Metabolic profiling of Jamun (Syzygium cumini) honey: NMR and HPLC driven studies uncover low glucose levels and high antioxidant properties

Comprehensive metabolic profiling of 82 unifloral Jamun honey samples from the Mahabaleshwar region (Apis cerana) was achieved using NMR spectroscopy, HPLC, solvent extraction, and targeted biophysical assays. This is by far one of the largest datasets characterised for a single type of honey. • Exceptionally low glucose and low total glucose+fructose content observed for the Jamun honey are among the lowest reported for honeys in general. These features are consistently observed across all 82 samples, yielding a high fructose-to-glucose ratio , indicative of a potentially low glycemic index . • NMR signatures showed minimal fermentation markers across all samples, demonstrating the intrinsic stability of Jamun honey despite its tropical origin. • HPLC analysis identified six phenolic acids and six flavonoids , including high levels of myricetin, kaempferol, and 4-hydroxybenzoic acid , underpinning the honey’s strong antioxidant capacity, confirmed through TPC, TFC, and antioxidant assays. • Melissopalynology revealed sparse Jamun pollen , emphasizing its limited reliability for floral authentication and demonstrating the need for metabolomics-driven approaches. • The study delivers the first robust reference dataset for saccharides, metabolites, and antioxidant markers in authentic Jamun honey, establishing a scientific foundation for quality control, fraud detection, and honey authentication . • The metabolic profile positions Jamun honey as a high-value medicinal honey , comparable to Manuka, with elevated antioxidant metabolites and relatively lower sugar levels. Jamun honey, produced by Apis cerana bees foraging on Syzygium cumini (Malabar plum), is traditionally recommended for diabetics and valued for its antioxidant and medicinal properties. This study analyzes 82 Jamun honey samples from Mahabaleshwar, India for a detailed metabolite profiling using NMR spectroscopy and HPLC. NMR spectroscopy was employed to profile the sugar composition of honey, enabling quantitative analysis of glucose, fructose, maltose, sucrose, and turanose. Polyphenols and flavonoids were isolated by solid-phase extraction and subsequently identified and quantified using HPLC. The antioxidant properties of the Jamun honey were further characterized through biophysical assays. NMR revealed generally lower glucose (25.91±0.28 g/100 g of honey) and lower total glucose+fructose levels (61.22±0.64 g/100 g of honey)- compared to other honeys- resulting in a high fructose-to-glucose ratio (1.36) and suggesting a potentially low glycemic index. All samples showed minimal fermentation markers (hmf at 0.0003±0.0007 g/100 g of honey, ethanol at 0.018±0.0006 g/100 g of honey), indicating excellent stability. HPLC and antioxidant assays confirmed high antioxidant capacity (85.10±3.50 %), with elevated levels of myricetin, kaempferol, 4-hydroxybenzoic acid, and nine other polyphenols. Pollen analysis showed low Jamun pollen content, underscoring limitations of melissopalynology for floral authentication. In the context of rising honey adulteration and honey quality control, this study provides a compositional reference for authentic Jamun honey using advanced NMR and data-based profiling approaches on a large sample set.