title: Thermal degradation of anthocyanins from purple potato (cv. Purple Majesty) and impact on antioxidant capacity.
abstract: Degradation parameters of purified anthocyanins from purple-fleshed potato (cv. Purple Majesty) heated at high temperatures (100-150 °C) were determined. Purified anthocyanins, prepared by removing salts, sugars, and colorless nonanthocyanin phenolics from the crude extract, were monitored and quantified using HPLC and spectrophotometry for heat-induced degradation products. Separation of colorless phenolics from the anthocyanins was confirmed using HPLC at two wavelengths, 280 and 520 nm. The degradation kinetics of purified anthocyanins followed a first-order reaction with reaction rate constants (k values) of 0.0262-0.2855 min(-1), an activation energy of 72.89 kJ/mol, thermal death times (D values) of 8.06-8789 min, and a z value of 47.84 °C over the temperature range of 100-150 °C. The enthalpy and entropy of activation were 59.97 kJ/mol and -116.46 J/mol·K, respectively. The antioxidant capacity in the purified anthocyanins, measured by DPPH and ABTS assays, was increased after the thermal treatment, indicating antioxidant activities of degradation products in the samples.
authors.affiliation: Department of Biological Systems Engineering, Washington State University, Pullman, Washington 99163, United States.
authors.forename: Balunkeswar
authors.initials: B
authors.lastname: Nayak
authors.forename: Jose De J
authors.initials: Jde J
authors.lastname: Berrios
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Powers
authors.forename: Juming
authors.initials: J
authors.lastname: Tang
mesh_terms: D000872:Anthocyanins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D004355:Drug Stability; D006358:Hot Temperature; D007700:Kinetics; D035281:Plant Tubers / Q000737:chemistry; D011198:Solanum tuberosum / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D000872:Anthocyanins; D000975:Antioxidants