© 2017 Agronomía Mesoamericana es desarrollada en la Universidad de Costa Rica y se encuentra licenciada con Creative Commons Reconocimiento-NoComercial-SinObraDerivada 3.0 Costa Rica. Para más información escríbanos a pccmca@ucr.ac.cr ResumenEl objetivo del presente trabajo fue evaluar las condiciones de cocristalización del zumo de naranja agria con sacarosa, sobre las propiedades fisicoquímicas del producto obtenido. El zumo de naranja agria fue obtenido con un exprimidor mecánico y concentrado en un rota-evaporador. Se preparó un jarabe de sacarosa a 70 °Brix, el cual fue sometido a calentamiento y agitación de 1000 rpm, hasta que se observó una coloración blanca (118 ºC). El zumo de naranja agria se adicionó al jarabe, y la mezcla fue sometida a agitación constante de 600 rpm, hasta observar la formación de un material sólido particulado. Los cocristales fueron secados, molturados y tamizados. A los cocristales secos se les determinó: humedad, densidad aparente, solubilidad, actividad de agua y el ángulo de reposo. Una alta proporción de zumo de naranja agria adicionada (20%) y bajo contenido de sólidos solubles (50 °Brix) producen cocristales con bajo contenido de humedad (2,59%), actividad de agua (0,52) y tiempo de solubilidad (69,4 s). El zumo de naranja agria concentrado con un pH de 4,5, produjo cocristales con bajos contenidos de humedad (1,96%). Los cocristales de zumo de naranja agria mostraron buenas características de reconstitución (alta solubilidad); sin embargo, presentaron alta humedad (2,5 a 4,5%) y actividad de agua (0,508 a 0,798). Palabras clave:Citrus aurantium L., encapsulación, cocristalización. AbstractThe aim of this study was to evaluate the conditions of co-crystallization of bitter orange juice with sucrose on the physicochemical properties of the product. Bitter orange juice was obtained with a mechanical juicer and concentrated on a rotary evaporator. Sucrose syrup 70 ºBrix was subjected to heating and stirring of 1000 rpm, until a white color (118 °C) was observed. Bitter orange juice was added to the syrup, and the mixture was subjected to constant stirring of 600 rpm, to observe the formation of a particulate solid material. The co-crystals were dried, grinded and sieved. A dry co-crystal was determined: moisture, bulk density, solubility, water activity and repose angle. High proportion of bitter orange juice added (20%) and low content of soluble solids (50 °Brix) produced co-crystals with low moisture content (2.59%), water activity (0.52) and solubility time (69.4 s). High pH (4.5) of bitter orange juice concentrate

Desarrollo y aplicación de recubrimientos comestibles en frutas mínimamente procesadasThe consumer's interest to purchase safe, nutritious, minimally processed, and healthy food has increased consumption of various fruits and vegetables. Generally, the quality of fruits depends on nutritional, microbiological and organoleptic properties, all of which are exposed to dynamic changes during harvesting, storage, and marketing. These changes are mainly due to the interactions between the fruits and its surroundings or migration among different inner components, which can result in loss of moisture and some volatile compounds (1, 2).The edible coatings technique is a good alternative to control some of these factors, it includes thin layers of edible materials formed directly onto the surface of the food that can be eaten as part of the whole product. Although edible coatings have been used for centuries to prevent moisture migration or to create a shiny surface for esthetic purposes; recently, there is considerable interest and more research on this application, driven to minimize the environmental impact of non-biodegradable materials and the increasing demand for minimally-processed foods (3, 4).Edible coatings are made from various materials, such as polysaccharides (starch, cellulose, pectin, alginate), proteins (gelatin, casein, albumins), and lipids (beeswax, fatty acids). Usually, mixtures of these materials are used to take advantage of each constituent. Polysaccharides and proteins based edible coatings could form cohesive molecular networks by strong interactions between molecules, which provide good mechanical properties and barrier to gases, O 2 and CO 2 (5). However; generally, these are polar polymers, resulting in a matrix with low cohesion and high water vapor permeability. Different alternatives have been used to improve this property, including the addition of hydrophobic compounds as lipids, modifying the polymer network and addition of nanocomposites (6).New matrices have been evaluated for coating fruit and minimally processed products; for instance, aloe vera mucilage has important biological, antimicrobial and antiviral properties. Aloe vera coatings have shown the capacity of reducing moisture loss, respiration rates, growth of microorganisms and oxidative browning in various fruits, such as strawberries, papaya and mango (7). Applying aloe vera coating on minimally processed mango (Tommy Atkins) has shown outstanding results, increasing shelf-life up to three days (8). Likewise, in Kiwi it has proved more efficient than other coating-forming matrices (alginate and chitosan), maintaining the sensory attributes, especially texture (7).The coating process involves a humectation (wettability) of the fruit coated by the suspension, a possible penetration of the suspension into the fruit, followed by a possible adhesion between the suspension and the fruit. Wettability stage is important, because it is a measure of compatibility between the suspension and the fruit; it affects the coating's time an...

Thin-layer yam (varieties 9811-089 and 9811-091) drying was evaluated in a laboratory-type dish dryer at 45°C, 55°C and 70°C and 1 m/s average air speed in the Universidad de Cordoba’s Applied Engineering laboratory. The samples were 3.19 cm long, 0.5 cm thick, in 0.5x3x5 cm slices. The effects of temperature, variety and geometry on drying-time were evaluated using a completely random factorial adjustment design: temperature (45°C, 55°C and 70°C), geometry (slices and fillets) and variety (9811-089 and 9811-091). Three repetitions were made per treatment, producing a 28.15% reduction in drying time at 70°C. Drying curves were constructed from the obtained results; it was observed that drying took place during the decreasing period, proving that diffusion was the mechanism involved in Discorea rotundata drying for the studied varieties. Drying curves were adjusted to Page, diffusion, Thompson, Newton, modified Page, Henderson and Pabis mathematical models. The logarithmic model (determined by determination coefficient (R2)) estimated mean error (SE) and relative mean deviation (%P), showing that the logarithmic model better described the drying process (R2 ≥ 99.17 and SE ≤ 0.0299).