Effects Of Thermal Processing On The Structural Characteristics And In Vitro Fermentation Of Whole Grain Oats ?-glucan And Arabinoxylan

In this study,the whole grain oats were processed with normal pressure steaming,high pressure steaming and microwave heating.The heat-treated whole grain oat?-glucan and arabinoxylan were extracted.The effects of thermal processing on the structural and In Vitro fermentation characteristics of whole grain oat?-glucan and arabinoxylan were studied.Using Metagenomic Microbial Classification Sequencing method to study the effects of?-glucan and arabinoxylan on acid production and on the diversity of fecal microbiota.Main results are as follows:The effect of heat processing on the structural properties of oat?-glucan and arabinoxylan was compared.The molecular weight results showed that the Mw of unheat-treated whole grain oat?-glucan was 1.067×10~6 g/mol,normal pressure steamed and high pressure steamed oat?-glucan were increased by 1.713×10~6 g/mol and 7.015×10~6 g/mol respectively,the Mw after microwave heating was reduced to 1.647×10~5 g/mol.Likewise,the Mw of unheated whole grain oat arabinoxylan was 3.256×10~5 g/mol,normal pressure steamed and high pressure steamed oat?-glucan were increased by 2.494×10~6 g/mol?4.574×10~5g/mol respectively.The Mw after microwave heating was reduced to 1.713×10~5 g/mol.The IR spectrum results showed that oat?-glucan and arabinoxylan had the polysaccharides absorption peaks characteristic,and there were no significant changes between different heat-treated samples;Scanning electron microscope microstructure results showed that the apparent morphology of heat-treated oat?-glucan was formed by many round small aggregates tight network.The uniformity of the heat treated particles was increased compared with control.There was a rod-like structure in the unheated whole grain oat arabinoxylan.After the thermal processing,the molecular structure is loose and irregular large-scale sheet structure.The flakes of high-pressure and microwave-treated arabinoxylan are smaller,and the large-scale sheet structure of normal pressure steaming was obvious.The effect of thermal processing on the functional properties of oat?-glucan and arabinoxylan were analyzed.The results of hydration characteristics showed that the water-holding and oil-holding properties of heat treated oat?-glucan and arabinoxylan were significantly reduced and there was a significant difference(p<0.05),but the swelling of?-glucan and arabinoxylan after thermal processing was significantly increased(p<0.05),and the swelling of high pressure was the highest;the results of glucose adsorption showed that microwave heated oats?-glucan and pentosan has the highest glucose adsorption capacity.The results of cholesterol adsorption showed that microwave-treated oat?-glucan and arabinoxylan have the highest adsorption cholesterol capacity;Compared to the cholesterol adsorption capacity of heat-treated oat?-glucan and arabinoxylan,the adsorb cholesterol ability of?-glucan is higher than that of arabinoxylan.In vitro fermentation of whole grain oat?-glucan and arabinoxylan and its effect on intestinal microflora were studied.The results of pH and short-chain fatty acids showed that oat?-glucan and arabinoxylan can reduce human fecal pH and produce a certain amount of short-chain fatty acids.The short-chain fatty acids concentration of microwave-heated oat was highest;Metagenomic Microbial Classification Sequencing results showed that oat?-glucan and arabinoxylan promoted the growth of Lactobacillus and Bifidobacterium and their abundance was higher than that of the blank group,while Escherichia abundance was lower than that of the blank group,these results proved that oat?-glucan and arabinoxylan could promote beneficial bacteria and inhibit the growth of harmful bacteria.The thermal processing group was compared and found that the probiotics effect of microwave heated oat?-glucan and arabinoxylan was the most siginificant.In addition,Butyricococcus was found in fermented arabinoxylan genome,Butyricococcus is a probiotic that exists in the intestinal tracts of humans and animals,which could produces butyric acid.It has important significance in regulating the microecological balance of the intestine,promoting the absorption of nutrients and inhibiting the development of pathogenic bacteria.