The Confirmation of Botanic Origin of the Croatian Black Locust Honey from the Krapina-Zagorje Region

According to its chemical composition, honey is a complex mixture of over 70 ingredients, which enter honey in a variety of ways. Not only that the different types of honey differ, but the honey within each species differs in its composition depending on its herbal and geographical origin, climatic conditions, the type of bees, and the work of the beekeeper. A number of European countries have the national legislation and the reference methods used for local quality control, but they are often specific for a particular country and cannot always be applied in the commercialization of honey for the international sales. Therefore, the profession in accordance with expert associations – such as the International Honey Commission (IHC) – seeks to harmonize the reference methods and standards for proving the authenticity of botanical origin of monofloral type of honey. Leading experts involved in this issue combine melissopalynological determination of the type and number of pollen with sensory analysis and physicochemical analysis such as determining the water content, HMF (hydroxymethylfurfural), electrical conductivity, diastasis activity, pH values, and the sugar content (fructose, glucose, sucrose, erlose, raffinose, melesitose) The purpose of this paper is to present the profile of physicochemical parameters of 40 samples of the black locust honey from Krapina-Zagorje region monitored by the season. Morevoer, it will point out their differences within each testing season. Botanical origin of all the samples, as declared by the manufacturer, was confirmed using the melissopalynological analysis-black locust. By conducting pollen analysis in the samples of black locust honey during both seasons pollen grains of 36 plant species were found. The most common are those of the family of Robinia (black locust family), Rosaceae (rose family), Brassicaceae (cabbage family), and Fabaceae (bean family) Every tested sample meets the requirements set by the Regulations on the quality of monofloral honey regarding physicochemical parameters: water (15, 21-19, 28%) ; free acid (6, 1¸-14, 00 mEq/1000g) ; electrical conductivity (0, 08-0, 22 mS/cm) ; reducing sugars (61, 57-71, 20 g/100 g) ; sucrose (0, 10-2, 58 g/100g) ; diastase (7, 15-17, 19 DN) and HMF (0, 97-11, 20 mg/kg). The analysis of variance gained an insight into the significance of differences (p-values) within the physicochemical parameters for water and electrical conductivity given the season black locust honey is from (p < 0, 05). Based on the results obtained, the following can be concluded: • The confirmation of botanical origin of all the honey samples, as declared by the manufacturer, was conducted using o melissopalynological or pollen analysis, o and by confirming the conformity of physicochemical parameters (water, free acid, electrical conductivity, reducing sugars, sucrose, diastase and HMF) • All the tested samples meet the requirements of the Regulations on the quality of unifloral honey • Using data analysis of variance an insight has been gained into the significance of differences (p-values) among physicochemical parameters – water and electrical conductivity – given the season that black locust honey comes from (p < 0.05).