Physical and antimicrobial characterization of bacterial cellulose obtained by green tea fermentation

Kombucha je osvježavajući napitak koji se dobiva fermentacijom zaslađenog čaja ili voćnih napitaka zahvaljujući snažnom simbiotičkom djelovanju bakterija octene kiseline i kvasaca. U radu je proučavano nastajanje octene i glukonske kiseline, etanola i bakterijske celuloze biotransformacijom kombuche u zelenom čaju zaslađenim saharozom (60, 80 i 100 g/L). Promjene pH vrijednosti posljedica su simbiotičke metaboličke aktivnosti osmofilnih kvasaca i bakterija octene kiseline i smanjivale su se s nastajanjem organskih kiselina. Analiziranjem uzoraka pomoću FT-IR spektroskopije, XRD analize i SEM pretraživanja, otkriveno je da su svi uzorci imali veći postotak amorfne strukture, a ne kristalične, kako je očekivano. Debljina i prinos bakterijske celuloze povećavali su se tijekom vremena fermentacije. Najveći prinos bakterijske celuloze bio je pri 100 g/L saharoze (143.66 %). Dobiveni rezultati ovog istraživanja ukazuju da maksimalni prinos bakterijske celuloze ovisi o mnogo čimbenika koje još treba dodatno optimizirati.Kombucha is a traditional refreshing beverage obtained by the fermentation of sweetened tea with a powerful symbiosis of acetic bacteria and yeasts. The production of acetic and gluconic acids, ethanol and bacterial cellulose by biotransformation of kombucha, in green tea sweetened with sucrose (60, 80 and 100 g/L) was studied. Changes in pH were related to the symbiotic metabolic activities of yeasts and acetic acid bacteria, and it is decreased by the formation of organic acids. Analysing samples by FT-IR spectroscopy, XRD analysis and scanning electron microscopy, it was detected that all the samples had higher precentage of amorphous regions, than crystalline regions, as it was expected. The thickness and yield of bacterial cellulose in creased with fermentation time. The highest yield of bacterial cellulose obtained was 120,27% (100 g/L). Findings from this study suggest that the yield of cellulose depends on many factors that need to be optimized to achieve maximum yield