Abstract:

Oat flour was fermented solely with two species of lactic acid bacteria, Lactobacillus plantarum (L.p) and Lactobacillus sanfrancisco (L.s) in order to analyze the changes in physio-chemical and thermaldynamic properties of oat starch during lactic acid bacterial (LAB) fermentation. Fermentation with each of the two stains resulted in a decrease in pH, and L.p -fermented oat flour exhibited a faster pH drop and lager amount of acid production when compared to L.s-fermented one, but similar pH values were observed in the late period of fermentation. For both L.p- and L.s-fermented oat flours, solubility and swelling power increased with increasing temperature. For oat flour fermented by one strain, the two parameters at different temperatures both had different change trends as fermentation time increased. L.p-fermented oat flour had lower swelling power but higher solubility than its L.s-fermented counterpart. The results obtained from rapid viscosity analyzer (RVA) and differential scanning calorimetry (DSC) showed that the peak viscosity of fermented oat starch decreased as fermentation time increased, and after fermentation, oat starch had lower onset gelatinization temperature, required longer time for gelatinization, presented higher gelatinization enthalpy, and L.s-fermented oat starch had higher gelatinization enthalpy than L.p-fermented one. Oat starch presented an increasing trend in amylose content during fermentation, and L.p-fermented oat starch had higher amylose content at 6 and 12 hours of fermentation when compared to L.s-fermented one, but the amylose content of the former was slightly lower than that of the latter at 24 hours.

Key words: lactic acid bacteria, fermentation, oat starch, gelatinization, amylose content