Characterisation and functionality of fructo-oligosaccharides affecting water status of strawberry fruit (Fragraria vesca cv. Mara de Bois) during postharvest storage.

Water status and analyses of free sugars, sugar-alcohols and fructo-oligosaccharides (FOS) were carried out in Fragaria x vesca treated with different high CO(2) concentrations applied to minimise damage caused by storage at 0°C. The thermodynamic parameters such as the amount of unfrozen water (U(w)), T(g), T(g)('), and peak position of the O-H stretching vibration were determined in various saccharides including FOS (1-kestose, nystose and kestopentaose) by infrared spectroscopy studies and differential scanning calorimetry. Beneficial high CO(2) treatment (20%) avoided the reduction of unfreezable water fraction and increased endogenous FOS levels, in contrast to that observed in air-stored and in those exposed to higher CO(2) levels (40%). The direct FOS-water interaction, possibly within the hydrogen-bond network of cellular structures, could explain the maintenance of water status, cell integrity and the low water leakage levels in 20% CO(2)-treated fruit at values similar to those found in freshly harvested fruit.