Colour changes during the processing of Arenga pinnata (palm) sap into sugar

Abstract

This study reports the colour changes using CIELAB measurements (L*a*b* color space) and their correlation with time, temperature, total soluble solids (TSS), and pH during the processing of Arenga pinnata (palm) sap into granulated sugar. As a function of time, the sap became darker, more red, and more yellow indicating a continuous decrease of L* values, and an increase in both a* and b* values. A constant decrease of L* and an increase of a* and b* were particularly observed when TSS of the sap was more than 33.5%. During the process, regression analysis showed that a linear pattern was indicated for total colour difference (ΔE*) with time, whereas a non linear relationship was shown for ΔE* with TSS, temperature and pH. Stirring the syrup changed the L*a*b* values while ΔE* showed a decrease throughout the process. This research will serve as a base for future developments for the manufacture and quality grading of A. pinnata (palm) sugar.