Garlic varieties and drying methods affected the physical properties, bioactive compounds and antioxidant capacity of dried garlic powder

This work aimed to determine the effect of freeze drying (FD), hot air drying (HD), vacuum drying (VD), and infrared hot air drying (IRD) on the quality of two key kinds of garlic varieties (white and purple garlic). The quality including colors, bioactive compounds, and antioxidant capacities of dried garlic slices were investigated. The highest whiteness of dried white and purple garlic was found in FD treatments with its values at 87.04 and 81.89, respectively. The higher active substances contents and antioxidant capacities was found in dried purple garlic slices compared to the white ones under the same drying methods. The allicin contents in FD and IRD treated purple garlic were 2.60 and 2.67 mg/g and the total phenolic in these two samples were 5.93 and 4.33 mg/g. Meanwhile, the highest DPPH, ABTS and FRAP (6.64, 2.85 and 5.70 mmol TE/g. DW) was found in the IRD treated purple samples. Principal component analysis revealed the higher allicin contents, total phenolic contents, and antioxidant capacities in purple garlic slices compared to the white one in different drying methods. These results suggested that dried purple garlic under IRD treatment is more suitable for drying industrials than white garlic.