Extraction and Functional Properties of Protein from Low-temperature Peanut Meal by Reverse Micelles

Peanut protein is a high-quality plant protein. A rich source of peanut meal inchina, but most of the peanut meal was used as feed or fertilizer, causing a huge wasteof protein resources. The reverse micelles have been widely used in separation ofprotein, as a new bio-separation techniques. The protein production separated fromlow-temperature peanut meal in reverse micelles was introduced systematically in thispaper including the forward extraction and backward extraction and its functionalproperties were also studied. The main conclusions are as following:(1) The effect of different surfactants (AOT, SDS, Triton X-100, and CTAB) onthe peanut protein was studied. The results showed that the anion surfactants AOT andSDS in reverse micelles would be benefit for protein solubilization compared withcation surfactants CTAB and non-ionic surfactants Triton-X100in reverse micelles.The optimal concentration of four reverse micelles system was0.08g/ml,0.08g/ml,0.07g/ml,0.08g/ml respectively.(2) The effect of different salt solutions (KCl, NaCl, LiCl, MgCl2, NaNO3, KNO3,Na2SO4, MgSO4) on the peanut protein was studied. The results showed that the KCland NaCl solutions in reverse micelles would benefit for protein extraction, theassignment of protein was54.22%and50.19%respectively and the different saltsolutions can be used to separate the different proteins.(3) The forward and backward extraction of AOT reverse micelles was studiedby Uniform-precision rotatble central composite design and Box-Behnken designrespectively, and found the regress equation. The results showed the optimalconditions of forward extraction protein were sample amount of0.02g/mL, samplesize of100mesh, W0,18, pH7.0,[KCl]0.05mol/L, temperature40℃, time60min,and the forward extraction rate of protein was greater than85%in this condition; Theoptimal condition of backward extraction protein were pH9.0,[KCl]1.0mol/L,temperature40℃, time90min, and the backward extraction rate of protein was 78.91%, the total assignment of protein was about70%.(4) The functional properties of the peanut protein extracted by reverse micelleswas studied. The results showed that compared with the peanut protein which wasextracted from aqueous phase, the foaming capacity and foaming stability of thepeanut protein which was extracted by reverse micelles is significantly better and theother functional properties was little different.(5) The effect of reverse micelles on the amino acid composition and thesecondary structure of peanut protein was studied. The results showed that reversemicelles extraction can improve certain amino acids, for example the flavor aminoacid; the secondary structure of the peanut protein can be caused a certain degree ofchange by the reverse micelles, no-rule structure increased and β-sheet reduced in acertain extent while α-hexli to appear.