The Study On Cell Wall Composition And The Activity Changes Of Pectin Decomposition Enzyme Of The Pear Fruits With The Differents Storability

Three 'Nanguoli''Pingguoli'and'Yanbianxiaoxiangshuili'species which have different storage quality were tested. This study was undertaken to compare and analyze the cell wall composition of the pear fruits and the activity changes of pectin decomposition enzyme. For knowing more about the relationship between the changes of the cell wall composition with the storability during the fruit soft process and the key enzymes involved in fruit softening, provide the basic data of the pear fruits for storing, transporting and processing.The results of experiment show that 'Nanguoli'and'Yanbianxiaoxiangshuili' which have poor storage quality softened obviously during storage, the content of the alcohol insoluble solids(AIS) reduced obviously, the content of the total pectin decreased sharply, the water soluble pectin content increased sharply in the prophase of the storage and reached peak in the 15th d and 10th d of storage, both the content of EDTA soluble pectin and Alkali-soluble pectin increased in varying degrees, the content of cellulose and hemicellulose reduced, all of those showed that the cell wall composition of 'Nanguoli'and'Yanbianxiaoxiangshuili'were in a large degree of decomposition during fruit storage.However, the Pingguoli whose storage quality is good did not softened obviously, the content of AIS reduced slowly; the content of the total pectin did not show too many changes, the content of water soluble pectin did not grow but reduced, the content of EDTA soluble pectin, Alkali-soluble pectin, cellulose and hemicellulose did not show too many changes. These results indicated that the cell wall composition of Pingguoli did not decompose largely.The polygalacturonase (PG) activity of'Pingguoli'which has high storage quality was lower during storage, the highest activity represented at the 20th d of storage. In contrast,β-Galactosidase (β-Gal) activity was higher, but the apparent highest activity did not appear. The PG activity of 'Nanguoli'and Yanbianxiaoxiangshuili'which has low storage quality was higher, but there was not apparent highest activity. Theβ-Gal activity of 'Nanguoli'was higher than that of'Pingguoli', while P-Gal activity of Yanbianxiaoxiangshuili'was lower than that of'Pingguoli'. The highest activity of 'Nanguoli'and'Yanbianxiaoxiangshuili'respectively represented at the 15th d and 10th d. Several evidences indicated that the storage life of pear was related to the content of the PG during storage, but did not matter whether the highest activity appeared or not. The storage life strength had nothing to do with theβ-Gal activity, but related to the appearance of highest activity. What's more, the highest activity appeared earlier, the storage life was weaker.