Preparation Of Dietary Fiber From Plant Wastes By Combined Enzyme-Ultrasound Treatment And Their Bioactivities

In thi study,sisal residue and Moringa oleifera stem were used to prepare dietary fiber by combined enzyme-ultrasonic treatment.Then their structure,physicochemical properties and bioactivity were studied.It is a useful reference for solving environmental pollution problems of sisal residue and Moringa oleifera stem waste and enhancing the high value of industrial and agricultural wastes.The main findings are as follows:By comparing the effects of three methods on the content of soluble dietary fiber in plant dietary fiber,the method of combined enzyme-ultrasonic tratment and its optimal condition were determined: after pretreatment with degreasing,deproteinized and starch removal,the cellulose complex enzyme were added into the plant material(3%,enzymolysis for 5h),and then 450 W power ultrasonic was used for 50 min to the substrate in 0.6% ammonium oxalate solution.The content of soluble dietary fiber under this condition was 20.1±1.2%,and the content of galacturonic acid was 60.1±0.8%.According to the optimal conditions obtained in Chapter 2,sisal residue dietary fiber(JM-EU)and Moringa oleifera stem dietary fiber(LM-EU)were prepared by combined enzyme-ultrasonic treatment.The FT-IR results showed that the two dietary fibers possessed the infrared characteristic absorption peaks of polysaccharides,The SEM results showed that the surface of JM-EU and LM-EU became rougher than the raw material.The particle size analysis showed that the specific surface area increased,and the granularity became smaller.The study of physical and chemical properties showed that JM-EU and LM-EU prepared by combined enzyme-ultrasonic treatment had better physical and chemical properties.At the same time,JM-EU and LM-EU had stronger adsorption capacity for nitrite,cholesterol and glucose than JM and LM.It showed that the combined enzyme-ultrasonic treatment can enhance the physico-chemical properties of dietary fiber,and at the same time confer various potential physiological functions of dietary fiber.The mice were fed with feed containing JM-EU and LM-EU respectively.The content of short chain fatty acids and bacteria in the feces of healthy mice after eating two kinds of plant dietary fiber were investigated.The HPLC resluts showed that the content of short chain fatty acids in the feces of mice fed with dietary fiber were significantly higher than those in the WDF group(p<0.05),indicating that LM,JM,LM-EU and JM-EU all have fermentability.Compared with the LM and JM groups,the amount of short-chain fatty acids produced by the LM-EU and JM-EU groups increased significantly(p<0.05),indicating that the fermentary properties of the dietary fiber prepared by combined enzyme-ultrasonic treatment were improved.The results of Illumina high throughput sequencing of intestinal flora in mice feces showed that compared with the WDF group,the intestinal flora of LM-EU and JM-EU group was significantly more abundant than that of WDF group.The population richness of the LM-EU and JM-EU groups was higher compared to the LM and JM groups.The β diversity results showed that the intestinal flora of mice fed with different types of dietary fiber had great differences,while the intestinal flora of JM-EU and JM had higher similarity,the similarity of intestinal flora between LM-EU and LM was high.Microbial structure analysis showed that after feeding diets containing dietary fiber,the Firmucutes increased at the level of Phylum;At the level of Familiy,Bacteroidaceae、Lachnospiraceae,Prevotellacete,Ruminococcaceae,Bacteroideceae were the dominant flora.The lead poisoning mice were fed with feed containing JM-EU and LM-EU separately.It was found that the lead content in liver,kidney and brain of group JM-EU and LM-EU mice was significantly lower than model group(p<0.05).The results showed that the two kinds of dietary fiber had good effect on detoxification of lead.The content analysis of SOD,GSH-PX and MDA in mouse organs showed that the JM-EU and LM-EU had good antioxidant capability,which were stronger than JM and LM group,respectively.The results showed that the two kinds of plant dietary fiber could reduce the harm caused by lead poisoning to the body,by stimulating the antioxidant enzymes and reducing lipid peroxidation.And its antioxidant mechanism may be related to phenolic compounds in two kinds of plant dietary fiber.