| Oatβ-glucan is a kind of high molecular polymer formed by the monomerβ-D-glucopyranose throughβ-(1→3)andβ-(1→4)glycosidic bonds.Oatβ-glucan has many functions such as promoting intestinal peristalsis,preventing cancer,lowering blood sugar,cholesterol and immune regulation,which is regarded as an indispensable functional nutrient in oats.The combination of size exclusion chromatography and multi-angle laser detector can be used to detect the molecular weight and distribution of polysaccharides,solution conformation,etc.And it has the advantages of good data reproductivity and relatively easy to use.In this paper,taking oat as the research object,the content of the main components in 7kinds of oats were determined,including basic components such as dietary fiber,protein,fat,etc.,and the difference in the content ofβ-glucan was emphatically analyzed,and the nutritional value was evaluated,which provided a theoretical foundation for the development of functional products on account of oats in the future.The extraction method of oatβ-glucan was firstly explored,and the optimal process conditions were determined as follows.Primarily,after the oat flour was passed through a40-mesh sieve,it was defatted by Soxhlet extraction and the degreasing rate was 79.39%.When degreasing was completed,added deionized water according to the material-to-liquid ratio.After leaching at 45°C for 3 hours,added 60 U/g of medium temperature amylase and enzymatically hydrolyzed at 60°C for 1.5 hours.Then raising the temperature to 95°C to inactivate the enzyme for 30 minutes and the starch removal rate was 95.43%.Posteriorly,using trichloroacetic acid method to remove protein and the protein removal rate was 76.11%.Subsequently,adding 90%anhydrous ethanol with a volume ratio of 1:3 to the concentrated solution,which is aimed at precipitating polysaccharides.Finally,oatβ-glucan was obtained by freeze-drying.Through orthogonal test analysis,it was concluded that under the conditions of solid-liquid ratio of 1:16,extraction temperature of 45℃,extraction p H of 12.5and extraction time of 3 hours,the average yield of seven kinds of oatβ-glucans was 7.48%.Oatβ-glucan was redissolved in deionized water and placed in a 10 w dialysis bag for 48 h before lyophilized.And Sephadex G200 was selected to further purify oatβ-glucan.After purification,its average purity reached 91.47%.The structure and conformation of oatβ-glucan were determined by SEC-MALLS-RI,dynamic light scattering and atomic force microscopy.In order to establish a detection and analysis method for oatβ-glucan,this experiment started with the solution concentration,mobile phase speed and temperature,and obtained the optimal detection conditions for SEC-MALLS:the solution concentration,flow rate and temperature respectively corresponded to2 mg/m L,0.5 m L/min and 40℃.The weight-average molecular weight of Bayou No.9,Yan Ke No.1,Neiyan No.5,Baiyan No.4,Wild-type,Jizhangyou No.3 and Moroccan oats were determined to be 4.082×10~5,2.367×10~5,4.067×10~5,1.920×10~5,2.464×10~5,1.625×10~6and 1.864×10~5.The radiuses of rotation were 42.1,34.8,41.1,26.2,35.5,52.9 and 25.4 nm,and the hydrodynamic radiuses were 25.21,31.35,56.30,25.69,45.51,66.13 and 22.28 nm,respectively.The results demonstrated that the molecular weight and size ofβ-glucan were greatly affected by different varieties.The conformational parameterρranged from 0.73 to1.67,and the exponent v of the formula Rg=k M_w~v ranged from 0.18 to 0.38.The results showed that Bayou No.9 was linear polymer with random linear group conformation,Moroccan oats,Yanke No.1 and Baiyan No.4 were highly branched molecules,and Wild type,Neiyan No.5 and Jizhangyou No.3 were rolled into spheroids in 0.1 M sodium nitrate solution.The morphology of these molecules was further confirmed by atomic force microscopy.According to the results,the differences ofβ-glucan of different oat varieties were found by using multivariate statistical analysis methods.A method for the difference analysis of oatβ-glucan was established,which laid a foundation for the study of the structural heterogeneity among different varieties. |
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