Abstract: The difference in pectin level, pectinesterase ( PE) activity and creasing-fruit rates between‘Hong 127’orange (Citrus sinensis Osbeck ‘Hong 127’) and ‘Hongjiang’orange (Citrus sinensis Osbeck ‘Hongjiang’) were studied. The creasing fruit rates for‘Hong 127’and ‘Hongjiang’orange were 7.06%
and 28.03% respectively. Upon fruit maturing, the PE, water soluble pectin (WP) , total pectin (TP) and hydrochloric acid soluble pectin (HP) in ‘Hongjiang’ increased by 260% , 827% , 65% and 54% , respectively. The change of PE in ‘Hong 127’was smaller. PE was positively correlated withWP and negatively correlated with HP. The content of TP, WP and PE in ‘Hongjiang’orange were obviously higher than those in ‘Hong 127’, but the content of HP in ‘Hongjiang’was higher in ‘Hong 127’. There were higher TP, WP and PE in shaded halves of fruits, but higher HP in exposed halves of fruits. The content of TP, WP, PE of the creasing fruits is higher than the normal fruit, and the content of HP is lower than normal fruit. There is no difference for hexametaphosphate soluble pectin ( PP) between the two varieties.

Key words: Citrus, Creasing fruit, Pectin, Pectinesterase activity