LC‐ESI‐QTOF/MS characterization of Australian herb and spices (garlic, ginger, and onion) and potential antioxidant activity

Abstract

Culinary herbs and spices have received great attention as rich sources of polyphenols, which contribute to their putative health benefits. Nevertheless, the comprehensive profiling of these polyphenols in herbs and spices is limited. Therefore, the purpose of this study was to comprehensively characterize phenolic compounds from three commonly consumed Australian herbs and spices, garlic (Allium sativum), ginger (Zingiber officinale), and onion (Allium cepa) using the LC-ESI-QTOF/MS, and to evaluate their antioxidant potential. The LC-ES-QTOF/MS analysis led to the tentative identification of 28, 67, and 118 phenolic compounds in garlic, ginger, and onion, respectively, with flavonoids and phenolic acids being the major components. The obtained results showed that the ginger exhibited highest radical scavenging capacities for the DPPH (0.22 ± 0.01 mg AA/g), ABTS (1.15 ± 0.01 mg AA/g), and ferric reducing capacity (0.08 ± 0.01 mg AA/g) as compared to garlic and onion. In HPLC, garlic contains high concentration of quercetin (>1 mg/g), while onion is enriched in protocatechuic acid (>1 mg/g). The current finding highlights the importance and potential application of garlic, ginger, and onion as ingredients in functional foods, nutraceuticals, and drug development.