Investigation of the Thermal Processing Effect on Physicochemical Properties of Honey and Process Optimization by Response Surface Methodology

Response surface methodology (RSM) was applied to investigate the effect of two independent variables, including temperature and time on the physicochemical properties of honey. Results showed that the thermal processing had no significant effect on free acidity, brix, moisture content, pH and sucrose of the samples (p> 0.05), while its effect on hydroxymethyl furfural (HMF), proline, diastase, red color and blue color index was significant (p< 0.05). The amount of proline varied between 140 to 230 mg/kg and the diastase content varied between 5 ± 0.1 and 16.5 ± 0.2 Goethe. The HMF content of treatments was obtained between 6.9±0.2 and 274.2±1.2 mg /kg. The range of color variations in the samples ranged from 1.0±0.06 to 6.8 ± 0.40 for red and 1.1±0.06 to 5.8 ± 0.40 for blue color. The optimization results of model showed that the best temperature and time of heating (in such a way that the amount of its diastase and proline was in the maximum and amount of its HMF and color darkness was in the minimum) is 50°C and 120 min, respectively.