Biodegradation of tannic acid in an in vitro ruminal system

The microbial degradation of tannic acid by ruminal fluid of cattle which had no prior exposure to tannin-rich diets, was studied in an in vitro syringe system. Tannic acid caused an increase in the gas volume and a decrease in the ammonia concentration of the buffered rumen liquor during incubation for 24-72 h. The fermentation products from tannic acid were gallic acid, pyrogallol and resorcinol. This is the first report on the ability of ruminal fluid taken from cattle unexposed and unadapted to tanniniferous diets to degrade tannic acid into simpler products. (C) 2001 Elsevier Science B.V. All rights reserved.