title: Pre-heating and polyphenol oxidase inhibition impact on extraction of purple sweet potato anthocyanins.
abstract: 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.
authors.affiliation: Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843-2254, United States.
authors.forename: Paula
authors.initials: P
authors.lastname: de Aguiar Cipriano
authors.affiliation: Department of Food Engineering, Erciyes University, Kayseri 38039, Turkey.
authors.forename: Lutfiye
authors.initials: L
authors.lastname: Ekici
authors.affiliation: Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843-2254, United States.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Barnes
authors.affiliation: Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, United States.
authors.forename: Carmen
authors.initials: C
authors.lastname: Gomes
authors.affiliation: Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843-2254, United States. Electronic address: stalcott@tamu.edu.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Talcott
mesh_terms: D000872:Anthocyanins / Q000737:chemistry*; D004156:Catechol Oxidase / Q000737:chemistry*; D006361:Heating; D027723:Ipomoea batatas / Q000737:chemistry*; D010084:Oxidation-Reduction; D010936:Plant Extracts / Q000737:chemistry
chemical_list: D000872:Anthocyanins; D010936:Plant Extracts; D004156:Catechol Oxidase
keywords: Anthocyanins; Polyphenol oxidase inhibition; Pre-heating; Purple sweet potato