Crystallization in "Tarassaco" Italian honey studied by DSC

The degree and rates of crystallization in honey stored at 5 degrees C, 10 degrees C, 15 degrees C, 20 degrees C and 25 degrees C were examined, with reference to rate enhancing and rate limiting factors of both thermodynamic and kinetic nature. Crystals of "Tarassaco" honey (from Taraxacum officinale Weber), mainly glucose monohydrate, were separated and purified from the residual amorphous phase and the enthalpy of melting was determined by DSC. The melting enthalpy resulted 108.39 +/- 6.16 J g(-1). The crystallization rates were 0.659, 0.755, 0.861, 0.815 and 0.593 g(crystals) x 100 g(honey)(-1) days(-1) at the cited temperatures. The water activity (a(w)) increased from 0.593 in the liquid honey to 0.658, 0.652, 0.647, 0.639 and 0.640 after 222 days storage. The relationships among crystallization, supersaturation, glass transition temperatures (T-g), melting temperatures (T-m), difference (T-T-g), viscosity and a(w) are discussed. (C) 2009 Elsevier Ltd. All rights reserved.