Résumé
Phytase activity was studied in natural sourdough bread starters to determine physicochemical characteristics [phytic acid hydrolysis, dough rising capacity and pH] in the flour and during sourdough fermentation. Fermentation microorganisms [yeasts and lactic acid bacteria] were also characterized. Results showed a decrease of phytic acid in sourdoughs started with traditional starters, and wide variation in phytase activity. Microorganism counts were high at the end of fermentation, indicating higher fermenting activity of the starters. Yeast populations showed wide variation and lactic acid bacteria had high counts in the fermentation. Phytase activity was demonstrated in starter cultures made of lactic acid bacteria and yeast isolates, the most interesting of which were Saccharomyces cerevisiae combined with Lactobacillus plantarum and Leuconostoc mesenteroides