Background. Honey is a popular food product because of its taste, nutritional and health values. It is valued for its rich composition. During storage, honey changes its consistency from liquid to solid. The length of this process varies depending on the botanical origin of honey. The goal of the study was to determine the impact of thermal treatment on the selected qualitative features of  honey and to extend the period during which honey remains liquid. The research material was non-purified, raw polyfloral honey. To prevent quick honey crystallization, hot air, microwave  radiation and ultrasonic treatment was carried out. In order to identify changes in the structure of honey, its moisture content, hydroxymethylfurfural (HMF) content, the degree of honey  crystallization during storage using the measurement of the amount of backscattered light (BS) and thermal properties using differential scanning calorimetry (DSC) were determined.
Results and conclusions. Each of these treatments was accompanied by an increase in the hydroxymethylfurfural content (HMF). However, the HMF content in heat-treated honey still meets the Council Directive 2001/110/EC criteria (< 40 mg/kg). To measure the progress of honey granulation during storage, the amount of backscattered light (BS) was checked. The microwave- heated honey remained in the liquid state for a long time, which was confirmed by a low amount of backscattered light. On the other hand, a common treatment preventing honey granulation,  i.e. hot air, was not the most efficient method to prolong the storage time of liquid honey. Moreover, the honey heated with hot air had the highest HMF content and BS amount.