Elsevier

Food Chemistry

Volume 141, Issue 3, 1 December 2013, Pages 2802-2811
Food Chemistry

Buckwheat honeys: Screening of composition and properties

https://doi.org/10.1016/j.foodchem.2013.05.102Get rights and content

Highlights

  • Screening of physicochemical properties and pollen spectra of 10 buckwheat honeys.

  • Identification and quantification of phenolic and volatile compounds in 10 buckwheat honeys.

  • 3-Methylbutanoic acid is the most widely distributed among volatile compounds in buckwheat honey samples.

  • p-Hydroxybenzoic and p-coumaric acids are the main phenolic compounds in buckwheat honey samples.

Abstract

The quality of 10 buckwheat honeys, collected from Italian and est European beekeepers declaring to produce monofloral honey, were evaluated by means of their pollen, physicochemical, phenolic and volatile composition data. The results of the traditional analyses and in particular electrical conductivity, optical rotation, pH and sugar composition revealed some poorly pure samples that could not fit in the buckwheat tipology. Honey volatiles, analysed by solid phase microextraction (SPME) and gas chromatography–mass-spectrometry (GC/MS), showed more than 100 volatile compounds, most of them present in all honey samples but with quantitative variation. Besides many furfural derivates, 3-methylbutanoic acid was the main volatile compound found in most of honeys. Also the presence of 2- and 3-methylbutanal and pheynalcetaldehyde confirmed the typical buckwheat aroma of some studied samples, corroborating physicochemical data. The HPLC phenolic profile was similar across the samples and p-hydroxybenzoic and p-coumaric acids proved to be the main components.

Introduction

Buckwheat honey, collected from the little pink flowers by honeybees, is characterised by a dark purple colour, almost black and by a strong animal odour, malty aroma and molasses flavor (Dalby, 2000). In several studies have been reported the high antioxidant properties of this honey (Gheldof, Wang, & Engeseth, 2002), as well as its antibacterial activity, highlighting its efficacy in respiratory tract infection (cough) and wound healing (e.g. burn wounds and venous leg ulcers) (Paul et al., 2007, Ranzato et al., 2012, van den Berg et al., 2008).

Buckwheat unifloral honey is mainly produced in North America (Canada and California), China and in some countries of Europe, such as Poland, Russia, The Netherland and Germany. Because of the quite low cultivation of buckwheat plants, in Italy the monofloral buckwheat honey is difficult to produce and it is usually found as a natural component of multifloral honeys.

The botanical and geographical origin of honey, which influence its quality and price, has been traditionally identified by the analysis of the bee pollen present in the honey, together with organoleptic and physicochemical determinations. However, this information should be enriched with data derived from the sensory profile and bioactive components. Therefore, new analytical methods have also been developed (Anklam, 1998, Ferreres et al., 1991) and among them, the determination of specific markers, such as phenolic compounds, is one of the most promising way for studying the healthy properties and quality of honeys (Gómez-Caravaca et al., 2006a, Gómez-Caravaca et al., 2006b, Tomás-Barberán et al., 2001, Yao et al., 2003.

Besides, the honey volatile fractions have been studied and different authors report that the same volatile components are present in the majority of honeys, although the mutual proportions of these substances can be different (Alissandrakis et al., 2007, Anklam, 1998, Baroni et al., 2006, Piasenzotto et al., 2003, Radovic et al., 2001, Soria et al., 2003). Similarly, certain specific volatile compounds are characteristic of a given floral origin (Cuevas-Glory, Pino, Santiago, & Sauri-Duch, 2007).

Buckwheat honey is produced at different levels of “uniflorality”, following the major or minor diffusion of the corresponding plant. In Italy taking into account the great attention in healthy foods, there is a growing interest for the production of foods made from buckwheat especially for celiacs, therefore farmers are planning more extensive cultivations and consequently the output of buckwheat honey will increase. There is a lack of investigation about this interesting botanical origin so the principal aim of this study was to analyse the quality of 10 buckwheat honeys collected from different producers, prefering those that come from areas where the cultivation is wide as in east Europe. The chemical composition of samples was evaluated by the use of traditional (melissopalynological and physicochemical analysis) and new analytical methods (phenolic and volatile compounds), emphasising correlations among the obtained data and also the presence of possible chemical markers of this honey.

Section snippets

Honey samples

Ten honey samples were bought from beekeepers claiming to produce monofloral buckwheat honeys. Honeys were kept at room temperature (25 ± 2 °C) and in the dark until analysed.

Reagents and chemicals

Unless otherwise stated, solvents and reagents used were of analytical grade and were from Merck (Darmstad, Germany). The standards used for the identification and quantification of phenolic acids and flavonoids were: protocatechuic acid, p-hydroxybenzoic acid, p-hydroxyphenylacetic acid, benzoic acid, apigenin, galangin from

Physicochemical and melissopalynological analysis

Table 2 lists the mean, standard deviations and ranges of the data obtained from the analysis of the different physicochemical parameters.

The electrical conductivity of honey usually shows great variability according to the floral origin and the results obtained for the samples under study varied between 0.33 and 1.86 mS/cm. In particular, the values of samples B-1, B-9 and B-10 (1.02, 1.37 and 1.86 mS/cm, respectively) exceeded the limit allowed for floral honeys (0.8 mS/cm), suggesting the

Conclusion

Since an exaustive characterisation of the buckwheat honey is not yet available, this study proposes a preliminary but comprehensive and detailed evaluation of composition and properties of that botanic origin. Besides the traditional descriptive analyses as pollen spectra and physicochemical proprieties, the aromatic and antioxidant profile were also included in order to improve the monofloral assessment of buckwheat honey.

Indeed volatile compounds, because of their relation to aroma and hence

References (46)

  • R. Mateo et al.

    Sugar profiles of Spanish unifloral honeys

    Food Chemistry

    (1997)
  • B. Plutowska et al.

    A headspace solid-phase microextraction method development and its application in the determination of volatiles in honeys by gas chromatography

    Food Chemistry

    (2011)
  • B. Radovic et al.

    Contribution of dynamic headspace GC–MS analysis of aroma compounds to authenticity testing of honey

    Food Chemistry

    (2001)
  • K. Ramanauskiene et al.

    The quantitative analysis of biologically active compounds in Lithuanian honey

    Food Chemistry

    (2012)
  • L. Yao et al.

    Flavonoids, phenolic acids and abscisic acid in Australian and New Zealand Leptospermum honeys

    Food Chemistry

    (2003)
  • J. Zhou et al.

    Protective effects of buckwheat honey on DNA damage induced by hydroxyl radicals

    Food and Chemical Toxicology

    (2012)
  • J.M. Alvarez-Suarez et al.

    Antioxidant characterization of native monofloral cuban honeys

    Journal of Agricultural and Food Chemistry

    (2010)
  • M.V. Baroni et al.

    Determination of volatile organic compound patterns characteristic of five unifloral honey by solid-phase microextraction–gas chromatography–mass spectrometry coupled to chemometrics

    Journal of Agricultural and Food Chemistry

    (2006)
  • Bodagnov, S. (2009). Harmonised method of the International Honey Commission. International Honey Commission,...
  • G. Campos et al.

    Volatile substances in floral honey and honeydew honey

    Ciência e Tecnologia de Alimentos

    (2000)
  • R. Dalby

    Classic American honey plants: Buckwheat

    American Bee Journal

    (2000)
  • F. Ferreres et al.

    Natural occurrence of abscisic acid in heather honey and floral nectar

    Journal of Agricultural and Food Chemistry

    (1996)
  • F. Ferreres et al.

    An HPLC technique for flavonoid analysis in honey

    Journal of the Science of Food and Agriculture

    (1991)
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