Optimization Of Extraction Process Of Selenoprotein And Analysis Of Antioxidant Capacity In Vitro Of Cynanchun Thesioides (Freyn).K.Schum

Selenium(Se)is an essential trace element for human body.It mainly exists in the form of selenium protein in plants.It is absorbed by human body along the food chain and takes part in important metabolic reactions in human body.Cynanchum thesioides(Freyn)K.Schum,also known as sand grandma,milk melon,etc.,is a kind of plant integrating feeding,medicinal,edible and industrial raw materials.Among them,Cynanchum thesioides(Freyn)K.Schum.var.australe(Maxim.)Tsiang et P.T.L.Is variant of C.thesioides.Relevant studies have shown that C.thesioides has strong selenium enrichment ability,and its selenium content is much higher than that of some common vegetables.Therefore,in this study,C.thesioides and C.australe fruits were used as experimental materials to determine the contents of water,vitamin C,crude fiber,crude fat,soluble total sugar,soluble protein and selenium in different fruit types.The selenium protein was extracted by water extraction,salt extraction,acid extraction,alkali extraction and organic solvent extraction,and the extraction technology was optimized by response surface method.Finally,plants of C.thesioides were treated with selenium fertilizer of different concentrations to explore the changes of selenium content and in vitro antioxidant activities of their fruits,in order to provide technical support for the extraction and utilization of selenium protein from C.thesioides fruits.The specific results are as follows:1.The water content of C.thesioides was the highest,90.01 %;C.australe had the highest content of vitamin C,soluble total sugar and soluble protein,which were 135.10mg/100 g,3.55 % and 8.04 mg/g,respectively.The contents of crude fiber,crude fat and selenium C.australe were the highest,which were 1.948 %,7.3 % and 1.06 mg/kg,respectively.2.The optimum extraction process of water extraction was as follows : the ratio of material to liquid was 1:15.87,the extraction temperature was 28.64 °C,the extraction time was 2.29 h,and the theoretical selenoprotein content was 2.741 mg/g;the optimum extraction process of alkali extraction was as follows : solid-liquid ratio 1:22.7,extraction temperature 44.62 °C,solvent concentration 0.243 mol/L,and theoretical selenoprotein content 5.925 mg/g.The optimum extraction process of acid extraction was as follows :solid-liquid ratio 1:28.6,extraction temperature 51.603 °C,solvent concentration0.192mol/L,theoretical selenoprotein content 2.762 mg/g.The optimum extraction process of salt extraction was as follows : solid-liquid ratio 1:21.74,extraction temperature 35.99 °C,solvent concentration 0.141 mg/L,theoretical selenoprotein content 4.731 mg/g;the optimum extraction process of organic solvent extraction method was as follows : the ratio of material to liquid was 1:23.3,the extraction temperature was 52.485 °C,the solvent concentration was 81.37 %,and the theoretical selenoprotein content was 3.271 mg/g.Among the five extraction methods,the selenoprotein content extracted by alkali extraction was the highest.3.The highest selenium content in C.thesioides fruit and extract was 1.92 mg/kg and0.58 mg/kg,respectively,when the diluted concentration of 2 mg/L selenium fertilizer sample was 5 mg/m L.The scavenging ability of selenium protein in C.thesioides fruit on DPPH free radical,hydroxyl free radical,superoxide anion and reducing ability was significantly stronger than that in other concentration treatments.