Kaempferol-3-O-galactoside as a marker for authenticating Lespedeza bicolor Turcz. monofloral honey

Honey produced from Lespedeza bicolor Turcz. (L. bicolor) is highly valued and relatively rare, leading to adulterated or ersatz substitutes in the marketplace, with no reliable authentication methods available for enforcement of regulations. Here, we characterize the physicochemical parameters (water content, pH, sugar content, amylase activity, and 5-hydroxymethylfurfural content) in L. bicolor honey and palynological characteristics of L. bicolor pollen as reference for assessment of quality and monoflorality. Mass spectrometry with Orthogonal Partial Least Square Discriminant Analysis of chemical constituent data from L. bicolor, chaste, acacia, jujube, and linden honeys, all commonly sold in China, identified kaempferol-3-O-galactoside as a candidate chemical marker of L. bicolor honey. We validated this screening method and quantified kaempferol-3-O-galactoside in L. bicolor, but not other honeys, at concentrations between 90.2 and 430.1 µg/kg, with high sensitivity (LOD = 0.002 mg/kg), linearity (R² ≥ 0.99), and recovery (90.2%-110.6%), supporting its use in authenticating L. bicolor honey.