Study On Silybum Marianum Extraction By Subcritical Extraction Technology And The Quality Of Seed Meal

Silybum marianum(L.)Gaertn is native to the Mediterranean coast,in the late 1960 s,China adopted it as a medicinal plant for liver care.The oil content of silybum marianum seed is about 30%,more than 80 percent of them are unsaturated fatty acids,it is a vegetable oil with high nutritional value,after defatted,the seed meal also contains high quality plant protein and dietary fiber,and silybum marianum contains abundant flavonoid active material in the seed shell,all in all silybum marianum seeds has very high officinal,edible value and a variety of physiological functions,with a great development value.Subcritical extraction technology has been widely used in the research of natural product extraction and has been paid more and more attention.This study is based on the present research and utilization of the silybum marianum seeds,using subcritical butane extraction technology to extract of silybum marianum seed kernel oil,using subcritical water extraction technology to extract the flavonoids in silybum marianum seed shell,and the study of extraction process optimization,the amino acid and protein detection of waterfly thistle,and the physical and chemical properties of the oil and thistle seed oil were studied.The subcritical extraction technology applied in the study of silybum marianum seeds,expands the application range of silybum marianum seeds,raises silybum marianum seed resources processing technology at the same time,also offers reference to the further development and utilization for silybum marianum seed kernel oil,meal and shell.The main contents and conclusions are as follows:Firstly,this study used subcritical butane extraction technology to extract the silybum marianum oil.The optimum extraction conditions were as follows: liquid-solid ratio 25 mL/g,extraction time 70 min,extraction temperature 60 ℃,under this condition the yield of fennel oil was 21.87%.The results of response surface optimization show that the effect of liquid-solid ratio and extraction time on the yield of oil resin is greater than that of extraction temperature during the extraction process.Total unsaturated fatty acids in milk thistle seed kernel oil is as high as 77.24%,mainly oleic acid(28.20%)and linoleic acid(48.28%),saturated fatty acid content is relatively low,mainly arachidic acid(3.21%)and palmitic acid(10.69%),on the whole milk thistle oil has a high nutritional and edible value.Secondly,the active constituents of flavonoids in the shell were extracted by subcritical water extraction.The content of total flavonoids was determined by the visible spectrophotometer and the antioxidant activity was investigated,and the content of total flavonoids in the silybum marianum shell was consistent with the antioxidant activity.The optimum extraction conditions were as follows: liquid-solid ratio 42 mL/g,extraction time 36 min,extraction temperature 134 ℃,under this condition the rate of the thistle flavone was 74.72%.Response surface optimization results show that the influence of subcritical water extraction silybum marianum seed shell flavonoid yield factors,liquid-solid ratio > extraction time > extraction temperature;silybum marianum seed shell flavone is mainly silymarin,in the aspect of prevention and treatment of liver disease has significant curative effect,and it also has anti-cancer effect.Finally,utilized silybum marianum’s meal,which defatted by subcritical butane extraction technology,to produce protein concentrate,and analyzed its protein composition.The results are as follows: the protein content of the milk thistle seed is up to 45.35%,which is a good source of plant protein.The functional characteristics of protein of milk thistle seed kernel pulp were studied,the results found that the isoelectric point of the meal protein was pH = 5.5,the water binding capacity is 1.43 mL/g,the oil binding capacity 4.03 mL/g,emulsification ability and emulsion stability and foaming ability and foam stability were highly correlated with meal protein solubility,reach the lowest at the isoelectric point,tend to rise when deviating from the isoelectric point;Four types of proteins were isolated from the seed meal,and the protein was mainly albumin.17 kinds of amino acids were detected in the milk thistle seed meal,the essential amino acid content was 15.46%,and the non-essential amino acid content was 27.53%.