CHANGES IN FIRMNESS AND PECTIC POLYSACCHARIDE SOLUBILITY IN THREE CULTIVARS OF STRAWBERRY FRUIT FOLLOWING SHORT‐TERM EXPOSURE TO HIGH PCO2

Abstract

ABSTRACT Fruit of three genetically related strawberry (Fragaria × ananassa Duchesne) cultivars, “Akihime”, “Seolhyang”, and “Maehyang”, were exposed to 100 kPa CO2 for 4 h at 4C to determine the residual influence on firmness during storage at 4C. Fruit firmness increased significantly in all cultivars in response to high CO2, from 97% in “Maehyang” to 66% in “Akihime.” Firmness increases were evident 24 h following 100 kPa CO2 exposures and persisted over 3 days at 4C. Fruit exposed to high pCO2 showed significant quantitative shifts in soluble pectin fractions, with increases of 44.8–66.7% in chelator‐soluble pectins and declines of 14.6–22.1% in water‐soluble pectins and 8.4–21.0% in Na2CO3‐soluble pectins. Changes to matrix glycans were unremarkable except in “Maehyang”, which showed 10–13% declines in 4% alkali‐soluble glycans and 8.5–13% increases in 24% alkali‐soluble glycans. Mol mass of the water‐ and chelator‐soluble pectin fractions was minimally affected by high pCO2. The increases in firmness and changes in pectin solubility patterns in response to CO2 are among the highest reported for strawberry fruit.PRACTICAL APPLICATIONSThe strawberry is among the most perishable of harvested fruits, experiencing rapid softening and general deterioration even at temperatures near 0C. Since strawberries do not ripen postharvest, they must be harvested when nearly full‐ripe, and during storage and handling are subject to high water loss, bruising, and decay. Alternative means of handling harvested strawberry fruit are being investigated. Strawberry firmness can be enhanced by treatment with high levels of carbon dioxide; however, long exposures to the gas can result in discoloration and fermentative metabolism. In these experiments, we demonstrate that fruit from three Asian strawberry cultivars show significantly and persistently enhanced firmness in response to a 4‐h exposure to 100 kPa CO2. This response is accompanied by highly significant changes in solubility of specific pectin fractions. Short‐term, high CO2 treatments could have application for extending shelf‐life and facilitating long‐distance transport of appropriate cultivars of strawberry fruit.