IMPACT OF THE DRYING METHOD ON THE PHYSICAL CHARACTERISTICS OF BACTERIAL CELLULOSE BIOFILM FROM SCOBY

SCOBY (Symbiotic Culture Of Bacteria And Yeasts) is the symbiotic colony responsible for kombucha's production. Its biomass grows during fermentation, whose surplus generates waste and can be used via dehydration processes as a biomaterial (manufacture of shoes, clothing, vegan leather, packaging and food ingredients). This study aimed to dehydrate SCOBY via cast-tape drying and convective oven drying at different temperatures and thicknesses to evaluate its impact on the physical characteristics of this biomaterial. The surplus SCOBY from kombucha fermentations was obtained, sanitized and crushed with water and spread on a flat surface for dehydration. To this end, an orthogonal central composite design 3² was applied, whose independent variables were drying temperature (65 °C, 75 °C and 85 °C) and biofilm thickness (3 mm, 4 mm and 5 mm), and its impact on the final thickness and color parameters (L*, a*, b*) and ΔE via convective drying - CD and cast tape drying - CTD. For the data obtained after the orthogonal PCC 3², the main effects and interactions of the variables were analyzed, determining the significant factors (p ≤0.10) and adjusting a second-order model to correlate the variables and their responses. According to the regression equations, CD showed a greater influence on the final thickness, a*, b*, with higher coefficients of determination (R²) (0.99). On the other hand, the CTD presented low values of R² for L* and a* (0.62 and 0.68), highlighting the final thickness and moisture as the most significant variables in this method (0.97 and 0.94).Regarding the final thickness, this was notably impacted by the three individual factors (temperature, thickness and drying method), as well as by the interaction between temperature and drying method. CD produced thicker biofilms (0.30 mm to 0.64 mm) than those produced by CTD (0.20 mm to 0.34 mm), indicating the influence of the different mass transfer mechanisms involved in the water exit from the samples. In addition, the drying method also impacted the color parameters, with CD exerting a more pronounced influence compared to CTD, in addition to the influence of higher temperatures on the color differences of the biofilms. It was concluded that the drying methods, temperature and initial thickness influenced all the parameters evaluated. However, CTD produced thinner biofilms and less impacted the color variation in the samples, which may be positive in their production.