Studies On Processing Milk Thistle Seeds By Extrusion And Microwave Extraction

Milk thistle, a plant of the herb, medicinal compositions of milk thistle whose name is silymarin can prevent and treat hepatobiliary disease. In addition, silymarin had antioxidant, anti-radiation, anti-tumor, and controled diabetes and enhanced immunity. A lot of fat was contained in the seed of milk thistle which was Natural health products with important medical value and the functions of nutrition and health. In addition, rich protein, starch and trace elements was contained in grains in distilled liquor of milk thistle which had high value in use. Therefore, the effective components of milk thistle has become the focus of research in recent years.The current situation of domestic milk thistle resource utilization existed the problem of high cost and low use of utilization. First, complicated machining processes, low state of the purity and yield of silymarin, and lots of solvents and energy consumption.Secondly, about70%fat in raw materials can only be extracted by adopting oil extraction process, and residue of a large number of oils and fats nearly30%made extraction of silymarin difficult and laborious. Thirdly, serious protein denaturation of milk thistle made the value of milk thistle low. This article presents the technique of extrusion cooking and microwave-assisted extraction into the pretreatment of extraction processes of silymain can raise the leaching speed of silymarin and the yield of silymarin, reduce energy consumption, improve the quality and the production rate of milk thistle oil. The technique of extrusion cooking applied in the pretreatment of extraction processes of silymain is highly valuable for academic study and application. In this paper, extrusion technology and microwave-assisted extraction was adopted to study on the extraction of silymarin and milk thistle oil. The main conclusions were as follows:1.The extraction and the MAE technology was joint used in the extraction of silymarin. The process were as follows:Clear up grass of milk thistle→Crush→Regulate moisture content of milk thistle→Extrusion and expansion→Leaching and removal of the fat→extraction of silymarin by MAE. Comparing to the traditional production technology, this technique shorten technics process, raise the yield of milk thistle oil, reduce the energy consumption.2.The influence law of microwave-assisted extraction system parameters on the yield of silymarin was studied in this paper. The factors affected on the yield of silymarin in decreasing order were as follows:solid-liquid ratio, extraction temperature, ethanol concentration, extraction time. And the optimal MAE parameters were as follows:extraction time50.20min, extraction temperature120.70℃, ethanol concentration82.91%, solid-liquid ratio1:23.37g/ml, in the conditions, the yield of silymarin was largest7.08%.3.The quality of milk thistle oil was analyzed and the influence degree of the extrusion parameters on the oil index was studied. The opu of milk thistle puffed material:moisture content of material, the ratio of feeding speed to rotational speed, extrusion temperature. Acidic value: moisture content of material, extrusion temperature, the ratio of feeding speed to rotational speed. Peroxide value:the ratio of feeding speed to rotational speed, extrusion temperature, moisture content of material. Stability of the oil:extrusion temperature, moisture content of material, the ratio of feeding speed to rotational speed.4.The influence law of extrusion system parameters on the quality of milk thistle oil was studied in this paper and the optimal parameters’ range were as follows:the ratio of feeding speed to rotational speed6.2～7.2g/r, extrusion temperature91～100℃, moisture content of material11%～12%. And the optimal extrusion parameters in this experiment condition were as follows:the ratio of feeding speed to rotational speed6.72g/r, extrusion temperature93.1℃, moisture content of material11.1%.