6533b7d8fe1ef96bd126b43c

RESEARCH PRODUCT

Study of microbial dynamics for the control of Kombucha production

subject

description

Kombucha is a fermented beverage obtained from the transformation of sugared tea infusion through the activity of a consortium of yeasts and bacteria, during which a cellulosic biofilm is formed. The study of microbial interaction that occur in this matrix aims at improving the control over the production process at industrial scale. The methodology used in this work is mainly based on the isolation and selection of yeasts and acetic acid bacteria from a determined kombucha consortium. The selected microorganisms are then used to inoculate monocultures and cocultures in sugared black tea. Different parameters were followed at the microbiological level (population counts, composition in genera and species), at the chemical level (composition in sugars, organic acids, amino acids, proteins, volatile compounds, oxygen) and at the sensory level (gustative and olfactive descriptions). Results point towards the essential role of yeast-acetic acid bacteria association during the production process of kombucha, regarding both volatile and non-volatile compositions. They underline specifically the importance of yeast metabolism in those transformations. The matrix also plays a determining role in the chemical composition and organoleptic profile of kombucha because of its abundance in carbon substrates and its poorness in nitrogenous substrates. The kombucha biofilm possesses a strong relationship with microbial interactions, both regarding its formation and its function. However, it is not mandatory for the essential microbial activities involved in the beverage’s production to occur. Highlighted interactions, including commensalisms and competitions, form as a whole a mutualistic system of interactions between kombucha yeasts and acetic acid bacteria.