Studies on the effects of microwave drying and cabinet tray drying on the chemical composition of volatile oils of garlic powders

Garlic cloves in the form of bits were dried in a cabinet tray dryer and a microwave dryer, and pulverized to obtain free flowing powder. The volatile oil was obtained by hydro-steam distillation method. Fresh cloves and the powders resulting from the two drying methods were used for obtaining the volatile oil, which was analyzed by GC-MS. The studies were mainly restricted to comparing the effect of drying methods on the volatile oil composition of the powders. Although the drying time was reduced considerably from 8 h in a cabinet dryer to 0.25 h in a microwave dryer, essential oil yield and color values were lower, and flavor quality varied considerably. The relative concentrations of major peaks such as diallyl disulfide, diallyl tetrasulfide increased in both the drying methods, and it was more so in microwave-dried samples. However, the concentrations of the other two major peaks, diallyl trisulfide and allyl methyl trisulfide, decreased in both drying methods, and they were lower in microwave-dried samples. Hunter values of L and b were lower for samples obtained by microwave drying as compared to those of cabinet-dried samples.