The Effect Of Soluble Viscous Dietary Fiber On Digestion Of Nutrients And Weight Loss

Adding dietary fiber to a meal as a substitute or diluent to provide some nutritional functions to meet the demands of seeking weight loss fiber by enhancing satiety after eating is becoming more and more popular.In order to study the influence of different soluble viscous dietary fiber（SVDF）on the digestion and absorption of protein and carbohydrates and subsequently weight loss,and satiety,effect,two systems have different state,liquid and gel state,in the gastrointestinal（GI）tract employed in the investigation.It is expected to broaden the application of dietary fiber in the diet product market,and provide some information for consumers to inform dietary choices.Firstly,xanthan gum,guar gum and locust been gum were chosen for the study due to their ability to assume liquid state in the GI tract.By using the in vitro digestion model,the system of the high viscosity system(1500 cP,30 s^-1)and low viscosity system(300 cP,30 s^-1)were employed to investigate effects of dietary fiber on nutrient digestion in these two systems.The results showed that in the high viscosity system,the different inhibition of xanthan gum,guar gum and locust been gum on starch digestion was revealed and led to different rate of glucose release,where it was observed that compared with control,the glucose release from starch decreased by 64.1%,52.9%,14.5%respectively.Prior to the digestion procedure,all the viscosities of the samples were normalized to give similar viscosity.However,the study showed obvious difference in viscosity after gastric and intestinal simulations.For example,in the high viscosity system,viscosity among samples was identical(1500±100 cP,30 s^-1)before the simulation,but following the in vitro digestion,xanthan gum showed significantly higher viscosity(130±1.4 cP,30 s^-1)in the end of intestinal digestion,compared with locust been gum(12.1±2.3 cP,30 s^-1).It can be suggested that the ability of xanthan gum to resist changes during digestion was the most prominent among the samples.After comparing the digestion regulation of nutrients,the results showed an inverse relationship between viscosity and nutrient release.Thus,the higher the viscosity the system,the stronger inhibitory influence on nutrient release was.In order to study such difference appeared in SVDF after digestion,dilution,pH and enzymes’effect on SVDF’s viscosity were studied respectively.The results showed that such difference was not relevant to the additive concentration of SVDF,but relevant to SVDF’s ability to resist changes during digestion including pH,enzymes and dilution.Next,as alginate could facilitate in keeping the soluble fibers in solid-like or gel-like state,alginate also been studied in the paper.Digestion conditions that break down gels as well as conditions with no effect on gel structure including secretion of gastric acid,compression of stomach wall and pylorus on chyme were simulated.Moreover,the digestibility of maltodextrin and whey protein isolate（WPI）in the mixture system was studied.The results showed that the formation of gel in stomach would inhibit the digestion of nutrients,and the degree of inhibition is related to the formation and fragmentation of gels,as nutrients were wrapped in the gels so that they could not interact with enzymes,subsequently would inhibit the digestion of nutrients.According to the results,compared with control samples,dextrin digestibility decreased by 79.1%and 89.6%for broken and unbroken system respectively,WPI was decreased by 84.0%and 92.5%.Finally,the effect of dietary fiber after having a short-term and long-term intake on body function was studied by in vivo.Different groups including control group（control）,low viscosity xanthan gum group（LX）,high viscosity xanthan gum group（HX）,low viscosity guar gum group（LG）,high viscosity guar gum group（HG）and alginate group（ALG）were studied.The results showed that the addition of dietary fiber could decrease protein utilization and blood glucose level in rat.The inhibition effect of HX was the most significant among all groups,protein utilization was 13.9%lower than control group and fasting blood content was57.3%lower than control group,which was corresponded to the in vitro digestion results.For rat’s feed intake,weight loss,hormone content,etc,it was found that for the short-term eating of SVDF,gavage samples containing SVDF could enhance rat satiety and decrease the feed intake 4 h after gavage;for the long-term eating of SVDF,weight of rat would be inhibited,the effect of HX was the most significant.After sacrificing the rats,chyme’s viscosity and volume in stomach and small intestinal was tested,the results showed that the addition of SVDF prolonged gastric emptying time and increased the viscosity of chyme,which was also consistent with the results in vitro digestion.