| Soybean dregs is the main by-product of processing soy products,and it is also a good source of dietary fiber.Studies have shown that the dietary fiber from soybean dregs has a laxative effect,but the effects of different processing methods on its physiological efficacy have been ignored.In order to find pretreatment methods that can improve the laxative effect of soybean dregs,this paper firstly compared the effects of commonly used vacuum drying and hot air drying on the physicochemical properties of the dietary fiber from soybean dregs,obtained the optimal drying conditions by principal component analysis and established the drying model of soybean dregs.Meanwhile,the optimal fermentation process was found by response surface methodology for solid-state fermentation of bean dregs by Mucor,and the changes in insoluble and soluble fiber content and physicochemical properties before and after fermentation were compared.Then,animal experiments were carried out with different pretreated dietary fiber of soybean dregs,and the pretreatment methods with significant laxative effect were screened out through the small intestine propulsion experiment and defecation experiment,and the feces were subjected to intestinal flora 16 S r RNA sequencing and short-chain fatty acids test.Finally,the pretreated soybean dregs,flour and corn starch were compounded and then extruded,so as to develop a puffed product of soybean dregs with a certain laxative effect.The main conclusions are as follows:(1)Vacuum drying and hot air drying of the dietary fiber from soybean dregs were carried out at 50 ? ? 90 ?,respectively,and their physicochemical properties such as color difference value,rehydration ratio,dissolution rate,expansion force and oil holding capacity were compared.The results showed that the physicochemical properties of dietary fiber after vacuum drying were better than those of hot air drying(P<0.05),and the best condition was vacuum drying at 70 ?,when the color difference value was-2.54,the rehydration ratio was3.41,the dissolution rate was 7.59 %,the expansion force was 6.04 m L/g,and the oil holding capacity was 1.99 g/g;and its microstructure was looser and had more pores.Based on this,the vacuum drying mode of soybean dregs was established,which could predict drying time,control moisture,and provide high-quality soybean dregs with different moisture contents for subsequent product development.(2)Solid-state fermentation of soybean dregs was carried out by Mucor racemosus,and the effects of fermentation time,fermentation temperature,initial moisture and inoculum amount on the content of soluble dietary fiber were investigated by single factor and response surface methodology.The results showed that when the fermentation time was 10.20 d,the fermentation temperature was 27.16 ?,the initial moisture was 76.78 %,and the inoculation amount was 3.44 %,the content of soluble dietary fiber was the highest,which increased from4.97 % to 18.82 %,and the content of insoluble dietary fiber decreased from 59.37 % to44.89 %.,and there was no significant change in total dietary fiber content(P>0.05).Analysis of physicochemical properties and electron microscopy showed that the rehydration ratio,dissolution rate,expansion force and oil holding capacity of the dietary fiber from fermented soybean dregs were significantly improved(P<0.05),and its microstructure was more finely divided.(3)The effects of different pretreated dietary fiber from soybean dregs on the laxative function of constipated mice were compared through animal experiments.The KM mice were divided into six groups,namely the blank group,the model group,the hot air drying group,the vacuum drying group,the unfermented group and the fermented group.Firstly,they were determined by the small intestine propulsion test and the defecation test.Then the groups with greater differences was subjected to 16 S r RNA sequencing of intestinal flora and determination of short-chain fatty acids.The results showed that the fermented dietary fiber had better effect on the small intestinal peristalsis of mice,the small intestinal propulsion rate of the fermented group and the unfermented group were 59.40 % and 52.03 %respectively(P<0.05),and it could shorten the defecation time and increase the defecation and the fecal water content.In addition,the number of beneficial bacteria in the intestinal tract of fermented group was higher,and the total acid content was higher too,which were 56.19?mol/g and 46.76 ?mol/g,respectively(P<0.05).The small intestine propulsion rate of the hot air drying group and the vacuum drying group were 51.38 % and 54.83 % respectively(P>0.05),and there was no significant difference in defecation time,defecation volume and fecal water content(P>0.05),indicating that vacuum drying cannot improve the laxative function of dietary fiber.(4)Using the drying model of soybean dregs,the fresh soybean dregs and the fermented soybean dregs were dried to the moisture content of 50 % ? 70 %,respectively compounded with wheat flour and corn starch in proportion,and then single-screw extrusion was performed.The effects of different moisture content of soybean dregs on the puffing degree,springiness,hardness,gumminess and chewiness of the product were investigated by single factor experiment and principal component analysis,and compared it with similar products with better sales in the market.The results showed that the fermented soybean dregs with the moisture content of 60 % had the best texture after compounding with wheat flour and corn starch in a mass ratio of 2:1:1,which was close to the similar product on the market,and the dietary fiber content in the product from fermented soybean dregs was significantly higher,with insoluble and soluble dietary fiber contents of 12.88 g/100 g and 4.77 g/100 g,respectively.Based on the dose conversion of mice and humans,the recommended daily intake of this product is 50 g,which has a certain effect of laxative. |
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