Caramelisation is distinct from the Maillard reaction — it is the thermal decomposition of sugar molecules themselves, not a reaction between sugar and amino acids. Pure sucrose heated above 160°C begins to break down into smaller compounds of greater complexity and colour. The compounds produced — furanones, pyranones, caramel-specific aldehydes — are the basis of caramel flavour and colour. Because no protein is required, caramelisation occurs in pure sugar solutions where the Maillard reaction cannot.
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