Mastication Of Citrus Fruit

Fruit mastication is an important index to evaluate citrus fruit quality, which directly influences the commodity quality of fruit. Dietary fiber properties in the pulp are related with mastication of citrus fruit, which may refer to cell wall metabolism. Nowadays, several citrus varieties with excellent characters got inferior mastication, due to the deterioration of variety and inappropriate cultivation and management. Thus, it is necessary to research into the citrus mastication to solve the problem.The study was conducted to gain insight into key factors and periods that impact citrus fruit texture by determining the dynamic changes of cell wall metabolism (pectin, cellulose, hemicellulose and lignin) from aspects of physiology, biochemistry and molecular throughout development of six varieties with different mastications. The main results were as follows:Cell wall metabolism of'FJ72-1'(FJ72-1, Citrus sinensis Osbeck cv. Fengjie 72-1) and'FJWC'(FJWC, C. sinensis Osbeck cv. Fengjiewancheng) in Fengjie, Chongqing area were measured. Contents of protopectin, cellulose and hemicellulose in 'Fengjiewancheng'with inferior mastication were obviously higher than in'Fengjie 72-1 novel orange'at mature stages and water soluble pectin content was the opposite. Lignin content of the two varieties had almost no difference. And changing patterns of cell wall materials of the two varieties were similar. Lower expression level of PG, PME and Cel at harvest time might also be associated with the inferior-mastication character.Cell wall metabolism of'PN'(PN, C. sinensis Osbeck cv. Putongnanfengmiju),'YN' (YN, C. sinensis Osbeck cv. Nanfengmijuyouxi),'MG'(MG, C. sinensis Osbeck cv. Miguang) and'HG'(HG, C. sinensis Osbeck cv. Huoguang) in Nanfeng, Jiangxi area were measured. Although the four varieties showed differences in mastication, pectin, cellulose, hemicellulose and lignin contents were similar during fruit development and cell wall substances didn't exhibit any obvious differences at harvest time. PG enzyme activities of the four varieties reached highest peak at 150d, and then decreased slightly.PAL gene expression of the four varieties was highest at 40d.