Research On Improvement Of Corn Food Performance By Combined Microorganism Co-fermentation

As one of the most widely distributed crops on the planet,maize is nutritious and cheaply available.However,the composition and processing characteristics of maize greatly limit the development of maize for food processing and high value-added product applications.Therefore,it is necessary to use microbial fermentation methods that can effectively improve the nutritional value and processing properties of maize in order to increase its added value.In this study,double strains of yeast and lactic acid bacteria were used for solid state fermentation of corn flour,and the fermentation process conditions were optimized at first.Then the changes of nutritional components and physical and chemical processing characteristics of corn flour before and after fermentation were measured and compared,and the influence of double strains of yeast and lactic acid bacteria fermentation on corn flour was understand.Finally,the corn flour before and after fermentation was used to make corn cakes and croissants,and the sensory evaluation was made.To provide sufficient theoretical basis for the application and development of corn meal.The results are shown as follows:4 yeast strains which named as YS,QS,AD and HM were isolated from the instant high active dry yeast of Yan Shan,Qixin,SAF and Hodgson Mill,respectively,and AD was selected as the target strain by sniffing and the determination of growth ability on corn meal and the experiment of gas production.Moreover,2 strains which named as BJ and SR were isolated from Angel yoghurt starter,and SR was selected as the target strain by determination the ability of acid production and growth ability on corn meal.In the process study of two-strain solid fermentation of maize flour,the single-factor test was done by the concentration of AD and SR fermentation broth,the fermentation time and the fermentation temperature taken as four factors,and the degradation rate of corn starch after fermentation taken as the index,separately.In single factor experiment,the optimum concentration of AD and SR were 8% and 6%,with optimum fermentation temperature 33?after 60 hours,respectively.Through the orthogonal experiment results can be seen,on the impact of various factors on corn flour degradation rate is significant to AD strains fermented liquid concentration > SR fermented liquid concentration > fermentation temperature >fermentation time and obtain the best concentration of the optimum process for AD strains fermented liquid of 8%,the optimal concentration of 6% fermented liquid,the SR strain for33 ? fermentation temperature,fermentation time of 72 h.Under this condition,the degradation rate of corn meal was 30.06%.After fermentation,the content of amylose,soluble sugar and reducing sugar in corn meal increased by 36.05%,69.12% and 68.19%,and the content of small molecular peptide was 11.48 times of the original,while the relative contents of other basic components decreased to different degrees.The starch molecules had more hydrogen bond due to the increase of amylose,which increased the cohesion of corn flour.The water holding capacity of corn meal decreased by 33.88%,and the gel strength increased by 29.38%.After fermentation,the gelatinization characteristics of corn flour are more similar to that of starch,and there are more obvious endothermic peaks in the gelatinization process,and the total endothermic enthalpy increases by 10.42%.The decay value and regenerative value decreased by 29.67% and 37.59% respectively during the gelatinization process,which proved that the fermented corn meal had better thermal stability and anti-regenerative ability.The content of aflatoxin in corn meal decreased during lactic acid bacteria fermentation.The results showed that the solid fermentation method could significantly improve the nutritional structure and processing properties of corn flour,and the dual strain fermentation of AD and SR strains was a safe and effective processing method.The texture characteristics and sensory evaluation of whole corn cake and whole corn croissant made from corn meal before and after fermentation were superior to those of unfermented group.