Influence of type and state of crystallisation on the water activity of honey

In total, 249 samples of different honey types were analysed concerning water content and water activity. The samples were identified by using physico-chemical parameters and melissopalynological methods. The water content was determined at 20 degrees C via refractometric measurement by using the refractive index. The water activity of liquefied and crystallised honeys was measured at 25 degrees C, using the instrument Novasina a(w)-Sprint. It was found that the water activity of crystallised honeys is higher than that of liquid honeys. Furthermore, a difference between flower- and honeydew honeys could be detected. In liquid state, honeydew honeys show higher water activities than flower honeys having the same water content. However, no significant difference between the water activities of different types of honeys could be found when the honey was crystallised. The results are dependent on the fact that the water activity in honey mainly depends on the glucose content. (c) 2005 Elsevier Ltd. All rights reserved.