Hydroxymethylfurfuraldehyde and amylase contents in Australian honey

The quality of Australian honey samples (processed and unprocessed) was assessed using HPLC techniques. 5-Hydroxymethylfurfuraldehyde (HMF) was used as the main quality indicator. Sampling included four commercially-processed honeys (Australian rainforest, Beechworth, Homebrand and Leabrook) and three unprocessed (Banksia, Grey box and Mallee). All honey samples, except Leabrook and Beechworth, showed an initial HMF content less than the Codex Alimentarius and International Honey Commission standard (40 mg/kg). HMF contents in Leabrook and Beechworth were 50.8 +/- 1.34 and 74.9 +/- 2.34 mg/kg, respectively. Heating unprocessed honey at 85 degrees C for 2 min caused significant (p <= 0.05) increment in HMF contents. The amounts of HMF in Mallee samples increased from 34.0 +/- 0.31 to 42.3 +/- 0.37 mg/kg after 2 min at 85 degrees C. All honey samples showed amylase activity above the minimum limit (8 Gothes). The physiochemical properties of honey showed significant variations among samples. The results revealed also that heating was not the only factor influencing HMF formation in honey, but also honey composition, pH value and floral source can contribute to these variations. Consequently, the amount of HMF may be an insufficient sole indicator of honey quality. (C) 2009 Elsevier Ltd. All rights reserved.