Comparative study of rapeseed, monofloral types and multifloral honey by some physico- chemical parameters

I. Zhelyazkova*, S. Lazarov

*Department of Animal Science – non-ruminants and other animals, Faculty of Agriculture, TrakiŠ° University, 6000 Stara Zagora, Bulgaria (Manuscript received 5 September 2017; accepted for publication 27 October 2017)

Abstract. The objective of the present study is to make a comparative analysis of some basic qualitative parameters of rapeseed (Brassica napus) honey, monofloral (acacia Robinia pseudoacacia, sunflower Helianthus annuus, coriander Coriandrum sativum, lime Tilia sp.,) and multifloral honey. The study uses 26 samples of bee honey from different regions in the country. The physicochemical study was carried out at the Scientific Research Laboratory of Trakia University according to the harmonized methods of the International Honey Commission and the methods described in Bulgarian State Standard (BSS) 3050- 80 and Regulation No. 48/2003. The following indicators have been investigated: water, glucose, fructose and sucrose content (%); hydroxymethylfurfural content (HMF, mg/kg); electrical conductivity (mS/cm). Based on the results obtained for glucose (G) and fructose (F) content in the honey samples, the sum total of G + F has been calculated. It has been found that the average values of the studied physico-chemical parameters in all analyzed honey samples (incl. rapeseed honey) are within the tolerable limits according to national regulations. The established deviations from the requirements concerning HMF content in rapeseed honey samples can be explained by technological errors rather than by plant origin. By glucose content the analyzed rapeseed honey samples have values close to those of sunflower honey (over 30%). These results can explain the rapid crystallization of rapeseed and sunflower honey. The lowest average electrical conductivity values have been established for rapeseed and acacia honey, which is a characteristic feature of light coloured honey types. Rapeseed and multifloral honey have higher average active acidity value (pH) compared to the average for the monofloral honey types. Based on the results, it can be concluded that rapeseed bee honey (Brassica napus) is of quality, does not differ from the monofloral and multifloral types produced in our country, complies with national and international regulatory documents and can be used by humans for food and as preventive agent.