Characterization of Botanical Origin of Italian Honey by Carbohydrate Composition and Volatile Organic Compounds (VOCs)

Abstract

Honey is a natural sweetener constituted by numerous macro- and micronutrients. Carbohydrates are the most representative, with glucose and fructose being the most abundant. Minor honey components like volatile organic compounds (VOCs), minerals, vitamins, amino acids are able to confer honey-specific properties and are useful to characterize and differentiate between honey varieties according to the botanical origin. The present work describes the chemical characterization of honeys of different botanical origin (multifloral, acacia, apple-dandelion, rhododendron, honeydew, and chestnut) produced and collected by beekeepers in the Trentino Alto-Adige region (Italy). Melissopalynological analysis was conducted to verify the botanical origin of samples and determine the frequency of different pollen families. The carbohydrate composition (fourteen sugars) and the profile of VOCs were evaluated permitting to investigate the relationship between pollen composition and the chemical profile of honey. Statistical analysis, particularly partial least squares discriminant analysis (PLS-DA), demonstrates the importance of classifying honey botanical origin on the basis of effective pollen composition, which directly influences honey's biochemistry, in order to correctly define properties and value of honeys.

Keywords: Italian honey; PLS-DA; apple–dandelion; carbohydrates; melissopalynological analysis.

Figure 1

Histograms of more intense (a) and less intense (b) VOCs in the honey samples. Error bars represent the standard deviations. Same letters indicate statistically significant differences.

Figure 2

Box and whisker plot of glucose (a) and benzaldehyde (b) in the honey samples. Same letters indicate statistically significant differences.

Figure 3

Box and whisker plot of erlose (a) and terpineol (b) in the honey samples. Same letters indicate statistically significant differences.

Figure 4

Box and whisker plot of raffinose (a) and melezitose (b) in the honey samples. Same letters indicate statistically significant differences.

Figure 5

Box and whisker plot of nonanoic acid (a), nigerose (b), and furfural (c) in the honey samples. Same letters indicate statistically significant differences.

Figure 6

Relative abundancies of pollen families in the multifloral honey samples.

Figure 7

Box and whisker plot of fructose (a), erlose (b), and benzaldehyde (c) in the honey samples. Same letters indicate statistically significant differences.

Figure 8

Three-dimensional score plot (a); VIP score (b); and performance parameter histogram (the red asterisk indicates the higher R2 value in relation to the component number) (c) of the PLS-DA model.