Effects of process parameters on the color quality of anthocyanin-based colorants from conventional and microwave-assisted aqueous extraction of sweet potato (Ipomoea batatas L.) leaf varieties

The study aimed to evaluate the effects of process parameters (time and raw material weight[RMW]) of conventional (boiling for 10- 45 min) and microwave-assisted (2-15 min) aqueous extraction (MAE) on the color quality (i.e. lightness [L*], chroma [C*] and hue [H°] of anthocyanin –based colorants of red and Inubi sweet potato (Ipomoea batatas L.) leaves. Using response surface methodology (RSM), it was found that RMW and boiling time (BT) and microwave time (MT) generally had a significant (p<0.05) effect on the color quality of the extract from both extraction methods. The effects were found to be varying depending on the extraction method and variety of the leaves used. The red sweet potato leaves produced a deep violet colored extract that also turns red violet when acidified. It is recommended that the anthocyanin content of the extracts be measured to validate the impact of the methods on the active agent. Nevertheless, the outcomes in this study may serve as baseline data for further studies on the potential of sweet potato leaf colorants (SPLC) as a colorant with functional properties.