An artificial neural network model for prediction of quality characteristics of apples during convective dehydration

In this study, the effects of hot-air drying conditions on color, water holding capacity, and total phenolic content of dried apple were investigated using artificial neural network as an intelligent modeling system. After that, a genetic algorithm was used to optimize the drying conditions. Apples were dried at different temperatures (40, 60, and 80 °C) and at three air flow-rates (0.5, 1, and 1.5 m/s). Applying the leave-one-out cross validation methodology, simulated and experimental data were in good agreement presenting an error < 2.4 %. Quality index optimal values were found at 62.9 °C and 1.0 m/s using genetic algorithm.Centro de Investigación y Desarrollo en Criotecnología de AlimentosFacultad de Ingenierí

Effect of dehydration temperature on physico-chemical properties and antioxidant capacity of goldenberry (Physalis peruviana L.)

Consumers are health conscious in order to have a nutritious diet leading to an increase of fruits intake due to their bioactive compounds. To prolong the shelf-life of fruits, dehydration is widely used In this work, the effect of convective dehydration on physico-chemical properties, color, vitamin C, -carotene, total phenolic content (TPC), flavonoids and antioxidant capacity during dehydration of Cape gooseberry (Physalis peruviana L.) fruits in the range 50-90 ºC was investigated. Chromatic parameters (L*, a*, b*) as well as Chroma and Hue angle were affected by drying temperature, which contributed to the discoloring of the fruits during this process. TPC, flavonoids and -carotene increased at 90 ºC from 321.05-356.68 mg gallic acid 100 g-1 dm, 99.25-144.29 mg quercetin equivalents 100 g-1 of dm and 722.30-783.16 mg 100 g-1 sample, respectively. The radical scavenging activity showed higher antioxidant activity at high temperatures rather than at low temperatures. Both, vitamin C content and TPC decreased as air-drying temperature decreased. A high correlation between TPC and flavonoids with antioxidant capacity of the fruits was observed. Based on these results, this fruit is a potential candidate to develop new functional products.Fil: Di Scala, Karina Cecilia. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química; Argentina;Fil: López, Jessica. Universidad de la Serena. Departamento de Ingeniería de Alimentos; Chile;Fil: Vega Galvez, Antonio. Universidad de la Serena. Departamento de Ingeniería de Alimentos; Chile;Fil: Torres, María José. Universidad de la Serena. Departamento de Ingeniería de Alimentos; Chile;Fil: Lemus Mondaca, Roberto. Universidad de la Serena. Departamento de Ingeniería de Alimentos; Chile;Fil: Quispe Fuentes, Issis. Universidad de la Serena. Departamento de Ingeniería de Alimentos; Chile

Thermodynamic Properties, Sorption Isotherms and Glass Transition Temperature of Cape Gooseberry (Physalis peruviana L.)

U ovom su radu gravimetrijski određene izoterme vlaženja (adsorpcije i desorpcije vode) svježih i sušenih bobica peruanske jagode (Physalis peruviana L.) pri temperaturama od 20, 40 i 60 °C. Dobiveni su podaci usklađeni uz pomoć sljedećih modela: Guggenheim-Anderson-De Boerov (GAB), Brunauer-Emmett-Tellerov (BET), Hendersonov, Cauriejev, Smithov, Oswinov, Halseyev i Iglesias-Chirifeov model. Za procjenu modela upotrijebljena je metoda najmanjih kvadrata i nelinearna regresijska analiza. Iglesias-Chirifeov je model bio najprikladniji za opisivanje rezultata pokusa. Entalpija je adsorpcije određena iz podataka o ravnoteži vlaženja pomoću Clausius-Clapeyronove jednadžbe, te je utvrđeno da se ona eksponencijalno smanjuje s porastom udjela vlage. Primjenom je teorije kompenzacije entalpije i entropije na izoterme vlaženja dokazano da su adsorpcija i desorpcija vode ovisile o entalpiji procesa. Temperatura je staklastog prijelaza (Tg) određena diferencijalnom pretražnom kalorimetrijom, a dobiveni su podaci uspoređeni s udjelom vlage pomoću Gordon-Taylorovog, Roosovog i Khaloufijevog modela, koji su bili najprikladniji za procjenu temperature pri kojoj dolazi do staklastog prijelaza bobica peruanske jagode.Adsorption and desorption isotherms of fresh and dried Cape gooseberry (Physalis peruviana L.) were determined at three temperatures (20, 40 and 60 °C) using a gravimetric technique. The data obtained were fitted to several models including Guggenheim-Anderson- De Boer (GAB), Brunauer-Emmett-Teller (BET), Henderson, Caurie, Smith, Oswin, Halsey and Iglesias-Chirife. A non-linear least square regression analysis was used to evaluate the models. The Iglesias-Chirife model fitted best the experimental data. Isosteric heat of sorption was also determined from the equilibrium sorption data using the Clausius-Clapeyron equation and was found to decrease exponentially with increasing moisture content. The enthalpy-entropy compensation theory was applied to the sorption isotherms and indicated an enthalpy-controlled sorption process. Glass transition temperature (Tg) of Cape gooseberry was also determined by differential scanning calorimetry and modelled as a function of moisture content with the Gordon-Taylor, the Roos and the Khalloufi models, which proved to be excellent tools for predicting glass transition of Cape gooseberry

Modelado de dinámica de fluidos y transferencia de calor y masa en procesos agroalimentarios por método de volúmenes finitos

Se describe la transferencia de momento, calor y masa transiente bi-dimensional en procesos agroalimentarios. Estos procesos son: la pre-cosecha y luego la deshidratación por aire caliente de frutas. La metodología incluye modelación matemática y simulación computacional para describir la convección y difusión de calor y masa conjugada que resulta de la interacción entre el alimento y el aire. El modelo matemático emplea las ecuaciones diferenciales parciales no lineales acopladas de continuidad, momento lineal, energía y materia. Se considera que las propiedades físicas de las frutas calculadas mediante correlaciones empíricas, varían con la temperatura y la concentración de humedad. El método de volúmenes finitos junto el algoritmo SIMPLE se utiliza para obtener los resultados de la variación en el tiempo de las distribuciones de velocidades (v), temperaturas (T) y concentraciones de humedad (C) para los procesos en estudio. Las propiedades termofísicas variables de los alimentos se obtuvieron a partir de modelos empíricos. Los resultados obtenidos incluyen distribuciones y perfiles de las variables dependientes (v, T, C) en el tiempo, los cuales se comparan con resultados experimentales y numéricos de la literatura especializada

Protective Effect of Red Algae (Rhodophyta) Extracts on Essential Dietary Components of Heat-Treated Salmon

Salmon paste contains nutritious components such as essential fatty acids (EPA, DHA), vitamin E and astaxanthin, which can be protected with the addition of red algae extracts. Phenolic extracts were prepared with an ethanol: water mixture (1:1) from the red seaweeds Gracilaria chilensis, Gelidium chilense, Iridaea larga, Gigartina chamissoi, Gigartina skottsbergii and Gigartina radula, obtained from the Pacific Ocean. Most algae had a high content of protein (>7.2%), fiber (>55%) and β-glucans (>4.9%), all expressed on a dry weight basis. Total polyphenols (TP), total flavonoids (TF), antioxidant (DPPH, FRAP) and antibacterial power of the extracts were measured. In addition, the nutritional components of the algae were determined. Results showed that the content of TP in the six algae varied between 2.6 and 11.3 mg EAG/g dw and between 2.2 and 9.6 for TF. Also, the extracts of G. skottsbergii, G. chamissoi, G. radula and G. chilensis showed the highest antiradical activity (DPPH, FRAP). All samples exhibited a low production of primary oxidation products, and protection of the essential components and the endogenous antioxidants tocopherols and astaxanthin, particularly in the case of G. skottsbergii, G. chamissoi, G. radula and G. chilensis. Furthermore, all algae had inhibitory activity against the tested microorganisms, coincident with their antioxidant capacity. Results show that the extracts may have future applications in the development and preservation of essential dietary components of healthy foodsS

An artificial neural network model for prediction of quality characteristics of apples during convective dehydration

In this study, the effects of hot-air drying conditions on color, water holding capacity, and total phenolic content of dried apple were investigated using artificial neural network as an intelligent modeling system. After that, a genetic algorithm was used to optimize the drying conditions. Apples were dried at different temperatures (40, 60, and 80 °C) and at three air flow-rates (0.5, 1, and 1.5 m/s). Applying the leave-one-out cross validation methodology, simulated and experimental data were in good agreement presenting an error < 2.4 %. Quality index optimal values were found at 62.9 °C and 1.0 m/s using genetic algorithm.Centro de Investigación y Desarrollo en Criotecnología de AlimentosFacultad de Ingenierí

Influence of backfill soil shear strength parameters on retaining walls stability

One of the problem of geotechnical engineering is the analysis of the retaining walls stability, where are several uncertainty sources. Some of these uncertainties relate to the inherent variability of fill soil, retained by the retaining wall, strength parameters. This feature can be quantified through a retaining wall stability probabilistic analysis using the Monte Carlo Simulation method (SMC), which enables to determine the wall reliability from collected testing shear strength information of existing soils in the cities of Coquimbo and La Serena, Coquimbo Region, Chile. An application example, the study of a cantilever retaining wall stability filled with silty sand soil (SM) with three different degrees of compaction (DC%: 80, 90 and 95%), with the objective to analyze the wall stability through statistical analysis of safety factors