Effects Of Micronizing Treatment Of Okara Dietary Fiber On Intestinal Microflora And Levels Of Serum Lipids In Mice

The particle size and hydration properties of dietary fiber are closely related to its functional properties, so as a modification method, the micronization treatment might play an important role in the physiological functions and application of dietary fiber.In the present study, okara dietary fiber (ODF) was micronized with wet granulating method by dynamic high pressure microfluidization (DHPM) (W-ODF sample) and with dry grinding method by ultra-micro pulverizer (D-ODF sample) respectively, and then the physical and chemical properties before and after treated were determined. And the effect of ODF to microflora populations in the cecum, cholesterol absorption capacity in vitro, and the levels of serum cholesterol and triglyceride in vivo were measured. The results were as follows:The conditions for DHPM were as follows:ratio of liquid to ODF was 1:25, treatment pressure was 90MPa for one cycle. The particle size was about 260.2nm, and after drying it was about 6.51±1.75μm. The particle size of sample treated by ultra-micro pulverizer was about 7.27±2.04μm. As the ODF before micronization treatment (C-ODF) was control, after micronization treatment, the content of soluble dietary fiber (SDF) was increased 6.79% in D-ODF and 11.69% in W-ODF, and the ratio of SDF to insoluble dietary fiber (IDF) was increased by 20.03% in D-ODF and 56.22% in W-ODF, respectively. Micronization treatment made the structure of ODF be loose and porous, and the specific surface area was increased. Compared with control group, the specific surface area was increased by 42.38% in W-ODF and 21.70% in D-ODF. Swell capacities and water holding capacities of D-ODF and W-ODF were also enhanced. Especially in W-ODF, swell capacity were increased from 6.53mL/g to 14.63mL/g(P<0.01), and water holding capacity increased from 9.32g/g to 23.94g/g(P<0.01).Compared with C-ODF, D-ODF and W-ODF could decreased the appetite and body weight growth rate of mice more obviously. The pH value of all groups decreased, and the moisture content of both feces and cecal contents were increased. But different treatment methods could lead to differences in physical and chemical properties, finally result in different functional effects, and the study indicated that the effect of W-ODF was superior to other two groups.The intake of ODF not only increased the counts of fecal E.coli, but also inhibited its proliferation in cecum, and effects of low doses W-ODF were more obvious (decreased from 7.77±0.06 to 5.52±0.00 log10 CFU/g). Meanwhile, the counts of lactobacilli and bifidobacterium excreted in the feces were also increased. After feeding for 28 days, lactobacilli counts in cecum were increased in all groups. After termination of feeding, lactobacilli counts in cecum of low dose groups were decreased, but high dose groups kept rising, especially in group W2. Bifidobacterium counts in cecum were increased with no significant difference in every group after feeding for 28 days, and in group D1 the proliferation was more quickly than other groups (increased from 8.30±0.22 to 9.77±0.03 log10 CFU/g). After termination of feeding, the counts of bifidobacterium in cecum were declined in all groups.In vitro experiments of cholesterol absorption, the optimized conditions of absorption were that C-ODF, D-ODF and W-ODF were respectively in the amount of 0.1g, cholesterol concentration was 0.1mg/mL, the absorption time was 90min. The results showed that cholesterol absorption capacities of D-ODF and W-ODF in vitro were better than C-ODF, and W-ODF was the best. In vivo, after feeding for 28 days both high and low doses of D-ODF decreased the levels of serum TC, and the HDL-C levels and HDL-C/TC ratio in all groups were improved compared to before feeding. The HDL-C/TC ratios in the groups which fed with high and low doses of W-ODF, were significantly higher than other groups after feeding for 28 days. Compared with feeding for 0 day, the levels of TG in group D1 and group W1 were decreased by 14.67% and 29.23%, respectively; and in the high dose group, the levels of TG in group C2, group D2 and Group W2 were decreased by 14.67%,27.54% and 29.33%, respectively.