Study On The Separation And Extraction Of Millet Gluten Protein And Its Functional Properties

Millet bran is the product of millet husking,which is rich in protein,fat and polysaccharide.Although China is rich in millet bran resources,its deep utilization is yet to be developed.Most of them are not processed and directly used as feed or discarded,resulting in a waste of resources.Using millet bran to develop new food or health care products can not only increase the enthusiasm of farmers,but also increase the source of food and economic benefits of enterprises,so the development and utilization of millet bran has practical significance.This subject mainly focuses on the enzymatic extraction,purification,amino acid composition and nutritional value evaluation of millet bran protein,as well as processing functional properties.The content of main components in millet bran was determined.In this study,amylase was the most suitable sugar enzyme and alkaline protease was the most suitable protease.On the basis of obtaining the optimal enzyme,the single factor test method was used to further optimize the optimal extraction conditions.On the basis of single factor test,box-behnken was used for the experimental Design,and design-expert8.0 software was used for data analysis.The best extraction conditions were obtained and the protein solution was prepared in large quantities.After the crude protein extract was obtained,the ultrafiltration tube was used to further concentrate and gel chromatography was used to remove the residual small molecules.The millet bran protein solution was precipitated by isoelectric point method and freeze-dried under vacuum.The purity of the dried product was measured and its nutritional value was evaluated by amino acid analysis.The basic properties and processing properties of proteins are important indexes in the application of proteins.In this experiment,the processing properties of millet bran protein,such as emulsification,foaming and solubility,were studied.This experiment studied the millet bran protein get the best reaction condition is: amylase(add enzyme amount: 1.8%,the extracting time: 2.2 h,extraction temperature: 55.6 ?,pH: 6.5)extraction rate is 48.53%;Alkaline protease(add enzyme amount: 0.7%,the extracting time: 1.8 h,extraction temperature: 50.0 ?,pH: 9.0)extraction yield of 72.29%.Therefore,it was determined that amylase was used first,and then alkaline protease was used to extract under their optimal conditions,and the extraction rate of bran protein was 87.96%.The purity of millet bran protein was 82.61%.The millet bran protein after the determination of the amino acid analysis,shows that its nutritional value very high,which accounts for 36.3% of the total amino acids,essential amino acids in addition to the content of phenylalanine,leucine and isoleucine is slightly less than the FAO/WTO recommended value,other essential amino acids are fine,histidine was baby the necessary amino acids,the AAS value is 205,more than 170(FAO/WHO)to recommend.Due to the low allergenicity of millet bran protein,it has great potential in the development of protein supplements for infant food.The isoelectric point of millet bran protein was determined as pH=4.4,and the molecular weight was between 11 and 35 kDa.The purified bran protein has good emulsification,foaming and solubility,which is suitable for food processing.