The Relationship Between Bound Water and Carbohydrate Reserves in Association with Cellular Integrity in Fragaria vesca Stored Under Different Conditions

Abstract

It has been recognized that high CO2 concentrations maintain the freshness of strawberries, reducing weight loss and the incidence of decay. Since strawberries have high tolerance threshold to CO2, it is of interest to know what changes occur in cellular water distribution when the threshold is reached or exceeded. Moreover, as strawberries are prone to producing exudate during storage at low temperatures, application of technologies improving water retention is needed. Changes in bound water content were analyzed in relation to simple sugars, polyols, and fructooligosaccharides (FOS) in Fragaria vesca stored at low temperature (0 °C) in the presence of 0, 20, or 40 % CO2. Fruits were analyzed at the end of a 3-day treatment and after transfer to air for one additional day. Unfavorable storage conditions were associated with a decrease in the levels of bound water and in that of 1-kestose and myo-inositol. However, the 1-kestose and myo-inositol content was enhanced when 40 % CO2-treated strawberries were transferred to air at the same time as an increase in bound water content and a restoration of intracellular water took place. The ability of the fruit to modulate the accumulation of these compounds, and by extension their water binding strength, in conjunction with the pool of the bound water fraction, appears to be a mechanism associated with the maintenance of cellular structural integrity. Variation in the percentage of air space and in the weight loss rate produced by enhancing the CO2 treatment during storage at 0 °C was also analyzed.