Study On Anti-browning Mechanism Of An Li Pear Fruit

In order to know the effect of internal factors on the characteristics of anti-browning in fruit of anti-browning strains(Yan An 3) in An Li pear,'Yan An 3'strain was chosen as material in this study, and compared with control varieties of An Li pear 'Yan An 1' and 'Yan An 2' , two browning ones. Some physiological chemical indexes in leaves and fruits of three An Li pear varieties (strain) were compared respectively. The composition and content of phenolics and mineral element contents in fruits were analyzed. The relationship were studied between browning degree and PPO activitie, POD activitie, PAL activitie, SOD activitie, soluble protein contents, phenolic contents, Vc contents of the three An Li pear varietie (strain) fruits respectively, in the period of storage. The main results and main conclusions are as follow:(1) PPO, PAL activities and phenolics content of'Yan An 3'pear fruit in pulp and core were lower than the same positions of the two control varieties'Yan An 1'and'Yan An 2'respectively, these showed that in the'Yan An 3'pear fruit, the lower activity of PPO and lower content of phenolics is the direct reason for anti-browning. (2) POD, SOD activities in pulp and core of'Yan An 3'pear fruit, were higher than that of the two control varieties,'Yan An 1'and'Yan An 2'in storage, which enhanced the scavenging ability of fruit tissue. This is another reason for anti-browning. (3) Vc contents in pulp and core of'Yan An 3'pear fruit were higher than that of the two control varieties,'Yan An 1'and'Yan An 2', in storage. Vc not only inhibit the PPO activity, but also can deoxidize the quinone which the production of inducing browning reaction by enzyme, so it can inhibit browning reaction effectively.(4) Two days after sampling, browning degree of An Li pear fruits was positively correlated to its PPO, PAL activities and its phenolics content, the correlation coefficients between browning degree and PAL activity, phenolics content were 0.96 **, 0.92 ** respectively; While the browning degree was negatively correlated to POD activity and Vc contents, the correlation coefficients were -0.95** and -0.81* respectively. All these suggest that, the higher the browning degree, the higher the PPO, PAL activity and phenolics content; while the higher the browning degree, the lower the POD activity and Vc content. The activity of PPO and content of phenol may be the main cause of inducing browning. (5) The higher activities of POD, CAT in leaves of'Yan An 3'may be enhance the scavenging of oxygen free radicals in fruit tissue, and it is still worth for further researching that whether the characteristic of enzymology can be used for the pre-selected indicators in anti-browning breeding of An Li pear.