Changes in fruit firmness, cell wall composition and cell wall degrading enzymes in postharvest blueberries during storage

• WSP increased paralleled by a decline of SSP, cellulose and hemicellulose in blueberries.
• Blueberry softening was associated with the changes of above cell wall components.
• Higher firmness in cold stored fruit was due to the lower WSP content and activities of cell wall degrading enzymes.

Blueberries are now the second most economically important soft fruit. However, they are highly perishable and susceptible to rapid spoilage. One of the main factors limiting postharvest life of blueberries is softening. The changes of fruit firmness, cell wall degrading enzymes and cell wall composition of ‘Brilliant’ blueberry (Vaccinium ashei cv. Brilliant) were investigated in this study. The results showed fruit firmness declined concomitantly with the increase of the content of water soluble pectin (WSP) during storage paralleled by a decreasing amount of sodium carbonate soluble pectin (SSP), cellulose and hemicellulose. Blueberries stored at low temperature (5 °C) maintained higher fruit firmness than those stored at 10 °C, which was due to the lower WSP content and higher contents of SSP, cellulose and hemicellulose. Meanwhile, the lower activities of cell wall degrading enzymes such as polygalacturonase, cellulase, β-galactosidase and α-mannosidase in blueberries at 5 °C were associated with greater fruit firmness and lower WSP content as compared to those in fruit stored at 10 °C.