Estudio del efecto de los empaques de atmósfera modificada (MAP) en la calidad postcosecha del raquis de uva en las variedades "Red Globe" y "Flame Seedless"
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Fecha
2013
Autores
Profesor/a Guía
Facultad/escuela
Idioma
es
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Universidad Andrés Bello
Nombre de Curso
Licencia CC
Licencia CC
Resumen
Junto con la minería y el área forestal, las exportaciones de fruta fresca representan uno de
los ingresos económicos más importantes para Chile. La uva de mesa representa
aproximadamente un tercio del volumen total de fruta fresca exportada. Uno de los parámetros de
calidad cosmética más importantes es el color del raquis, si este posee una coloración verde en
los anaqueles de los mercados, los consumidores asociarán esto con un producto fresco. Por el
contrario, los racimos con un raquis pardeado no causan atracción al consumidor, reduciendo los
ingresos económicos de los productores. Este problema ha sido asociado principalmente a
deshidratación, pero además, existe la posibilidad de que otros factores estén involucrados en este
proceso. Los empaques de atmósfera modificada (MAP), son una tecnología utilizada para
extender la vida postcosecha de los racimos de uva de mesa. El objetivo de este estudio fue
analizar el efecto causado por MAP durante el almacenaje a 0°C sobre el pardeamiento del
raquis en las variedades de uva de mesa 'Red Globe' y 'Flame Seedless'. Después del almacenaje
a 0°C los raquis de ambas variedades mostraron mayores porcentajes de color verde con el
almacenaje en MAP, junto con un contenido menor de clorofila-a y mayor de feofitina-a al
comparar con el almacenaje en aire regular. Con el objetivo de comprender estos resultados se
realizó un análisis transcripcional de genes involucrados en la ruta de degradación de clorofila. Se
observó que el almacenaje a 0°C en aire regular provocó una disminución significativa en el
nivel de transcrito de todos los genes analizados en ambas variedades, respecto a los valores
medidos en cosecha. Sin embargo, MAP produjo respuestas distintas entre variedades, ya que en
'Red Globe' se observó una reducción significativamente mayor en el número de transcrito de los
genes MCS, PPH y RCCR en comparación al almacenaje en aire regular, excepto PaO que no
mostró diferencias entre ambas condiciones. En el caso de 'Flame Seedless' la abundancia de
trascrito de los genes MCS, PaO y RCCR aumentó, mientras que PPH no mostró variaciones,
respecto al almacenaje en aire regular. Por otra parte, el análisis histológico reveló que los raquis
pardeados poseen una mayor cantidad de capas de células suberizadas respecto a los raquis no
pardeados. Nuestros resultados sugieren que MAP, es una estrategia de almacenaje adecuada para
reducir el pardeamiento postcosecha del raquis sin afectar la calidad de las bayas. Finalmente,
podemos sugerir que el pardeamiento del raquis en uva de mesa es un proceso multifactorial que
se puede explicar a través de la suma de fenómenos de pérdida de color verde asociados a la
catálisis de clorofila y ganancia de color pardo por formación de peridermis.
Besides mining and forestry, fresh fruit exports represent one of the most important economic incomes for Chile. In this area, table grapes represent approximately one third of total fresh fruit volume exported. In quality terms, one of the most important visual parameter corresponds to rachis color, which has been associated by consumers with a fresh product. Thus, table grape clusters with brown rachis are not attractive for consumers inducing a reduction on economical incomes to producers. Mainly this problem has been associated to water loss, but the involvement of other factors is a plausible possibility. Modified atmosphere packaging (MAP) is a technology used to extend table grape postharvest life. The objective of the study was to analyze the MAP effect on table grape rachis browning during cold storage at O oc in 'Red Globe' and 'Flame Seedless' varieties. After O oc storage, rachises from both varieties showed higher green color percentage under MAP storage, concomitant with a lower chlorophyll-a content and higher amount of pheophytin-a compared with regular air storage. In order to understand these results, we carried out a transcriptional analysis of genes related to chlorophyll breakdown process. We observed that storage at O °C plus regular air induced a decrease in transcript level of all analyzed genes in both varieties, compared to levels at harvest. However, MAP storage caused different responses between varieties, in 'Red Globe' was observed a significant reduction oftranscript accumulation ofMCS, PPH and RCCR compared to regular air storage, except Paü that showed no differences between both storage conditions. In case of 'Flame Seedless' was found an increase in transcript abundance ofMCS, Paü and RCCR, while PPH showed no changes respect to regular air storage. Moreover, histological assay revealed that browned rachis showed more suberized cells layers than green rachises. Our results suggest that MAP represent a suitable storage strategy to reduce rachis browning without affecting berries quality. Finally, results suggest that table grape rachis browning correspond to a multifactorial process that can be explained by a decrease of green coloration associated to chlorophyll breakdown and a brown color gain due to periderm formation.
Besides mining and forestry, fresh fruit exports represent one of the most important economic incomes for Chile. In this area, table grapes represent approximately one third of total fresh fruit volume exported. In quality terms, one of the most important visual parameter corresponds to rachis color, which has been associated by consumers with a fresh product. Thus, table grape clusters with brown rachis are not attractive for consumers inducing a reduction on economical incomes to producers. Mainly this problem has been associated to water loss, but the involvement of other factors is a plausible possibility. Modified atmosphere packaging (MAP) is a technology used to extend table grape postharvest life. The objective of the study was to analyze the MAP effect on table grape rachis browning during cold storage at O oc in 'Red Globe' and 'Flame Seedless' varieties. After O oc storage, rachises from both varieties showed higher green color percentage under MAP storage, concomitant with a lower chlorophyll-a content and higher amount of pheophytin-a compared with regular air storage. In order to understand these results, we carried out a transcriptional analysis of genes related to chlorophyll breakdown process. We observed that storage at O °C plus regular air induced a decrease in transcript level of all analyzed genes in both varieties, compared to levels at harvest. However, MAP storage caused different responses between varieties, in 'Red Globe' was observed a significant reduction oftranscript accumulation ofMCS, PPH and RCCR compared to regular air storage, except Paü that showed no differences between both storage conditions. In case of 'Flame Seedless' was found an increase in transcript abundance ofMCS, Paü and RCCR, while PPH showed no changes respect to regular air storage. Moreover, histological assay revealed that browned rachis showed more suberized cells layers than green rachises. Our results suggest that MAP represent a suitable storage strategy to reduce rachis browning without affecting berries quality. Finally, results suggest that table grape rachis browning correspond to a multifactorial process that can be explained by a decrease of green coloration associated to chlorophyll breakdown and a brown color gain due to periderm formation.
Notas
Tesis (Magister en Biotecnología)
Palabras clave
Uva de Mesa, Tecnología de Postcosecha, Almacenamiento, Calidad, Chile