No abstract

Betalains are plant pigments with biological properties and can be used instead of synthetic colorants to confer color and functional properties to foods. The objective of this work was to carry out the chemical characterization of two varieties of prickly pear of Opuntia ficus‐indica, one of yellow‐orange coloration (Mandarina) and the other of purple coloration (Vigor), through measurements of chemical parameters and color in pulp, antioxidant activity, total phenolic compounds, and betalain content. Considering the thermolability of betalains and their potential applications in food, the thermal stability and activation energy of betacyanins from Vigor variety and betaxanthins from the Mandarina variety were also evaluated and compared with those from beetroot, the main source of betalains. Results for chemical characterization agreed with previous prickly pear reports of other regions, while the thermal degradation kinetics of betalains showed a first‐order degradation pattern with respect to time and temperature treatment. Betacyanins from Vigor prickly pear showed similar thermal stability to those from beetroot, which was reflected in similar values of activation energy, while betaxanthins from Mandarina prickly pear showed a higher stability, and therefore a higher activation energy, than those from beetroot. Based on the results, the prickly pear varieties used in this study can be considered as a good source of betalains with potential applications in food and, in addition, the methodology for the evaluation of thermostability can be used to compare the stability of betalains from different sources in a temperature range of 50–90°C. Practical Application The varieties of prickly pear used in this study can be considered a good source of red‐purple and yellow‐orange easily extractable pigments. In addition, we report a methodology that can be used for the evaluation of the thermal stability of these pigments and to compare this stability between different plant sources. Gaining knowledge on betalain thermal stability will make it possible to propose specific applications, for example, in processed foods requiring different pigment stabilities.

totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

Abstract. The cactus stem of Atlixco cultivar is consumed for its pharmacological properties and it is marketed not only in Mexico but also in other countries. Despite this, its complete phenolic profile is not known which are recognised as powerful antioxidants. This work aimed to develop a standardised methodology for optimise the conditions for phenolic compounds extraction in the cactus stem of Atlixco cultivar and to identify these compounds using mass spectrometry (MS). Results indicated the following: a) it is recommended to use one unit of freeze-dried cactus stem for every 50 units of solvent. Subsequently, the blend should be eluted with water/methanol/acetonitrile in a ratio of 25:25:50 by the column chromatography technique; b) samples maintained in a reflux system with an acidic medium after two hours of heating at 65°C showed the greatest amount of phenolic compounds by MS, and c) trans-caffeic acid, ferulic acid, kaempferol, quercetin, and isorhamnetin were identified. In conclusion, only some of the phenolic compounds identified in this work had been reported in other cactus stem cultivars.                 Resumen. El nopal del cultivar Atlixco se consume por sus propiedades farmacológicas y se comercializa no solo en México sino también en otros países. A pesar de esto, se desconoce su perfil de compuestos fenólicos, los cuales son reconocidos como potentes antioxidantes. Este trabajo tuvo como objetivo desarrollar una metodología estandarizada para optimizar las condiciones para la extracción de compuestos fenólicos en el nopal del cultivar Atlixco e identificar estos compuestos usando espectrometría de masas (EM). Los resultados indicaron lo siguiente: a) se recomienda usar una unidad de nopal liofilizado por cada 50 unidades de disolvente. Después la mezcla deberá ser eluida con agua/metanol/acetonitrilo en una  proporción de 25:25:50 por la técnica de cromatografía en columna, b) las muestras mantenidas en un medio ácido después de dos horas de calentamiento a 65°C mostraron el mayor número de compuestos fenólicos por EM, y c) se identificaron el ácido trans-cafeico, ácido ferúlico, campferol, quercetina e isoramnetina. En conclusión, solo algunos de los compuestos fenólicos identificados en este trabajo han sido reportados en otros cultivares de nopal.