Study On Fermentation Modification Technology And Physicochemical Properties Of Kidney Bean By-product Dietary Fiber

Dietary fiber,as the seventh nutrient,has an increasingly prominent physiological effect on regulating metabolism of the body.As a cash crop in the main producing area of Northeast China,kidney bean will produce more than 70% of the by-product rich in dietary fiber-soybean dregs during processing.How to obtain high-quality dietary fiber has attracted much attention.It is essential to enlarge new sources of dietary fiber to acquire high-quality dietary fiber products.In this study,soybean dregs,a by-product of kidney bean processing of different varieties,was screened.According to the difference between different varieties,dietary fiber of kidney bean dregs was extracted by ultrasonic assisted enzymatic method.After fermentation modification of kidney bean dregs,soluble dietary fiber and water-insoluble dietary fiber were separated.Measured before and after the modification of dietary fiber fourier transform infrared,X-ray diffraction and thermal stability,water holding capacity,oil holding capacity,adsorption,ion exchange capacity,ion exchange capacity and the ability of scavenging free radicals and other physicochemical properties.Finally to discuss the modification effect on the physicochemical properties of dietary fiber,it provides theoretical guidance for the application of dietary fiber of kidney bean dregs in food industry.The results of the research are as follows:(1)Using dietary fiber content as the screening index of kidney bean dregs,determine the basic components and infrared spectra of milk white flower kidney bean dregs,purple flower kidney bean dregs,Nongyun No.5 dregs,Beiguo white kidney bean dregs,red kidney bean dregs,and large white kidney bean dregs,and select milk white flowers Kidney bean dregs was used as the experimental material.The results of fourier transform infrared showed that there was no significant difference in the characteristic absorption peaks of dietary fiber components of different varieties of kidney bean dregs,and it was conjectured that the functional groups and chemical structures were consistent.(2)Using ultrasound-assisted complex enzymes(1% alkaline protease and 0.2%high-temperature ?-amylase)to extract dietary fiber from defatted white kidney bean dregs,the effect of ultrasound conditions on the extraction rate of IDF and SDF was studied and optimized Extraction process conditions,and study the structure and physical and chemical properties of kidney bean dregs dietary fiber.The test results show that when the ultrasonic time is 25 min,the intensity is 250 W,and the temperature is 60?,the IDF extraction rate reaches 60.11%,and the SDF extraction rate is 5.63%.(3)Compound strains are used to ferment and modify kidney bean dregs.In this experiment,solid-to-liquid ratio,bacterial load,fermentation temperature and fermentation time were taken as factors,and the extraction rate of SDF of kidney bean dregs was taken as response value.By single factor test combined with response surface experimental design,the optimal conditions of modification were obtained.The results indicated that under the optimal conditions of solid-to-liquid ratio of 1:20.09(g/m L),bacterial load of 3.68%,fermentation temperature of36.56? and fermentation time of 21.36 h,the extraction rate of SDF was 17.96%,which was close to the theoretical value of 17.82%.(4)Ultraviolet full-wavelength scanning can be seen in Fermented soluble dietary fiber.FSDF is a pure SDF.Fourier transform infrared analysis showed that there was no significant difference in the absorption peaks of the IDF components before and after fermentation.They all contained cellulose,hemicellulose,lignin and other substances.The SDF before and after fermentation were all typical polysaccharide characteristic infrared spectra,and all of them might contain acidic polysaccharides,Sugar substances such as amino polysaccharides and glucose.Scanning electron microscopy results show that after modification of IDF and SDF,the microstructure and molecular size have changed,and the molecular chain has broken.The X-ray diffraction pattern showed that IDF showed the characteristic X-ray diffraction curve of cellulose type I before and after fermentation,and the modification reduced the crystallinity of SDF.Differential scanning calorimetry results show that the thermal stability of SDF and IDF after fermentation is better than that of untreated SDF and IDF.(5)Fermented insoluble dietary fiber Fermented insoluble dietary fiber,FIDF water holding capacity increased by 2 times,reaching 5.13 g/g,swelling power increased by 1.9 times,reaching 3.83 m L/g,oil holding capacity increased by 6 times,reaching 1.21 g/g,FIDF adsorption capacity for cholesterol,sodium cholate and glucose are significantly improved,and FIDF ion exchange capacity is significantly improved.The antioxidant capacity of FSDF is significantly better than SDF,and the ability of FSDF to absorb glucose is significantly increased;FSDF had antibacterial activity against Staphylococcus aureus,Shigella and Escherichia coli,SDF only had antibacterial activity against Shigella,and SDF had no antimicrobial activity against Salmonella before and after fermentation.The research results showed that the modified significantly improved the SDF fermentation yield,and by changing the SDF and IDF of microscopic structure,spatial location and the size of the particles,improve the IDF holds water,oil,the physical and chemical properties such as adsorption,improve the SDF oxidation resistance and adsorption,and have a certain bacteriostasis in vitro,the experimental results for fermentation modification applied to provides a theoretical basis for deep processing of bean dregs dietary fiber.