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

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. Practical applications Food processing requires quick and more efficient tools to screen and characterize bioactive compounds especially polyphenols from different plant-based materials. This study suggests that the application of advance mass spectroscopy and some spectrophotometry techniques could be a viable and fast techniques, which can be used for the screening, characterization, and monitoring of novel bioactive compounds from different food materials and suggest to further estimate their biological activities including antioxidant potential. These cutting-edge techniques could be helpful for the development of novel functional food products in food industry.