Modification of the rheological properties of honey in the honeycombs by the high frequency heating prior to honey extraction
Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague 6 – Suchdol, Czech Republic
This paper addresses the issue of the extraction of highly viscous honey from the honeycombs. High viscosity can be caused by many factors. In the operational practice it is mainly about the difficult conditions (cold weather), post seasonal honey extraction or honey with naturally high viscosity (honeydew honeys). The objective was to design and validate a technology that will enable to reduce the viscosity of honey in the honeycombs by the high frequency heating and increase the effectiveness of honey extraction. The experimental part is based on the high frequency heating of honey, so called dielectric heating. In this process the heating of honey occurs evenly throughout the full volume of the honeycomb. To verify the proposed procedure, several groups of samples of the capped honeycombs were selected that contained honey of different botanical origin and rheological properties. For heating of the honeycombs, a high frequency chamber was prepared in the laboratory conditions. Honeycombs were placed into the chamber and heated to the desired temperature (from 15 °C to 45 °C). During extraction, the time dependence of honey extraction on the temperature of the pre-heated honeycombs was monitored. It was proved that the high frequency heating is suitable for the pre-processing of the honeycombs; heating is quick and reduces the viscosity. As a consequence of different permittivity of honey and beeswax, the strength of the comb is not changed when the electromagnetic field conditions are set properly, the honeycomb remains compact. Measurements demonstrated the time reduction of honey extraction based on the temperature.