For
PSP extracts used as an industrial color additive, the rapid inhibition
of PPO was singled out as a critical step to prevent phenolic acid
oxidation and subsequent anthocyanin degradation. However, since
rapid PPO inactivation is not assured by pre-heating PSP on a commercial
scale due to varying tubers sizes and density, the use of chemical
inhibitors as extraction aids were evaluated with the addition
of citric acid, oxalic acid, and sodium borate to the aqueous extraction
solution. In these trials, non-heated and pre-heated at 90 C
for 10 min PSP, the latter with oxidase enzyme denaturing capabilities,
were evaluated with modifications to the aqueous extraction
solution for optimal polyphenolic extraction. Extractions were conducted
immediately for minimal air exposure and compared to a
PSP group held in air for 15 min prior to extraction.