Antioxidant potential and quality traits of black garlic from microwave heating and hot steam incubation

Abstract

This research evaluated the effect of curing duration on moisture loss and phytochemical qualities of dehydrated garlic. Fresh garlic was shade-dried at 35°C then moisture content and antioxidant properties were measured at 10-day intervals until constant weight was reached. Furthermore, the dried garlic samples were hot-steam processed into black garlic with two different processing schemes, namely microwave heating and hot-steam incubation. The chemical quality of the finished product was analysed. Results demonstrated that the moisture content of garlic decreased continuously during the first stage of the drying process and became steady after 30 days. Outstandingly, antioxidant properties decreased during the curing process. After thermal processing of black garlic, both microwave heating and hot-steam incubating, significantly improved the antioxidant compounds and antioxidant activity. The finished product showed a completely black colour with soft and elastic texture while the garlic odour was significantly declined. Microwave heating shortened the processing time up to 2.6-folds lower than the hot-steam incubation. In summary, the antioxidant properties of fresh garlic decreased during the curing process while heat processing can improve the chemical properties of garlic.