| The digestion and metabolism of dietary polysaccharides in the body can provide positive regulation for gastrointestinal health.Due to differences in physical structure and chemical properties,different dietary polysaccharides lead to different hydrolysis rates,which in turn affect their physiological digestion process and intestinal microbial metabolism.At present,a large number of studies have proved that dietary polysaccharides can interact with intestinal flora to restore intestinal barrier,regulate host immunity,reduce intestinal inflammation,and reduce the incidence rate of colon cancer.The polysaccharide of Tremella fuciformis(TFP)is the main active ingredient in Tremella fuciformis and has multiple functional activities such as antioxidation,anti-tumor,blood sugar control,improvement of colitis,and repair of intestinal mucosa.To explore the in vitro digestion behavior of TFP and their interaction with intestinal microorganisms,and to clarify the structure activity changes during the digestion process of TFP and their impact on intestinal microflora,which has certain significance for the prevention and treatment of obesity,chronic intestinal inflammation,and other diseases caused by diet and lifestyle.Therefore,in this study,active polysaccharides were obtained from Tremella fuciformis by hot water extraction and fractional alcohol precipitation,and their chemical composition and physical structure were preliminarily characterized.To explore the digestive stability of tremella polysaccharides and their impact on the diversity of intestinal microbial communities through in vitro simulated digestion models,fecal bacteria fermentation models,and 16 sr RNA gene amplification sequencing analysis,and to promote the design and development of healthy foods based on natural edible polysaccharides.The specific research results are as follows:(1)Active polysaccharides were obtained from tremella fruit bodies by hot water extraction and fractional alcohol precipitation.Three crude polysaccharide components,TFP40,TFP60,and TFP80,were prepared by changing the volume fractions of ethanol at 40%(v/v),60%(v/v),and 80%(v/v)during ethanol precipitation.Their chemical composition and physicochemical properties were studied.The results showed that the content of total sugar(81.24%)and protein(3.10%)in TFP60 was the highest,while the content of uronic acid(12.98%)in TFP80 was the highest.The order of molecular weight from high to low is TFP40,TFP60,and TFP80.With the increase of alcohol precipitation concentration,the weight average molecular weight of polysaccharide components decreases,indicating that hierarchical alcohol precipitation can separate polysaccharide components with different molecular weights.(2)An in vitro simulated digestion experiment of TFP was conducted.The in vitro digestive characteristics of TFP were investigated by simulating the digestive processes of the oral cavity,stomach,and intestine.The results showed that there was no significant change in reducing sugar content during simulated oral digestion,and TFP did not degrade,indicating that saliva amylase could not digest TFP.During the simulated gastrointestinal digestion stage,due to the lower p H value of the gastric juice environment,the glycosidic bonds of TFP break,and macromolecular aggregates undergo depolymerization,resulting in an increase in reducing sugar content and a decrease in molecular weight.(3)Analysis of the physicochemical properties and biological activity of the products during simulated digestion in vitro.Thermogravimetric analysis showed that the heat loss curves of TFP,TFP-S,TFP-G,and TFP-I were similar in the range of 25-600℃,indicating that the thermal stability of TFP at different digestion stages was similar.Infrared spectral data showed that the FT-IR spectra of TFP,TFP-S,TFP-G,and TFP-I after simulated digestion were similar,indicating that in addition to the decomposition of glycosidic bonds,in vitro digestion would not change other structural characteristics of TFP.Congo red staining experiments showed that TFP is a polysaccharide with a triple helix structure,and the structure remains unchanged after simulated digestion in vitro.The results of antioxidant activity in vitro showed that the antioxidant capacity of TFP decreased slightly after digestion,but the antioxidant activity of TFP increased slightly after gastric digestion,which may be related to its lower molecular weight.In addition,TFP can suppress α-Amylase activity showed a significant doseeffect relationship.After simulated gastrointestinal digestion,the polysaccharide structure was damaged,resulting in a decrease in its inhibitory capacity.The α-glucosidase inhibitory activity of TFP-G and TFP-I was also significantly reduced after gastrointestinal digestion.,possibly due to changes in chemical composition and molecular weight.(4)In vitro fermentation experiment of TFP.The polysaccharides that remained undigested after in vitro simulated digestion were subjected to in vitro fecal co-fermentation experiments to simulate the final destination of Agaricus polysaccharides throughout the digestion process.The results showed that the total sugar content in the medium decreased significantly after fermentation,and the consumption of TFP by microorganisms was about 66.08%,indicating that TFP could be effectively utilized by microorganisms.The results of reducing sugar detection showed that the reducing sugar released from TFP could be fully utilized by intestinal microorganisms.Due to the production of acidic substances such as SCFAs during the fermentation process,the p H value of the fermentation broth is significantly reduced.The results of 16 S r RNA gene sequencing suggest that TFP can affect the alpha and beta diversity of intestinal microflora to a certain extent,and change the composition of intestinal microflora at the phyla and genus levels,facilitating the maintenance of intestinal homeostasis.(5)Product development using tremella polysaccharide as an active ingredient.With maltitol and isomaltonol as raw materials,gelatin as gel agent,fructooligosaccharides and TFP as additive ingredients,a gel jelly was developed.Through single factor experiments and orthogonal experimental design,the formula was optimized,and the optimal addition amount of gelatin was determined to be 10%,the ratio of maltitol to isomaltonol was 3:1,the addition amount of Tremella polysaccharide was 0.4%,and the addition amount of citric acid was 0.05%.The prepared soft sugar acid was moderately sweet,had good elasticity and chewing ability,and met the market quality requirements. |
PDF Full Text Request