Harvesting uncapped immature honey (IMH) followed by dehydration is a typical counterfeit honey production process, but the differences between IMH and capped mature honey (MH) have not been well described previously. In this study, MH and IMH from Apis mellifera colonies during the same rapeseed flower season were compared. MH was found to have lower water content, lower acidity, and higher fructose content. High-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry-based untargeted metabolomic analysis indicated that MH had a distinct metabolite composition to IMH. Targeted metabolomic analysis on 20 major polyphenolic constituents showed higher accumulation in MH. MH had greater bacteriostatic effect and stronger free radical scavenging effect. While both the honeys mitigated cell damage caused by H2O2, the effective dosage of IMH was higher and its inducing effect on the antioxidant gene expression was weaker. Overall, MH was shown to be of better quality than IMH not only because of its richer polyphenolic composition but also because of its stronger biological activity.
Keywords: HPLC-Q-TOF/MS; bioactivity; honey; immature; mature; metabolomic analysis.