Effect Of Pulsed Electric Field-assisted Water Generation On The Quality And Protein Properties Of Sesame Oil

Pulsed electric field(PEF)is a new food processing technology,compared to the heat treatment,with a low processing temperature,short time,low energy consumption and low pollution characteristics,but also to avoid due to the heating of food nutrients destroyed,to better retain food quality and nutritional characteristics.Sesame oil as the first condiment to be used.The processing of sesame is mainly concentrated on the extraction of sesame oil.The oil-based fragrance obtained by the water law is rich and long-lasting.The source of its flavor needs to be roasted at a high temperature,resulting in the recovery of sesame protein Low,high degree of degeneration,the resulting sesame meal is often used as a low-value by-product animal feed,have not been fully utilized.PEF as a pretreatment to extract oil has been a lot of research.In this study,PEF was used to pretreat the pre-conditioned white sesame seeds.Taking the pulse voltage,pulse processing time,pulse frequency and pulse width as the parameters,the oil yield and the functional properties of sesame protein were taken as the indexes to understand the PEF operation conditions on the oil yield,fat quality,the functional properties of sesame protein and sesame oil lignan affect the development and utilization of sesame water on behalf of the new methods and ideas.The main results are follows:(1)Through the single factor experiment,the extraction temperature,extraction time,pH,liquid-to-solid ratio and shaking speed were all determined to effect the oil yield in the process of aqueous extraction method.Taking the oily yield of sesame as an index,using orthogonal design optimization experiment,the results of influencing factors on the oil yield is pH>extraction temperature>extraction time>material-liquid ratio>shaking speed.The optimum parameters of sesame oil prepared by aqueous extraction method were as follows:extraction pH 11.0,extraction time 1.0 h,solid-liquid ratio 1:7,extraction temperature 70? and shaking speed 200 r/min.Under this condition,sesame oil yield up to 56.32%.(2)The pulse electric field pre-treatment sesame can increase the oil yield.Pulse voltage,processing time and time,pulse frequency and pulse width all have an impact on the oil yield,and all showed an increasing trend,indicating that pulse electric field assisted water generation method sesame oil low temperature feasible.The PEF assisted oil recovery was optimized by software response surface.The optimal process conditions according to the prediction model were:voltage 9 kV,material residence time 3 min,pulse frequency 520 Hz,pulse width 9 ?s.The sesame oil yield measured in this process was 63.13%,with a relative error of 0.72%from the theoretical predictions.(3)After PEF treatment,the acid value,saponification value,peroxide value and color were lower than the control group,sesame oil quality almost in line with national standards of sesame oil,and the oil has the lighter grease color,at the same time,it with the inherent smell and taste,no precipitate was seen in the PEF-treated and control groups during the heating test.Sesame oil detected six major fatty acids,namely:oleic acid,linoleic acid,palmitic acid,linolenic acid,stearic acid and arachidic acid.PEF treated sesame oil fatty acid species did not change,the relative percentage of unsaturated fatty acids increased,the relative percentage of saturated fatty acids decreased.(4)Extraction of lignan from sesame oil with methanol and measured by high performance liquid chromatography.The sesamin contents of the control,PEF and commercial oil groups were 296.31 mg/100 g,930.61 mg/100 g and 413.68 mg/100 g,respectively,and the sesamin content was 111.27 mg/100 g,140.02 mg/100 g and 185.83 mg/100 g respectively;sesame phenol content was 78.04 mg/100 g,17.95 mg/100 g and 21.78 mg/100 g respectively.After PEF treatment,the content of sesamin and sesamin increased,the content of sesamin decreased.Sesame oil has a scavenging effect on DPPH·,·OH and O2-·.PEF pre-treatment group were higher than the antioxidant effect,so PEF treatment can significantly increase the antioxidant activity of oil(P<0.05).Oven aging accelerated oxidation test showed that the acid value,peroxide value and p-anisidine value of sesame oil increased steadily with the increase of storage days.The indexes of PEF group were lower than the control group at the late storage stage.(5)Alkali-acid-precipitation method was used to prepare water-phase protein and sesame residue,and pH value 12 was used to extract the sesame protein.The pH value was 4.0.Sesame albumin,globulin,prolamin,and glutelin were prepared according to the differences in protein solubility.PEF treatment has a positive effect on the functional properties of sesame proteins(water holding capacity,oil holding capacity,emulsifying capacity and emulsifying stability,foaming capacity and foam stability).The PEF-treated sesame aqueous protein and sesame grade protein functional properties were better than the control group,and albumin protein functional properties were overall better than the water-phase protein and globulin,glutelin and prolamin.