Effect of Exogenous Fructose Treatment on Postharvest Softening of Apricot Fruits

The present research was undertaken in order to study the effect of exogenous fructose treatment on postharvest softening of apricot fruits. ‘Saimaiti’ apricots were subjected to osmotic treatment in 300 mmol/L fructose solution at 0.05 MPa for 2 min followed by normal pressure for another 5 min before storage at (0 ± 1) ℃. Distilled water was used as control treatment. Fruit hardness, cell membrane permeability, water soluble pectin (WSP), chelate soluble pectin (CSP), Na₂CO₃ soluble pectin (NSP) and cellulose contents, and polygalacturonase (PG), pectin methyl esterase (PME), β-galactosidase (β-Gal) and cellulase (CEL) activities were determined every seven days during storage, and cell ultrastructure was observed by transmission electron microscopy (TEM). The results showed that exogenous fructose treatment could significantly inhibit the activity of cell wall degrading enzymes and maintain the contents of CSP, NSP, and cellulose, thereby inhibiting the degradation of the cell wall. On day 49 of storage, compared with the control group, the contents of CSP, NSP and cellulose in fructose-treated apricot fruits increased by 31.30%, 10.58%, and 14.30% (P < 0.05). The WSP content and cell membrane permeability of the control group were 1.09 and 1.25 times as high as those in the control group, respectively. Furthermore, this treatment maintained the integrity of organelles and the membrane system, and effectively delayed the decline in fruit hardness.