Response surface optimization of kombucha fermentation to enhance bacterial cellulose yield and its physicochemical, mechanical, and structural properties
摘要
Kombucha is a fermented tea beverage obtained through the metabolic activity of a symbiotic culture of acetic acid bacteria and yeasts (SCOBY). During fermentation, specific bacterial strains, particularly Komagataeibacter xylinus, synthesize bacterial cellulose (BC), an extracellular biopolymer with high purity, crystallinity, and biocompatibility. This study aimed to optimize the fermentation parameters to enhance BC yield and improve its physicochemical, mechanical, and structural properties. A central composite design based on response surface methodology was applied to evaluate the effects of starter tea volume (18–54 mL), glucose concentration (18–36 g), and fermentation temperature (25–35 °C) on key response variables. The production yields of SCOBY (wet basis) and purified BC (dry basis) were assessed, along with swelling capacity, water dispersion, water vapor permeability, tensile strength, percent elongation, and crystallinity. Individual and simultaneous optimizations were performed. The best individual condition yielded 65.14 g/L of SCOBY and 2.70 g/L of BC, using 5.72 mL of starter tea and 29.04 g of glucose. Simultaneous optimization resulted in 70 g/L of SCOBY and 2.94 g/L of BC with 66.27 mL of starter tea, 22.37 g of glucose, and 38.4 °C. The optimized BC exhibited favorable properties: tensile strength (4 MPa), elongation (3.8%), swelling capacity (400%), water vapor permeability (27 g·s⁻1·m⁻1·MPa⁻1), and crystallinity (59.89%). These findings demonstrate the feasibility of tailoring kombucha fermentation to obtain BC with promising functional characteristics for applications in agriculture, cosmetics, and biomaterials.