Optimization of honey powder productiion conditions with different drying methods and determining the storage stability

Direct usage of honey in the food industry is very difficult due to its viscous and sticky features. In this study, honey was converted from liquid form to a powder form via spray and freeze drying methods. In order to determine the feeding solution properties in terms of dry matter content of feeding solution (%), anti-caking agent ratio (%) and the ratio of honey to maltodextrin prior to drying process, optimization study was carried out at constant spray drying conditions according to D-optimal combined design. Optimum composition of feeding solution honey powder production was determined considering production yield, flowability (CI) and Hunter b value (yellowness index) of obtained honey powder. In accordance with the obtained model by D-optimal combined design, the optimum feeding solution parameters were defined as the ratio of honey to maltodextrin of 58:42, dry matter content of feeding solution of 30% and the amount of anti-caking agent in the final product of 0.25%. After determination of the optimum feeding solution content, the effect of spray drying process conditions in terms of air inlet temperature, air outlet temperature and atomization pressure were investigated based on CCRD experimental design. The effect of these independent variables on aroma content, glass transition temperature, HMF content and flowability of honey powder were determined in the optimization study. The optimum spray drying conditions were selected as 187°C air inlet temperature, 75°C outlet air temperature and 462 kPa atomization pressure by using Design-Expert software. Moisture content, water activity, hygroscopicity, Hunter L, a and b values, particle diameter, span, uniformity, particle density, particle morphology, bulk and tapped density, wettability, dispersibility, and solubility of honey powder obtained at different spray drying conditions were also determined. But these properties were not used as response in optimization study. To investigate the effect of drying method in honey powder production, the feeding solution having the same composition was also dried in freeze dryer as well as spray dryer and the physical and chemical properties of obtained honey powder were compored to those of spray dried. After that the feeding solution having 58% honey and 42% maltodextrin was dried at optimum spray drying conditions, the product was packaged in aluminium polyethylene pouches and stored at different temperature of 4, 25 and 45°C. During the storage period physical and chemical properties of spray dried honey powder were analysed. The adsorption properties of honey powder produced via spray and freeze drying methods were determined at different temperatures of 4, 25 and 45°C according to the static-gravimetric method by using saturated salt solutions.