Glass Transition temperature of honey using Modulated Differential Scanning Calorimetry (MDSC): Effect of moisture content

Glass transition phenomena in nine Korean pure honeys (moisture content 18.3∼20.1%) and honey-water mixtures by different water contents (0, 2, 5, and 10% w/w) were investigated with modulated different scanning calorimetry (MDSC). The total, reversing, and non-reversing heat flows were quantified during heating using MDSC. Glass transition was observed from reversing heat flow separated from the total heat flow. The glass transition temperatures (T_g) of pure honeys, which are in the range of -42.7°C to -50.0°C, varied a lot with low determination coefficient (R ²=0.63), whereas those of honey-water mixtures decreased with a decrease in honey content. The T_g values were also more significantly different among honey-water mixtures when compared to pure honeys, indicating that in the honey-water mixture system the T_g values appear to be greatly dependent on moisture content. The measured heat capacity change (δC_p) was not influenced by moisture content.