Solid State Fermentation Of Corn Flour By Rhizopus Oryzae And Lactobacillus And Change Of Its Physicochemical And Processing Properties

In this study,corn flour was fermented in solid state by mixing Rhizopus Oryzae and Lactobacillus in optimized fermentation conditions.Effect of fermentation on corn meal could be understood by comparison of physicochemical properties and components of corn meal before and after fermentation.Finally,the fermented corn flour and wheat flour were mixed to make corn cake.The main results were as follows:In the study of solid-state fermentation of corn flour with mixed bacteria,the viscosity of corn dough was used as an index to observe whether the processability was improved;the four influencing factors of the concentration of Lactobacillus fermentation liquid,the adding amount of Rhizopus Oryzae,fermentation temperature and fermentation time were used to measure the fermentation effect.In the single factor experiment,the optimal concentration of Lactobacillus fermentation liquid is 15%,the optimal adding amount of Rhizopus Oryzae is 1.5mg/g,the optimal fermentation temperature was 32 ?,and the optimal fermentation time was 72 h.Through the results of orthogonal experiment,it could be seen that the significant effect of each factor on the viscosity of corn dough is Rhizopus Oryzae adding amount > Lactobacillus fermentation liquid concentration > fermentation temperature > fermentation time,and the optimal technology was obtained The results showed that the concentration of Lactobacillus fermentation liquid was 15%,the addition of Rhizopus Oryzae was 1.5mg/g,the fermentation time was 60 h,and the fermentation temperature was 30 ?.Under these conditions,the viscosity of corn dough was 32.6mJ,which was 4.8 times higher than that of unfermented corn dough.After fermentation,the water holding capacity of rice noodles decreased by 32% and the gel power increased by 12% after fermentation.As the relative content of starch increased,the pasting properties of fermented maize flour also tended to starch,with more obvious endothermic peaks and the total enthalpy of heat absorption increased by 30%.The decay value and regeneration value decreased by 23% and 34%,higher total endothermic enthalpy.The attenuation value and regeneration value decreased during gelatinization process,which proved that the fermented maize flour had better thermal stability and anti-regeneration.It had been improved that the texture indexes and creep-recovery of the fermented maize dough characteristics,which was more conducive to food processing.After fermentation,the relative content of starch in corn flour increased by 27.8%,among which the amylose content increased by 8.7%,and the relative content of other components decreased to different degrees.Through the changes of molecular structure of zein before and after fermentation,it could be seen that after fermentation,the proportion of alpha-helix and beta-turn in gluten molecule increased,and the structure of starch was more stable;molecules show more hydrogen bonding due to the increase of amylose,which in turn increases the cohesiveness of corn flour.In texture and sensory evaluation,the fermented group was better than the unfermented group.