| As a new type of bio-separation technology,reverse micelle extraction has been widely used in protein separation.Walnut protein is an important plant protein resource because of high nutritional value and good processing performance.As the world's largest producer and consuming country of walnut,the utilization rate of walnut and the low value-added products urgently need to be improved.So it is very interesting that the reverse micelles were applied in extraction of proteins from walnut meal.The main conclusions are as following:1)The influence of reverse micelle system on walnut protein is studied.The results show that reverse micelle formed by anion surfactants AOT and SDS combining with cation surfactant CTAB has better dissolvability of walnut protein than that formed by nonionic surfactant TritonX-100.And the well-behaved concentrations are at 0.10 g / mL,0.06 g / mL,0.12 g / mL and 0.04 g / mL.The influence of salt solution on walnut protein in reverse micelles is studied.The results show that the protein rate of electrolyte solution in KCl and NaCl is high,59.45 % and 63.04 % respectively.Optimum scheme of extracting walnut protein by reversed micelle method:during forward extraction,conditions of extraction are of 0.05 g /mL,W019,pH 7.5,0.25 mol / L NaCl,180 r / min 40 ? and water-bath vibrating of 80 min respectively.And the resulting rate of extraction is larger than 75%.During forward extraction,conditions of extraction are of pH 7.5,1.25 mol / L NaCl,40 ? with ultrasonic vibration of 40 min and water-bath vibration of 30 min respectively.And the resulting rate of extraction can reach 71.22%,which is close to the theoretical value of the optimization scheme 71.22%.Two methods of walnut protein differ in appearance.The one extracted by reversed micelles is bright,white powder.the other is floc morphology and dark sinking.The walnut protein prepared by reversed micelles has good emulsifying and emulsifying stability,which,at pH 7.0,reach 52.5 % and 68 % respectively,better than alkali extracting acid sinking method.Also,it has better foaming ability andfoaming stability,which,at pH 10.0 after 20 min,reach 56 % and 99.55 %respectively.5)The surface hydrophobicity of walnut protein extracted by two methods is not very different.However,the surface hydrophobicity of globulin and glutenin extracted by alkali extraction method is much higher than that of reversed micelles.Whereas,the albumin and gliadin extracted by reversed micelles are higher.Protein extracted by reversed micelles method has relatively poor hydrophilic capacity.The solubility decreases.The water absorption is slightly lower.Emulsifying is improved.Oil absorption can be slightly higher.6)The walnut protein extracted by reversed micelles is rich in 17 amino acids(using aqueous solution,tryptophan could not be checked).The total amino acids accounted for 61.56 %.Seven essential amino acids were at 10.56 %,higher than17.78 % of the alkali extraction acid precipitation method.At the same time,the contents of the three fresh substances of aspartic acid,glutamate and arginine in reverse micelles are significantly higher than that of alkali extraction acid precipitation method.7)The albumin extracted from the reversed micelles is flaky.And the surface is cleaner,edges are sharp.The globulin is smaller,but sphere is intact and surface is smooth.The prolamins are similar in two methods.But the protein surface obtained by alkali acid precipitation is rougher.Glutelin extracted by reversed micelles shows in flake structure,which is relatively large.And glutelin by alkali extraction acid precipitation is finer and twig-like.8)Compared with the protein derived by acid precipitation method,the fluctuation of the second-level structure of the walnut protein prepared by reversed micelles was not obviously changed in the frequency of amide.However,the second-level structure of walnut protein produced by reversed micelles is shifted to the right of the entity.Results also show that secondary structure of the protein changes,the Beta-folding and the disordered structure are higher content in the reversed micelles group.The main structure of another group is the Beta-folding and the Beta-rotation.the Alpha-helix and the Beta-rotatio of alcohol soluble protein distributions of protein components derived from reversed micelles are narrow,however,the content is higher.TheBeta-rotation structure of the globulin extracted by reversed micelles accounted for a fraction of26.08%,much higher than that of alkali extraction acid precipitation method.In general,the content of the Alpha-helix and the disordered structure extracted by reversed micelles is higher.Also,the Alpha-helix of glutenin and the disordered structure of albumin by alkali extraction and acid precipitation do not appear. |
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