Desenvolvimento de celulose bacteriana: otimização do processo e avaliação das propriedades físico-químicas

Abstract

Kombucha is a traditional Chinese fermented beverage produced by fermenting black or green tea (Camellia sinensis) using a symbiotic culture of bacteria and yeast (SCOBY) in a nutrient-rich medium for approximately 7 to 10 days. The bacterial cellulose (BC) membrane produced during the fermentation process is currently the subject of extensive research due to its various applications; however, its production is still time-consuming and costly. In this context, this study aimed to optimize the production of BC and characterize the medium and BC. The following factors were analyzed as hypotheses to maximize BC growth: coffee grounds, green tea, vitamin complex, sucrose, SCOBY size, incubation time, and kombucha. The Plackett-Burman and Box-Behnken experimental designs were employed to optimize the culture medium, with BC production (g cellulose/day.L) used as the evaluation parameter. The results indicated that sucrose at a higher level, kombucha at a higher level, and SCOBY size at a lower level were the most significant factors in BC production compared to others. The production in the optimized medium was approximately 86.7% more efficient than the basic green tea medium. The optimized medium was analyzed for fermentation kinetics over a period of 7 days. At the end of fermentation, there was an 80% increase in total phenolic concentration and a 22.5% increase in total flavonoids. It also exhibited relevant levels of antioxidant activity with 943.50 μM for DPPH and 2789.00 μM for ABTS. Furthermore, the pure BC produced showed high water absorption capacity (524.45%), enabling the adsorption of phenolics from the membrane in a green tea medium, which allowed the maintenance of bioactive compounds even after membrane purification. As a result, the optimized medium showed potential for the production of kombucha-like beverages rich in bioactive compounds, as well as for the more productive and efficient production of BC, serving as a potential adsorbent for phenolics.