Preparation Of Mixed Fermentation Of Peanut Meal And Effect On Lipid Metabolism In Mice Fed A High-fat Diet

ObjectiveTo explore the technological conditions of preparing pancreatic lipase inhibitor from peanut meal by mixed fermentation,and its effects on lipid metabolism and intestinal barrier function in mice fed high fat diet,and the possible mechanism of action.Methods1.Using single factor test and orthogonal experiment,with pancreatic lipase inhibition rate as the index,the fermentation temperature,time,inoculation amount,and the proportion of strains of Monascus and Bacillus natto were optimized,to explore the optimal fermentation conditions for pancreatic lipase inhibitor of peanut meal by mixed fermentation.2.Sixty C57BL/6J mice were randomly divided into 6 groups(10 mice/group):normal control group(N),model group(M),positive control group(Ato,atorvastatin 10mg/kg),nonfermented peanut meal group(NF,150 mg/kg),fermented peanut meal low-dose group(FL,50 mg/kg),fermented peanut meal high-dose group(FH,150 mg/kg).N group was fed with basic diet,and the other groups were fed with high-fat diet.The experiment lasted for 6 weeks.After the experiment,the mice were sacrificed by removing the eyeball,and the levels of serum lipids,leptin,glucose,alanine aminotransferase(ALT)and aspartate aminotransferase(AST)were determined.The liver and ileum tissues were taken for pathological observation,the height of villi was measured,and the expression of Occludin and ZO-1 was detected by Western Blot.Results1.The inhibitory effect of fermented peanut meal(FPM)on pancrelipase is better than that of nonfermented peanut meal(NFPM),and the fermentation effect of mixed strains is better than that of single bacteria.The optimal fermentation process conditions were determined as follows: temperature 31?,time 34 h,inoculation amount 6%,strain ratio(Monascus: Bacillus natto)is 1:2.Under these conditions,the inhibitory effect of FPM on pancrelipase reached 96.17±0.47%,and the inhibition rate of pancrelipase was increased by 46.23% compared with NFPM.2.Compared with the N group fed with basic feed,the food intake of mice fed with high-fat feed was significantly reduced(P<0.05),however,there was no significant difference among mice in high-fat diet groups(P>0.05).The body weight and Lee's index in the M group were markedly higher than N group(P<0.05).Except for NF group,the body weight and Lee's index of mice in other groups were markedly lower than those of M group(P<0.05).3.Compared with the N group,the serum total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)levels in group M were increased by 21.55%,25% and 106.67% respectively,and the high density lipoprotein cholesterol(HDL-C)level was decreased by 50.36%(P<0.05).The serum TC,TG,and LDL-C levels in FL and FH groups were decreased,whereas the serum HDL-C levels were markedly increased(P<0.05).However,there was no significant difference in TG and HDL-C levels between NF group and M group(P>0.05).4.The serum leptin and glucose levels in the M group were increased by 81.32% and59.3% respectively than in the N group.Compared with the M group,serum leptin and glucose levels in FL group were reduced by 22.82% and 16.58%,while those in FH group were reduced by 34.07% and 21.47%,respectively.Importantly,the serum leptin level in FH group decreased by 14.75% and 25.45% compared with Ato group and NF group,respectively(P<0.05).5.Compared with the N group,serum ALT and AST levels in group M were increased by 99.54% and 138.36%,respectively.Compared with the M group,serum ALT and AST levels in FL group were reduced by 24.87% and 28.50%,while those in FH group were decreased by 34.54% and 37.60%,respectively(P<0.05).HE staining of liver showed that compared with group N,mice in group M had incomplete liver cell morphology,disordered hepatic cord arrangement,and filled many small fatty vacuoles in the cytoplasm.Different degrees of improvement in the other groups,but there were still a few fat vacuoles in NF group.6.The HE staining of the ileum showed that compared with the N group,the ileal villi of the M group were shortened and shedding.Different degrees of improvement for villi shedding were found in other groups compared with the M group,among which the villi of the FH group were neat and height increased.Western Blot results showed that the expression levels of ZO-1 and Occludin in M group were decreased by 52.22% and60.92% respectively than those of the N group(P<0.05).Compared with the M group,the expression level of ZO-1 in FL group was increased by 58.14%(P<0.05),whereas no notable differences can be observed in Occludin level(P>0.05),whereas the expression levels of ZO-1 and Occludin in FH group were increased by67.44% and 88.24%,respectively(P<0.05).Interestingly,there were no eminent differences of expression levels of ZO-1 and Occludin between the Ato group and the M group(P>0.05).Conclusion1.The inhibitory effect of FPM on pancreatic lipase is better than that of NFPM,and the optimal fermentation process conditions were determined as follows: temperature31?,time 34 h,inoculation amount 6%,strain ratio(Monascus: Bacillus natto)is 1:2.Under these conditions,the inhibitory effect of FPM on pancrelipase reached96.17±0.47%.2.FPM could regulate the lipid metabolism of mice on a high-fat diet.The mechanism may be related to inhibiting pancreatic lipase activity,improving leptin resistance,and protecting the intestinal mucosal barrier.