Purple sweet potatoes (PSP) have been used as a natural food colorant with high acylated anthocyanins
concentrations. Commercially extracting pigments from PSP can be challenging due to firm texture and
high polyphenol oxidase (PPO) content. These studies evaluated hot water immersions (30, 50, 70, and
90 C for 10 min) as pre-heating treatments and addition of PPO inhibitors (citric acid, oxalic acid, and
sodium borate) to aqueous extraction solutions to aid pigment recovery. Predominant PSP anthocyanins
included acylated cyanidin or peonidin derivatives. Non-pigmented cinnamates acted as oxidase substrates
and induced co-oxidation reactions with anthocyanins. Pre-heating PSP significantly increased
polyphenolic yields in a temperature-dependent manner, consistent with tissue softening and PPO inactivation.
The use of solvent modifiers in the extraction solution associated with heat helped minimize
enzyme action and increased polyphenolic recovery. Minimizing the impact of PPO with heat was critical
to the extraction and recovery of PSP anthocyanins, suitable for food use.