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

The aim of this 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 the method of the Commission Internationale de l'Eclairage (CIE L*a*b*); four types of honey were used for identification: multifloral, acacia, rape, and honeydew. The mean values of physico-chemical indicators were as follows: water content: 16-21%, acidity: 6-42 mekv/kg, pH: 3.68-5.15, water activity: 0.505-0.667, electrical conductivity: 0.155-1.585 mS/cm and HMF concentration: 0.17-78.5 mg/kg. The highest HMF concentration was found in forest honey with one sample above the limit established by the 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. The differences in physico-chemical indicators and colour of honey samples were found to be significant. The CIE L*a*b* method can be used to identify different honey samples.