Effect of heat treatment on the antioxidant capacity of garlic

Abstract

The determination of the antioxidant capacity of dry and wet-heated garlic, at 70, 100, and 121 C by 3 different methods, namely ferric reducing antioxidant power (FRAP) assay, improved ABTS radical cation decolourization assay, and DPPH free radical scavenging activity, together with the determination of total phenolic content and formation of browning pigments of the same materials was carried out. The result showed that the antioxidant capacity of heated garlic was decreased by the decomposition of some phenolic and sulfur-containing compounds. However, when browning pigments developed, the antioxidant capacity of the heated brown garlic increased with the degree of browning, provided that it was not too dark. In addition, this study showed that ABTS and FRAP assay were better methods for expressing the antioxidant capacity of garlic due to its total phenolic content, although FRAP and DPPH assay were better if the antioxidant capacity of garlic was mainly caused by browning pigments.

Keywords

• garlic
• antioxidant capacity
• heat treatment