Preparation of garlic powder with high allicin content by using combined microwave–vacuum and vacuum drying as well as microencapsulation

Garlic powder with high allicin content was prepared using microwave–vacuum and vacuum drying as well as microencapsulation in order to protect alliinase activity throughout the human stomach and improve the ratio of alliin transforming into allicin. The results showed that the optimal microwave–vacuum drying condition was drying for 3 min under the microwave output power 376.1 W, then 282.1 W for 3 min, followed by 188.0 W for 9 min, and finally for 3 min under the output power 94.0 W. The thiosulfinates retention after drying was 90.2%. Following drying, garlic powder was microencapsulated by modified fluidized bed technique. Scanning electron microscope revealed good integrity and core materials that were embedded in microcapsules. Studies on the release kinetics of microencapsulated garlic granulates in vitro using simulated intestinal fluid indicated that release of garlic powder could be controlled in intestine by passing through human stomach conditions.