Crystallisation of sugar in dried fruits and honey is a well-noticed phenomenon. In most of the instances crystallisation is an undesirable aspect of these low moisture sugar-rich products. The dried fruits will show whitish yellow specs on the surface of the fruit. This defect makes the fruits look moldy or having infested by insects although this is purely due to the crystallisation sugar. The affected fruits can be gritty in texture. This phenomenon is sometime referred as “sugaring”. This is prevalent in many fruits such as raisins (dried grapes), prunes (dried plums), figs, dates, persimmons etc. In honey, this is caused by the low temperature exposure of the honey such as in winter days. The major sugars found in these fruits and honey are invert sugars (glucose and fructose). The composition of sugars in above fruits and honey are normally similar, in particular in sugar composition. In both type of products the glucose crystallises out due to its low solubility and favourable crystallising conditions during storage.<br/>Various measures are taken to prevent or inhibit the crystallisation of sugar in these products. However, there is still a mechanistic type of approach needed to understand the crystallisation of glucose in a complex composition as the exact cause is not clearly defined and the control measures are not yet fully effective. Several factors such as the concentration of sugars (or moisture), ratio of glucose to fructose and amount of organic acids may all contribute to the crystallisation of glucose. There is no such study published to date. In addition, the glass transition approach is one of the fundamental methods that has also not been reported for understanding the mechanism of crystallisation of sugar in these dried fruits and honey. This presentation will highlight the potential mechanisms that are responsible for sugar crystallisation and understanding this mechanism from the angle of glass transition in model sugar composition, dried raisins and honey.

Predicting the crystallisation of sugar in dried raisins and honey

255th National Meeting (2018)

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