The growing market of functional beverages requires characterize specifically the sources of bio-actives to select those with the highest quantity of the compound needed in the formulation. The composition of phenolic acids and the content of anthocyanins and proanthocyanidins, from aqueous extracts of the calyxes of three varieties of jamaica (Hibiscus sabdariffa L.) were assessed using HPLC-DAD: dark red (Sudan), light red (Criolla Nayarit) and white (Alma Blanca). Antioxidant activity was also determined. The experimental design was completely randomized with three replications. The highest contents of total phenolic acids were detected in Sudan and Alma Blanca (10.71±0.29 and 8.22±0.30 mg GAE g-1 DM). The fraction of free phenolic acids (FPA) was abundant and was highly complex in the calyxes of the three colors. Chlorogenic acid and its two isomers were predominant in the FPA, and the glycosylated phenolic acids (GPA) accounted for 77.4 to 81.5 % of the total phenolic acids in the three varieties. The white Alma Blanca calyxes contained more caffeic and protocatechuic acid derivatives than the red calyxes of the other varieties. The highest antioxidant activity (p≤0.05) was found in the Sudan extract (CI50=113.3 μg mL-1). The color of the calyxes can indicate the predominant type of phenols in H. sabdariffa L. and aid in the selection of varieties for formulations with particular nutraceutical properties.

El creciente mercado de bebidas funcionales requiere la caracterización específica de las fuentes de bioactivos, para seleccionar aquellas con la mayor cantidad del compuesto necesario en la formulación. La composición de ácidos fenólicos y contenido de antocianinas y proantocianidinas, de extractos acuosos de tres variedades de jamaica (Hibiscus sabdariffa L.), con rojo oscuro (Sudán), rojo claro (Criolla Nayarit) y blanco (Alma Blanca) en sus cálices, fueron evaluados mediante HPLC-DAD. Además, se determinó su actividad antioxidante. El diseño experimental fue completamente al azar y con tres repeticiones. El contenido mayor de ácidos fenólicos totales se detectó en Sudán y Alma Blanca (10.71±0.29 y 8.22±0.30 mg EAG g-1 MS). La fracción de ácidos fenólicos libres (AFL) fue abundante y con complejidad alta en los cálices de los tres colores. El ácido clorogénico y sus dos isómeros predominaron en las fracciones AFL y los ácidos fenólicos glucosilados (AFG) representaron entre 77.4 y 81.5 % del total de ácidos fenólicos en las tres variedades. Los cálices blancos tenían la cantidad mayor de ácido cafeico y derivados de protocatéquico. La actividad antioxidante mayor (p≤0.05) se presentó en el extracto de Sudán (IC50=113.3 μg mL-1). El color de los cálices puede ser un indicador del tipo predominante de fenoles en H. sabdariffa L. y ayudar en la selección de variedades para obtener formulaciones con propiedades nutracéuticas particulares.

The well-known CGAM optimization problem was formulated to serve as a benchmark for comparison of different thermoeconomic methodologies. The CGAM cogeneration plant produced 30 MW of power and 14 kg/s of saturated vapor at 20 bar. The objective function was the total cost rate of the system, related to thermodynamic variables and installation costs. Because the CGAM problem originates from an academic viewpoint, its models do not reflect the industrial reality of energy systems, and do not conform to important operational and technological restrictions. The objective of this work is to propose an alternative cogeneration-system optimization problem, denoted the MPCP problem - Maximum Profit Cogeneration Plant, which incorporates functional economic concepts and modern technologies. The objective function is the net present value (NPV) of the monetary gain for the period of plant operation. The optimum (i.e., maximum) NPV value is obtained using two different professional optimization toolboxes appropriate for multivariable nonlinear constrained functions. The optimal operational conditions indicate that the MPCP plant reaches the allowed physical limits of the main equipment, namely, maximum efficiency of the gas turbine generator set and minimum temperature difference inside the heat recovery steam generator. Formal findings like these help to direct efforts to improve current technologies.