Changes in the antioxidant activity and metabolite analysis of black elephant garlic

Abstract

This study aimed to investigate the effects of the aging period on the black elephant garlic manufacturing process. Black elephant garlic is a processed elephant garlic product prepared by high temperature and high humidity treatment for 40 days. The proximate composition (moisture, crude lipid, crude protein, carbohydrate, and ash), minerals, color values, reducing sugars, pH, and antioxidant activities of elephant garlic and black elephant garlic were evaluated. The browning intensity of elephant garlic increased with the aging period, but the browning reaction terminated after aging for 30 days, showing the same browning level. Reducing sugars increased with increasing the aging period until 20 days, then decreased with the aging period, in contrast to the pH, which decreased from 6.47 to 3.68 with the increasing aging period. Antioxidant components, including the total polyphenol and total flavonoid contents of black elephant garlic, increased significantly until day 30 of aging. Through metabolite profiles from GC/MS analysis, it was confirmed that primary metabolites related to antioxidant components, such as lactic acid and 5-hydroxymethyl-2-furoic acid, were generated during the aging process of elephant garlic.