The degradation kinetics of anthocyanins in a Roselle infusion (Hibiscus sabdariffa L.), as assessed by visible absorption spectroscopy (absorbance at 520 nm), was verified (60-100°C). The rate constants for absorbance retention were obtained from first-order reaction kinetic plots. Based on an Arrhenius-type model, the experimental data showed an energy of activation of 15.83 kcal mol )1 (66.22 kJ mol )1 ) and a Q 10 value of 1.01. The obtained pattern allows to predict the retention of these antioxidant compounds as a function of temperature and time of thermal treatment.

No abstract

Cereal products made from pigmented grains are attractive to consumers. We determined the variability in color, phenolic composition and antioxidant activity (AA) of blue tortillas made from 18 landraces belonging to three blue/purple grained Mexican maize races -Chalqueño (Chal), Elotes Cónicos (Ec) and Bolita (Bol). The color of the tortillas produced ranged from yellow-green to bluegreen. Ec tortillas were the only true blue type. Total anthocyanin content (TAC) varied between 3.67 and 1.11 mg equivalents of cyanidin 3-glucoside/kg dry weight (DW). Total soluble phenolics (TSP) were between 9.42 and 5.16 mg equivalents of gallic acid/kg DW. AA was highly correlated (p < 0.01) with TAC, but not with TSP. Blue Ec tortillas had the highest AA, and Bol tortillas had the lowest AA. Color parameters, TSP and TAC allowed the appropriate grouping of blue tortillas according to the maize race they belong to and were made from.Color, composición fenólica y actividad antioxidante de tortillas azules de razas mexicanas de maíz RESUMEN Los productos de cereales elaborados con granos pigmentados son atractivos para los consumidores. Se determinó la variabilidad en color, composición fenólica y actividad antioxidante (AA) de las tortillas azules de dieciocho variedades nativas de maíz con grano azul/púrpura de tres razas mexicanas: Chalqueño (Chal), Elotes cónicos (Ec) y Bolita (Bol). El color de las tortillas varió de amarillo-verdoso a azul verdoso; las de Ec fueron las únicas verdaderamente azules. El contenido total de antocianinas (TAC) varió entre 3,67 y 1,11 mg equivalentes de cianidina 3-glucósido/ kg muestra seca; los fenoles solubles totales (TSP) variaron de 9,42 a 5,16 mg equivalentes de ácido gálico/ kg muestra seca. El TAC fue altamente correlacionado con AA. Las tortillas de la raza Ec tuvieron la mayor AA. Las tortillas de la raza Bol tuvieron la AA más baja. Los parámetros de color, TSP y TAC permitieron agrupar de forma adecuada las tortillas azules según la raza a la que pertenecen. ARTICLE HISTORY

No abstract

No abstract