| Mannan has a variety of useful effects on the human body,such as controlling blood sugar,anti-inflammatory and probiotics.However,due to its high viscosity and strong water absorption,it is limited by the safety and the application in the food formulation,and the manno oligosaccharide has a low viscosity,and it is easy to use by human digestion,so it can expand its food.Application in related fields.In this study,three manidin oligosaccharides were prepared by the enzymatic solution,and the physicochemical characteristics of the sample before and after the enzymatic deterioration and its effect on intestinal microorganisms were explored in the freezing dough.(1)In this study,three kinds of mannans,Konjac gum(K),Guar gum(G)and Locust bean gum(L),were digested by the enzymatic solution of Bacillus amylolyticus,and four mannans with different degrees of digestion were prepared by controlling the digestion time of 5 h,10 h,15 h and 20 h.The apparent structure,particle size distribution,structural changes and molecular weight of the samples before and after digestion were measured.The results showed that the particle size and molecular weight of oligosaccharides decreased gradually with the increase of enzymatic digestion time,and the surface of the particles changed from rough flakes and stripes to smooth round spheres,and the Fourier infrared spectra showed that the structure of the samples before and after enzymatic digestion did not change.The optimal enzymatic digestion time was determined as 15 h with the content of short-chain fatty acids as the index;the dynamic rheological results showed that the oligosaccharides G’ and G" decreased significantly after enzymatic digestion,and the gel network structure of the samples was weakened.(2)In vitro fermentation results showed that the results showed that the addition of polysaccharides increased the content of short-chain fatty acids in the intestine,with konjac mannan and oligosaccharide having the highest yield of short-chain fatty acids at 24 h and guar oligosaccharide having the highest content of short-chain fatty acids at 12 h.The 16 S r RNA results showed that the enzymatic digestion of oligosaccharides decreased the ratio of Firmicutes to Bacteroidetes,increased the relative abundance of Prevotella spp.and decreased the relative abundance of pathogenic genera such as Bacteroides,Klebsiella and Escherichia-Shigella.Among them,konjac mannan was the most selective for Prevotella spp.and was significantly enriched for butyric acid producing Faecalibacterium,while guar mannan and acacia mannan were enriched for Bifidobacterium and Megamonas in addition to Prevotella.(3)By adding three types of mannan oligosaccharides(1%,3% and 5%,respectively)to the dough,the relevant indexes of the fresh and frozen doughs and their steamed buns after rising were measured separately.The results showed that the appropriate amount of mannan oligosaccharides could improve the rheological properties and increase the bound water content of frozen dough,but the effect on fresh dough was not significant.The analysis of specific volume and textural properties of steamed buns showed that different additions of mannan oligosaccharides could improve the specific volume of frozen steamed buns,enhance the gluten network,and reduce the hardness and chewiness of steamed buns,among which the effect was more obvious when the addition amount was 1%,but the effect on fresh steamed buns was not significant.Among the three oligosaccharides,the addition of locust oligosaccharide at 1% and 3% was the best,and guar oligosaccharide was the second. |
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