Study On Mass Transfer Process Of Peanut Protein Extracted By AOT/Enzyme Reverse Micelles Systems

Reverse micelles extraction is a new technology of separation and purification of biological macromolecules which is suitble for the proteins, antibiotics, polysaccharides and so on. Because of high nutritional value and good processing performance, peanut protein becomes an important material of plant protein in modern food industry. Therefore, the study on reverse micelles extraction of peanut protein is very important.This paper studied that sodium bis(2-ethylhexyl) sulfosuccinate(AOT)/isooctane reverse micelle system with alkaline protease extracted the peanut protein, which contains forward extraction and backward extraction, and optimized the extraction parameters according to the regression tests. The results showed that the forward extraction efficiency of peanut protein increased greatly through adding alkaline protease. And the effects of ratio of enzyme and substrate([E]/[S]), W0, pH of buffer solution, temperature, extraction time were investigated. According to the response surface analysis, optimum conditions were that [E]/[S] 40000 U/g, W0 12.8, pH 7.3, temperature 60 °C, extraction time 50 min. The maximum forward extraction rate was(92.37%±0.58)%. Then backward extraction of peanut protein by enzyme-containing reverse micelles was studied. And the effects of the pH, KCl concentration, the temperature of extraction and oscillation time were investigated. The optimum conditions of backward extraction conditions of peanut protein in enzyme-containing reverse micelles were the pH 8.1, KCl concentration 1.53 mol/L, temperature 40 °C and oscillation time 120 min. And the backward extraction rate was(78.43±0.87)%.The mass transfer process of peanut protein extracted by AOT reverse micelles were analyzed according to the Shrinking Core Model. The effects of stirring speed, temperature of extraction, peanut particle size, solid-liquid ratio and ratio of enzyme and substrate([E]/[S]) were examined. The results showed that the extraction rate was increased with higher temperature, reduced particle size and increased solid-liquid ratio. The apparent activation energy of extraction process calculated was 10.02 kJ/mol. In brief, the extraction process was controlled by the diffusion of protein from interior to the surface of the particles and it was the first order reaction. The equation of mass transfer process of peanut protein extracted by AOT reverse micelles was established. And the results indicated that the experimental value and the calculated value had a good match. The mass transfer process of peanut proteins extracted by reverse micelles containing enzyme was studied in this paper. The results showed that the optimum [E]/[S] was 40000 U/g. And the apparent activation energy of extraction process calculated was 9.64 kJ/mol. Compared with two extraction processes, it found that they had the same control steps, but the apparent activation energy of the later was lower, and it had higher extraction efficiency.The differences of functional properties of peanut protein extracted by reverse micelle changing the pH of systems and the extraction temperatures were investigated. By analysis of their structures and properties, we got the results that with the rising temperatures the S-S bonds increased, α-helix and β-turns decresed, unordered structures increased. The content of α-helix decreased with the pH increased. When pH was 8.0, the content of S-S bonds was highest, and there was lowest degree of degeneration of peanut proteins and the best thermal stability.