RESuMENEl objetivo de este trabajo fue determinar las isotermas de adsorción de humedad de harina de maíz a tres temperaturas (7, 22 y 45 °C) para el rango de a w entre 0,10 y 0,95. Las isotermas se modelaron utilizando siete ecuaciones comúnmente aplicadas en alimentos. La calidad de ajuste se evaluó con el coeficiente de regresión (r 2 ) y el porcentaje de error medio relativo (% E), en función de los cuales se observó que los modelos propuestos por GAB, Oswin y Halsey ajustaron de mejor manera los datos experimentales. La humedad de la monocapa (X m ) y la humedad de seguridad (X S ) presentaron dependencia con la temperatura con valores de E a de 13,6 y 3,3 kJ/mol, respectivamente. Se cálculo el calor isostérico de adsorción (Q S ) usando la ecuación de Clausius-Clapeyron, obteniéndose un máximo de 21 kJ/mol, para una humedad de 0,075 g agua/g m.s., este parámetro se modeló utilizando la ecuación propuesta por Tsami. Palabras-clave: harina de maíz, isotermas de adsorción, Arrhenius, calor isostérico. RESuMOISOTERMAS DE ADSORÇÃO EM FARINHA DE MILHO (Zea mays L.). O objectivo deste trabalho foi determinar as isotermas de adsorção de umidade da farinha de milho a três temperaturas (7, 22 e 45 °C) para um rango de a w entre 0,10 e 0,95. As isotermas foram modelizadas por meio de sete equações normalmente utilizadas em alimentos. A qualidade do ajuste foi avaliada mediante o coeficiente de regressão (r 2 ) e a porcentagem de erro médio relativo (% E), em função dos quais se observou que os modelos propostos por GAB, Oswin e Halsey apresentaram um melhor ajuste dos dados experimentais. A umidade da monocapa (X m ) e a umidade de segurança (X S ) mostraram dependência da temperatura com valores de E a de 13,6 e 3,3 kJ/mol, respectivamente. Calculou-se o calor isostérico de adsorção (Q S ) utilizando-se a equação de Clausius-Clapeyron, obtendo-se um máximo de 21 kJ/mol. Para uma umidade de 0,075 g água/g m.s., este parâmetro modelizou-se utilizando a equação proposta por Tsami. Palavras-chave: milho, modelos, Arrhenius, calor isostérico. -INTRODuCCIÓNEl maíz (Zea mays L.) es un cereal ampliamente utilizado en el mundo entero tanto para consumo humano como para alimentación animal. Constituye junto con la patata y la tapioca, las materias primas más importantes para la obtención de almidón, de jarabes de glucosa y de bebidas alcohólicas. Para consumo humano se pueden obtener harinas de maíz, aceite de germen, productos para desayuno y conservas de maíz dulce, entre otros alimentos. Por su alto contenido de almidón, las harinas y sémolas de maíz son una fuente importante de calorías en la dieta de países de América Central y del Sur, donde este cereal es alimento básico [22].La harina de maíz, al no contener gluten, sirve de base de harinas panificadoras para los enfermos celíacos, al igual que las harinas de arroz, quínoa, soya y mandioca [18]. La celíaquia se caracteriza por la intolerancia al gluten, en concreto son las prolaminas presentes en el trigo (gliadinas), avena (avidina), cebada (hordeína), centeno (secal...

El objetivo de este trabajo es estudiar y modelar la cinética de secado por aire caliente del alga Gracilaria (Gracilaria chilensis) utilizando un secador convectivo diseñado y construido en

In this study, Kageneckia oblonga leaves were dried under different drying conditions and techniques [oven drying (NC), vacuum drying (VNC), convective drying (FC), and microwave-assisted convective drying (MWFC)]. Thus, the effect of temperature, vacuum, and microwave on the drying features of K. oblonga leaves was determined. Fick's second law was used to calculate the effective moisture diffusivity that varied from 3.94 to 8.14 × 10−11 m2/s, 1.12 to 1.40 × 10−11 m2/s, 7.83 to 11.36 × 10−11 m2/s, and 6.93 to 16.72 × 10−11 m2/s for NC, VNC, FC, and MWFC methods, respectively. In addition, the Weibull and Midilli–Kucuk models accurately predicted all experimental drying curves of K. oblonga leaves. Regarding the energy consumption and efficiency values for different drying methods of K. oblonga were found to be in the range of 0.20–7.50 kW·h and 0.10–3.70%, respectively. The results showed that MWFC method does not significantly affect the phenolic compounds and could be used for large-scale production of K. oblonga dried leaves.

Numerical prediction of heat transfer by natural convection of a Herschel-Bulkley non-Newtonian fluid inside a square cavity has been computationally analyzed. Unsteady 2D fluid mechanics and heat transfer were described in terms of the non-linear coupled continuity, momentum and heat equations. These equations were solved by the control volume finite element method (CVFEM) with Gauss-Seidel/System Over-Relaxation coupling algorithm. The effect of the Ra, Pr, Bn and the rheological behavior index (n) on the non-Newtonian fluid thermal and momentum behavior were studied. The non-Newtonian fluid flow was described by the rheological model of Herschel-Bulkley. Results for the streamlines and isotherms along the enclosure walls are presented. It was found that the effect of the Pr and Bn is more important when the Ra is lower (10 3 ). In addition, the behavior index had a significant effect on the CPU time for the different studied cases.

BACKGROUND: There is consumer interest in berries due to their nutritional properties, especially biologically active compounds. Spray drying technologies improve products stability and shelf life, and the agglomeration process subsequently enhances powder instantaneousness and flow properties. OBJECTIVE: The aim was to evaluate the effect of the fluidized bed agglomeration process on flow, reconstitution, and antioxidant properties of cape gooseberry, strawberry, and blackberry powder mix obtained by spray drying and a water and vitamin C binding solution. METHODS: A face-centered central composite design with 15 experiments was used; independent variables were fluidization temperature (T), binder solution atomization pressure (P), and process time (t), while dependent variables were moisture, solubility, wettability, particle size, antioxidant capacity, total phenols, Vit. C, β-carotenes (β-car), and total anthocyanins. RESULTS: The best process conditions from experimental optimization were T = 70 °C, P = 1.1 bar, and t = 29.1 min. This agglomerated product had low moisture values, good solubility, and 0.5 min wettability; the values for Vit. C = 246.4±3.4 mg/100 g db, β-car = 4.0±0.5 mg/100 g db, and total anthocyanins = 230.7±3.0 mg C3G/100 g db were noteworthy. CONCLUSIONS: An agglomerate berry-based powder product was obtained with 100% Vit. C RDA (Recommended Dietary Allowances) and 15% vitamin A RDA. Flow and instantaneousness properties of the agglomerated powder also significantly improved with the applied process.