Effect of vacuum-steam pulsed blanching (VSPB) on drying characteristics and quality properties of garlic slices

Abstract

To explore the effects of vacuum-steam pulsed blanching (VSPB) on drying characteristics and quality attributes of garlic slices, the surface color, texture, peroxidase (POD) activity, total phenolic content, antioxidant capacity (DPPH and FRAP), rehydration ratio and thiosulfinate content under various blanching cycle of times (2, 3, 4, and 5 times) and atmospheric pressure duration (20, 30, 40, and 50 s) were investigated. Results indicated that VSPB treatment can inactive POD completely under all VSPB conditions. The hardness of garlic cloves was reduced after VSPB treatment, while hot air drying increased the firmness of garlic slices. The porosity of the garlic surface evidently declined after VSPB treatment, which hindered the moisture diffusion and thus prolonged the drying time from 3 h to 9 h. The total phenolic content, DPPH and FRAP values of blanched garlic cloves were significantly (p < 0.05) lower than those of the raw garlics. VSPB treatment resulted in undesirable color degradation and thiosulfinate degeneration. The highest rehydration ratio was found for the sample blanched at atmospheric pressure duration of 30 s with the blanching cycle times of 3. The findings in the current work will enhance the better understanding of the effect of VSPB on drying behavior and quality attributes of garlic and may provide clues about on selecting suitable blanching methods for garlic.