Study On Flavor And Edible Quality Of Soybean Dregs Modified By Fungus And Bacteria Fermentation

Soybean dregs are processed byproducts of traditional soy products such as soy milk,tofu and dried tofu.Although bean dregs are rich in nutrients,only a small amount of bean dregs are consumed as food.This is mainly due to the coarse taste and poor flavor of bean dregs,especially the flavor of bean smell and grass,which limits the use of bean dregs as food and in processed foods.In order to effectively utilize soybean dregs and reduce resource waste,this study took soybean dregs as raw material,aimed at improving flavor and quality,and made biological modification of soybean dregs through microbial fermentation,so as to provide support for the application of soybean dregs in food and processed food.The main research contents are as follows:1.Optimization of microbial fermentation modified soybean residue process(1)Majorization of fungal fermentation of soybean dregs: select two fungi(M and A),and conduct single-factor experiments in biologically modified soybean dregs.The change trend of the content of taste quality indicators such as total acid and reducing sugar.At this time,the fermentation sample of M is the best;when the fermentation time of A is 2.77 d,fermentation The temperature is 28.55 ?,the water content is69.49%,the inoculation amount is 2.71%,and the expected satisfaction is 64.56%.At this time,the sample of microbial fermentation modified soybean dregs A is the best.(2)Majorization of the fermentation process of soybean dregs with fungi combined with bacteria: select two bacteria(L and B).The satisfaction function was used to optimize the fermentation conditions,and the measure of the amount of self-transformation in a single factor were tested by a single factor.When the fermentation time of ML is 2.08 d,temperature is 42?,the water content is 68.03%,the inoculum amount is 2.84%,and the expected satisfaction function is 71.23%,the fermented bean dregs sample ML is the best;when the fermentation time of AL is 3.56 d,temperature is 38.34?,the inoculum amount is 1.80%,the water content is 59.42%,and the expected satisfaction value is 85.5%.At this time,the fermented bean dregs sample AL is the best;when the fermentation time of MB is 2.9 d,temperature is39.74?,and the water content is 51.26 %,the inoculation amount is 2.97%,and the expected satisfaction function is 93.67%.At this time,the fermented bean dregssample MB is the best;when the fermentation time of AB is 2.10 d,temperature is 39.88?,inoculation amount is 1.95%,water content is 50.49%,it is expected The satisfaction value is 77.2%,and the fermented bean dreg sample AB is the best.2.Comparative analysis of biologically modified soybean dregs by microbial fermentationThe modified soybean dregs were prepared under the above-mentioned optimized conditions,including the fermented soybean dregs modified by fungi(M and A)and the fermented soybean dregs modified by fungi combined with bacteria(ML,MB,Al and AB),and the physicochemical properties and flavor quality of the modified soybean dregs modified by different microorganisms and combinations were compared and analyzed.(1)Physical and chemical properties of microbial fermented soybean dregs:The physical properties of different microbial fermentation modified soybean dregs showed that the modification significantly reduced the particle size of the soybean dregs,by up to 50%,and improved the sensory quality of the soybean dregs.,The particle size of Okara with M and AL is the most delicate;The most.Research on the main functional components of modified soybean dregs by different microbial fermentation shows that the free polyphenols of soybean dregs modified by microbial fermentation have been significantly improved,and the functionality of the soybean dregs has been enhanced.The most significant increase in the content of free polyphenols is ML.And AL,the most obvious increase in free flavonoid content is ML and AB;the soybean dregs crude polysaccharides and oligosaccharides modified by microbial fermentation have increased in varying degrees,the highest increase is nearly 4 times,of which ML and AL are oligosaccharides.The highest,crude polysaccharides M and A are the highest;biological modification can significantly increase the SDF content of soybean dregs and reduce the content of IDF,but the total dietary fiber content remains basically the same.Among them,the SDF content of ML and AL increases the most,while the IDF content decreases.At most;during the period of microbial fermentation modification of soybean dregs,the increase of microbial enzymes and protease activities can promote the degradation of protein in soybean dregs,These indicators represent the umami quality of fermented soybean dregs.The best umami quality after microbial fermentation modification is AL and AB;the sweet and sour taste after microbial modification has also been improved to varying degrees.Among them,the best sweet taste after microbial fermentation modification is AL and AB,and the sour taste is the best.The ones are ML and AL.(2)Volatile flavor substances in microbial fermentation modified soybean dregs:GC-MS was used to separate and identify 6 different microbial fermentation modified soybean dregs.The characteristic flavor substances were 76,62,77,76,64,67 volatile respectively.OVA analysis was performed on different fermented okara samples and unfermented okara samples,and it was found that there were 48 characteristic flavor substances in different fermented okara samples and unfermented okara samples,among which AL grassy taste and fat taste were the lowest,and tasteful radiation Mucor combined with Lactobacillus bulgaricus fermented okara has a unique brandy aroma,and the clear aroma of melons and fruits dominates.Through the relative analysis of the main components of volatile flavor substances in different fermented soybean dregs,the first,second,and third main components can better compare the soybean dregs samples fermented by different microorganisms.The first principal component mainly reflects the melon and fruit fragrance and floral fragrance of fermented okara,the second principal component mainly reflects the roasted aroma of fermented okara,and the third principal component mainly reflects the aldehyde and floral fragrance.3.Application of biologically modified soybean dregs in noodlesBased on the physicochemical characteristics and flavor quality characteristics of the above-mentioned biologically modified soybean dregs,the modified soybean dregs sample Al was selected as the raw material to prepare noodles by adding different proportion of fermented soybean dregs,and the effect of the modified soybean dregs on the noodle quality was studied.The results showed that the gelatinization properties of the mixed flour with fermented bean dregs were enhanced compared with those without fermented bean dregs,which was beneficial to improve the quality of dough.The rheological index of the biologically modified soybean dregs noodles also showed that the elasticity and viscosity of the noodles made by adding proper amount of biologically modified soybean dregs were better than that of ordinary noodles.Compared with ordinary noodles,the noodles made by adding an appropriate amount of biologic modified soybean dreg have improved in sensory score,cooking loss,water absorption,elongation and other indexes,and the appropriate addition amount of modified soybean dreg sample is 20%.