Food Safety Focus (196th Issue, November 2022)– Article 4

Natural Colour Pigment in Sweet Potatoes and Produces

Purple sweet potato is a popular food item in winter locally. However, some people might be concerned that the sweet potatoes may have been artificially coloured, as significant amount of colour can seep out into the water and hands when washed or boiled.

Purple sweet potatoes are known to contain anthocyanin, a pigment that is naturally found in common produce like beetroot, berries, red dragon fruit, grapes, red cabbages, red onions, eggplant skin and black rice. Anthocyanin is water-soluble and generally harmless to humans. Some of these varieties of produce are selected and bred for their vibrant colours that appeal to consumers. When these produce are handled, it is natural for some pigments to seep into the water or be rubbed onto hands. There is no need for undue concern.