Lipidomics of herbal tea revealed their potential lipid nutrients including novel fatty acid esters of hydroxy fatty acids

Herbal tea is considered natural and harmless. With a long history of use, herbal tea acts as a healing remedy in various traditional medicines and has become a popular beverage worldwide. However, detailed lipid nutrient data have not been thoroughly investigated. This study applied lipidomics strategy using liquid chromatography/mass spectrometry to profile the lipid nutrients in ten types of herbal tea. Comprehensive lipidome analysis of herbal tea led to the identification of 299 lipid molecular species. Multivariate analysis revealed unique lipid compositions among different types of herbal tea. Five major lipid classes were characterized and semi-quantified including fatty acyls, sphingolipids, glycerophospholipids, glycerolipids, and sterols. Fatty acyls are the major lipids with polyunsaturated fatty acids (PUFA) are abundant in lemon balm, whereas saturated fatty acids (SFA) in lavender. Evaluation of the PUFA to SFA ratio for ten herbal teas showed that lemon balm and blue mallow have the highest values of 1.57 and 1.21 respectively. Furthermore, we uncovered seven isomeric fatty acid esters of hydroxy fatty acids (FAHFAs) in these herbal teas for the first time using high-resolution mass spectrometry and tandem mass spectrometry analyses. Hierarchical heatmap analyses revealed an abundance of phytoceramides in blue mallow and lysophospholipids in lemon balms. Triacylglycerols are unchanged in all the herbal teas analyzed. This extensive investigation of the lipid composition of herbal tea will help assess their nutritional benefits and potential uses in the food and health industries.