In foods, tannins are considered nutritionally undesirable. Spectrophotometric methods have been used to detect tannin degradation by L. plantarum strains isolated from food substrates. Enzymatic degradation of tannic acid by L. plantarum CECT 748T was examined in liquid cultures and in cell-free extracts by HPLC. Significative reduction of tannic acid was not observed during incubation in the presence of L. plantarum cells after 7 days incubation. However, tannic acid was effectively degraded by cell-free extracts of L. plantarum during 16 h incubation. We have partially characterized L. plantarum tannase activity by measuring its esterase activity on methyl gallate. Tannase activity was optimal at pH 5.0 and 30 degrees C, and showed nearly 75% of the maximal activity at 50 degrees C. The biochemical characteristics showed by L. plantarum tannase are considered favourable for tannin biodegradation in the food-processing industry.