| Co-Investigator(Kenkyū-buntansha) |
KITAHARA Haruo HIROSAKI UNIV., FAC.EDUC., ASSOCIATE PROFESSOR, 教育学部, 助教授 (60186260)
KATO Yoji HIROSAKI UNIV., FAC.EDUC., PROFESSOR, 教育学部, 教授 (20194863)
ARAKAWA Osamu HIROSAKI UNIV., FAC.AGRIC.& LIFE SCI., PROFESSOR, 農学生命科学部, 教授 (70184265)
NISHIZAWA Takashi YAMAGATA UNIV., FAC.AGRIC., ASSOCIATE PROFESSOR, 農学部, 助教授 (10208176)
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| Research Abstract |
Softening of fruit occur generaly along with maturation, but the texture of the softened fruit differd by species. Ripened fruits of Rosaseae, such as apple, pear and strawberry also demonstrate different texture.
(1) In apple, the texture of softened (over-ripened) fruit can be classified into two types, mealy and soft flesh. In the study of apple flesh, based on the fact that in mealy flesh adhesion between cells loosened and cell separation was observed, to quantify the degree of mealines, four methods were compared. In this study, flesh disks were shaken in sucrose solution, the weights of the disks before and after shaking were maesured, and the percentage decrease was expressed as the degree of mealiness. In comparison of the degree of mealiness of 9 cultivars of ripened apple fruits, the flesh of 'Iwai', 'Jonagold' and 'Starking Delicious' were comparatively easy to be degraded and that of 'Tsugaru' and 'Golden Delicious' were degraded little. Pectic substances in the flesh of 'S
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tarking Delicious(SD)'and 'Golden Delicious(GD)' was fractionated into three fractions (H20, EDTA and HCl soluble), and uronic acid and neutral sugar contents in each fraction were determined. In the mealy flesh of 'SD', pentose content in EDTA fraction was remarkably less than the not mealy flesh and 'GD' . As the pectic substances in EDTA fraction include less neutral sugars as compared with the other pectic fractions, it is considered that this fraction is considered to be the polysaccharides exist in middle lamella between cells. Sugar composition of pectic fractions were compared using gas chromatography, and it was found that the arabinose content of EDTA fraction in mealy flesh was rekarkably low compared with not mealy flesh. By the methylation analysis of the the linkage of sugars, it was found that in 'SD', the terminal arabinose residue on the neutral sugar side chain on the rhamnogaracturonan of pectic substances decreased with the progress of mealiness. In contast, terninal galactose increased with the degree of mealiness. From thse results, during the apple fruit ripening, it was suposed that the mealiness can beinduced by the release of terminal arabinose from the galactose residue on the neutral sugar side chain on the rhamnogalacturonan main chain of the pectic substances of middle lamella between flesh cells.
(2) Structural changes in cell wall polysaccharides during fruit growth of seven apple cultivars, structural analysis of xyloglucans isolated from the fruit cell walls of four apple cultivars, changes in permeability of apple cell membrane during fruit growth of three apple cultivars, effects of age, vigor and shape of pear trees and bagging of fruit on the fruit quality, and characterization of cell wall poly-saccharides of Chili strawbwrry in comparison with Japanese strawberry, were investigated. Less
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