Studies On Isolation And Purification Of Allicin By Supercritical CO₂-molecular Distillation

Garlic(Allium Sativum L.) is the perennial herb of lily family. Allicin, whose chemical name is Allyl, 2-Porpenethiosulfinate, is a main functional substances of garlic. It comes from alliin by action of alliinase when the fresh garlic is crashing. Allicin plays an important role in anti-coagulation, lipid-lowering, detoxification, anti-tumor, anti-oxidation, anti-aging as well as in the regulation of cell-mediated immunity and humoral immunity. Allicin is easy to degenerate and different components can be obtained under different conditions of extraction. Using Pizhou garlic as the raw material, this paper studied the effects of pressure, temperature, time, flow of CO₂, particle size and the enzyme conditions on the extraction of allicin. Allicin from supercritical CO₂ extraction was purified by Molecular Distillation. And the effects of temperature, pressure, feed rate, and frequency on the molecular distillation were studied and the technologic condition of multi-molecular distillation was established. The main results were as follows:1 The optimum process conditions of supercritical CO₂ extraction.The effects of pressure, temperature, time , flow of CO₂ and particle size on the extraction of allicin were studied. And the mathematical model were obtained by the quadratic general rotary unitized design.The optimum conditions of pressure, temperature, time, flow of CO₂, particle size were 33.7 MPa, 41.2℃, 3.4 h, 120 L·h-1 and 4 mm respectively. The enzyme conditions of allin were optimized by orthogonal tests that include 4 factors and 3 levels. The optimum conditions of temperature, time and dosage of Mn2+ were 35℃, 30 min and 0.001mmol·g-1 respectively,and the final extracting rate was 0.418%.2 Studies on purification of allicin by molecular distillationThe effects of temperature, pressure, feed rate, and frequency on the purification of allicin by molecular distillation were studied. On the basis of single factor experiments, the technological parameters were optimized by orthogonal tests that include 4 factors and 3 levels. The results reveal that the optimum condition of absolute pressure, distillation temperature and feed flow rate in first-stage distillate were 50℃, 200 Pa, 15 mL·min-1 respectively; the technological condition of second- stage distillate were 45℃and 150Pa respectively and the technological condition of third-stage distillation was absolute pressure 100Pa and distillation temperature 40℃respectively.The purity and yield of allicin were 87.19% and 47.45% respectively, obtained after 3 stages of molecular distillation. The relative contents of Allicin, DADs and DATs was 83.14%,determined by HPLC.3 The thermal stability of Allicin, DADs and DATsThe thermal stability of Allicin, DADs and DATs were observed at -20℃, 4℃and 25℃respectively. After 150 days, the stability of them sharply decreased as the temperature rised, the order of stability was DADs>DATs>allicin.