Effect Of Fermented Bran Dietary Fiber On Lipid Metabolism In Model Rats

Research background:Obesity increases the likelihood of various diseases such as fatty liver and hypertension,and has become an important health issue.Developing functional food that can control weight and prevent obesity without or with low side effects has become one of the hot topics in current research.As one of the main by-products of flour processing,wheat bran(WB)is full of nutrients such as insoluble dietary fiber(IDF),among which IDF has the effects of reducing energy density,promoting intestinal peristalsis,and improving defecation.Currently,most studies on wheat bran insoluble dietary fiber(W-IDF)focus on the optimization of preparation conditions and physical and chemical properties,while there are few studies on the prevention of obesity by W-IDF.Research objective:In this paper,W-IDF was extracted through fermentation modification,and its structure characterization and physicochemical activity analysis were conducted.By establishing high-fat model rats,the possible mechanism of dietary intervention of W-IDF in regulating lipid metabolism in high-fat model rats was further explored,as well as its impact on intestinal microorganisms.Research method:In this paper,wheat bran was used as raw material to ferment and modify wheat bran using Bacillus subtilis,Lactobacillus acidophilus,Lactobacillus plantarum,and mixed lactic acid bacteria(Lactobacillus acidophilus: Lactobacillus plantarum=1:1)to extract W-IDF.Its structure was characterized by Fourier transform infrared spectroscopy(FT-IR),differential scanning calorimeter(DSC),and scanning electron microscopy(SEM);Then,the physical and chemical properties and antioxidant activity of the oil holding capacity,water holding capacity,cation exchange,and nitrite adsorption capacity were studied.Subsequently,a high fat rat model was established to further explore the effects of modified IDF on lipid metabolism in high fat diet rats,including blood lipid indicators,histopathological sections,and fluorescence quantitative PCR experiments.Finally,high-throughput sequencing analysis was used to further explore the regulatory effect of W-IDF on intestinal flora of disorders in hyperlipidemia model rats.Research results:(1)Preparation,Characterization,and Physicochemical Activity Analysis of Wheat Bran Insoluble Dietary Fiber: FT-IR studies have found that after fermentation with mixed lactic acid bacteria,the hydrogen bonds between cellulose and hemicellulose in wheat bran insoluble dietary fiber molecules and pectin β-glycosidic bonds are destroyed,and the spectra are basically similar except for differences in some characteristic bands of absorbance or wave number.DSC study found that compared to the blank group,IDF fermented by mixed lactic acid bacteria showed better thermal stability,with a degradation temperature of 282.40℃.SEM study found that the blank group IDF had a smooth surface and a relatively complete wall structure.After fermentation,IDF exhibited more holes and cracks in the honeycomb structure.The physicochemical function and antioxidant activity of the extracted IDF were analyzed.The results showed that after fermentation with mixed lactic acid bacteria,the water holding capacity,oil holding capacity,cation exchange and nitrite adsorption capacity,total phenol content,and total reducing power of IDF were significantly improved(P<0.05),showing a relatively superior antioxidant capacity.The results showed that the physical and chemical functional activities of bran dietary fiber modified by mixed lactic acid bacteria fermentation were improved,providing a theoretical basis for further exploring its impact on lipid metabolism in high-fat diet rats.(2)Study on the Effect of Wheat Bran Insoluble Dietary Fiber on Lipid Metabolism in Rats on a High Fat Diet: By adding 5% Fermentation Modified IDF to a High Fat Diet,after dietary intervention,compared with rats in the HFD model group,rats in the Fermentation Modified C-IDF group had lower body weight,significantly lower serum TG,TC,and LDL-C levels(P<0.05),and higher HDL-C levels,which could effectively improve the body’s ability to scavenge oxygen free radicals and regulate lipid metabolism in the High Fat Model rats.At the same time,it reduces the degree of fatty degeneration in liver cells and the accumulation of fat droplets,alleviating the pathological characteristics of the colon.At the transcription level,the fermentation modified C-IDF group significantly upregulated the m RNA expression levels of Fasn and Ppara genes in the liver(P<0.05),which has the same trend as the m RNA expression levels of Fasn and Ppara in rats in the PC group.It can be inferred that the C-IDF group may prevent the accumulation of fat in high fat diet by regulating the Fasn/Ppara signaling pathway,thereby promoting the body’s lipid metabolism.(3)Study on the effect of wheat bran insoluble dietary fiber on intestinal microflora in rats fed a high fat diet: In the alpha diversity analysis,the Ace and Chao indices of the HFD model group decreased compared to the Normal group,and the values of the modified C-IDF group were closer to the Normal group,indicating that the diversity and richness of intestinal microflora in rats fed a high fat model group decreased,C-IDF intervention can effectively regulate the decrease of intestinal flora diversity and imbalance of flora abundance in HFD model rats.Analysis of species composition and differences at the phyla and genus levels found that a high-fat diet increased the relative abundance ratio(F/B value)of Firmicutes to Bacteroidota in the intestinal microflora of the cecum,while the F/B value decreased in the modified C-IDF group after dietary intervention,while significantly increasing the relative abundance of Lactobacillus and Bifidobacterium,The proportion of various bacterial species tends to approach the Normal group.These results indicate that C-IDF intervention can promote the increase of probiotics in the cecum,inhibit the growth of harmful bacteria,increase the relative abundance of intestinal flora,thereby improving the interference of high-fat diet on the intestinal flora of rats,and promoting the health of intestinal flora.Research conclusion:The results showed that using probiotic fermentation to modify W-IDF can effectively enhance the physicochemical properties and antioxidant activity of IDF.The dietary intervention of IDF reduced the fatty degeneration in the hepatocytes of model rats to some extent,and alleviated the pathological characteristics of the colon;At the same time,it can regulate the Fasn/Ppara signal pathway,slow down the accumulation of fat in the body,accelerate the oxidation of fatty acids,and promote the body’s lipid metabolism.In addition,after dietary intervention with W-IDF,the changes in intestinal flora caused by high fat diet were reversed,the relative abundance ratio of Bacteroides to Thickwalled Bacteria in the high fat model group was effectively reduced,the intestinal flora was reshaped,the interference of high fat diet on rat intestinal flora was improved,and the health of intestinal flora was promoted.This study provides a reference and theoretical basis for the application of W-IDF in the field of food processing and the development of related functional foods.This study is of great significance for human health.