Fermentação de matcha e água de arroz com kombucha: avaliação da concentração de compostos fenólicos e atividades antioxidantes para aplicação cosmética

Abstract

Given the growing consumer awareness of the impact of cosmetics on skin health and the environment, the cosmetic industry has intensified the search for natural and sustainable formulations. In this context, the aim of this study was to evaluate the antioxidant potential and total phenolic content of samples fermented with the symbiotic culture of bacteria and yeasts (SCOBY) from kombucha, using matcha, green tea, and rice, with a focus on their application as cosmetic actives. The research builds on previous studies developed at the Bioprocesses Laboratory 2 of the Federal University of Technology - Paraná, Ponta Grossa campus (UTFPR-PG), which investigate kombucha as a promising biotechnological ingredient for skin care. Five infusions were tested: matcha, green tea, matcha with rice, rice with green tea, and rice water. Matcha was selected for its high catechin content and recognized antioxidant activity, while rice was included for its moisturizing and soothing properties, traditionally used in Asian cosmetology. The samples underwent a 21-day fermentation process, and the final fermentate was evaluated for its antioxidant potential using the DPPH method and the Folin-Ciocalteu assay (total phenolic content quantification, using gallic acid as standard). The matcha control sample (MC) showed the best antioxidant performance, reaching 94.23% inhibition at a concentration of 60 μL, along with high phenolic content (GAE ≈ 139 μg/mL). In contrast, the rice water fermentate presented the lowest phenolic content (24.80 μg/mL), which can be explained by the removal of the outer layers in polished rice. The presence of rice influenced the color and absorbance of the samples, possibly due to starch, without completely compromising antioxidant activity. Although rice did not enhance the antioxidant potential or phenolic content of the fermentate, it remains an ingredient of interest in cosmetology, potentially offering benefits such as hydration and soothing effects, which were not measured in this study but reinforce its complementary potential for dermatological use. It is concluded that the fermentation of matcha infusion with SCOBY is highly effective for developing natural, sustainable, and functional cosmetic actives, combining biotechnology and plant-based ingredients with high functional value.