Effect Of Mucor Combined With Lactic Acid Bacteria Fermentation On Soluble Dietary Fiber In Soybean Dregs And Its Application Characteristics

Okara is a by-product in the process of making soymilk.Due to the dietary habits of Chinese residents,soy products are in great demand,so the output of Okara is very abundant.Because the moisture content in fresh okara is too high,it is not easy to store,among which soybean soluble dietary fiber is a physiologically active substance with potential application value.Therefore,how to use soybean dregs dietary fiber reasonably and apply it to industrial production on a large scale has become a problem to be solved.This article uses soybean dregs as the main raw material to study the effects of single fermentation of Mucor and lactic acid bacteria and combined stepwise fermentation on soluble dietary fiber(SDF),physicochemical and main nutritional indicators of soybean dregs,and compare and analyze the physicochemical properties of SDF produced by fermentation of different strains.Performance,structural characteristics and antioxidant activity,and preliminary research on the application of fermented SDF in the production of yogurt.The specific results are as follows:(1)By optimizing the compound fermentation of Mucor,Lactobacillus fermentum and Lactobacillus paracasei,and optimizing the fermentation conditions by a single factor,the fermentation conditions of the combined fermentation of Okara with Mucor,Lactobacillus fermentum and Lactobacillus paracasei are obtained as:20 g fresh soybean dregs,fermentation method is Mucor,Lactobacillus paracasei,Lactobacillus fermentum compound fermentation,Mucor fermentation time is 60 h,fermentation temperature is 28?,inoculation amount is 3%,spore number is 4×107,The natural pH value,the water content is 85%,the fermentation time of lactic acid bacteria is 48 h,the inoculation amount is 1%,Lactobacillus fermentum:Lactobacillus paracasei=1:1,the fermentation temperature is 37?,and the number of spores is 106(2)Ferment the bean dregs according to the optimized optimum conditions,and measure the nutrient components during the fermentation process.The results show that with the extension of the fermentation time,the acid detergent fiber decreases from the initial 45.94%to 24.27%;the soluble sugar content is overall The proportion increased from 2.315%to 4.072%,which was an increase of 49.76%.The protein content in unfermented bean dregs was 6.78 mg/g;after 24 hours of fermentation,its content reached 8.93 mg/g;24 The soluble protein content in?36 h increased significantly,increasing by 4.6mg/g.During the whole fermentation process,the degree of hydrolysis increased from 1.897%to 15.274%.In addition,the microstructure analysis of the soybean dregs before and after fermentation revealed that the fermented soybean dregs have small particles,honeycomb holes are formed on the surface of the particles,and the surface structure is looser.(3)By studying the different fermentation treatment methods of soybean dregs,using water extraction to extract soluble dietary fiber,and by detecting the water retention,oil retention,swelling power and solubility index of the dietary fiber to reflect the best fermentation processing method of water-soluble soybean dregs Physical properties,the best effect is the compound fermentation of Mucor,Lactobacillus fermentum and Lactobacillus paracasei.The water solubility index,water holding capacity and swelling power of soybean dregs are respectively 3.9 times,2.75 times and 2.03 times that of the untreated group.;Then test the cation exchange capacity and cholesterol adsorption capacity of the water-soluble dietary fiber of soybean dregs;(4)The content of total polyphenols in different treatments was determined by the Folin method,and the in vitro antioxidant activity was studied.The content of polyphenols in fresh okara was 0.136 mg GAE/g.After 60 h of fermentation by Mucor,the detection The polyphenol content in okara did not increase significantly,and the polyphenol content in okara was 1.79 times that of fresh okara after lactic acid fermentation was carried out on the basis of Mucor fermentation to 108 h.Okara SDF after fermentation by Mucor and lactic acid bacteria has the best DPPH free radical scavenging effect compared with fresh Okara,which is increased by 1.27-1.71 times.The antioxidant capacity of Mucor,Lactobacillus paracasei,and Lactobacillus fermentum after compound fermentation is 5 times that of unfermented soybean dregs,and SDF has a certain reduction ability after fermentation.(5)Through electron microscope analysis and Fourier infrared spectroscopy analysis,it is found that compared with untreated bean dregs,the surface morphology of the soluble dietary fiber after fermentation has changed,honeycomb holes are formed on the surface of the particles,and the surface structure is more loose.This feature becomes more obvious after compound fermentation of mold,Lactobacillus fermentum and Lactobacillus paracasei.In addition,the infrared spectrum shows that all five SDFs exhibit the infrared spectrum characteristics of polysaccharides.(6)Preliminary application of fermented soybean dregs SDF yogurt:After adding Mucor and lactic acid bacteria fermented soybean dregs SDF to yogurt in different proportions,the physical and chemical properties and sensory quality of soybean dregs yogurt were compared The results showed that different additions of SDF had no significant effect on the pH,acidity and viable cell count of the yogurt.When the addition was 1.0%,the viscosity and water holding capacity reached(256±12)cp and(0.66±0.03),and the yogurt had a strong sour taste Moderate,natural and non-obtrusive in combination with the aroma of bean dregs.It tastes slightly frosted and has a richer taste.Therefore,considering the dietary fiber content of the product and the taste of the product,1%addition ratio is the appropriate ratio of Okara SDF yogurt.