Melissopalynological origin determination and volatile composition analysis of Corsican “Erica arborea spring maquis” honeys

Abstract

Melissopalynology and volatiles’ analysis are applied for origin identification of 45 Corsican “spring maquis” honeys, regionally representative of this Protected Denomination of Origin “Miel de Corse–Mele di Corsica” range. They are dominated by Erica arborea pollens. Studies of statistical distribution, biogeographical typology and altitudinal distribution of the 50 characteristic taxa certify the Corsican origin of these honeys. The volatile fraction extracted by headspace solid-phase microextraction (HS-SPME) from Corsican E. arborea flowers was dominated by octen-3-ol, (E)-β-ocimene and (Z)-β-ocimene whereas 4-propylanisol, p-anisaldehyde, benzaldehyde and 3-furaldehyde were identified as the main volatile components of Corsican honeys. Taking into account the volatile fraction and melissopalynological and physicochemical data, cluster analysis and principal component analysis highlighted the correlation between the relative frequency of E. arborea pollens, the total peak areas of spring maquis honeys and the amounts of p-anisaldehyde and 4-propylanisol.

Introduction

The Corsican honey was certified by two official designations of origin: the national Appellation d’Origine Contrôlée (AOC) and the European Protected Designation of Origin (PDO), both marketed as “Miel de Corse–Mele di Corsica”. It is a common and diversified product that is classified into six ranges: “spring,” “spring maquis,” “honeydew maquis,” “chestnut grove,” “summer maquis” and “autumn maquis” according to the geographic location of the apiaries and the harvest season (Battesti, Gamisans, & Piana, 1997). The control of geographical and botanical origins of Corsican honeys takes into account the statistical treatment of melissopalynological data supplemented by the sensory characteristics and physicochemical parameters (Battesti, 1990, Battesti and Goeury, 1992, Von Der Ohe et al., 2004). The sensorial characteristics of Corsican “spring maquis” honeys were used by beekeepers and consumers to distinguish them from the five other ranges of the AOC and PDO (Battesti et al., 1997). Effectively, all of these honeys have a high granulation rate (because of glucose super-saturation), however, the intensity of colouration showed a variability from light brown to dark brown. It is a product with medium to high olfactory and aromatic intensities, and has a typical description: warm, caramel, cacao (Battesti et al., 1997, Persano Oddo et al., 1995).

In Europe, many Ericaceae species such as Erica vagans, Erica cinerea, Erica carnea and Calluna vulgaris are visited by bees for nectar and/or pollen, and can give uniflorous honeys (Maurizio & Louveaux, 1965) commonly qualified as “heather honey.” In Corsica, the Ericaceae family is represented by four genera and seven species. Among them, Erica arborea and Arbutus unedo have the highest density, being widespread over the whole island territory. Relative to A. unedo, which flowers from October to December, E. arborea is the first spring apiarian resource (flowering period: February to May) for the quantities of nectar and pollen provided (Ricciardelli d’Albore & Persano Oddo, 1978). It is a steno-Mediterranean ubiquitous species that is widespread in Corsica from littoral to 1200 m. The distribution of E. arborea is concentrated in (i) meso-Mediterranean level (0–700 m north facing and 0–1000 m south facing) with many associations with other spring flowering species: Lavandula stoechas, Rosmarinus officinalis, Viburnum tinus, Ge corsica, Calicotome spinosa, Calicotome villosa, Cytisus villosus, Pistacia lentiscus, Phyllirea angustifolia, Cistus creticus, Cistus monspeliensis and Cistus salviifolius, with proximity of Quercus suber and Quercus ilex series or Castanea sativa facies; (ii) supra-Mediterranean level (700–1000 m north facing and 1000–1300 m south facing) associated with more mesophilous species such as Crataegus monogyna, Genista lobelii var. salzmannii, Buxus sempervirens, Ilex aquifolium and Anthyllis hermanniae. The distribution of E. arborea and its plant associations explains the complexity of Corsican “E. arborea spring maquis” honey. This range includes not only the uniflorous E. arborea honey as defined in the “characterisation of unifloral honey” (Persano Oddo et al., 1995) but also the “spring maquis” honey characterised by E. arborea and other nectariferous or honeydew contributions.

Taking into account the flavour-rich proprieties of honeys, use of the aroma profiles has been proposed to improve the classical approaches (melissopalynological, sensory and physicochemical analysis) of the origin determination (Bogdanov, Ruoff, & Persano Oddo, 2004). Several analytical techniques, such as headspace solid-phase microextraction (HS-SPME), infrared spectroscopy and ¹H nuclear magnetic resonance (NMR) spectroscopy have been recently applied to the analysis of Corsican honeys (Cajka et al., 2009, Donarski et al., 2008; Donarski et al., 2010, Hennessy et al., 2010, Stanimirova et al., 2010, Woodcock et al., 2009). These studies focused on the discrimination between Corsican and non-Corsican honeys but did not provide results to characterise the diversity of each Corsican honey range.

The “heather honeys” (botanical origin not specified) have also been the subject of research for identifying floral markers. Flavonoids such as myricetin and its derivatives, 3,5,5-trimethylcyclohex-2-ene derivatives such as abscisic acid and isophorone, and some shikimate-pathway derivatives such as benzoic acid, p-anisaldehyde and p-anisic acid have been considered as markers of heather honey (Guyot, Scheirman, & Collin, 1999). To our knowledge, only one work has described the volatile fraction of E. arborea honey extracted by simultaneous distillation/extraction (Guyot et al., 1999). In this study, three shikimate-pathway derivatives were identified as markers of E. arborea honey: p-anisaldehyde, p-anisic acid and methyl vanillate (methyl 4-hydroxy-3-methoxybenzoate). No research has previously focused on the volatile fraction of the E. arborea flowers.

In the present work, the HS-SPME volatile fractions of Corsican “E. arborea spring maquis” honey and E. arborea flowers were investigated using GC–FID and GC–MS analysis. The aim of this work was to establish for the first time: (i) the volatile composition of Corsican “E. arborea spring maquis” honeys with botanical and geographical origins certified by detailed analysis of pollen spectra; (ii) the chemical relationship between the volatile compounds of E. arborea flowers and the corresponding honeys; and (iii) the correlation between volatile components and the melissopalynological and physicochemical characteristics of the Corsican “E. arborea spring maquis” honeys.