Caracterização e extração de filmes de celulose bacteriana a partir do scoby da kombucha

Abstract

Cellulose can be obtained from plants, microorganisms or representatives of the phylum Chordata. Its obtainment in large quantities and the search for alternative sources of production have been widely studied. Starting from this point, the present dissertation aims to extract bacterial cellulose from the SCOBY of kombucha and characterize it. SCOBY is a microbial consortium, consisting of bacteria and yeasts capable of producing cellulose. The methodology is divided into two phases. For the production of teas used in kombucha, in both phases, 20 g of green tea was infused in 2 L of boiling water for 10 minutes, with 100 g of crystal sugar being added at the end. In the first phase, to obtain bacterial cellulose, the fermentation process was carried out using SCOBY of pre-existing fermentation. Every 14 days, the formed son SCOBY was removed and submitted to the bleaching process. For the bleaching process, sodium hypochlorite (NaClO) and hydrogen peroxide (H2O2) were used. In the first phase, 10 fermentations were carried out, with 10 different bleaching processes, with the amount of NaClO varying between 50 mL and 500 mL and of H2O2 varying between 100 mL and 500 mL. For the characterization of the films obtained, the bacterial cellulose yield in percentage and in mass was evaluated, correlating to visual aspects such as conformation, malleability, integrity and coloration of the same, in which the best result was obtained in bleaching 5, with yield of 20.97% and 68.76 g of cellulose extracted. In addition, FT-IR and DSC analyzes were also carried out, seeking to verify the efficiency of the bleaching and pulp extraction process. In the second phase, based on the results obtained in the first phase, the standardization of the beginning of fermentation was carried out from an inoculum, the thickness of the films removed from such a process between 5-6 mm and the amount of NaClO and H2O added in the bleaching process at 500 mL/300 mL, in addition to the study of two variables: amount of H2O2 used in bleaching and drying temperature of the films. 4 fermentation processes were carried out, with 4 bleaching processes and different drying temperatures. For the characterization of the films, analysis of yield in percentage and mass was carried out, observing visual aspects such as conformation, integrity and malleability, in which the best result was obtained in sample 2 with extraction of 15.72% and 44.46 g of cellulose. In addition, instrumental analyzes of DSC, FT-IR, DRX and SEM were performed, aiming to evaluate the purity of the material obtained, obtaining better results in sample 4. And the analysis of instrumental color, degree of swelling and permeability to vapor of water, thinking about future commercial applications, with better results obtained in sample 3. It was concluded that, depending on what purpose the bacterial cellulose will be extracted: high quantity/yield, commercial application or high purity, the parameters used in the bleaching and drying process.