Study Of Extraction Technics And Identity Of Four Proteins In Rice Bran

Rice bran protein had high nutrition,low allergy unique nature,wich was recognized as aquality plant protein resource in the world.Rice bran protein consists mainly composition ofalbumin,globulin,gliadin and glutenin,The various isolated protein hada different processings andfunctional properties,According to the different nature of the protein isolate,rice bran proteinincreased the use of plant protein species and value of the rice bran,wich had importantly practicalsignificance.Rice bran was as raw material,using Osborne classification method for preparing protein inturn obtain albumin,globulin,gliadin and glutenin,The protein extraction rate was as index,Solid-liquid ratio,extraction time,extraction temperature,extraction solution concentration,solutionpH was as impact factor,Through the single factor experiment and orthogonal experiment tooptimize the extraction process of four proteins,Determining the optimum extractionconditions.The results showed that:(1)The optimum extraction process of albumin:Solid-liquidratio was1:14, extraction time was3h,temperature was45℃,Precipitated in isoelectric point pHwas4.0,Finally get albumin extraction rate was58.07%,The purity was74.18%.(2)The optimumextraction process of globulin:Solid-liquid ratio was1:10,extraction time was2h,temperature was45℃,concentration of NaCI was3%,Precipitated in isoelectric point pH was4.3,Finally getglobulin extraction rate was18.88%,purity was79.52%.(3)The optimum extraction process ofgliadin:Concentration of ethanol was75%,solid-liquid ratio was1:10,extraction time was2h,Precipitated in isoelectric point pH was5.5,finally get gliadin ex traction rate was2.52%,thepurity was69.73%.(4)The optimum extraction process of glutenin:Solid-liquid ratio was1:8,extraction time was1.5h,temperature was45℃,pH was9,Precipitated in isoelectric point pHwas4.6,finally get glutenin extraction rate was16.53%,The purity was81.67%.Detecting the physicochemical properties of albumin,globulin,gliadin and gluten samples,Theresults show that:the isoelectric point of albumin,globulin,gliadin and glutenin respectively werepH4.0,pH4.3,pH5.5,pH4.6;the surface of albumin,globulin and gliadin was roughness and hadMore holes,wich had the greater role in the grease retention;Thermal denaturation temperature offour kinds protein was71.25℃,62.81℃,60.31℃,67.58℃;Albumin subunit had distributionprobably in94.04KDa,74.99KDa,53.56KDa,molecular weight glutenin probably had distributed in96.43KDa,68.45KDa,56.54KDa,44.63KDa,The gliadin had only one band,distributing in14.27KDa,Glutenin subunits was distributed about in58.33KDa,43.44KDa,36.3KDa,20.82KDa, The small proteins has conducively digested;The amino acid composition analysis showed that:Amino acid composition and content of the four proteins were different,Compared with theFAO/WHO model,Some essential amino acids have much more than the FAO/WHO recommendedmode,And was rich in functional amino acids.Based on determination of the functional characteristic of albumin,globulin, gliadin andgluten samples,The results show that:associated Surface hydrophobicity and amino acidcomposition of the protein,In particular closely related,the residues number of hydrophobic aminoacid and spatial distribution for the surface protein,Compared with soy protein isolate,Hydrophobic gliadin,glutenin greater than soy protein isolate,globulin,albumin were less thanthat,the solubility of four proteins were less than soy protein isolate,Correlation analysis of fiveproteins both solubility and surface hydrophobicity,There between is a very significant negativecorrelation(r=-0.837),The soluble protein has good other functional properties,Albumin andglobulin has good solubility,water holding held oily,emulsifying and foaming properties,thebalance of Amino acid composition,poor functional of gliadin,limited application range,Thefunctional properties of gluten are better,High levels of some essential amino acids,has higherutilization value.