Screening Of Phytic Acid-degrading Yeast In Jiaozi And Its Characteristics Of Fermented Whole Wheat Steamed Bread Dough

Phytic acid is the main storage form of phosphorus in plant seeds.It has strong electronegativity and can form complexes with proteins and minerals,reducing its bioavailability.The human body lacks enzymes that can hydrolyze phytate,so it is for humans.Phytic acid is an anti-nutritional substance.There are many methods for phytic acid degradation in food.Fermenting whole wheat dough with yeast with phytic acid degradation ability is an effective method to reduce phytate content in whole wheat food.In this study,yeasts with phytic acid degradation ability were screened out from the yeast,and the phytic acid degradation characteristics and characteristics of the fermented whole wheat dough were studied to develop strain resources capable of reducing the phytic acid content of whole wheat food.And provide a reference for improving the nutritional value of whole wheat food.An strain of Wickerhamomyces anomalus P4 and a strain of Saccharomyces cerevisiae P19 with phytic acid degradation ability were obtained from the yeast and whole wheat dough by separation and screening.The extracellular phytase activities were 18.52 U/mL and 19.74 U/mL,respectively,and the intracellular phytase activities were 0.5 U/mg and1.36 U/mg.The two strains of yeast were cultured in the medium with phytic acid as the phosphorus source.It was found that the phytic acid degradation rate of the medium inoculated with yeast P4 was 72.8%,and the phytic acid degradation rate of the medium inoculated with yeast P19 was up to 89.3%.The yeast was inoculated into different concentrations of phytic acid solution to simulate the phytic acid degradation curve,and it was found that the degradation of phytic acid in the solution accorded with the first-order reaction of degradation kinetics.The yeasts P4 and P19 were used as fermenting agents to ferment the whole wheat dough.It was found that the fermenting power and gas producing capacity of the yeast were P19>P4,and the reducing sugar content in the dough fermentation process was P4>P19.The phytic acid degradation rates of the whole wheat dough after the dough was found to be8 h after fermentation were 25.5%and 36.8%,respectively.Phytic acid can affect the quality of the dough by affecting the protein properties of the dough.The content of SDS-unextractable protein which is closely related to the quality of the dough after P4 and P19 whole wheat dough fermentation is significantly higher than that of the control group（p<0.05）;whole wheat dough During the fermentation process,the combined water content is reduced,and the semi-bound water and free water content are increased.The internal structure of the dough was observed by scanning electron microscopy.It was found that the internal protein structure of the dough gradually formed during the fermentation process,indicating that the two P4 and P19 degrade the phytic acid during the dough fermentation process and improve the dough characteristics.The concentration of Fe²⁺,Zn²⁺and Mg²⁺in the whole wheat dough was increased by 38.7%,13.7%and 3.4%after fermentation for 12h with P4 as the starter.The concentration of Fe²⁺,Zn²⁺and Mg²⁺increased by 66.1%after P19 fermented whole wheat dough for 12 h,respectively.10.4%and 18.1%,indicating that yeast P4 and P19 have the potential to improve the nutritional properties of whole wheat steamed bread.Using two strains of yeast to make steamed bread,it was found that the hardness,elasticity and chewiness of the steamed bread made by P4 were higher than that of P19 steamed bread,and the specific volume was smaller than that of P19 steamed bread,indicating that the quality of the steamed bread made by yeast P19 was better than that of P4 steamed bread,and the steamed bread made by P4 and P19.The specific volume is smaller than the steamed bread made by Commercial Yeast,but its specific volume is greater than 1.7,in line with national standards.