米糠蛋白的分级提

发布时间：2020-06-01 14:43

【摘要】：In recent years,the source of plant protein has become a research hotspot,and rice bran is a valuable resource with super high nutritional value.However,due to the existence of excessive disulfide bonds in rice bran protein,it is difficult to completely separate and extract it,resulting in rice bran protein.The development of functional properties is limited.In this study,the rice bran protein was fractionated and extracted by physical method,and the structural and functional properties of the different protein components were studiedThe rice bran protein was extracted by the method of alkali-soluble acid precipitation using defatted rice bran as raw material,and the extracted rice bran protein was fractionally extracted by sucrose density gradient centrifugation.First,the effective sucrose concentration gradient was established by pre-experiment in the range of 10%to 50%.On the basis of establishing the sucrose concentration gradient,the experiment uses the protein extraction rate as an index,the SDS-PAGE gel electrophoresis analysis chart as a reference,and the ultracentrifuge as the core equipment to determine the sucrose density gradient method to fractionate the rice bran protein fraction.Good process parameters,sucrose solution concentration(50%,40%,30%,20%,10%),centrifugal force(15000g/min,20000g/min,25000g/min.30,000g/min,35000g/min),rice bran The concentration of protein solution(10mg/mL,20mg/mL,30mg/mL,40mg/mL,50mg/mL)was used as the experimental condition.The optimal classification conditions after optimization were:centrifugation speed 25000g/min,centrifugation time 30min,rice bran protein The concentration of the sample solution was 30 mg/mL,and the basal rice bran protein component Ⅰ,rice bran protein component Ⅱ,rice bran protein component Ⅲ,rice bran protein group were separated under the conditions of sucrose concentration of 50%,40%,30%,and 20%.respectively.Divided into Ⅳ.The extraction rates of the four protein components were 21.6%,24.4%,17.2%,and 12.5%,respectivelyThe functional properties of four different rice bran protein fractions were studied by using four kinds of rice bran protein components by solubility,water holding capacity,oil holding property,foaming and foam stability,emulsifying property and emulsion stability.The results showed that the functional properties of the four rice bran protein components were different.The functional properties of the protein depended on the nature of the surface groups of the protein and also closely related to the protein structure.Four different components of rice bran protein were studied by Fourier transform infrared spectroscopy,DSC thermal denaturation,scanning electron microscopy,sodium dodecyl sulfate-polyacrylamide gel electrophoresis,amino acid analysis and surface hydrophobicity.Changes in the structure of the rice bran protein component.The results showed that there were differences in the secondary structure of the four rice bran protein fractions,with RBPⅠ and RBPⅡ peaking the most.The denaturation temperatures of the four rice bran protein fractions were:68.42℃,83.51℃,89.79℃,and 68.33℃.Scanning electron microscopy revealed that the surface of the four rice bran protein components was rough and porous,which affected the oil retention of the protein.SDS-PAGE gel electrophoresis showed that the molecular weight range of the four rice bran protein components ranged from 74.0KDa to 97.4KDa,41.0KDa to 53KDa,29.0KDa to 30.0KDa,and 13.0KDa to 21KDa.
【图文】：

流程图,米糠蛋白,分级工艺,组分

逦—？｜收集沉淀ｈ￣？ｌ水洗邋Ｉ￣透析逦冷冻丨？燥ｉ￣米糠蛋白组分ｆ逡逑图２－１四种米糠蛋白组分分级工艺流程逡逑四种米糠蛋白组分分级工艺流程如图２－１，具体试验操作如下：逡逑将一定量脱脂米糠，按照料液比１：８的比例加入蒸馏水，并用ｌｍｄ／ＬＮａＯＨ逡逑溶液调节ｐＨ至９，室温下搅拌２ｈ，在４０００ｒ／ｍｉｎ条件下离心２０ｍｉｎ，，，收集上清逡逑液，用ｌｍｏｌ／ＬＨＣＬ溶液将上清液ｐＨ至４．５，在４０００ｒ／ｍｉｎ条件下离心２０ｍｉｎ，逡逑收集沉淀，调至ｐＨ为７，冷冻干燥得米糠蛋白。配制５０％浓度的蔗糖溶液，４°Ｃ逡逑下静置过夜，然后取一定量米糠蛋白加入蒸馏水配制成一定浓度的蛋白溶液，取逡逑１０ｍＬ５０％蔗糖溶液装入５０ｍＬ离心管中，用移液枪吸取ｌｍＬ米糠蛋白溶液沿离逡逑心管壁小心打入蔗糖溶液上方，使用超速离心机在４°Ｃ和一定转速下离心一段时逡逑间。将离心得到的沉淀经过水洗

分子量分布,米糠蛋白,蔗糖溶液,组分

逦？邋；．？＞．－逦／逦，逡逑＝—邋■逡逑图３－２蔗糖溶液浓度对米糠蛋白组分Ｉ分子量分布的影响逡逑Ｆｉｇｕｒｅ邋３－２邋Ｅｆｆｅｃｔ邋ｏｆ邋ｓｕｃｒｏｓｅ邋ｓｏｌｕｔｉｏｎ邋ｃｏｎｃｅｎｔｒａｔｉｏｎ邋ｏｎ邋ｍｏｌｅｃｕ
【学位授予单位】：沈阳师范大学
【学位级别】：硕士
【学位授予年份】：2019
【分类号】：TS201.21

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