Chemical composition profiles of Apis cerana fabr. produced Acacia honey: a comparative study on optimal non-acidified ACN extraction with water-dilution by widely targeted metabolomics

Non-acidified acetonitrile-water extraction (NA-AWE) was designed and optimized for rapid and high-fidelity enrichment of non-sugar components in honey, achieving 68.41% sugar-removing rate, with 63.17% polyphenol recovery and little degradation of glycosides. By NA-AWE, widely targeted metabolomics using UPLC-ESI-TOF-MS identified 313 components (75 glycosides) in Apis cerana Fabr. produced acacia (Robinia pseudoacacia L.) honey, including terpenoids, polyphenols, alkaloids and amino acids, while only 198 compounds (33 glycosides) in water-diluents. Heatmap, PCA and OPLS-DA analysis showed the complementarity of NA-AWE and water-dilution: NA-AWE favored weak-polarity and trace-amount compounds, such as terpenoids and methoxyflavonoids, while water-dilution for polar compounds. The high MS-response compounds were verified and quantified by comparison with standards, indicating polyphenols (2021.77 ng/g chrysin, 424.25 ng/g caffeic acid, 399.15 ng/g syringic acid, 157.41 ng/g ellagic acid, 93.63 ng/g kaempferol), organic acids (473.45 ng/g abscisic acid, 99.68 ng/g 3-phenyllactic acid, ) and the new-found compounds, dichotomitin, auraptene and deoxyneocryptotanshinone, whose content in honey was 21.77 ng/g honey, 51.66 ng/g, and 33.28 ng/g respectively, as potential functional ingredients in acacia honey. Furthermore, the minor nectar sources were revealed according to the identified trace-amount compounds and verified by melissopalynological observation.