H. A. V&quiro | Ing, PhD | University of Tolima, Ibagu& | UT | Departamento de Producci&n y Sanidad Vegetal | ResearchGate
· Ing, PhD59Research items5,131Reads167CitationsH. A. Váquiro currently works at the Departamento de Producción y Sanidad Vegetal, University of Tolima. H. does research in Chemical Engineering, Thermodynamics and Food Science.Sep 2009Facultad de Ingeniería AgronómicaIbagué, ColombiaSep 2005 - Sep 2009Jul 1997 - Dec 2003Ibagué, ColombiaView AllUniversidad del CaucaS?o Paulo State UniversityUniversitat Politècnica de ValènciaUniversidade Federal do Maranh?oUniversitat Politècnica de ValènciaGrant · Sep 2005- Doctoral grantView AllUniversidad del CaucaS?o Paulo State UniversityUniversitat Politècnica de ValènciaUniversidade Federal do Maranh?oUniversitat Politècnica de ValènciaView AllUniversidad Pontificia BolivarianaNational University of ColombiaNational University of ColombiaUniversity of TolimaUniversidad de La SabanaView AllMetropolitan Autonomous UniversityUniversidad Miguel Hernández de ElcheUniversity of PadovaUniversity of PadovaUniversity College LondonProjectDescription: The adsorption kinetics at the air-water interface of protein isolate from fish viscera are being modelled using fuzzy logic. The surface activity and the adsorption rate of the protein at pH 5 and 7 and protein concentrations between 0.05 and 2.0% (w/v) were experimentally determined. The suggested model had presented good fitting statistics and allowed to quantify the time and transition rate between the adsorption mechanisms of diffusion, penetration and rearrangement. The effect of protein concentration on the model parameters is being studied. We hope to use the model to study the adsorption behavior in protein hydrolysates.[...more]ProjectBusca fortalecer y mejorar el sistema de beneficio, distribución y calidad de los productos provenientes de las centrales de animales de abasto público. Su objetivo en evaluar los criterios de infraestructura, sanidad e impacto ambiental de las centrales de beneficio. Asimismo, evaluar el nivel de cumplimiento de los criterios de calidad e inocuidad de acuerdo a los criterios formulados por INVIMA de las CBAP y expendios. De igual manera, verificar sus planes de contingencia para mejorar las BPM y su proceso de implementación de los prerrequisitos del sistema HACCP. Se estableció el plan de recomendaciones para superar las deficiencias de las plantas de acuerdo a la normativa vigente colombiana.
Para tal efecto, se implementó como estrategia métodos de caracterización y estandarización de la calidad en expendios, procesos e instalaciones para obtener carne en adecuadas condiciones de inocuidad en plantas de sacrificio del departamento del tolima y en expendios del municipio de ibagué
Esta estrategia fue financiada por COLCIENCIAS convocatoria 569. Implementación efectiva de herramientas en el Sistema de Análisis de Riesgos y Puntos Críticos de Control (HACCP) de las principales Centrales de Beneficio de Animales de Abasto Público (CEBAP) del Tolima, mediante el uso y manejo de tecnologías de escáner por fluorescencia correlacionados con comportamientos microbiológicos de las canales en los puntos críticos de la línea de proceso de beneficio de bovinos,
Asimismo, se plantea evaluar la incidencia de dichos criterios en el proceso de maduración de las carnes.
De igual forma se han desarrollado proyectos orientados al mejoramiento e implementación de planes que garanticen la calidad e inocuidad en plantas de sacrificio de peces y expendios de pescado.[...more]ProjectBusca caracterizar las propiedades fisicoquímicas, microestructurales y el efecto antimicrobiano de soluciones coloidales formadoras de recubrimientos y películas comestibles a partir de matrices biopoliméricas de bajo y alto peso molecular. Asimismo, evaluar el efecto de la adición de partículas sólidas y la incorporación de nanoemulsiones sobre las propiedades fisicoquímicas e interfaciales de recubrimientos y películas compuestas y conformación tipo bicapa.[...more]Sep 2012Drying Technology[...]In the cheese industry, the longest phase in the manufacture of cheese is ripening, during which a considerable loss of water occurs. An understanding of the mass transfer mechanisms of drying would thus contribute to improving engineering design and the quality of the final product. In this work, a mathematical model for a cubic shape was proposed to predict the drying kinetics and moisture distribution during cheese drying. The model was developed taking into consideration both the external and internal resistances to mass transfer and an effective diffusion dependent on local moisture and temperature. Furthermore, a specific model for sorption isotherms was established from experimental results and used to complete the overall model formulation. The drying experiments were carried out at 6.3, 12.2, and 18.2°C and 1.0 m s until a moisture content of approximately 0.30 kg kg (db) was reached. Moisture distribution was experimentally measured from the center of the cheese cube to the center of the surfaces and to the vertexes using a time-domain nuclear magnetic resonance (TD-NMR) method. The proposed model was solved using a finite element method and validated by comparing the experimental moisture profiles with those simulated by the model. A satisfactory simulation was obtained for both the drying curves and the moisture profiles. For both groups of data, a mean relative error lower than 6% and a percentage of explained variation higher than 97% was achieved.Apr 2015Industrial Crops and ProductsVarious pretreatment techniques can change the physical and chemical structure of lignocellulosic biomass and improve the hydrolysis rates. High-intensity ultrasound could be a promising technique in the biomass pretreatment process. The objective of this work was to study the effect of biomass concentration, pH, ultrasonic power level and sonication time on the production yield in total sugars (ST ) and reducing sugars (SR) during the pretreatment of banana flower-stalk biomass. A qualitative evaluation was carried out by scanning electron microscopy, showing a disruptive effect on the biomass structure at high ultrasonic power levels and low biomass concentrations. An experimental design with three-levels for the four-variables was used in order to set the conditions for the pretreatments. Stepwise regression (SRG) and an artificial neural network (ANN) were applied in order to establish mathematical models that could represent and be used to study the dependence of the factors on both the ST and SR yields. The statistical results indicated that the ANN approach provided a more accurate estimation than SRG.Mar 2011Journal of Food EngineeringFresh cheese composition was assessed by measuring ultrasonic velocity in cheese and cheese blends at different temperatures. Twenty types of commercial, fresh cheeses with fat contents ranging from 0.2% to 17.6% w.b. were analyzed. Ultrasonic velocity was not only heavily dependent on the composition of the cheese but also on its structure. Based on the different effect temperature has on velocity in water and fat, a semi-empirical model was used to estimate the cheese composition from velocity measurements at six temperatures ranging from 3 to 29 °C. The model provided good results for the assessment of the fat (R2 = 0.984/0.996; RMSE = 4.6/1.1 for whole and blended cheese, respectively) and water (R2 = 0.964/0.995; RMSE = 6.5/0.7 for whole and blended cheese, respectively) content. The ultrasonic measurements could be carried out during the cooling process that takes place after curdling and used as a quality control tool to detect process anomalies in-line.Nov 2015Food and Bioproducts Processing[...]Mango pulp mixed with drying aids (maltodextrin and skimmed milk) was spray dried to obtain three powder formulations. The water sorption behavior of these mango mix formulations was determined at temperatures of 20, 30, 40 and 50 oC in water activity ranging between 0.059 and 0.907. The Guggenheim, Anderson and De Boer (GAB) model was applied to modeling the adsorption isotherms of mango mix powders, resulting in statistical values of mean relative error (MRE≤5.14%). Differential and integral thermodynamic properties related to water sorption for the mango powders were determined by the analytical derivation of the water activity with respect to temperature based on the GAB model fitting. The differential thermodynamic properties indicated a decrease in the water sorption energy with increasing water content and the negative values of the Gibbs free energy revealed that the sorption process was spontaneous for the three powder formulations. In spite of the formulation containing skimmed milk have shown the higher monolayer water contents, the minimal integral entropy zone observed at similar values of water activity for the three mango mix powders indicated that all of them could be safely stored at the same relative humidity condition.Jul 2009Chemical Engineering Research and Design[...]Intermittent drying is an alternative technology to continuous heat-supply drying that could improve the energy efficiency of the process and the product quality as it reduces both the material enthalpy gain and the heating time. In this study, the application of intermittent drying technology to mango (Mangifera indica L. cv. Tommy Atkins) drying was analyzed and optimized for different drying temperatures and cycles. The heating and resting times during the intermittent drying were optimized by minimizing an objective function that represents the average enthalpy increment of the material through the process. To quantify the objective function, a model was developed for a cubic shape considering mass and heat transfer and showing non-negligible external resistances, and transport properties as being moisture and temperature dependent. Moreover, specific models for sorption isotherms and heat capacity were identified experimentally for M. indica L. cv. Tommy Atkins that, together with other reported models, were used to complete the overall model formulation. According to intermittent and continuous drying simulations, the average enthalpy gain for the optimized intermittent process decreased between 9% (45°C, one cycle) and 23% (65°C, three cycles), and the heating time decreased between 3% (65°C, three cycles) and 11% (45°C, one cycle). The optimization results show that there is an advantage of intermittent over continuous drying one as regards material enthalpy and heating time under the operating conditions and constraints that were considered, which indicate a decrease in the energy consumption and an eventual improvement of quality.Mar 2018International Journal of Biological Macromolecules[...]Chitosan is a promising material that could be used for the development of edible coatings and films on an industrial level because of its film-forming, biodegradable, non-toxic, and antimicrobial characteristics. The aim of this work was to evaluate the effect of the polymer concentration (0.5%, 1.0%, and 1.5%) and drying temperature (2 °C, 25 °C, and 40 °C) on the physicochemical, mechanical, and thermal properties of chitosan edible films. Chitosan edible films were successfully produced using various processing conditions. The use of lower drying temperatures had a positive effect on certain properties of the films, such as the moisture content (MC), solubility (S), water vapor permeability (WVP), and optical properties. However, the use of greater drying temperatures (40 °C), combined with a higher chitosan concentration, enhanced certain properties of the films, such as the tensile strength (TS), swelling power (SP), and greenness value, while diminishing their luminosity. The chitosan films developed in this study showed many desirable characteristics, which may enable their future use as packaging for food products.Nov 2017III International Conference on Applied Mathematics and InformaticsThe diffusion of purchasing online has dramatically increased its business volume in recent years due to saving time and travel when making a purchase of an article, the availability of detailed characteristics of goods, the possibility of comparing costs and bids without going to outlets, etc. Models of diffusion are powerful tools to explain and predict the process of adoption of an innovation over time. A nonlinear system of difference equations is considered whose parameters are the innovation coefficients associated related to advertising and the imitation coefficients associated to the influence of an adopting technology. These parameters are estimated by probabilistic fitting with available data using the technique developed in Cortés et al., (2015) (doi.org/10.1016/j.amc.). A probabilistic prediction study of purchasing online user is included.Oct 20173rd International Congress of Mechanical Engineering and Agricultural Science CIIMCA 2017In this study, a model based on a modification of the Gompertz equation was used to determine the percentage of production (P) and the digestible requirements of lysine (Lys), methionine + cystine (Met + Cys) and threonine (Thr) for the H & N brown hens during 16 weeks of production. The productive performance model was adjusted to field data of 23 treatments, which were defined from a composite central design that combines five levels of Lys, Met + Cis and Thr between 0.636% and 1.000%, 0.579% and 0.910%, 0.483% and 0.760%, respectively. The proposed model showed to be adequate to evaluate the efficiency in the use of digestible amino acids for the egg production and can be a useful tool to diagnose the effectiveness of the nutritional requirements in each of the production phases.Oct 20173rd International Congress of Mechanical Engineering and Agricultural Science CIIMCA 2017The growing concern about limited natural sources and pollution has aroused the interest of developing bio-packaging based on agricultural polymers. The Andean tuber ulluco (Ullucus tuberosus Caldas) is a promising source of starch that can be used in the production of edible films or coatings for preserving the quality of food products. Color is an important feature for edible films production due to can alter the visual perception of the coated product. In this study, the effect of drying temperature (T) (40 to 60°C), starch concentration (SC) (2.0 to 3.0% w/v) and glycerol concentration (GC) (1.0 to 3.0% v/v) on the color parameters (L*, a* and b*) of ulluco edible films was evaluated. A composite central design was used to combine five levels of the three factors (T, SC and GC). Artificial neural network (ANN) were applied to establish mathematical models that could represent the dependence of the factors on the color parameters. The edible films showed luminosity values between 87.4 and 90.3. Results indicated that the higher T, the lower a* and b* parameters and the higher luminosity of the films. Likewise, the lower G, the higher luminosity of edible films. Sensibility analysis shows that SC has an important influence on L*, a*, b* parameters. Statistical results indicated that the ANN approach provided an accurate estimation (R2adj = 0.885 and MSE = 0.054) of the color parameters. ANN use a feed-forward architecture with five neurons in the hidden layer, hyperbolic-tangent transfer function, and Bayesian regularization backpropagation as training algorithm. ANN could be an alternative tool for modelling the complex relationship between the color parameters and the temperature, starch and plasticizer concentrations on ulluco edible films.Oct 20172nd International Conference Science and Technology of Drying CiCTS 2017The hot-air drying is an operation of great importance in the transformation of agricultural products to obtain characteristics that favor the handling, conservation, storage, transport and utilization of dried products. However, a negative aspect of this operation is the high energy consumption and the negative effect of the operating conditions on the quality of the final product. One of the most important tools to consider in the design and optimization of drying processes is the use of mathematical models to study product properties, transport mechanisms and reaction kinetics that imply changes in the product quality and the performance of the operation. A mathematical model for these purposes should be validated in-depth, be accurate and able to coherently represent major phenomena during the process. In this sense, regression and sensitivity analysis are essential tools to validate and verify the model suitability and to investigate which parameters are most significant for accuracy of estimations. This talk addressed the elements necessary for a comprehensive regression analysis in models of drying processes for solid foods, when internal transport mechanisms are governed by thermal and mass diffusion. In addition, the global sensitivity analysis based on variance was presented as a useful technique to quantify the first-order and the interaction effects of input factors (system properties or operating conditions) on the process efficiency. The knowledge about model sensitivity is highly useful in the simplification of models based on physicochemical principles to become them practical for optimization in accordance with the process requirements and objectives.Jun 2017Food ChemistryThe aquaculture and fishery chain is an important part of the economy of many countr in recent years it has experienced significant growth that generates more and more quantities of waste, which are mostly discarded, impacting the environment, despite having a useful chemical composition in various industrial sectors. This article presents a review of the agroindustrial potential of fish wastes, especially viscera, as a source for obtaining native protein and hydrolysates, explaining their production process, chemical composition and functional and bioactive properties that are important to the agricultural, cosmetic, pharmaceutical, food and nutraceutical industryMar 2017Agronomia ColombianaSamples of starch from broken grains of three rice varieties grown in Colombia were analyzed to determine their physicochemical and thermal properties: Fedearroz 473 (F473), Fedearroz 50 (F50) and Fedearroz 60 (F60). The granule size, solubility, swelling capacity, amylose content, syneresis, turbidity, thermal and pasting properties of starches were determined. The average size of starch granules was 9.4, 7.4 and 7.2 um for F473, F50 and F60 samples, respectively. The amylose content showed significant differences between the studied varieties and ranged between 21.4% and 23.0%. Turbidity ranged between 1.95 and 2.34 absorbance units at 620 nm. Thermal properties evaluated by differential scanning calorimetry (DSC), registered values between 61.6 and 64.6°C for the onset temperature, between 66.6 and 69.3°C for the peak temperature, between 72.1 and 73.9°C for the end temperature, and between 8.38 and 9.47 J g-1 for the gelatinization enthalpy. The higher amylose content the higher grain size, turbidity, syneresis, viscosity, gelatinization temperature and enthalpy, and the lower swelling capacity and solubility. This paper is the first reported research on physicochemical and functional properties of starches from these Colombian rice varieties.Question - What is the best software for & 4 variable nonlinear regression/fit?Feb 2017AnswerI'm in agreement with Prof. García-Alvarado. I you are interested in a function that correlates the independent variables, but without represents the physical meaning of phenomena, you could start from a central composite desing (CCD) for four factors and use the stepwise regression (SR) to identify the model. Both, CCD and SR, could be implemented from Matlab.Jan 2017[...]Se evaluó la extracción ácida (ácido cí pH=3) asistida con ultrasonidos de pectina de muestras de guayaba. Una extracción con Hidrólisis ?cida (HA) y una con Hidrólisis ?cida Asistida con Ultrasonidos (HAUS) fueron llevadas a cabo a tres diferentes tiempos (10, 30 y 40 minutos) a temperatura constante (75±0.1°C). Para los ultrasonidos, un máximo del poder eléctrico fue utilizado (100%). El rendimiento de la extracción (%RE) el grado de esterificación (%GE) y el contenido de ácido anhidrogalacturónico (AAG%) fueron evaluados, así como la identificación de la pectina mediante una espectrofotometría FT-IR. La extracción con HAUS afectó el %RE de la pectina (p&0.05), mostrando los mayores valores (6.4%) que con la HA (2.6%). El %GE de la pectina con HAUS fue mayor al 80.58 %, mientras que con HA se alcanzó un 70.66%, por lo que se consideró como una pectina de alto metoxilo ya que cuenta con un GE mayor al 50%. La espectrofotometría permitió observar que a mayor tiempo de extracción, menor el porcentaje de transmitancia (%T) para un mismo tiempo, así, un menor %T, una mayor concentración de pectina. La extracción con HAUS puede ser considerada como una herramienta útil para la extracción de pectinas a partir de la guayaba.Dec 2016Japan Journal of Food Engineering[...]A model to identify the effective diffusivity and to predict the drying kinetics during non-isothermal convective drying of yellow passion fruit (Passiflora edulis Sims f. flavicarpa Degener) seeds was formulated and validated. The governing equations for coupled mass and heat transfer phenomena were expressed in a generalized coordinate system in order to obtain a one-dimensional model suitable for the non-regular geometry of the seeds. Solid shrinkage, moisture and temperature-dependent transport properties, convection heat and mass transfer at the seed surface and symmetrical distribution of moisture content and temperature inside the material were considered. To identify the moisture effective diffusivity, model estimations were fitted to data from drying experiments carried out at air temperatures of 40, 50, and 60 °C and at air velocities of 0.6 and 1.4 m·s-1. The air velocity promoted a lower effect than the air temperature on drying rate, suggesting the internal resistance to mass transfer controlled the water diffusion. The proposed model could contribute to understand the diffusion mechanisms in the material, offering an alternative approach to study the convective drying of non-regular particles due to it requires a simpler solving process and a shorter calculation time than some multidimensional approaches.Dec 2016Dec 2016Agronomia ColombianaDec 2016Agronomia Colombiana[...]Dec 2016Agronomia ColombianaPineapple guava (Acca sellowiana (O. Berg) Burret) is a fruit with export and production potential in Colombia. However, there are few reports about its composition concerning physiological behavior throughout different ripening phases. Intending to confront this situation, a study was proposed in order to evaluate the physicochemical properties and the nutritional composition of pineapple guava fruits in three different phases of ripening, determined by the weeks elapsed after anthesis, considering it undeveloped for week 17 (W17), ripe for week 20 (W20) and overripe from week 21 (W21). Pineapple guava fruits were preliminarily characterized, they underwent a bromatological analysis and their content of vitamin A and C content was established. Results show a significant content of crude fiber and total carbohydrates in the three phases evaluated. There is also a decrease in the neutral detergent fiber of 38% between W17 and W21. The highest level of vitamin C was reported in W17 (67.82 mg ascorbic acid/g dry sample), as well as for vitamin A (12.65 mg β-carotene/g dry sample). Concerning physical-chemical characterization, the existence of a particular physiological behavior is possible due to the development in size and mass of the fruit after physiological ripening. Additionally, calcium and reducing carbohydrate content can be associated to the pulp browning phenomenon. Clearly, pineapple guava is a promising fruit thanks to its nutritional properties, according to with the current consumption tendencies.Project - MODELING ADSORPTION AT THE AIR-WATER INTERFACE OF FISH PROTEIN BY FUZZY LOGICNov 2016MODELING ADSORPTION AT THE AIR-WATER INTERFACE...UpdateArticle
Nov 2016Conferencia Internacional Ciencia y Tecnología de Alimentos (CICyTAC 2016)El VI Congreso Internacional de Ciencia y Tecnología de los Alimentos (CICyTAC), busca afianzar lo realizado en las cinco ediciones anteriores mediante la presentación de ponencias de alto valor científico-técnico que contribuyan al desarrollo de nuevos alimentos y tecnologías en los procesos productivos asociados a este sector. En este sentido, CICyTAC 2016 apunta a: 1. Promover un ámbito de debate, intercambio de experiencias y actualización de nuevos avances científico-tecnológicos en el área de los alimentos a nivel internacional, nacional y regional. 2. Fortalecer la vinculación entre las organizaciones del Sistema de Ciencia, Tecnología e Innovación con el sector productor de bienes y servicios, con base en intereses estratégicos que confluyan. 3. Fomentar el dise?o y ejecución de programas y proyectos que respondan a necesidades y demandas productivas y sociales vinculadas a la alimentación, en articulación estrecha con organizaciones a nivel nacional e internacional. 4. Desarrollar acciones encaminadas a sensibilizar, promover e impulsar, la coordinación de esfuerzos interinstitucionales, para producir y comercializar alimentos con mayor calidad e inocuidad alimentaria que cumplan con las exigencias del mercado nacional e internacional. Las ediciones anteriores se llevaron a cabo en los a?os ,
y 2014 con muy buena repercusión, tanto en la cantidad y calidad de presentaciones, como en la concurrencia de asistentes.Nov 2016Agronomia ColombianaFish production chain is one of the promising productive chains in the country, needing the quality assurance of the final product. The luminometry is seen as a rapid screening technique coupled with the implementation of screening instruments, ensures compliance with safety protocols and hygiene in the food industry with fast, accurate and sensitive through a simple operation results. The smear was performed on an area of 100
cm? vertical and horizontal direction and the swab is inserted into the wad and then into the luminometer for reading, according to the reading utensils that come in contact with fish, making necessary corrective measures to ensure the quality of the final product.Nov 2016Agronomia Colombiana[...]The adsorption kinetics at the air-water interface of protein isolate from viscera of Brycon siebenthalae were modelled using fuzzy logic. The surface activity and the adsorption rate of the protein at pH 5 as well as protein concentrations between 0.1 and 2.0% (w/v) were experimentally determined. The suggested model presented good fitting statistics, with determination coefficients greater than 0.990 and mean relative errors less than 1.4%; the model also allowed to quantify the time and transition rate between the adsorption mechanisms of diffusion, penetration and rearrangement. Diffusion was the mechanism that controlled the adsorption kinetics for concentrations of 0.1, 0.5 and 1.0%. The protein rearrangement and the transition time increased as the protein concentration was augmenting.Nov 2016Agronomia Colombiana[...]Edible films were developed by casting method at three different chitosan concentrations (0.5, 1.0 and 1.5% w/v), acetic acid (1% v/v), glycerol (0.3% v/v) and Tween 80 (0.1% v/v). The films have been dried at three temperatures (40, 25 and 2°C). The temperature effect on the barrier, mechanical and microbiological properties of the chitosan films was studied. Finally, physical and microbiological properties have been influenced by drying temperature, affecting negatively the water vapor permeability, while the mechanical and microbiological properties were affected positively.Nov 2016Agronomia ColombianaFish by-products such as viscera are a growing problem, if the increasing consumption volumes are contemplated. Proximate analysis was determined (protein, wet, fat and ash contents) of an isolate protein (IP) obtained from viscera tilapia (Oreochromis sp.), which was hydrolyzed with gastrointestinal enzymes. The curves of hydrolysis degrees (DH) versus time were established for each enzyme, including its combination,
and the highest values in the hydrolysis reactions carried out were achieved. Protein in viscera was about 28% (wet basis). The DH values achieved after finishing the reactions with pepsin, pancreatin, and the combination were 5.25, 22.22, and 23.83%, respectively.Nov 2016Agronomia ColombianaProtein isolate was obtained through enzymatic hydrolysis from yamu (Brycon siebenthalae) viscera. Kinetic hydrolysis was carried out using alcalase 2.4 L, under different initial enzyme concentrations (23 to 96 AU/kg) with pH, temperature, and constant substrate concentration. Hydrolysis degree was measured and compared as an independent variable. The mathematical model was developed based on exponential tendency of hydrolysis rate obtained in the different kinetic experiments. The estimated parameters of the model fit quite
well with En values over 0.97. Finally, another mathematical model was proposed with the capability to simulate all the different experiments conditions proposed. The model proposed shows a good fit with respect the experimental data with En values over 0.95.Project - MODELING ADSORPTION AT THE AIR-WATER INTERFACE OF FISH PROTEIN BY FUZZY LOGICAug 2016MODELING ADSORPTION AT THE AIR-WATER INTERFACE...UpdateA) Variación de la presión superficial con el tiempo y B) variación de la velocidad de adsorción con en función de la concentración de proteína (x: 0.1, 0.5, 1.0, 2.0%) en la interfase aire-agua . Project - MODELING ADSORPTION AT THE AIR-WATER INTERFACE OF FISH PROTEIN BY FUZZY LOGICAug 2016MODELING ADSORPTION AT THE AIR-WATER INTERFACE...UpdateFunciones de pertenencia de parámetros de transición de los diferentes mecanismos de adsorción del aislado de proteina en la interfase aire-agua a pH 5.Aug 201620th International Drying Symposium IDS 2016[...]A model to identify the effective diffusivity and to predict the drying kinetics during non-isothermal convective drying of yellow passion fruit (Passiflora edulis Sims f. flavicarpa Degener) seeds was formulated and validated. The governing equations for coupled mass and heat transfer phenomena were expressed in a generalized coordinate system in order to obtain a one-dimensional model suitable for the non-regular geometry of the seeds. Solid shrinkage, moisture and temperature-dependent transport properties, convection heat and mass transfer at the seed surface and symmetrical distribution of moisture content and temperature inside the material were considered. To identify the moisture effective diffusivity, model estimations were fitted to data from drying experiments carried out at air temperatures of 40, 50, and 60 °C and at air velocities of 0.6 and 1.4 m s-1. The air velocity promoted a lower effect than the temperature on drying rate, suggesting the internal resistance to mass transfer controlled water diffusion. The proposed model could contribute to understand the diffusion mechanisms in the material, offering an alternative approach to study the convective drying of non-regular particles due to it requires a simpler solving process and a lower calculation time than multidimensional approaches.Aug 201620th International Drying Symposium IDS 2016Mathematical models for the degradation kinetics of the total polyphenol content (TPC), antioxidant activity (AA) (measured by ABTS assay), and browning index (BI) of Granny Smith apples during convective drying were determined. Drying experiments were carried out at temperatures of 30, 50 and 70 °C and air velocity of 1.0 m/s until a moisture content of 0.3 kg kg-1 (dry basis). Weibull models for TPC and BI and First-order model for ABTS offered the best fitting statistics. A Weibull model was used for the drying kinetics. Highest retention of quality attributes was attained at lowest temperatures, being this of 35.4 °C (drying time: 7.44 h) which lead to a retention of 90.2% and 99.9% of the TPC and AA, and a change of 13.6% of the BI.Aug 2016Agronomia ColombianaPineapple guava (Acca sellowiana [O. Berg] Burret) is a fruit with export and production potential in Colombia. However, there are few reports about its composition concerning physiological behavior throughout the different ripening phases. Intending to confront this situation, a study was proposed in order to evaluate the physicochemical properties and the nutritional composition of pineapple guava fruits in three different phases of ripening, determined by the weeks elapsed after anthesis, considering it undeveloped for week 17 (W17), ripe for week 20 (W20) and overripe from week 21 (W21). Pineapple guava fruits were preliminarily characterized, they underwent a bromatological analysis and their content of vitamin A and C content was established. The results showed a significant content of crude fiber and total carbohydrates in the three evaluated phases. There was also a decrease in the neutral detergent fiber of 38% between W17 and W21. The highest level of vitamin C was reported in W17 (67.82 mg ascorbic acid/g dry sample), as well as for vitamin A (12.65 mg β-carotene/g dry sample). In a physical-chemical characterization, the existence of a particular physiological behavior is possible because of the development in size and mass of the fruit after physiological ripening. Additionally, the calcium and reducing carbohydrate content can be associated with the pulp browning phenomenon. Clearly, pineapple guava is a promising fruit thanks to its nutritional properties, according to the current consumption tendencies.Mar 2016VitaeBackground: The increasing interest in the development of biodegradable packaging, and high consumer demand for safe, fresh and of excellent quality food, foster research on compounds such as xanthan gum as biomaterials with characteristics and properties suitable for use in the forming coatings or films whose potential allows various applications in the food industry. Objectives: To develop and characterize film forming dispersions (DFP) and films (P) based on xanthan gum (GX), to study the behavior of the hydrocolloid-forming agent as coatings / films. Methods: DFP were prepared at different concentrations of GX (B1: 1%, B2: 0.5% and B3: 0.25%) with the addition of glycerol and natamycin (plasticizer and antimicrobial agents). In these DFP physicochemical parameters of pH, conductivity and density they were evaluated. P were conditioned and tested on moisture content, thickness, permeability to water vapor (PVA) and transparency. Analysis of variance and multiple range tests with 95% confidence were performed. Results: significant differences (p&0.05) for the conductivity and density of DFP were obtained, related to the concentration of GX, while the pH was significantly higher in B1. The P obtained showed strong concentration dependence of gum. GX increased leading to a decrease in moisture and transparency, the latter significantly lower in B3 (3.305 ± 0.024) remain. GX diminishing, led to decrease in thickness, the latter being higher in B1 (0.042 ± 0.004 mm), the incidence of this parameter in properties such as PVA was confirmed, which was considerably higher than that reported in the literature. Conclusions: The chemical structure of the molecule GX influenced the physicochemical parameters in DFP. The GX was confirmed as an excellent film-forming agent, demonstrates a continuous and homogeneous structure. The results reaffirmed the need to improve the properties of P, in order to harness the potential of the GX.Mar 2016I Congreso Internacional de Conservación para la Industria Agroalimentaria CINCIA 2016El uso de modelos matemáticos es de gran importancia en el mejoramiento de los procesos agroindustriales, dada la necesidad de transformar, tan eficientemente como sea posible, productos que son valiosos pero al mismo tiempo perecederos. Dentro de los procesos agroindustriales, el secado es una de las operaciones más importantes para la conservación de productos agropecuarios, sin embargo, también es uno de los procesos más intensivos en términos energéticos. El estudio del proceso de secado, a través de modelos matemáticos que describen los mecanismos de transporte, contribuye al conocimiento del comportamiento de los productos así como al dise?o y optimización de operaciones y equipos de procesamiento. Sin embargo, la demanda creciente de productos agroalimentarios estables y de alta calidad, también exige que las condiciones de operación sean optimizadas en términos de la calidad final del producto seco. En tal sentido, la modelización matemática puede ayudar a establecer tales condiciones para minimizar el deterioro de las propiedades nutricionales, funcionales y organolépticas de los productos. La validación experimental de los modelos matemáticos se fundamenta en la precisión que ofrecen las estimaciones con respecto al comportamiento real del sistema, y constituye una etapa crucial al momento de escoger el modelo apropiado y establecer la capacidad de predicción en un rango de condiciones dadas. Aún en los enfoques más simples, la representación matemática del proceso de secado considerando principios físicos, químicos y biológicos es, con frecuencia, no lineal, y su validación experimental representa cierta complejidad. En esta presentación se abordaron resultados de diferentes estudios en donde se realiza la validación experimental de modelos no lineales aplicados al secado de productos agroindustriales. La resolución y validación de los modelos fue realizada usando algunas herramientas de simulación y optimización de Matlab(R), incluyendo casos prácticos donde se utilizaron diferentes algoritmos para la optimización de sistemas de ecuaciones no lineales con y sin restricciones. En la validación experimental se consideraron, además de la bondad de ajuste del modelo, los intervalos de confianza de los parámetros y el análisis de residuos.Mar 2016VitaeAntecedentes: El secado es una alternativa de conservación de arveja, considerando su naturaleza perecedera, sin embargo el proceso posee complejidad debido a los fenómenos implicados. Es así como el modelado del proceso, al igual que el cálculo del coeficiente de difusividad efectiva (Deff) es conveniente para describir el comportamiento del alimento durante el proceso y así contribuir al mejoramiento de las condiciones de secado. No se reportan estudios en el secado de las variedades de arveja cultivadas en el departamento de Nari?o. Objetivo: Ajustar datos experimentales del secado de arveja variedad San Isidro (SIO), Santa Isabel (SIL) y Alcalá (ALC) a modelos matemáticos, estimando la calidad de ajuste y determinar la difusividad efectiva. Métodos: Se realizó el secado por triplicado de arveja variedades SIO, SIL y ALC a temperaturas de secado de 55 y 60 °C con velocidad de aire de 1.5 m/s, Los datos experimentales se ajustaron a 6 modelos empíricos, considerando el coeficiente de determinación ajustado R2adj, el error medio relativo MRE y los intervalos de confianza. La Deff se calculó por medio de la solución analítica de la Segunda Ley de Fick para esferas. Resultados: La temperatura de secado incidió en la humedad de equilibrio y el tiempo de secado. Los modelos evidenciaron un buen ajuste debido a que se obtuvo R2adj mayores que 0.97 y MRE inferiores al 10%, sin embargo el modelo de Page se destacó puesto que los términos de la expresión tuvieron significancia estadística en la predicción de datos experimentales según cada temperatura y variedad. Por su parte la Deff se incrementó conforme aumentó la temperatura de secado. Conclusiones: Las variedades de arveja estudiadas describieron un comportamiento similar durante el secado, el cual fue descrito por el modelo de Page. La Deff y la temperatura describieron una relación directamente proporcional.Feb 2016En este estudio se realizó el secado de arveja variedades Obonuco Andina y Sure?a a temperaturas entre 45 y 60?C con velocidad de aire de 1.5 m/s. El incremento de la temperatura redujo el tiempo de proceso en ambas variedades. El modelo de Verma describió satisfactoriamente el proceso en términos del coeficiente de determinación ajustado, el error medio relativo y los intervalos de confianza para los parámetros del modelo. La difusividad efectiva (Deff) y la energía de activación (Ea) se calcularon empleando la solución analítica de la segunda Ley de Fick para geometría esférica y resistencia externa despreciable. La difusividad efectiva Deff se incrementó con el aumento de la temperatura, fluctuando entre 1.649×10-10 y 2.585×10-10 m2/s para variedad Obonuco Andina y entre 1.752×10-10 y 2.586×10-10 m2/s para la variedad Sure?a. La energía de activación Ea para la variedad Obonuco Andina fue de 26.87 kJ/mol y para la variedad Sure?a fue de 25.29 kJ/mol.Jan 2015Environmental Progress & Sustainable Energy[...]An accurate determination of the thermal properties of biomass is particularly important when studying biomaterials for the second-generation ethanol industry. This study presents the thermograms of aqueous solutions of banana flower stalks obtained using differential scanning calorimetry. The samples were prepared using a detailed procedure to obtain normalized specific heat values as a function of temperature, pH, and biomass concentration. The specific heat capacity data were fitted using empirical first-order equations with an algorithm for nonlinear regression, followed by a statistical analysis. All the models applied in modeling of the specific heat capacity showed statistically significant goodness of fit (R2adj &0.996) for all the parameters in the selected expressions. The results obtained in this research can provide information for the modeling, design, and control of the unit operations involved in the second generation ethanol industry.Dec 2014International Journal of Food Engineering[...]Passion fruit seeds are an important by-product of the juice industry. In this study, physical, thermal and water-sorption properties of passion fruit (Passiflora edulis Sims f. flavicarpa Degener) seeds were determined. The knowledge of such properties is useful to design equipment or operations for storage or processing purposes. The physical properties of bulk density, particle density and bulk porosity, and the thermal properties of conductivity, diffusivity and specific heat were determined between water mass fractions of 0.126 and 0.493. The thermal properties were determined for packed beds of seeds (effective properties), by means of which the thermal properties of the seeds (particle properties) were estimated. Different empirical models were evaluated for modeling the physical and thermal properties as function of moisture content. Physical and thermal properties were successfully described by a second-order polynomial, except by the specific heat which was described by a second-order logarithmic relationship. The isosteric heat, the differential entropy and the Gibbs free energy of water sorption were estimated using the Henderson model, which best fitted the experimental desorption isotherms at temperatures between 30°C and 70°C and relative humidities between 2% and 90%.Dec 2014Alginato, es un término que se refiere a un grupo de polisacáridos presentes en las algas pardas, los cuales cuentan con una importancia especial para diferentes industrias (alimentaria, textil, farmacéutica, cosmética, entre otras), atribuida a su capacidad para formar geles fuertes en presencia de cationes calcio (Ca+2). El alginato de sodio es la forma más comercializada de alginato y sus aplicaciones en la industria alimentaria hoy en día están generando avances en el desarrollo de nuevos e innovadores biomateriales con características únicas, tales como, propiedades de barrera contra la pérdida de humedad causada por la deshidratación en alimentos de alto contenido de humedad, soporte para el transporte de compuestos antimicrobianos y probioticos entre otros, para mantener la calidad de productos alimentarios en almacenamiento. En este trabajo se recopiló información referente a la incidencia de diferentes polímeros, biocompuestos, aditivos y del proceso de gelificación en la producción de películas comestibles destinadas a la ingeniería del empaque.Oct 2014International Conference on Science and Technology of Drying 2014The aim of this study was to formulate and solve a mathematical model representing the drying kinetics of passion fruit (Passiflora edulis Sims f. flavicarpa Degener) seeds, an important byproduct of the juice industry in Brazil. A mathematical model in a geometry describing the shape of the seeds was formulated, based on a deformation of the spherical coordinate system. Mass and heat transfer governing equations were expressed in a generalized coordinate system by conversion of Cartesian coordinates into deformed-spherical coordinates. The assumption of symmetrical distribution of moisture content and temperature in the material allowed to simplify the governing equations in a one-dimensional form. Matlab(R) was used to develop the algorithm to solve the equation system through the finite-difference method. The model was used to identify the effective diffusion coefficient and to estimate the drying curves for different experimental conditions of hot-air temperature and velocity with satisfactory results.Jun 2014II Congreso Internacional de Investigación e Innovación en Ingeniería, Ciencia y Tecnología de AlimentosThermal degradation kinetic of vitamin C, in banana passion fruit (Pasifora tripartita var. Mollissima) juice was studied at pH 3.38 and 11.5 ? brix. The juice stability was measured at temperatures (25, 60, 70 and 90°C) according to preliminary assay. The results showed that thermal degradation of L-ascorbic acid followed a first-order kinetic. The temperature effect on kinetic constant was modelled by an Arrhenius equation (R2 = 0.956), where the parameters related to the activation energy and the factor frequency were 45.18 kJ/mol and 13.07 1/h, respectively.Jun 2014II Congreso Internacional de Investigación e Innovación en Ingeniería, Ciencia y Tecnología de Alimentos[...]This work aimed to evaluate bi-layer films made from hydrocolloids with opposite electric charge (chitosan and sodium alginate) with addition of nanoemulsions prepared by phase inversion temperature method and characterized using atomic force microscopy. The color of films was assayed by tristimulus colorimetry using the CIEL*a*b* color space. The particle diameter of nanoemulsions was found in the range 100 to 220 nm. Chitosan and nanoemulsion addition significantly affected film color values reducing the luminosity among 5 and 9 %Jun 2014II Congreso Internacional de Investigación e Innovación en Ingeniería, Ciencia y Tecnología de AlimentosJun 2014II Congreso Internacional de Investigación e Innovación en Ingeniería, Ciencia y Tecnología de AlimentosThe effect of seven solvent mixtures on the antioxidant activity and the total phenolic content in fresh samples of peel, pulp and seed-pulp of feijoa (Acca Sellowiana (O. Berg) Burret) was evaluated. The results obtained in the DPPH, ABTS and total phenols determinations for peel (52.6 %, 91.3 % and 13.1 mg AG / g), pulp (29.4 %, 58.4 % and 6.82 mg AG / g) and seed-pulp (16.5 %, 35.4 % and 4.17 mg AG /g) showed significant differences. The mixture acetone:water (70:30) was the solvent with the best results for its affinity to proanthocyanidins, the major antioxidant compounds in feijoa.Jun 2014II Congreso Internacional de Investigación e Innovación en Ingeniería, Ciencia y Tecnología de AlimentosIn this study, water activity and moisture content of bee-pollen were analyzed in order to determine the desorption isotherms at 50 and 60 ?C, by the gravimetric method with saturated salts. Both GAB and three empirical models were used for modeling the sorption isotherms. Isosteric heat was determined by using the Clausius – Clapeyron equation from the GAB model, which provided the best fit to the contents of moisture, both experimental and calculated.Jun 2014II Congreso Internacional de Investigación e Innovación en Ingeniería, Ciencia y Tecnología de Alimentos[...]The content of β-carotene (Vitamin A precursor) in lyophilized samples of pulp and peel of feijoa (Acca sellowiana (O. Berg) Burret) and sour guava (Psidium friedrichsthalianum (O. Berg.) Niedenzu) was determined at two maturity stages (green and ripe stage), in order to recognize the conditions in which there are significant contribution of provitamin A. The quantification was performed by spectrophotometry to hexane extracts of β–carotene. Data were expressed as μg β-carotene per gram of lyophilized sample (μg β-C/g ML). Results obtained revealed no significant differences for green (5.3±0.4 μg β-C/g ML, 36.3±1.2 μ β-C/g ML) and mature (3.7±0.1 μg β-C/g ML, 44.6±2.7 μg β-C/g ML) feijoa pulp and peel, as well as for green (2.4±0.2 μg β-C/g ML, 26.3±1.3 μg β-C/g ML) and mature (3.7±0.4 μg β-C/g ML, 13.1±0.8 μg β-C/g ML) sour guava. The highest concentration of β-carotene was in the peel due to the high content of ether extract and photosynthetic tissues. Likewise, during the maturity stages the fruit behavior varies according to structural changes associated with cellulose and chloroplasts.Jun 2014Revista Facultad Nacional de Agronomía Medellín[...]Jan 2014Acta horticulturae[...]A study was conducted to evaluate the fungistatic activity of a sample of Colombian propolis. The crude matrix was extracted with ethanol (96% v/v); the thus obtained ethanolic extract of propolis (EEP) was centrifuged, concentrated at low pressure and used to determine its effect on the mycelial growth of economically important phytopathogenic fungi (Aspergillus niger, Penicillium sp., Rhizopus oryzae and Botrytis cinerea) with the poisoned food technique on potato dextrose agar. The results, expressed as the median effective concentration of emulsified propolis extract, indicated that A. niger was the most susceptible fungus (0.09% w/v), followed by Penicillium sp. (0.42% w/v), R. oryzae (0.53% w/v) and B. cinerea (1.09% w/v). From the obtained information, it may be concluded that EEP had a suppressing effect on pathogen growth of the above-mentioned fungi. Consequently, EEP may have the potential to be used alone or in combination with others procedures as an alternative source of antifungal agents for the protection of plants and highly perishable fruits and vegetables during the crop and postharvest stages.Jul 2013XIX SIMP?SIO NACIONAL DE BIOPROCESSOS, X SIMP?SIO DE HIDR?LISE ENZIM?TICA DE BIOMASSASO presente trabalho de pesquisa apresenta os termogramas do pedúnculo de banana (Musa acuminata AAA var. nanica) em pó em solu??o aquosa como fun??o da concentra??o de biomassa, pH e temperatura. O calor específico foi determinado experimentalmente usandoum calorímetro diferencial analítico (DSC). Os resultados experimentais foram simulados usando modelos empíricos de primeira ordem, através do uso de um algoritmo n?o linear com subsequente análise estatístico. Todos os modelos mostraram um bom comportamento frente aos resultados experimentais, mostrando valores do coeficiente de correla??o ajustado superior a 0.998. Os resultados obtidos nesta pesquisa podem proporcionar informa??es úteis para a modelagem, desenho e controle das opera??es unitárias envolvidas na indústria de etanol de segunda gera??o.Dec 2012Mango is an agricultural product of great economic importance for various developing countries, which has increased demand for its nutritional properties and exotic characteristics. The relationship between moisture content and water activity provides useful information for mango processing, especially for drying and storage operations. Water activity and moisture content of mango pulp (Mangiferaindica L. cv. Tommy Atkins) were analyzed to determine the sorption isotherms. The water activity was measured using an electric hygrometer at five different temperatures (10, 20, 30, 40 and 50 °C) and wide ranges of moisture content (2.829?0.031 kg kg-1 d.b.) and water activity (0.977?0.215). One theoretical (GAB) and four empirical equations (Oswin, Henderson, Halsey and Ratti) were used for modeling the sorption isotherms. After following several criteria to evaluate the models, the GAB model appeared as the best option to represent the hygroscopic equilibrium of mango pulp (RMSE = 0.057, VAR = 0.996). The sorption isotherms behaved as expected in agro-foodstuffs and similarly with the mango pulp of other cultivars. The isosteric heat of sorptionwas computed using the Clausius-Clapeyron equation by means of the GAB model.A decrease in the isosteric heat of sorption was observed when the equilibrium moisture content increase, with a strong moisture effect at values lower than 0.8 kg kg-1 (d.b.).Oct 2012Memorias Seminario Internacional Secado de Productos Agrícolas SPA 2012Oct 2012Seminario Internacional Secado de Productos Agrícolas SPA 2012Oct 2012Seminario Internacional Secado de Productos Agrícolas SPA 2012Oct 2012Seminario Internacional Secado de Productos Agrícolas SPA 2012Jan 2012International Journal of Food EngineeringBanana is an agricultural product of great economic importance for various developing countries. The relationship between moisture content and water activity provides useful information for the processing and storage of banana waste. The water activity and moisture content of three banana (Mussa spp. Haploid AAB cv. Nanica) waste items were analyzed to determine the desorption isotherms at six different temperatures (20, 30, 40, 50, 60 and 70°C). The desorption isotherms of the peel, pedicel and pulp of overripe bananas were determined in wide ranges of moisture content (0.001–6.360 kg kg-1 d.b.) and water activity (0.02–0.907). The theoretical GAB model was used for modelling the desorption isotherms. An analytical solution of the Clausius-Clapeyron equation was proposed to compute the isosteric heat of sorption, the differential entropy and Gibbs' free energy by way of the GAB model when the effect of temperature on the hygroscopic equilibrium was considered.Oct 2011The water activity and moisture content of Key lime seeds were analysed to determine the desorption isotherms at five different temperatures (30, 50 and 70?C). The GAB model was used for modelling the desorption isotherms. The Clausius-Clapeyron equation was used to compute the isosteric heat sorption and the differential entropy by using the GAB model. The estimated values for these properties describing a strong moisture effect at values lower than 0.05 kg kg -1 (dry basis). A decrease in the isosteric heat of sorption and entropy was observed when the equilibrium moisture content increase.Apr 2010Journal of Food EngineeringThe density, heat capacity and thermal conductivity of mango pulp (Mangifera indica L. cv. Tommy Atkins) were determined at moisture contents of between 0.9 and 0.52kgkg-1 (w.b.) and temperatures of between 20 and 80°C. The experimental data were satisfactorily fitted (explained variation values &99.1%) as functions of the moisture content and temperature by using multivariate linear models. In the range of conditions considered, the moisture content exhibits a greater influence on the studied properties than temperature.Mar 2010Computers & Chemical EngineeringIn order to increase product quality and to minimize energy consumption and impact on the environment, it is necessary to optimize the food process design and operation. Therefore, the aim of this work was to study the optimization feasibility of the milk pasteurization process using a general process simulator (ProSimPlus). To simulate the pasteurization process, a simulation flowsheet was developed using the simulator, and a database was built in the simulator with the values and/or functions to estimate the necessary physical properties of the whole milk. Using the ProSimPlus utilities (control units) an objective function was set up in order to optimize the process design and the process operation of the milk pasteurization process. For that purpose a ProSimPlus module (optimization: OPTI) was used. By introducing physical properties related to other products and redefining the objective function the application of this general simulator could be extended in the Food Industry.Aug 2009[...]Intermittent drying technology implements varying-time operating conditions to improve process energy efficiency in comparison with other conventional convective drying techniques. One method of intermittent drying involves heating and resting periods. In heating periods, hot air removes the moisture and increases the material temperature by forced convection. In resting (or tempering) periods, the change of the temperature and moisture content takes place without heat supply by free convection. The mass transfer phenomena that take place during resting period may be modified by power ultrasound application. External resistance to mass transfer may be affected by pressure variations, oscillating velocities and microstreaming at the solid-gas interfaces. Internal resistance may be reduced by alternating expansion and compression cycles produced by ultrasound in the material and also through some effects on the interfaces of intercellular spaces, which may contribute to faster water diffusion and shorten the total drying time. In this work two mathematical models (lumped-parameters model and distributed parameters model) to simulate the evolution of the moisture content and temperature of the system during the drying process, and to determine the effects of power ultrasound application on intermittent drying processes during the resting period, were developed. The mathematical models were analyzed and compared using experimental results of the intermittent drying of mango (Mangifera indica L. cv. Tommy Atkins.).Aug 2009[...]The final composition of cheese products constitutes one of their quality attributes and its knowledge in quality control is important. The measurement of ultrasonic velocity is a non-destructive technique, which allows the determination of foodstuff composition. Ultrasonic velocities in both cheese analogues and commercial cheese spreads were determined at different temperatures. The protein, fat and moisture contents of the samples ranged between 8.54 and 12.1 % (wb), 0.2 and 30.1 % (wb) and 57.5 and 81 % (wb), respectively. At 18?C the ultrasonic velocity was not dependent on the cheese composition. The ultrasound velocity increased with the increase of fat content at temperatures lower than 18?C and decreased for higher temperatures. From ultrasonic velocity measurements on cheese analogues, a model was developed to correlate the ultrasonic velocity, temperature and composition. This model allowed a good assessment of the composition of independent samples of cheese spreads.Jul 2009La tecnología del secado intermitente ha sido empleada con el fin de mejorar la calidad y minimizar el consumo energético en el secado de materiales sensibles al calor y donde la cinética está controlada por mecanismos de transferencia internos. El objetivo del presente trabajo fue estudiar y optimizar el secado intermitente y en particular su aplicación al secado de mango, con el fin de mejorar la eficiencia energética del proceso mediante el suministro periódico de energía térmica. Para el estudio y optimización del secado intermitente de mango fue necesario el previo desarrollo y validación de un modelo que representara adecuadamente los fenómenos físicos que gobiernan el proceso, así como la formulación de una función objetivo que permitiera optimizar tanto la eficiencia energética del proceso como la calidad del producto. Con el fin de especificar el modelo, fueron analizados los fenómenos de transferencia de materia y calor en un sistema con geometría cúbica. El modelo del proceso fue ajustado con cinéticas de experiencias de secado continuo e intermitente con el propósito de identificar la difusividad efectiva. El modelo fue posteriormente validado a diferentes condiciones de operación mediante experiencias de secado intermitente. El modelo del proceso describió satisfactoriamente los datos experimentales para la humedad y la temperatura para los conjuntos de datos empleados en la identificación paramétrica y la validación. El problema de optimización del proceso de secado intermitente fue definido como la búsqueda de los tiempos de duración de cada periodo de calentamiento y reposo, que minimizaran una función objetivo definida a partir de la ganancia entálpica del producto. Según los resultados optimizados, la aplicación y optimización del secado intermitente de mango permitió una disminución, respecto al proceso de secado continuo, entre el 13.4 % y el 20.1 % para la ganancia entálpica media, y entre el 2.8 % y el 8.6 % para el tiempo de calentamiento, seJul 2008World CongressA Fick?s model that includes a Takagi-Sugeno fuzzy model to estimate the effective diffusivity was analyzed. The modelling of drying kinetics on mango trough this diffusional-fuzzy model was compared with the theoretical Fick?s model and the empirical Peleg and Weibull models. The identification and validation was performed from experimental drying curves of ripe mango slices (Mangifera indica L. cv. Tommy Atkins) at constant air velocity (4 m/s) and different drying temperatures (40, 50, 60 and 70 ?C). The fuzzy sets for the antecedent of Takagi-Sugeno system were identified by the Gustafson-Kessel clustering algorithm and approximated by membership functions of piecewise exponential form. On identification and validation, the diffusional-fuzzy model showed best results than the Fick?s model, whereas it showed little difference with the Weibull and Peleg models. The diffusional-fuzzy model keeps the interpretability of Fick?s model, improves the process simulation and avoids phenomenon and property considerations which require additional experimental and modelling work.Jan 2008Defect and Diffusion Forum[...]Intermittent drying is an alternative technology to continuous drying that improves the product quality as result of diminishing the average material temperature and the heating time. In this study, the application of the intermittent drying technology to mango drying (Mangifera indica L.) was analyzed and optimized. To formulate the optimization problem, an objective function was proposed in order to improve the product quality and decrease the energy consumption. To quantify the objective function, a mathematical model for a cubic shape was formulated and validated, considering diffusional mass and heat transfer with non-negligible external resistances.Jan 2008International Federation of Automatic Control - PapersOnLineA Fick's model that includes a Takagi-Sugeno fuzzy model to estimate the effective diffusivity was analyzed. The modelling of drying kinetics on mango trough this diffusional-fuzzy model was compared with the theoretical Fick's model and the empirical Peleg and Weibull models. The identification and validation was performed from experimental drying curves of ripe mango slices (Mangifera indica L. cv. Tommy Atkins) at constant air velocity (4 m/s) and different drying temperatures (40, 50, 60 and 70 ?C). The fuzzy sets for the antecedent of Takagi-Sugeno system were identified by the Gustafson-Kessel clustering algorithm and approximated by membership functions of piecewise exponential form. On identification and validation, the diffusional-fuzzy model showed best results than the Fick's model, whereas it showed little difference with the Weibull and Peleg models. The diffusional-fuzzy model keeps the interpretability of Fick's model, improves the process simulation and avoids phenomenon and property considerations which require additional experimental and modelling work.View AllUniversidad del CaucaS?o Paulo State UniversityUniversitat Politècnica de ValènciaUniversidade Federal do Maranh?oUniversitat Politècnica de València}