| In this paper, the effects of acetaldehyde on fruit softening and its related physiological changes in"Dagai"persimmon (Diospyros kaki L..) and"Okubao"peach (Prunus persica L. Batsch. cv. Okubao) were investigated. The combinations of ethanol (10 ml/kg) in various ratios to acetaldehyde in persimmon were also observed. The results were as follows:1. The acetaldehyde treatments, to some extent, delayed fruit softening in persimmon, the concentration in 10 ml/kg showed the best. The acetaldehyde treatments had no obvious effects on pection contents, activities of polygalacturonase andβ-galactosidase, the PE activities in 5,10 ml/kg fruits were higher than in 0 and 2 ml/kg. The changes of insoluble tannin to soluble tannin were delayed, but the contents of soluble solids and proanthocyanidins were not influenced by the acetaldehyde treatments.2. The appropriate concentrations of acetaldehyde treatments kept higher firmness or lower respiration rates of peach fruits than control, and decreased the soluble pectin contents of fruits both at room temperature (20℃) and 0℃. At 20℃,the activities of PG in fruits with 0.5 ml/kg and 2 ml/kg acetaldehyde were lower than those in control and 1 ml/kg fruits. The acetaldehyde treatments tended to increase PE and decreaseβ-galactosidase activities, and had little effect on contents of soluble solids and titratable acid. At 0℃, there were no obvious differences on activities of PG, PE, orβ-galactosidase among acetaldehyde fruits and control, the soluble solids contents were higher, or the titratable acid contents were lower in treated fruits.3. The combined treatment in ethanol: acetaldehyde = 1:2 had significant effect on the maintaining flesh firmness in persimmon, and the other ratio combinations showed no obvious diffenences. The treatments of ethanol and its combinations with acetaldehyde had little effect on the contents of soluble solids, proanthocyanidins and insoluble pectin, soluble pectin, theβ-galactosidase activities in fruits. |
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