Study On The Characteristics Of Degrading Galactomannan In Vitro Fermentation And Its Effect On Intestinal Flora

Gleditsia microphylla Gordon ex Y.T.Lee and Guar gum are both seed gum of leguminous plants that are rich in galactomannans,which are widely used as thickeners and stabilizers in many industrial applications.It is of great significance to investigate the behavior in vitro fermentation of seed polysaccharide gum after partial degradation,in order to expand its functional characteristics in food processing and the physiological effects of dietary fiber.In this paper,Gleditsia microphylla Gordon ex Y.T.Lee and Guar gum were selected for oxidative degradation,acid hydrolysis and enzymatic hydrolysis respectively.The partially degraded polysaccharide products were used as the sole carbon source to simulate the distal caecum digestion behavior in vitro,and the differences of the glycolysis after three partial degradation pretreatment were compared,which is of great significance for expanding the application of galactomannans in the food industry.In this paper,oxidative degradation,acid hydrolysis and enzymatic hydrolysis Gleditsia microphylla Gordon ex Y.T.Lee and Guar gum were characterized.The partial degradation of Gleditsia microphylla Gordon ex Y.T.Lee galactomannan(GMG)and Guar gum galactomannan(GG)was carried out with the different mass fraction of H2O2 solutions by oxidative degradation pretreatment hydrolysis pretreatment,the different volume fraction of hydrochloric acid-alcohol solution by acid hydrolysis pretreatment,the different mass fraction of ?-mannanase solution by enzymatic hydrolysis pretreatment,respectively.After different pretreatment degradation with different mass fraction(or volume fraction),the relative molecular weight of GMG and GG were significantly different.It can be observed from the infrared spectrum that the partial degradation of the enzyme solution and hydrochloric acid-alcohol solution does not change the polysaccharide structure.However,GMG and GG were oxidatively degraded by H2O2 except the carboxyl band was generated at 1720 cm-1,and the other functional groups did not change significantly.From the results of monosaccharide composition,the degradation of GMG and GG by oxidative degradation of H2O2 solution was uneven.As the concentration of H2O2 solution increased,there was no difference in M/G ratio of GMG,while the M/G ratio of GG decreased first and then Increase.The degradation of polysaccharides in alcohol solution is more uniform than the reaction in water.As the volume fraction of hydrochloric acid increases,the M/G value gradually increases.For GMG and GG degraded by ?-mannanase,the M/G value gradually decreased with the increase of the enzyme's mass fraction.The behavior of the intestinal flora of SD rats on pretreated GMG and GG in vitro fermentative was compared.A blank control group and a pretreated GMG and GG experimental group were set up to simulate the cecal fermentation of the distal cecum in vitro.The p H value,carbohydrate consumption rate,reducing sugar,and short-chain fatty acid(SCFAs)and branched-chain fatty acid(BCFAs)concentrations,enzyme activity,and microbial flora composition diversity,while predicting its functionality to organisms,were measured and evaluated at different times.while predicting its functionality to organisms.A comprehensive evaluation of the use of galactomannans by the intestinal microbial flora within 48 hours showed that the pretreatment of the GMG and GG experimental groups was significantly better than that of the blank control group.There was no significant difference in the p H value of the three pretreatment methods for the degradation of GMG and GG,but there were significant differences in the content of SCFAs and BCFAs and the total carbohydrate consumption.The accumulation of SCFAs produced by oxidative degradation of GMG was the largest,ranging from 29.88 to 45.05 mmol / L,but a small amount of BCFAs were also produced.And the accumulation of SCFAs produced by oxidative degradation of GG was 35.53-38.67 mmol/L,without BCFAs accumulated.The total SCFAs accumulation of GMG hydrochloric acid-alcohol solution degradation was between 32.43 and 35.66 mmol/L,and there was no significant difference with the accumulation of GG oxidative degradation.Total SCFAs accumulation of GG degraded by hydrochloric acid-alcohol solution was slightly lower,ranging from 31.27 to 32.72 mmol/L.The total SCFAs accumulation of the enzymatically hydrolyzed GMG and GG was the smallest,ranging from 15.13-18.67 mmol/L.It can also be seen from the changes of enzyme activity and reducing sugar concentration that the fermentation reaction of the three groups is more intense.Enzyme activity and reducing sugar concentrations increased rapidly in the early stages of fermentation,and then gradually decreased.At the same time,this study measured the composition diversity of microbial flora.From the results of microbial flora sequencing,the oxidatively degraded GMG and GG have a significant promotion effect on Bifidobacteria.After 48 hours of fermentation,Bifidobacterium increased by 32.86 times to 50.95 times,and GMG are more likely to stimulate Bifidobacterium growth than GG polysaccharides after oxidative degradation.But it also stimulated the growth of some harmful bacteria,such as the relative abundance of Prevotella was reduced,and the relative abundance of Clostridium was increased,which has a certain regulatory effect on the intestinal flora,but there is a certain risk of disease.GMG and GG after acid hydrolysis can stimulate the proliferation of some bacteria that produce SCFAs and organic acids,such as Lactococcus_garvieae_subsp._garvieae,Lactobacillus_murinus,Bacteroides_fragilis,Clostridium butyricum and so on,while inhibiting the growth of Clostridium_sp._ND2,which has a certain effect on increasing intestinal peristalsis,enhancing the function of the excretory system,and promoting digestion.GMG and GG after enzymolysis promote intestinal flora such as Bacteroides_thetaiotaomicron,Bacteroides_fragilis,Lactococcus_garvieae_subsp.etc.,but the relative abundance of Lactobacillus_murinus and Lactobacillus_gasseri were decreased,And from the functional point of view,the impact on the digestive system is little.