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ESTIMACIóN DE LAS ISOTERMAS DE ADSORCIóN Y DEL CALOR ISOSTéRICO EN HARINA DE YUCA
AYALA-APONTE,ALFREDO;
Biotecnología en el Sector Agropecuario y Agroindustrial , 2011,
Abstract: moisture adsorption isotherms of cassava flour were determined using a gravimetric static method at 20,25, 30 and 35°c in the range of water activity from 0.111 to 0.901. the experimental values of sorption were fitted by the models of gab, bet, oswin, smith, henderson and chung, and pfost. the isosteric heat of sorption (qst) was determined by the clausius-clapeyron equation. the isotherms obtained were sigmoid shape (type ii). the equilibrium moisture content (che) decreased with increasing temperature to a constant value of water activity. the sorption models of gab, oswin and smith were found to be the most suitable for description of the sorption data. the qst decreased with increasing che obtaining a maximum and a minimum between 118.84 and 45.20 kj/mol for moisture between 5 and 35 (g water / g db) respectively.
ESTIMACIóN DE LAS ISOTERMAS DE ADSORCIóN Y DEL CALOR ISOSTéRICO EN HARINA DE YUCA ESTIMA O DAS ISOTERMAS DE ADSOR O E DO CALOR ISOSTéRICO EM FARINHA DE MANDIOCA ADSORPTION ISOTHERMS AND ISOSTERIC HEAT ESTIMATION IN CASSAVA FLOUR
ALFREDO AYALA-APONTE
Biotecnología en el Sector Agropecuario y Agroindustrial , 2011,
Abstract: Se determinaron las isotermas de adsorción de humedad en harina de yuca a 20, 25, 30 y 35°C mediante el método gravimétrico en el intervalo de actividad de agua entre 0.111 y 0.901. Los valores experimentales de adsorción se ajustaron mediante los modelos de GAB, BET, Oswin, Smith, Henderson y Chung and Pfost. El calor isostérico de sorción (Qst) se determinó mediante la ecuación de Clausius-Clapeyron. Las isotermas obtenidas presentaron una forma sigmoidea (Tipo II). El contenido de humedad de equilibrio (CHE) disminuyó con el aumento de la temperatura para un valor constante de actividad de agua. Los modelos de sorción GAB, Oswin y Smith fueron los que mejor ajustaron los valores experimentales. El Qst disminuyó con el aumento del CHE obteniéndose un valor máximo y un mínimo entre 118.84 y 45.20 kJ/mol para humedades entre 5 y 35 (g agua/g ms) respectivamente. Se determinaram as isotermas de adsor o de humidade dafarinha de mandioca, 20, 25, 30 e 35°C utilizando-se o método estático gravimétrico numa faixa de atividade de água entre 0.111 e 0.90. Os valores experimentais de adsor o foram ajustados pelos modelos de GAB, BET, Oswin, Smith, Henderson e Chung, e Pfost. O calor isostérico de adsor o (Qst) foi determinado pela ecua o de Clausius-Clapeyron. Os resultados mostraram que as isotermas obtidas foram de forma sigmoidal (Tipo II). O teor de humidade de equilibrio (CHE) apresentou dependência com a temperatura, diminuindo com o aumento desta a um valor constante de atividade de água. Os Modelos de adsor o GAB, Oswin e Smith foram os que presentaram melhor ajuste aos valores experimentais. O Qst diminuío com o aumento de CHE, obténdo-se um máximo e um mínimo entre 118,84 e 45,20 kJ / mol de humidade entre 5 e 35 (g de água/g bs), respectivamente. Moisture adsorption isotherms of cassava flour were determined using a gravimetric static method at 20,25, 30 and 35°C in the range of water activity from 0.111 to 0.901. The experimental values of sorption were fitted by the models of GAB, BET, Oswin, Smith, Henderson and Chung, and Pfost. The isosteric heat of sorption (Qst) was determined by the Clausius-Clapeyron equation. The isotherms obtained were sigmoid shape (Type II). The equilibrium moisture content (CHE) decreased with increasing temperature to a constant value of water activity. The sorption models of GAB, Oswin and Smith were found to be the most suitable for description of the sorption data. The Qst decreased with increasing CHE obtaining a maximum and a minimum between 118.84 and 45.20 kJ/mol for moisture between 5 and 35 (g water / g d
ISOTERMAS DE DESORCION DE HUMEDAD EN PITAHAYA AMARILLA (Selenicereus megalanthus)
AYALA-APONTE,ALFREDO A.; SERNA COCK,LILIANA; RODRIGUEZ,GLORIA;
Biotecnología en el Sector Agropecuario y Agroindustrial , 2012,
Abstract: moisture desorption isotherms for yellow pitahaya fruits were studied at 15, 25, and 35°c using the gravimetric method for a 0.111-0.901 water activity range. experimental values were adjusted by using the gab, henderson, smith, oswin y chung y fost models. the isosteric heat of adsorption (qst) was determined using the clausius-clapeyron equation. the results showed that yellow pitahaya fruits exhibit type iii adsorption isotherms and that the equilibrium moisture content (emc) is temperature-dependent. for the same water activity value, the emc decreased when temperature increased. the gab model presented the best fit to the experimental values. the qst dropped from 61.43 a 45.11 kj/mol when the emc increased from 0.08 to 0.56 g water/g dry matter, respectively.
ISOTERMAS DE DESORCION DE HUMEDAD EN PITAHAYA AMARILLA (Selenicereus megalanthus) ISOTERMAS DE DESSOR O DE UMIDADE EM PITAIAIáS AMARELO (Selenicereus megalanthus) MOISTURE DESORPTION ISOTHERMS IN YELLOW PITAHAYA (Selenicereus megalanthus)
ALFREDO A. AYALA-APONTE,LILIANA SERNA COCK,GLORIA RODRIGUEZ
Biotecnología en el Sector Agropecuario y Agroindustrial , 2012,
Abstract: Se determinaron las isotermas de desorción de humedad en pitahaya amarilla a 15, 25 y 35°C mediante el método gravimétrico en el intervalo de actividad de agua entre 0.111 y 0.901. Los valores experimentales de desorción se ajustaron mediante los modelos de GAB, Henderson, Smith, Oswin y Chung y Fost, usualmente usados en alimentos. El calor isostérico de desorción (Qst) se determinó mediante la ecuación de Clausius-Clapeyron. Los resultados mostraron que las isotermas fueron de tipo III. El contenido de humedad de equilibrio (CHE) presentó dependencia con la temperatura, esta disminuyó con el aumento de la temperatura para un valor constante de actividad de agua. El modelo GAB fue el de mejor ajuste de los valores experimentales. El Qst disminuyó con el aumento del CHE, desde 61.43 hasta 45.11 kJ/mol para humedades de 0.08 hasta 0.56 (g agua/g ms) respectivamente. Se determinaram as isotermas de dessor o de humidade da pitaiaiás amarela, 15, 25 y 35°C utilizando-se o método estático gravimétrico numafaixa de atividade de água entre 0.111 e 0.90, Os valores experimentais de adsor oforam ajustados pelos modelos de GAB, Henderson, Smith, Oswin y Chung y Fost, O calor isostérico de adsor o (Qst) foi determinado pela ecua o de Clausius-Clapeyron. Os resultados mostraram que as isotermas obtidasforam do tipo III. O teor de humidade de equilíbrio (CHE) apresentoudependênciacom a temperatura, diminuindocom o aumento desta a um valor constante de atividade de água. O modelo de GAB foi o que apresentou o melhor ajuste dos valores experimentais. O Qstdiminuíocom o aumento de CHE, obténdo-se um máximo e um mínimo entre 61.43 a 45.11 kJ / mol de humidade entre 0.08 e 0.56 (g de água / g bs), respectivamente. Moisture desorption isotherms for yellow pitahaya fruits were studied at 15, 25, and 35°C using the gravimetric method for a 0.111-0.901 water activity range. Experimental values were adjusted by using the GAB, Henderson, Smith, Oswin y Chung y Fost models. The isosteric heat of adsorption (Qst) was determined using the Clausius-Clapeyron equation. The results showed that yellow pitahaya fruits exhibit type III adsorption isotherms and that the equilibrium moisture content (EMC) is temperature-dependent. For the same water activity value, the EMC decreased when temperature increased. The GAB model presented the best fit to the experimental values. The Qst dropped from 61.43 a 45.11 kJ/mol when the EMC increased from 0.08 to 0.56 g water/g dry matter, respectively.
Efecto de la agitación sobre la deshidratación osmótica de pitahaya amarilla (selenicereus megalanthus s.) Empleando soluciones de sacarosa
Ayala-Aponte,Alfredo Adolfo; Serna-Cock,Liliana; Giraldo-Cuartas,Carlos Julián;
Interciencia , 2009,
Abstract: the effect of the stirring (180, 220, y 240rpm) on water loss and sugar gain in the process of osmotic dehydration of pitahaya slices was studied, using osmotic solutions of sucrose with two concentration levels, 45 and 55°brix. additionally, the porosity of the pitahaya in fresh and osmotically dehydrated states was determined and related to the stirring speed. the results showed that stirring level has a significant effect on water loss, with a greater relative variation for the treatments at 45°brix. sugar gain did not show significant differences as an effect of agitation speed. this is explained by the low porosity of the pitahaya in fresh state (2.78 ±0.35%), which hinders the entry of the sucrose molecules into the fruit. the results suggest that osmotic dehydration is emerging as an appropriate pretreatment technique for the yellow pitahaya due to the low gain in solids during the process.
Efecto de la madurez, geometría y presión sobre la cinética de transferencia de masa en la deshidratación osmótica de papaya (Carica papaya L., var. Maradol)
Chavarro-Castrillón, Lina Marcela;Ochoa-Martínez, Claudia Isabel;Ayala-Aponte, Alfredo;
Ciência e Tecnologia de Alimentos , 2006, DOI: 10.1590/S0101-20612006000300018
Abstract: las papayas obtenidas en el raleo (papayas menos desarrolladas entresacadas de los árboles para beneficiar el crecimiento de las otras) generalmente se descartan. alternativamente, estas papayas pueden secarse por un proceso de deshidratación osmótica y secado térmico convencional para usarlas como snacks o como ingrediente para otros productos. se comparó la cinética de transferencia de masa en la deshidratación osmótica de papayas de raleo frente a papayas desarrolladas con diferente grado de madurez, considerando el efecto de la geometría de la muestra y de la presión del proceso. la deshidratación osmótica se efectuó en una solución agitada de sacarosa a 50 °brix, a 25 °c. se consideraron tres niveles de madurez: raleo, verde y pintona, tres geometrías: lámina, cilindro y anillo y dos niveles de presión: atmosférica y vacío. se estudiaron como variables cinéticas la variación de peso (wr), pérdida de agua (wl) y ganancia de sólidos (sg) entre 10 y 180 min. la madurez tuvo efecto significativo sobre las tres respuestas de la cinética a 30 min y sobre sg a 180 min; la geometría tuvo efecto sobre wr y sg a 30 min y sobre los tres parámetros cinéticos a 180 min y la presión solamente tuvo efecto sobre wl y sg a 30 min. la mayor pérdida de agua (65%) se obtuvo a 30 min para la combinación raleo/cilindro/vacío; mientras que la mayor ganancia de sólidos fue 31% para el tratamiento verde/lámina/vacío a 180 min.
APLICACIóN DE ENDOPEPTIDASA ALCALINA EN CARNAZA BOVINA PARA MEJORAR LA CALIDAD DE LA GELATINA
Serna-Cock,Liliana; Pineda-Cuervo,Darío; Ayala-Aponte,Alfredo;
Revista Colombiana de Química , 2007,
Abstract: the international market price of gelatine is determined by its physical-chemical properties, that depend on the raw material, the collagen extraction method and the concentration method. in this work, using class b gelatine production processes in pilot plant, the effect of application of alkaline endopeptidase was evaluated in the pre-treatment of three types of bovine hide on the gelatine final quality as measured by bloom, viscosity and clarity. the results were compared with processes in which the same raw materials were used without enzymatic pre-treatment. the statistical analysis showed significant differences among the treatments. the best bloom, viscosity and clarity results were presented using enzymatic pre- treatment in the whole hide, obtained in thirteen hours of process 61.5% of the gelatine with bloom higher than 300g, 51.3% with viscosities values higher than 42 mp and 82 ,1 % with high clarities value, with values lower than 39 nephelometric turbidity units. the whole hide without enzymatic pre-treatment showed 41% of high values of bloom, 7.7% of high viscosities and 76.9% of high clarities .
Plan de saneamiento para una distribuidora de alimentos que atiende a ni?os y adultos mayores
Serna-Cock,Liliana; Correa-Gómez,Maria D.C.; Ayala-Aponte,Alfredo A;
Revista de Salud Pública , 2009, DOI: 10.1590/S0124-00642009000500014
Abstract: the responsibility for providing healthy food involves all members of the production chain from input supplier to the distributor and consumer of food. children and older adults represent the most vulnerable consumers for acquiring food-borne illness (fbi), meaning that the risk factors produced in food-processing targeted for this population group must be reduced. a clean-up plan was thus designed and implemented following the guideline laid down in decree 3075/1997 to reduce fbi risk factors in a population of children and older adults. a training plan was also conducted for handling staff involved in receiving, storing, packaging and distributing raw materials in a food distributor. the clean-up plan and training led to a 40 % to 70 % increase in compliance with best manufacturing practices (bpm). these results represent a solid basis for ensuring food safety and reducing the risk of acquiring fbi in the study population. this article also provides an outline for easily acquiring the necessary methodology for implementing a clean-up plan in a food industry.
Modelos reológicos aplicados a masas de trigo y maíz
Rodriguez Sandoval,Eduardo; Fernández Quintero,Alejandro; Ayala Aponte,Alfredo;
Ingeniería e Investigación , 2005,
Abstract: rheological models of a food system are useful for simulating a material?s response to an applied stress or strain and for predicting the effect of composition and processing conditions. rheological models can be applied when experimental data is expressed in fundamental units. this article describes two rheological models used for studying wheat and corn dough: the biaxial extensional model and the oscillatory dynamic model. the results of research related to this topic are also reported.
Effect of the immersion in 1-MCP on the physicochemical and physiological properties of yellow pitahaya fruit (Selenicereus megalanthus How) with minimum processing
Serna Cock Liliana,Segura Rojas Diego Fernando,Ayala Aponte Alfredo
Acta Agronómica , 2011,
Abstract: La pitahaya amarilla (Selenicereus megalanthus How) es una fruta exótica con gran potencial comercial. No obstante, sólo ha sido aprovechada comercialmente como fruta entera, sin procedimientos que le den valor agregado y mayor tiempo de vida de anaquel. En este trabajo se evaluó la aplicación de 200 mg/lt de 1-MCP en pitahaya amarilla mínimamente procesada (rodajas con cáscara y sin cáscara), empacada al vacío y almacenada bajo refrigeración, sobre la intensidad respiratoria y parámetros de calidad como sólidos solubles, acidez total titulable, pérdida de peso, azücares totales, firmeza y color. La aplicación de 1-MCP aumentó la producción de CO2, lo cual se manifestó en mayores contenidos de sólidos solubles y azúcares totales, pero no incidió en la pérdida de peso, variación de la acidez total titulable, cambios de color y retención de la firmeza. En ambos tipos de procesamientos se logró reducir durante el almacenamiento la pérdida de vitamina C.
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