Application of lactic acid and acetic acid bacteria for production of alcohol-free fermented beveragesRovtar, Barbara (Avtor) Čadež, Neža (Mentor) O Sullivan, Tadhg (Komentor) lactic acid bacteriaacetic acid bacteriaalcohol-free beverageslow-alcohol beveragesfermentationunhopped worthopped wortwater kefirlactic acidgluconic acidThe main goal of the master thesis was to evaluate the possibility to isolate new strains from complex microbial communities and their use in controlled fermentation processes to create novel alcohol free or low-alcohol beverages. The methods used were metagenomics for characterization of the microbial communities of water kefir and molecular identification of isolated colonies. Next steps were focused to characterize and compare the identified bacteria from water kefir to the commercially available lactic acid bacteria (LAB) and acetic acid bacteria (AAB). Further, some of the selected LAB and AAB strains were used for fermentation of (un)hopped wort to produce alcohol free and low-alcohol beverages. Low-alcohol beverages were created with sequential fermentations using non-maltose fermenting strains of Saccharomyces cerevisiae. To create more complex flavor of the products, apple juice was also fermented using strains of AAB and then blended with the fermented unhopped wort by LAB strains. The results showed that isolated water kefir strains were not better for wort fermentation than commercially available lyophilized strains and that the primary fermentation did not have a significant effect on the production of aroma compounds (e.g. esters) during secondary fermentation when sequential fermentations were performed. AAB isolated from water kefir had better sensory characteristic than the AAB strains from laboratory collection. The results showed that novel strains can be isolated from complex microbial communities and used in controlled fermentations processes for production of novel beverages.[B. Rovtar]20212021-06-12 07:15:09Magistrsko delo/naloga127526UDK: 663.8+663.15:579.67VisID: 191241COBISS_ID: 66773507sl