PLANT PHENOLIC METABOLITES AND FLORAL ORIGIN OF ROSEMARY HONEY

Phenolic metabolites present in rosemary honey and floral nectar were studied to find biochemical markers for honey floral origin. Rosemary nectar, from bee honey stomach, contained kaempferol 3-sophoroside (93 %) and quercetin 3-sophoroside (7%) as the only significant constituen ts. All samples had a common flavonoid profile comprised of 15 flavono ids. Nectar glycosides were not detected in honey suggesting that they are hydrolyzed by the bee enzymes to render the corresponding aglycon s. Honey flavonoid profiles were similar to those found for propolis, a plant resin collected by bees, and confirmed that the majority of th e flavonoids present in honey originate from this source. The amount o f kaempferol in the honey samples ranged between 0.4 and 1.2 mu g/g. T he coefficient of variation of kaempferol in the honey samples was muc h smaller than those observed for the rest of flavonoids, supporting i ts floral origin, and the propolis origin for the rest of flavonoids. The presence of kaempferol in rosemary honey cannot be considered as p roof of its floral origin because this flavonol can originate from dif ferent flower nectars. However, its absence or presence in small level s (< 0.3 mu g/g of honey) could be considered additional evidence of a different floral origin.