INFLUENCE OF WHEAT-FLOUR AND LACTOBACILLUS STRAINS ON THE DYNAMICS OFBY-PRODUCTS FROM AMYLOLYTIC ACTIVITIES

Amylolytic activity of six flours from three European wheat cultivars (Obelisk, Camp Remy and Fresco, at 70 and 100% extraction level), and five lactobacilli strains (Lactobacillus plantarium B-39, L-73; L. bre vis 25a, L-62, and L. sanfrancisco L-99), as well as the dynamics of b y-products from amylolytic degrading action in mixed flour-lactobacill i systems have been investigated. alpha-Amylase activity of flours dep ended on ash content; whole flours from the three cultivars had simila r values, which were of the order of three to ten times that of white flours. L. sanfrancisco showed the lowest alpha-amylase activity, and L. plantarum the highest. At the concentrations of lactobacilli used i n sourdough processes, flour was the main contributor to final ol-amyl ase action in flour-lactobacilli mixtures. Production of monosaccharid es followed variable trends, depending on the extraction level of the flour and on the Lactobacillus strain. The dynamics of monosaccharides , due to their active and variable involvement in metabolic pathways, could not be adjusted to model regression equations. Maltose levels in creased during fermentation, although an effective incorporation in La ctobacillus metabolism was observed. A second order polynomy could be used to describe changes in maltose. Low molecular weight dextrins (LM WD) with degrees of polymerization (DP) from three to seven, only appe ared and accumulated during the late stages of fermentation. LMWD with a DP of three was the only oligosaccharide capable of being incorpora ted by lactobacilli, and, of the strains tested, only by L. brevis (25 a). The larger dextrins seemed to be involved in further degrading enz ymic reactions yielding smaller size fragments. Dynamics of LMWD follo wed exponential curves, with highly significant regression coefficient s.