The Research On Aqueous Extraction Of Peanut Oil And Peanut Protein By Small Molecule Surfactant

Peanuts was a dominant oil crop,and the efficient use of peanut resources was of great significance to ensure the safety of domestic edible oil supply.The aqueous extraction could simultaneously extract peanut oil and protein,but a large amount of emulsion would be formed so as to reduce the extraction rate of free oil.Small-molecule surfactants had been proven to inhibit the formation of emulsions,but they were currently used in large amounts and the demulsification mechanism was unknown.This article first began with peanut pretreatment and surfactant compounding(Tween 20,sucrose ester and citrate ester),then optimized the aqueous extraction process to reduce the amount of surfactant,finally improved the extraction rate of free oil and protein.The demulsification mechanism of surfactant was discussed.Different protein chemical modifiers(succinic anhydride,sodium tripolyphosphate and sodium sulfite)were added during the aqueous extraction to compare the effects of different modifiers on the extraction rate and properties of peanut oil and protein.Through the study of four different types of peanuts,it was found that Dabaisha(Chen)peanuts had the highest extraction rate of free oil by aqueous extraction.The peanut slurry obtained by dry pulverization was stored,and it was found that the appropriate storage time(2-6 d)and storage temperature(room temperature or 37?)could promote the mutual accumulation of oil and ultimately increase the extraction rate of free oil.As the storage time went on,the demulsification effect of Tween 20 gradually decreased.The low-temperature roasting(60?)and removing the skin significantly reduced the extraction rate of peanut free oil,and the low-temperature roasting(60?)without removing skin had the better effect of Tween 20 on demulsification during the aqueous extraction.The small molecule surfactants Tween 20,sucrose ester and citrate ester alone could improve the extraction rate of peanut free oil to a certain extent,but had no significant effect on the extraction rate of peanut protein.When the three were compounded at 1:1:2(use concentration was 1%),under appropriate shaking conditions(shaking temperature 50?,shaking speed 150 r/min,shaking time 40 min),the extraction rate of peanut free oil was 79.7%,and the extraction rate of free oil could reach 82.7%by expanding the use of raw materials.The results showed that the replacement of small molecule surfactants for adsorb proteins on the emulsion interface decreased the strength of the interface membrane and the absolute value of the Zeta potential.This might be the main reason for the unstability of the emulsion and increasing the extraction rate of free oil.During the process of extracting peanut oil with compound surfactant-assisted aqueous extraction,it was found that succinic anhydride and sodium tripolyphosphate significantly reduced the extraction rate of free oil,while sodium sulfite had little effect on the extraction rate of free oil and peanut protein.The application of sodium sulfite modification in the process of aqueous extraction didn't change the subunit composition of peanut protein,but causes the blue shift of its endogenous fluorescence spectrum.The results of the functional properties of peanut protein showed that the solubility,water holding capacity,oil holding capacity,emulsification activity index and foaming properties of the protein were significantly improved when the composite surfactant and sodium sulfite were used in concert,but the emulsion stability and foaming stability were worst.Sodium sulfite had a good decolorizing effect on peanut protein.Comparing the quality of peanut oil from different sources,the water content and volatile content of peanut oil extracted by aqueous extraction were significantly higher than peanut oil extracted by petroleum ether,the former had lower acid value,peroxide value and lighter color.The content of total V_E and?-V_E in peanut oil extracted by aqueous extraction was significantly higher than peanut oil extracted by petroleum ether.Peanut oil extracted by petroleum ether had a longer oxidation stabilization time(11.46 h),indicating that its oxidation stability was the best.The oxidation stabilization time of peanut oil extracted by pure water was shorter(6.79 h),and the synergistic effect of surfactants and sodium sulfite could improve the oxidation stability of water-based oils.