Portuguese Monofloral Honeys: Molecular Insights and Biochemical Characterization

Abstract

Honey is a multifaceted substance whose composition is intricately affected by various biotic and abiotic elements generated in the bee colony's surroundings, including botanical and geographical origins, climatic conditions, soil characteristics, and beekeeping techniques. Monofloral honeys are identified by pollen analysis and are derived from the nectar of a predominant plant species, exhibiting rich sensory and nutritional profiles, making them food matrices with unique characteristics and excellent qualities. To explore the monofloral honey potential harvested in different regions of Portugal, a comprehensive study was conducted including the determination of phenolic composition and the assessment of biological activities. In addition to this evaluation, the inter simple sequence repeat (ISSR) was used to help differentiate honeys by botanical origin. The phenolic content and the antioxidant capacity were evaluated by spectrophotometric methods, observing, in general, differences between monofloral honeys. The honey from Citrus sinensis (Silves) exhibited the lowest phenolic content, including total phenols, ortho-diphenols, and flavonoids, whereas honeydew (Vinhais) showed the highest values. Regarding the antioxidant capacity, honey from Lavandula stoechas (Almodôvar) presented the lowest values, while honeydew (Vinhais) displayed the highest values for both DPPH and FRAP assays. In relation to the ABTS assay, the honey from Metrosideros excelsa (Aveiro) exhibited the lowest values, whereas the honey from Eucalyptus spp. (Arouca) showed the highest. The ISSR marker analysis allows the distribution of the samples based on the honey's botanical origin, suggesting its potential role in honey authentication.

Keywords: antioxidant capacity; geographical and botanical origin; honey; molecular marker; phenolic compounds.

Figure 1

Agarose gel of primer UBC-840. Cast—Castanea sativa; Lav—Lavandula stoechas; Euc—Eucalyptus spp.; Mel—honeydew; Tri—Trifolium spp.; Til—Tilia spp.; Cit—Citrus sinensis; Arb—Arbutus unedo; Eri—Erica umbellata; Mul—multifloral; M—DNA marker GeneRuler 100 bp.

Figure 2

Dendogram estimating the genetic distance between the honey samples based on eleven ISSR markers.

Figure 3

Pearson correlation between phenolic composition and antioxidant capacity. MS. Statistically significant correlations: * p < 0.05, ** p < 0.01.

Figure 4

Canonical correspondence analysis (CCA) scatter plot applied to the phenolic compounds, antioxidant capacities, and molecular markers of the honey samples. Three different groups were identified based on botanical origin.