title: Effect of pH and temperature on the thermostability of prickly pear (Opuntia ficus-indica) yellow-orange pigments.
abstract: The colour stability of the yellow-orange pigment (lambda max = 476 nm) of prickly pear (Opuntia ficus-indica) fruit was determined as a function of temperature and pH. The experiments were carried out at three different temperatures (50, 70 and 90 degrees C) with pigment solutions at pH values ranging from 2-7. The degree of pigment retention decreased with increasing temperature as a function of increasing thermal exposure time with least pigment degradation at pH 5. The reaction rate constants were determined as 0.0062, 0.0383 and 0.1102 min-1 for a thermal degradation reaction rate of pseudo-first order. The activation energy was calculated as 65.1 kJ.mol-1.
authors.affiliation: University of Mersin, Engineering Faculty, Department of Food Engineering, Turkey.
authors.forename: Y
authors.initials: Y
authors.lastname: Coskuner
authors.forename: N
authors.initials: N
authors.lastname: Turker
authors.forename: H I
authors.initials: HI
authors.lastname: Ekiz
authors.forename: S
authors.initials: S
authors.lastname: Aksay
authors.forename: E
authors.initials: E
authors.lastname: Karababa
mesh_terms: D003116:Color; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010860:Pigments, Biological / Q000032:analysis*; D010944:Plants / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D010860:Pigments, Biological