To Study The Effect Of The The Ability Of Lactobacillus Paracasei L1Combined With Starch On Producing Amylase Activity Changing Of Starch Properties

AbjectiveThis topic to research Lactobacillus paracasei L1combined with starch onstarch have an effect on metabolicing starch. Discuss Lactobacillus paracaseiL1‘s ability of combine with starch have influence of the productive amylaseactivity and the influence of chemical and thermodynamic properties of starchafter.MethodsThrough single factor and orthogonal experiments, the condition forenzyme production was optimized. L1mutant strains are obtained by ultravioletmutation does not have the activity of starch in combination with strain. L1mutant strains and L1wild strains fermentation with starch, and then analysis ofamylase activity and starch chemical and thermodynamic properties.ResultsThrough single factor and orthogonal experiments, the condition of enzymeproduction was optimized. The result showed that the Lactobacillus paracaseiL1could produce the highest amount of amylase when the initial culturemedium pH was4.0, culture temperature was42℃,6%of potato starch wastaken as carbon resource and when it was cultured96h. The amylase produced by Lactobacillus paracasi L1has relevant high activity under acidic conditions.The amylase activity was highest when the pH was4.0,and the optimumreaction temperature for the amylase was40℃.Under this conditions, thehighest activity of amylase could reach102.95U/mL. Lactobacillus paracasei L1which used starch without gelatinizing could produce more amylase than whichof using starch with gelatinizing. That means Lactobacillus paracasei L1coulduse raw starch to produce amylase.L1mutant strains are obtained by ultraviolet mutation does not have theactivity of starch in combination with strain. L1mutant strains and L1wild strainsfermentation with starch, and then analysis of amylase activity and starchchemical and thermodynamic properties. The experiments show: L1wild strainsto produce amylase activity up to102.95U/mL is significantly higher than15.67%of the L1mutant strains. After fermentation, starch physical andthermodynamic properties change, including L1wild strains fermentation ofstarch amylose content is higher than that of L1mutant strains; Under the sametemperature, with the increase of fermentation time, increased starch solubility,swelling degrees after the first decreases with increasing fermentation timeincreases, the L1wild strains fermentation starch solubility and swelling degreeof change is more obvious; The transparency of starch paste drop fellsignificantly than L1mutant strains; The L1wild strains fermentation starchretrogradation, gel structure characteristics, RVA properties change than L1mutant strains fermentation starch is obvious.ConclusionsLactobacillus paracasei L1in combination with starch can be added toproduce amylase activity and good for the changing nature of the starch.