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Manejo cosecha y tecnología postcosechaChanges in the physico-chemical properties of four lettuce (Lactuca sativa L.) varieties during storage ResumenLa lechuga es una hortaliza de amplio consumo popular, por sus beneficios para la salud y la nutrición. Se estudiaron los cambios en calidad de cuatro variedades (Alpha, Parris Island, Graziella y Lollo Rossa) almacenadas durante 12 días a 5,5 ºC y 90 % HR. Se determinaron contenido de agua, sólidos solubles totales (SST), acidez titulable (AT), vitamina C, fenoles totales, polifenol oxidasa (PFO), color y textura. Las variedades de lechuga tuvieron tasas diferentes de pérdida de agua y modificaciones en los SST y la AT. La variedad Graziella tuvo el más alto nivel de vitamina C. El contenido de fenoles totales se redujo significativamente en el día 12 de almacenamiento.No se observaron alteraciones en la actividad de la PFO excepto en Lollo Rossa. El análisis Biplot mostró correlaciones positivas y negativas de las coordenadas L*, a* y b*, con lo cual se observó una clara definición de dos grupos de lechuga: verde y roja. Se hizo evidente la modificación en la tonalidad del color de acuerdo con la posición de las hojas. Se registraron cambios en la textura al final del almacenamiento, que no alteraron la calidad del follaje. Si bien los parámetros evaluados varían según la variedad, la refrigeración contribuye a mantener las propiedades del vegetal para el consumo directo.Palabras clave: bioquímica, Lactuca sativa, hortalizas de hoja, nutrición de las plantas, tecnología postcosecha AbstractLettuce, a popularly consumed leafy vegetable, is well known for its health and nutritional value. Thus, the current study focused on the qualitative changes of four lettuce varieties, namely Alpha, Parris Island, Graziella and Lollo Rossa, stored at 5.5 ºC and 90 % RH for 12 days. The analyzed parameters were water content, total soluble solids (TSS), titrable acidity (TA), vitamin C, total phenols, polyphenoloxidase (PPO), color and texture. Under storage conditions, the studied varieties exhibited different rates of water loss. TSS was found to increase until day 8 of storage, which is also when TA differences were observed. The Graziella variety showed the highest vitamin C levels. Total phenol content decreased significantly during the 12 days of storage. No significant PPO activity changes were found, except for those of the Lollo Rossa variety. Biplot analysis allowed observing not only positive and negative correlations between coordinates L*, a* and b*, but also the separavtion of the green lettuce varieties from the red one, together with color variations depending on leaf position. Although textural changes were recorded at the end of the study, foliage quality was not altered. In short, the studied parameters, which contribute to lettuce direct consumption properties, can be said to be variety-dependent and better preserved under refrigeration.

“High-Andean fruits” are deemed important because of their potential for domestic consumption and exportation. Among them, gulupa (Passiflora edulis Sims) is an exotic fruit of good acceptance in European markets. However, the technological support associated with the crop is incipient and its short shelf life leads to rapid deterioration of the product. This fact makes it necessary to investigate the physical, physiological and biochemical processes that characterize fruit ripening, in order to take actions to ensure that it arrives in its best possible condition to the consumer. In this context, the current study aimed at identifying enzymatic activity in gulupa fruits during pre and postharvest. Plant material from the Colombian Gene Bank (administered by Corpoica) was used. Fruits of known age were periodically harvested to determine the activity of the enzymes α-amylase, polygalacturonase (PG), pectinmethylesterase (PME) and polyphenol oxidase (PPO) through destructive samplings. It was found that α-amylase and PG are linked to the increase of soluble solids, which favors the sweet taste of the fruit. In turn, the low activity of PPO enables agroindustrial processing without severe fruit browning.

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<p>Se estudió el efecto de los factores ambientales sobre la población de Monalonion velezangeli Carvalho &amp; Costa en aguacate cv. Hass, plantado en los Andes colombianos.Se obtuvieron datos de clima correspondientes al período 2010-2011, usando seis estaciones meteorológicas automáticas. La actividad del insecto fue monitoreada mediante el registro de individuos de M. velezangeli y la presencia de daño fresco en doce ramas marcadas en cada árbol, ubicadas en los cuatro puntos cardinales, en los estratos bajo, medio y alto. Se establecieron relaciones entre los índices de población obtenidos con valores de temperatura, humedad relativa y velocidad del viento, mediante representaciones Biplot y análisis de correlación. Estos análisis se hicieron no solo con los registros tomados el mismo día, sino que incluían también los valores retroacumulados de los factores climáticos, esto es, la suma durante un período de días antes de la evaluación.Los resultados sugieren que la temperatura y la humedad relativa tenían una influencia directa sobre el insecto,mientras que la velocidad del viento tenía una relación inversa. Este estudio ilustra cómo el análisis de la información climática puede mejorar la capacidad predictiva sobre el establecimiento de M. velezangeli en cultivos de aguacate, un aspecto clave para direccionar el manejo integrado de la plaga.</p>

From a socioeconomic and environmental standpoint, rubber cultivation is potentially important for Colombia, because it not only constitutes an alternative to the traditional mining, agricultural, and livestock activities, but also a beneficial option in the substitution of illegal crops. Thus, there is need to determine the factors restricting the productivity of the species, particularly soil-related aspects. In this context, the current research undertook the description and identification of soil physical and chemical properties in three rubber plantations located in a region known as Bajo Cauca Antioqueño, at the lower course of the Cauca river. The results indicate that these soils are classified as Ultisols, they are deep, with acid reaction and low levels of soil organic matter. Essential elements also exhibited low levels, except Cu. Fe and Al are also present in very high concentrations, while the cation exchange capacity is limited. These observations alert on the need for agronomic management techniques that allow the crop to express its full potential under conditions that are not very adequate for its growth and development.