Comparative Study On Masticaton Of Segment Membranes Of Large-fruit Nanfeng Tangerine ’97-2’ And ’hongguang’

Masticaton is an important factor affecting the quality of citrus fruit.The main edible composition of broadbark citrus fruits are segments,containing juice sacs and segment membranes.The masticaton of fruit is mainly related to the texture of segment membranes.In this experiment,large-fruit Nanfeng tangerine ‘97-2’(Inferior masticaton)and ‘Hongguang’(Superior masticaton)with different Masticaton were used.In order to find out the factors that affect masticaton of citrus fruits to study the dynamic changes of texture,cell wall components and related metabolic enzymes during fruit development in2019 and 2020.The results are as follows(1)In the process of fruit growth and development,the transverse diameter,longitudinal diameter and single fruit weight of ‘Hongguang’ were greater than those of large-fruit Nanfeng tangerine‘97-2’;the soluble solid content of ‘Hongguang’was significantly higher than that of large-fruit Nanfeng tangerine ‘97-2’,and its color was brighter and redder than that of large-fruit Nanfeng tangerine ‘97-2’.With the development of fruit,there was a significant negative correlation between fruit transverse diameter,longitudinal diameter and single fruit weight and texture index.(2)The results showed that the segments texture index of fruit of the two varieties decreased with the development of fruit.In the ripening stage of fruit,the shear force,fiber strength,fiber ductility,fiber toughness,chewiness and hardness of ‘Hongguang’were significantly lower than those of large-fruit Nanfeng tangerine‘97-2’.There was a significant positive correlation between the fiber strength and the fiber ductility,the shear force and the fiber ductility,the capsule hardness and the capsule chewness and the fiber ductility.(3)In the ripening stage of fruit,the soluble pectin content of ‘Hongguang’was higher than that of large-fruit Nanfeng tangerine‘97-2’,and the content of protopectin,cellulose,hemicellulose and lignin were lower than that of large-fruit Nanfeng tangerine‘97-2’.In 2019,the lignin content of large-fruit Nanfeng tangerine‘97-2’ was significantly higher than that of Nanfeng Hongguang,and in 2020,the cellulose content of large-fruit Nanfeng tangerine‘97-2’ was significantly higher than that of Nanfeng Hongguang.The Masticaton of citrus fruit is exoglucanaseosely related to the content of pectin,cellulose,hemicellulose and lignin.(4)The activities of enzymes related to masticaton metabolism were different in the same developmental period in different years.In 2019,the activities of PE enzyme and PG enzyme of ‘Hongguang’in the middle expanding stage and ripeing stage of fruit were higher than those of large-fruit Nanfeng tangerine‘97-2’,and the activities of PG enzyme of ‘ Hongguang ’ in the late expanding stages were higher than those of large-fruit Nanfeng tangerine ‘ 97-2 ’.In 2020,the activities of PE enzyme and PG enzyme of ‘Hongguang’ in the early,late expanding stages and the color turning stage of fruit were higher than those of large-fruit Nanfeng tangerine‘97-2’,and the activities of PG enzyme of ‘Hongguang’in the color turning stage were higher than those of large-fruit Nanfeng tangerine ‘ 97-2 ’.In 2019,the activity of endoglucanase in the capsular of ‘Hongguang’ in the early,middle,late expanding stages and the color turning stage of fruit,the activity of exoglucanase in the middle,late expanding stages and ripeing stage of fruit,the activity of β-glucosidase in the middle,late expanding stages and ripeing stage of fruit,and the activity of xylanase in the middle expanding stage and the color turning stage of fruits were higher than that of large-fruit Nanfeng tangerine‘97-2’.In 2020,the activity of endoglucanase in the middle expanding stage,color turning stage and ripeing stage of fruit,the activity of exoglucanase in the color turning stage and ripeing stage of fruit,the activity of β-glucosidase in the middle,late expanding stage,color turning stage and ripeing stage of fruit,,and the activity of xylanase in the color turning stage and ripeing stage of fruits were higher than that of large-fruit Nanfeng tangerine‘97-2’.In 2019,the activity of POD enzyme in the capsule of‘Hongguang’in the early expanding stage of fruit,the activity of PPO enzyme in the early,middle expanding stages and the color turning stage of fruit,and the activity of CAD enzyme in the middle,late expanding stages of fruit were lower than that of large-fruit Nanfeng tangerine ‘ 97-2 ’.In 2020,the POD enzyme activity of‘Hongguang’in the early,middle expanding stages,the PAL enzyme activity of‘Hongguang’in the middle expanding stage,and the 4Cl enzyme activity of‘Hongguang’in the early,middle expanding stages and color turning stage of‘Hongguang’ were lower than that of large-fruit Nanfeng tangerine‘97-2’.The results showed that there were a significant negative correlation between hemicellulose content and endoglucanase enzyme and exoglucanase enzyme activity,and a significant positive correlation between hemicellulose content and PAL enzyme and 4exoglucanase enzyme activity.of large-fruit Nanfeng tangerine ‘ 97-2 ’.There were a significant positive correlation between soluble pectin and β-glucosidase activity,and a significant negative correlation between soluble pectin and PPO activity of ‘Hongguang’.