Physico-chemical indicators and identification of selected Slovak honeys based on colour measurement

Abstract

The aim of study was to characterize 52 samples of Slovak honeys of six types (multifloral, acacia, rape, honeydew, forest and mixed). Physico-chemical analysis of honey included the water content, free acidity, pH, water activity, electrical conductivity, and hydroxymethylfurfural (HMF) content. In addition, the colour of honeys was measured using spectrophotometer and Commission Internationale de I`Eclairage method (CIE L*a*b*); four types of honey were used for identification: multifloral, acacia, rape, and honeydew. Mean values of physico-chemical indicators were as follows: water content 16–21%, acidity 6–42 mekv·kg-1, pH 3.68–5.15, water activity 0.505–0.667, electrical conductivity 0.155–1.585 mS·cm-1 and HMF content 0.17–78.5 mg·kg-1. The highest HMF content was found in forest honey with one sample above the limit established by Council Directive 2001/110/EC. The colour of Slovak honeys analysed in this study was very variable and ranged from pale yellow to dark brown. Differences of physico-chemical indicators and colour of honey samples were found to be significant (P < 0.05). The CIE L*a*b* methods can be used for identification of selected honey samples. This is the first similar study on Slovak honey.