title: Monitoring by liquid chromatography coupled to mass spectrometry the impact of pH and temperature on the pigment pattern of cactus pear fruit extracts.
abstract: The influence of pH and moderate heating (50 degrees C) on the color and individual betacyanin content of pigment extracts from cactus pear fruits (Opuntia stricta) is studied in the course of this paper. The study is carried out by using a high-performance liquid chromatograph equipped with a photodiode array detector and coupled to a mass spectrometer. The results point to a pH-dependent degradation mechanism, which is reflected in the chromatographic patterns obtained at different exposure times (0-28 h). At pH 3, 15-descarboxy-betanin is the most resistant betacyanin derivative. At pH 5, seven peaks are detected after 8 h, the most prominent being betanin, cyclo-dopa-5-O-beta-glucoside, and betalamic. In the assay conducted at pH 7, rapid color loss affects all the pigments, except for betanin.
authors.affiliation: Department of Chemical Engineering, Polytechnic University of Cartagena, Paseo Alfonso XIII 52, E-30203 Cartagena (Murcia), Spain. josea.fernandez@upct.es
authors.forename: José A
authors.initials: JA
authors.lastname: Fernández-López
authors.forename: Rosario
authors.initials: R
authors.lastname: Castellar
authors.forename: José M
authors.initials: JM
authors.lastname: Obón
authors.forename: Luis
authors.initials: L
authors.lastname: Almela
mesh_terms: D050859:Betacyanins / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry / Q000379:methods*; D029747:Opuntia / Q000737:chemistry*; D010860:Pigments, Biological / Q000032:analysis / Q000302:isolation & purification*; D010936:Plant Extracts / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D050859:Betacyanins; D010860:Pigments, Biological; D010936:Plant Extracts