Studies On Aqueous Enzymatic Extraction Of Peanut Oil And Protein Hydrolysates

The extraction of peanut oil by aqueous enzymatic has a simple process and safeoperation.The aqueous enzymatic extraction could get oil and hydrolyzate protein with goodquality. However, due to the mild conditions of oil extraction, the production of peanut oilwere still lacking in flavor; peanut hydrolyzate protein in the purity could not be completelymatch with industrial demand. In this article, peanuts were roasted before aqueous enzymaticextraction, the influence of peanuts roasting temperature on the quality of peanut oil andhydrolyzed protein were the mainly investgated. And at the best peanuts roasting temperature,the better optimum parameters of aqueous enzymatic extraction and the purification of proteinwere studied by Response surface methodology (RSM), in this paper. The main conclusionswere as follows:Firstly, the influence of peanut-roasting temperature on the quality of peanut oil obtainedby aqueous enzymatic extraction was investigated. The results indicated that, roastingtemperature had no obvious influence on moisture, insoluble impurities, refractive index, thevalue of acid and saponification, fatty acid composition, content of conjugated trienes of theoils, but it had great effect on colour, the value of peroxide, the content of conjugated dienes,Compared with the oil produced by expelling method, the oil obtained by aqueous enzymaticextraction had lower peroxide value and conjugated dienes content. The VEcontent of oilswas first decreased and then increased as the roasting temperature was increased. The peanutseeds were roasted at190℃or more than190℃, the obtained oil had good flavor.Secondly, the influence of peanut-roasting temperature on the quality of hydrolyzedprotein obtained by aqueous enzymatic extraction was investigated. The results indicated that,roasting temperature had no obvious influence on the DH of protein, the composition ofamino acid, foaming properties, emulsifying stability and fluorescence spectra. As temperatureincreased, the browning index of peanut protein hydrolyzate was gradually increased; peanuthydrolysis on190℃have better protein hydrophobicity estimation, stronger emulsifyingcapacity (alkaline conditions) and reducing power, higher scavenging effect on DPPH.Therefore, the peanuts roasted at190℃for20min is the best pretreatment condition.Thirdly, the2709Protease was chose for the aqueous enzymatic extraction of peanut oiland peanut hydrolyzed. The optimal processing conditions were established by the single factor and the Response surface methodology (RSM). The optimal processing conditions wereas follows: pH10.5, enzyme amount1%(w/w) reaction time3.5h. Under these condition theoil yield were83.25%, hydrolyzed protein yield were74.67%.The powdered activated carbon was chosen for the decolouration of peanut hydrolysate,the optimum conditions were as follows: active carbon amount8%(g/mL), pH3.2,temperature50℃, time30min.Under these conditions, the decoloration rate was up to79%.The DA201-C macroporous was chosen for the purification of peanut hydrolysate, theoptimum conditions for protein adsorption were as follows: pH4.2,40℃,time5h; and forprotein desorption were55%ethanol solution of analytical13h. The protein content of purifiedpeanut hydrolysate was raised from53%to72%, the oil-holding capacity, emulsifyingcapacity and stability, surface hydrophobicity of peanut hydrolyzed protein are better than theprotein obtained by alkali-soluble and acid-insoluble; but the foaming capacity and stabilitywas weaker than the protein obtained by alkali-soluble and acid-insoluble. After thedecolouration of activated carbon and purification of macroporous, the value of IC50forscavenging effect of peanut hydrolysate was1.90mg/mL on DPPH.