Preparation Of Garlic Powder With High Allicin And Its Biological Activities

The health care and medical treatment value of garlic are very high. It has antimicrobial, anti-inflammatory, antivirus, antioxidant, antithrombotic, anticancer, and antiatherosclerotic activities, as well as the capacity to lower serum lipid levels. Allicin occupied about 75% of total thiosulfinates in garlic. The aim of this work was to prepare of garlic powder with high allicin content using microwave-vacuum combined with vacuum drying technology and microencapsulating technology in order to protect alliinase activity throughout the stomach and improve the ratio of alliin transforming into allicin.Firstly, in this paper it has described a modified spectrophotometric assay for the determination of allicin and total thiosulfinates in fresh garlic. Improved the accuracy and reproducibility of the method by changing the concentration of crysteine and DTNB and prolonging reaction time. Also enlarged its using fields such as determination of thiosulfinates in garlic extract , garlic powder and microencapsulated garlic powder.Enzyme character of crude garlic alliinase from fresh, freeze dried and microwave vacuum drying combined with vacuum drying(MV/VD) were compared using chemical synthesized alliin. Garlic alliinase from fresh and MV/VD were purified using Sephacryl S-200 gel column and compared their spectral characteristic of ultraviolet/visible(UV/Vis), fluorescence and CD spectroscopy in order to explore the mechanism that both the heat stability and the optimal temperature of alliinase were increased after MV/VD. The results showed that the optimal temperature of alliinase from both fresh garlic and freeze dried garlic were 40℃, but alliinase of MV/VD was 45℃and when the temperature was above 45℃the heat stability increased. RP-HPLC result showed that the purity of alliinase through Sephacryl S-200 was very high, and SDS-PAGE electrophoresis results showed that alliinase achieved electrophoresis pure. The results of UV/Vis, fluorescence and CD spectroscopy of alliinase showed that MV/VD caused the conformation of alliinase was more orderly. That the reason why both the heat stability and the optimal temperature of alliinase were increased after MV/VD. The results of alliinase heat inactivation dynamics showed that alliinase belongs to intolerance high temperature enzyme. Thiosulfinates extracted by using ethonal was not stable. The thiosulfinates was very unstable at 30℃. When the thiosulfinates was stored at 4℃, it could stable for 12hrs. Even stored at–20℃for 30 days, the retention was only about 50%. The glass-transition temperature measured by DSC was–36.9℃. That can explain why thiosufinates was very instable at room temperature.MVD kinetics of garlic were studied. The internal temperature of garlic were measured during drying under differents vacuum pressure 4kPa,6kPa,8kPa, mostly of alliinase activity can be reserved keeping vacuum pressure below 6kPa. MVD kinetics of garlic can be described by using a theoretical model introduced by Cui. But the difference of drying critical point XW=2 (db) in carrot slices drying and XW=1 in garlic slices drying and must be modified by using a correction factor k=10.924e-3.2394Xw. Texture analysis and SEM measurement displayed the material texture and microstructure of fresh garlic, fresh carrot, garlic slices and carrot slices...