Crystallisation behaviour of sunflower and longan honey with glucose addition by absorbance measurement.

The present work aimed to study the crystallisation behaviour of honey with glucose addition by using the absorbance measurement at 660 nm. The Avrami model was used to explain the crystallisation kinetic. The effect of glucose addition on the colour and microstructure of crystallised honey was also determined. Sunflower and longan honey were used in the present work. The biochemical compositions of honey samples were analysed before the addition of glucose powder at four concentrations (1.0, 1.5, 2.0, and 2.5%; w/w) and stored at 10 - 15°C. The absorbance at 660 nm, colour, and microstructure were measured until full crystallisation. The results showed that different honey compositions exhibited different crystallisation behaviours, which could be monitored by the absorbance measurement at 660 nm as well. The addition of glucose powder could stimulate the crystallisation time, thus affecting the crystallisation rate. The Avrami equation was found to be a good model for describing the crystallisation behaviour from the intensity of absorbance values. The highest crystallisation rate was found at 2.0% (w/w) glucose addition at the rate constant (k) of 0.177 ± 0.038 and 0.083 ± 0.039 in sunflower and longan honey, respectively. The Avrami index (n) was relevant to the crystallisation rate, but not clearly related to crystal shape or size. The crystals of all glucose-added honey contained small crystals in bouquets. The yellow colour became lighter during storage period. Suitable glucose content and absorbance monitoring at 660 nm could be used to control the crystallisation of honey for obtaining creamed honey product with good texture. [ABSTRACT FROM AUTHOR]