbial community, has gained popularity with market growth projections worldwide. However, there are still challenges regarding the standardization of production and stabilization of starter cultures, as well as the lack of alternative methods that utilize local and abundant raw materials, such as agricultural by-products, to diversify the sensory and bioactive profile of the beverage. This study aimed to contribute to the advancement of knowledge on kombucha production by addressing (1) the stabilization of starter culture by spray drying and freezedrying techniques, and (2) the use of alternative fermentation substrates, such as the infusion of passion fruit leaves (Passiflora edulis). In the first study, the impact of spray and freeze-drying techniques using maltodextrin and gum Arabic as encapsulating agents, was evaluated on the physicochemical properties of kombucha powders and the viability of the starter culture. Analyses included moisture content, water activity, hygroscopicity, solubility, scanning electron microscopy (SEM), X-ray diffraction (XRD), metabolic activity (fermentation metabolites and viable cells), and phytochemical profile (total phenolic compounds and antioxidant activity). Results showed that kombucha powders had suitable physicochemical characteristics and preserved microbial viability after drying. Freeze-dried powders, in particular, had better preserved microbial viability and metabolic activity, resulting in higher acetic acid production during fermentation. Gum Arabic proved to be effective in protecting microbial cells during spray drying, indicating potential for industrial applications. In the second study, the potential of passion fruit leaves as an alternative substrate for kombucha production was investigated by characterizing the beverage in terms of chemical profile, antioxidant activity, and sensory acceptance. The kombucha produced with passion fruit leaves had a chemical profile that complied with legal standards (alcohol content below 0.5% v/v), along with higher concentrations of phenolic compounds, flavonoids, and antioxidant activity after fermentation. Sensory acceptance was comparable to that of traditional kombucha (made with green tea), demonstrating its potential for market application. Taken altogether, our study delivers effective techniques for stabilizing kombucha microbial community with potential contribution to process standardization, besides showing the viability of valorizing agricultural by-products to provide diversification of kombucha’s sensory and bioactive profile. These technological data are fundamental for the development of the kombucha industry that is aligned with new consumer demands and market trends that value health and innovation.