Disseny d'estratègies conjuntes i aplicació de diferents eines d'un entorn d'aprenentatge virtual (Atenea-Moodle) en els ensenyaments de nous Graus de l'Escola Superior d'Agricultura de Barcelona (ESAB-UPC)

Peer Reviewe

Effect on quality and shelf-life of an aloe vera edible coating in fresh-cut kiwi

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Effect of citric acid on browning of fresh-cut potatoes and on texture after frying

Fresh-cut potato (Solanum tuberosum L.) is a product widely consumed, but the susceptibility of this tube.r to browning is a drawback and limiting factor for its shelf life. This study aimed to evaluate the predisposition of different potato cultivars for being minimally processed, the effect of citric acid in inhibiting browning and the quality of the fried potato during the product shelf-life.Postprint (updated version

A First approach of using ultrasound as an alternative for blanching in vacuum-packaged potato strips

The effect of ultrasound (US) (40 kHz, 200 W, 3 min), blanching (85 °C, 3.5 min), and the combination of both methods was evaluated on the quality of vacuum-packaged potato strips stored at 3 ± 1 °C for up to 10 days. For this study, two cultivars of potatoes were assessed. For blanched Agata samples, the lightness (L*) decreased over 12 % (p < 0.05). Moreover, their hue increased up to 100, obtaining lesser yellow potato strips. In contrast, US did not affect the hue values. The losses of firmness of blanched potato strips were notable (35 % for Agata and 51 % for Agria), whereas US did not change this property (p < 0.05). Nevertheless, no significant differences were found in the total starch content at 10 days. Agata and Agria showed different metabolic behaviors of sucrose in the refrigerated storage. Therefore, Agria cultivar retained better color after frying. These results suggest that US had less impact on color and improve the firmness in vacuum-packaged potato strips with no added chemicals.Postprint (author's final draft

Estudio de crioconcentración en bloque asisitida por vacio para zumo de granada

La crioconcentración es una técnica de concentrar soluciones conservando sus propiedades nutritivas y compuestos bioactivos, debido al uso de temperaturas por debajo del punto de congelación. Existen varios métodos de crioconcentración entre los que se encuentra el sistema en bloque (BFC) asistido por vacío como una alternativa para mejorar el rendimiento y la eficiencia del producto concentrado. Se ha realizado este estudio con zumo de granada ya que es una de las frutas que contiene una mayor capacidad antioxidante y contenido de compuestos fenólicos, entre ellos la punicalagina. Por esto, el propósito de este trabajo es evaluar el sistema BFC asistida por vacio para crioconcentrar el zumo de granada. Se realizó un diseño experimental con la Metodología de Superficie de Respuesta para estudiar el efecto de los factores tiempo y presión de vacío sobre las variables respuestas: Índice de Concentración (IC), Eficiencia (Eff) y Rendimiento de Soluto (RS). Posteriormente se buscó optimizar el sistema en función de cada una de las variables y considerando todas las variables en conjunto. Los resultados mostraron que la presión de vacío tiene un efecto significativo en el IC, que el tiempo de tratamiento tiene un efecto significativo en el RS, y que ambos factores tienen efectos significativos en la Eff (p<0.05). El IC óptimo fue de 3.24. Este se obtuvo con 2 kPa de vacío durante 12 min, alcanzando una concentración máxima de 52.2°Brix, partiendo de un zumo inicial de 15.3°Brix. El RS óptimo fue de 68.2%, este se obtuvo con 35.9 kPa durante 12 min. La Eff óptima fue de 86%, esta se obtuvo con 22.9 kPa durante 12 minutos. Tomando en cuenta la deseabilidad de cada variable respuesta: CI, RS y Eff, se encontró un valor de deseabilidad de 0,74 este se obtuvo con 17.3 KPa durante 12 min, siendo IC de 2.96, RS de 61.4% y la Eff del 85,8%. Se comparó el color, contenido en compuestos fenólicos totales, capacidad antioxidante por DPPH, antocianinas, punicalagina y ácido elágico del zumo inicial con el obtenido por crioconcentración a 45 ºBrix. A partir de los resultados se demostró que el BFC asistido con vacío es una tecnología efectiva para concentrar el zumo de granada, conservando el color y sus componentes bioactivos.Postprint (published version

Comparative study of block cryoconcentration in pomegranate juice: centrifugation versus vacuum

Block cryoconcentration is a technique that can be applied to obtain fruit juice concentrates while preserving their nutritional, bioactive and organoleptic properties. Until now, the investigations present both the centrifugation and vacuum cryoconcentration method independently for different matrices, but with different purposes such as observing the effect of the initial freezing temperature, the freezing direction, whether radial or unidirectional, the effect of several cycles of cryoconcentration, comparing cryoconcentration with other concentration methods, etc. However, there is no study that compares both methods in the same matrix considering some common parameters such as cryoconcentration time. The objective of this research work was to compare two block centrifugation methods, centrifugation-assisted (CABC) and vacuum-assisted (VABC). A factorial experimental design was used. The operation conditions evaluated were 110 RCF and 2360 RCF, and 10 and 70kPa at the same time conditions (4 and 12min). Pomegranate juice was frozen at -20°C unidirectionally for 48h before treatments. For the response studied—concentration index (CI), solute yield (SY, %) and efficiency (Eff, %)—CABC at 110 RCF for 12min showed the best overall results (SY=59.2% and Eff=84.3%) and the desirability was .91. For VABC at 10¿kPa for 12¿min, the desirability was .98 but SY was lower. In both methods, the CI in one cycle was up to 3.0. The advantage of both systems is that in one cycle the CI, SY and Eff were higher than those obtained by other investigations on pomegranate juice.e>Practical applications Cryoconcentration is an emerging technology for concentrating a food solute in a solution based on the separation of ice crystals from a freeze-concentrated solution. The nutritional and sensory quality of cryoconcentrated fruit juices is higher than those concentrated conventionally by means of evaporation due to the low processing temperatures. Consumer demand for food rich in bioactive components for a healthy lifestyle is growing. With the use of the block freeze concentration technique, it is possible to produce a pomegranate juice concentrate with excellent nutritional properties. Two techniques for assisted block cryoconcentration of pomegranate juice—vacuum and centrifugal—were compared in a single cycle. Both methods showed better performance in once cycle than other cryoconcentration methods at lab scale. The generated knowledge in this study can be easily adapted for the juice industry in order to improve the process parameters of block freeze concentration in the elaboration of concentrated pomegranate juice.Postprint (published version

Effect of citric acid on browning of fresh-cut potatoes and on texture after frying

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An inline optic sensor technology to determine milk pH in yogurt manufacturing

Accurate determination of yogurt fermentation end-point (i.e., the end of the fermentation process at pH = 4.6) is essential for yogurt manufacturing. As a result of the high complexity of milk fermentation induced by lactic acid bacteria, an inadequate fermentation end-point selection could significantly compromise manufacturing cost and the final yogurt quality. Currently, acid coagulation to produce yogurt in the industry is monitored from discontinuous pH measurements that are measured manually every 10-15 minutes, a laborious and inaccurate techniquePostprint (published version

Training for the use of Moodle in university

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Effect of chitosan and calcium salts in the maintenenance of shelf-life and quality of fresh-cut pineapple

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