Effect of sucrose on thermal and pH stability of Clitoria ternatea extract

The aim of this work was to investigate the effect of sucrose on the stability of Clitoria ternate extract against thermal and pH degradations. Lyophilised extract of the flower (1 mg/ml) was added into a series of sucrose solutions with concentrations ranging from 0.1% to 20% at pH7. The thermal stability of the extract in the solutions at 60oC was monitored using a UV-VIS spectrophotometer over 24 days. High temperature (60oC) accelerated degradation of the anthocyanin-rich extract but the presence of sucrose appeared to have slowed down the degradation process. However, sucrose asserted no protective effect against pH even at a concentration of 20%. It was thought that sucrose enhanced the thermal stability of anthocyanins by reducing water activity, partially preventing nucleophilic attack at the pyrylium ring of anthocyanins by water molecules. The present work provides some useful information for evaluating the potential of C. ternatea extract on food applications.