Influence of different sugars on the metabolism of the tea fungus

Abstract

The tea fungus is a symbiosis of osmophilic yeasts (mainlySchizosaccharomyces pombe, Saccharomycodes ludwigii, Pichia spec.) and acetic acid bacteria (Acetobacter xylinum, A. xylinoides, Bacterium gluconicum) used to produce teakwass with sugared black tea as substrate. The influence of the following sugars on the production of ethanol and lactic acid was studied using enzymatic tests: sucrose, lactose, glucose and fructose. Maximal yields of ethanol were recorded with 150 g fructose/l (8.11 g ethanol/l and 50 g sucrose/l (6.3 g ethanol/l). Lactose and glucose yielded only minor amounts of ethanol. Lactic acid was produced in relatively high concentrations with 50 sucrose/l (0.9 g acid/l); the other sugars in all tested concentrations stimulated the synthesis of this acid only to a moderate degree. The pH values of the teakwass preparations generally dropped during incubation as a result of acid formation. Test persons estimated the teakwass products as refreshing with a fruitlike taste within 6 to 10 days of incubation; prolongation of fermentation yielded a distinctly sour flavour like vinegar.