Effect of Carotenoid Extract on the Properties of Reconstructed Sweet Potato Starch

ABSTRACT Carotenoids extracted from orange sweet potato flour (OSPF) can influence the properties of reconstructed sweet potato starch. Orange sweet potato flour extract (ExOSPF) was prepared by extracting the carotenoids with a hexane, acetone, and ethanol mixture. The crude carotenoid extract was added to the blanched flour to obtain reconstructed OSPF (20 and 80 µg). The addition of carotenoids increased the peak, final, and setback viscosities of the reconstructed flour, which had lower gelatinization enthalpy. The gel structure studied under a light microscope showed that the starch granules in the reconstructed flour were more disrupted than in OSPF. Carotenoid localization was different in both samples, OSPF contained internal carotenoids while reconstructed flour contained surface carotenoids. XRD analysis showed no differences between OSPF, ExOSPF, and the reconstructed flour while FTIR spectroscopy showed that starch and carotenoids underwent interaction, inducing a lower glycemic index compared to OSPF. The carotenoid content and localization in the samples resulted in variations in the starch properties that could be used to formulate functional food with lower starch digestion by natural carotenoids.