Originating in Latin America, the purple sweet potato now has the most plantings in Asia and is extracted from the storage root of the plant.
The purple sweet potato juice may be used for naturally colouring food and beverage applications. It is one of the most stable in terms of light stability in beverages.
Purple sweet potato anthocyanins are primarily cyanidin 3-sphorioside-5-glucoside and peonidin 3-sphorioside-5-glucoside, both di-glycosylated. This di-glycosylation, coupled with acylation on the on the glycosides, contributes to the colouring’s stability through intramolecular stacking. The stacking blocks reactive hydroxyl groups from interacting with environmental stresses. Like other anthocyanin sources, the hue shifts from red to purple as pH increases. It is most stable in acidic conditions.