Effects of Bagging and Fruit-expander on Ca, Pectin Content and the Quality of Huangguan Pear Fruits

Bagging and fruit-expander are used as a common technique in the Huangguan pear fruit production,which often influence fruit quality and induce superficial browning spot. In order to investigate the regulation mechanism of bagging and fruit-expander, young Huangguan pear fruits were bagged outside with grey paper bags and inside with dark paper bags and then fruit pedicels were smeared with fruit-expander during the early development stage. The results show that bagging and fruit- expander increase significantly weight per fruit, induce significantly superficial browning spot of fruits stored at cool temperature (0℃), but bagging has no obvious influence on Soluble Solid Content (SSC), firmness, Titration Acid(TA) and soluble sugar content, except for a higher starch content of fruit. On the other hand, the fruit - expander could decrease firmness, TA and starch content, increase TSS/TA, accelerate fruit maturation. Bagging also decreases markedly fruit Ca content, particularly in peel of fruit, and also reduces the content of Cell Wall Substance (CWS), soluble- and proto-pectin of fruit peel, which might be stimulated by fruit- expander. Meanwhile, bagging enhances the content of CWS, soluble- and proto-pectin of flesh, while the fruit-expander decreases the content of CWS and proto-pectin, but increases soluble pectin of the fruit flesh. In summary, it is shown that bagging and fruit-expander mainly decease the content of Ca, and cell wall substance and the pectin content in peel of Huangguan pear fruits, which may be a part of mechanism of superficial browning spot incidence induced by bagging and fruit-expander.