Honey moisture reduction on the inclined plate system: optimization of process parameters

Honey is prepared by bees from natural sugars, which they collected in the form of nectar from different flowers. In the present study, an inclined plate system was developed and evaluated for moisture reduction of honey by recirculating hot water beneath the drying surface and the process conditions were optimized for getting honey with more shelf life. The water temperature and plate inclination were selected as process parameters ranging from 40 to 70 °C and 30-60° respectively. The honey quality during the process was adjudged on the basis of heat sensitive variables such as hydroxymethylfurfural (HMF) content, diastase activity and colour. The experiments were conducted by following full factorial design of experiments with each variable interaction. It was found that HMF and diastase activity after moisture reduction varies from 17.48 to 51.83 mg/kg and 12.5 to 7.7 from 70-40 °C drying temperature respectively. Less colour loss of raw honey was observed at higher process temperature and low plate inclination that varied from 3.64 to 7.97 in terms of L, a,b colour difference. The ambient temperature and relative humidity during the process was 30.5 °C to 34.8 °C and 78.6 to 89.8% respectively. The optimum conditions of process parameters viz. water temperature and plate inclination were found to be 60 °C and 60° respectively that resulted in minimum increment of HMF formation, less loss of diastase activity along with minimum colour change and less energy requirement during the process.