Estudio experimental de la deshidratación de tomate verde (Pysalis ixocarpa brot) utilizando un secador solar de tipo directo

El tomate verde (Pysalis Ixocarpa Brot), conocido también con los nombres de tomatillo, tomate de cáscara, miltomate, etc., es muy apreciado en la gastronomía de muchos países como Guatemala, Colombia, Chile, Brasil, España, Polonia, Estados Unidos, Israel Sudáfrica, India, Australia y principalmente en México, en donde ocupa el 4º lugar como la verdura más consumida en el país. A nivel nacional se producen 8 tipos: Silvestre, Milpero, Arandas, Tamazula, Manzano, Rendidora, Salamanca y Puebla. Además de sus propiedades culinarias, tiene propiedades nutrimentales con un alto contenido de vitaminas, principalmente A, C, y de Potasio y otros minerales. Se le atribuyen propiedades medicinales. En este trabajo se realizó un estudio experimental conducente a conocer el potencial de este producto en estado deshidratado, a través de un análisis de las cinéticas de secado en un dominio de temperaturas de 40, 50 y 60 ºC, bajo condiciones controladas, así como las cinéticas de deshidratación utilizando un secado solar tipo directo (directo) con funcionamiento pasivo (convección natural) y activo (convección forzada). Se analizó la influencia de la temperatura sobre la cinética de secado con velocidad de aire establecida de 2 m/s. Los experimentos se realizaron en el Laboratorio de Secado Solar del Instituto de Energías Renovables de la Universidad Nacional Autónoma de México, localizado en la Ciudad de Temixco ubicado a 18º 51´ de L.N. y 99º 14´ L.O. a 1280 msnm. Durante el período de pruebas, la irradiancia solar varío entre 526 y 1083 W/m2. Con la tecnología de secado solar tipo directo se obtuvieron humedades finales entre el 7 y el 8.5% para convección natural y 9 y el 13% para convección forzada. Los tiempos de secado de entre 13 y 13.5 horas y entre 13 y 14 horas con convección natural convección forzada respectivamente.Palabras clave: deshidratación de tomate verde tomate verde con cascara, secado solar

Effect of the solar dehydration on the antioxidant capacity and the content of flavonoids of the blackberry pulp (rubus spp)

[EN] Technical performance of two solar drying technologies was evaluated: Solar Greenhouse Drying (SGD) with auxiliary heating system, and Direct Solar Drying (DSD) in order to evaluate its effect on antioxidant activity (AA) and total flavonoids of blackberry (rubus spp) waste destined. The SDG and DSD results were compared with those of the dehydrated samples in an electric stove (ES). The fresh and dried fruits were evaluated; the blackberry seedless pulp was used. The AA and flavonoids showed degradation of 70% and 20% compared to the fresh sample. For both compounds, SGD is the one that offers the greatest conservation.Silva-Norman, A.; López-Ortiz, A.; García-Valladares, O.; Pilatowsky-Figueroa, I.; Ramirez, JR. (2018). Effect of the solar dehydration on the antioxidant capacity and the content of flavonoids of the blackberry pulp (rubus spp). En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 1083-1090. https://doi.org/10.4995/IDS2018.2018.7843OCS1083109

Moisture content modeling and effective moisture diffusivity determination during convective solar drying of blackberry (rubus spp) and basil (Ocimum basilicum L.)

[EN] The goal of reducing energy consumption (EC), losses and waste (FL) in the food processing is a challenges in the worldwide. The use of active solar greenhouse dryers (GHD) for EC and FL reductions has increased due to its capacity, and low operating costs. In this work the effective diffusivity (Deff) and the moisture content modeling were analized for basil (Ocimum basilicum) and blackberry pulp (Rubus rosoideae) dried in a conventional stove (CD) and an GHD coupled to an additional air solar heating system (SCHa). The loss of water and the drying rate in food materials dehydrated in the GHD is consistent with the increment or decrement of temperature during the solar day. The Deff values for basil and blackberry pulp was ranged between -1.1044x10-7 and -3.9167x10-9. The solar energy obtained in the GHD supplied the heating requirements. In general, the Page’s model was the best fit for the drying kinetics for basil and blackberry pulp.López-Ortiz, A.; Gallardo-Brígido, JC.; Silva-Norman, A.; Pilatowsky-Figueroa, I.; García-Valladares, O.; Rodríguez-Ramírez, J. (2018). Moisture content modeling and effective moisture diffusivity determination during convective solar drying of blackberry (rubus spp) and basil (Ocimum basilicum L.). En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 505-512. https://doi.org/10.4995/IDS2018.2018.7841OCS50551

Saline Diffusion Modeling for Sodium Chloride Aqueous Solutions: Freezing for Desalination Purposes

Given the high human demand for freshwater and its consequent scarcity, desalination processing seems to be a key solution, given the vast amount of seawater on the planet. Currently, desalination plants provide about 95 million m3/day freshwater in 177 countries worldwide. However, desalination is an energy-intensive, demanding technique that generally uses fossil fuels and contributes to global warming via greenhouse gas emissions. Freezing/melting desalination (F/M) uses about 70% less thermal energy than the boiling process. Unfortunately, this technique is rarely used, mainly because of salt separation problems at low temperatures close to 0 °C. Most models have determined their results assuming a saline concentration value of the retained liquid; however, there is a significant disagreement in this value. This study proposes a unidimensional model based on thermal and mass diffusion evolution. The model predicts the successful separation of salt-free ice to avoid salt diffusion before encapsulation; the process depends on temperature, saline gradients, and time. The calculations in this paper are based on the salt concentration in the liquid-solid interface, which has been extensively studied, achieving an accurate performance of the proposed model