Changes in cell wall polysaccharides of kiwifruit and the visco-elastic properties detected by a laser Doppler method

Citation
S. Terasaki et al., Changes in cell wall polysaccharides of kiwifruit and the visco-elastic properties detected by a laser Doppler method, J JPN S HOR, 70(5), 2001, pp. 572-580
Citations number
40
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences
Journal title
JOURNAL OF THE JAPANESE SOCIETY FOR HORTICULTURAL SCIENCE
ISSN journal
0013-7626 → ACNP
Volume
70
Issue
5
Year of publication
2001
Pages
572 - 580
Database
ISI
SICI code
0013-7626(200109)70:5<572:CICWPO>2.0.ZU;2-T
Abstract
Visco-elastic properties of kiwifruit were measured by a laser Doppler meth od over an eight day ripening period. After ethylene treatment, fruit flesh elasticity decreased exponentially. However, viscosity of the flesh increa sed from day 0 to 2 and then decreased. Fruit tissue was boiled in 80% etha nol to extract soluble sugars (EtOH fraction); the EtOH-insoluble residue w as treated with alpha -amylase to solubilize starch. The amount of sucrose, glucose, fructose and inositol in the EtOH fraction on unit FW basis incre ased from day 0 to 3, while starch decreased during the ripening period. Ce ll wall material was fractionated into the hot water-soluble (WS), hot EDTA -soluble (pectin), alkaline soluble (hemicellulose) and residual (cellulose ) fractions. The quantity of hydrolyzed sugars in the WS fraction decreased exponentially during ripening, whereas that in the pectin and hemicellulos e fractions increased slightly on day 1 and then decreased rapidly. The amo unt of cellulose remained nearly constant during ripening. The iodine metho d revealed appreciable amounts of xyloglucan in the hemicellulose fraction. Gel permeation chromatography of polymers in the hemicellulose fraction re vealed that xyloglucan had degraded rapidly by day 2. The molecular weights of both total sugar and uronic acid components of the pectin fraction incr eased from day 0 to 2, and then decreased. The amount of total cell wall po lysaccharides and starch decreased by 80% during ripening, which indicates that a decrease in the molecular weight of xyloglucan correlates with a los s in fruit tissue elasticity, while the changes in the molecular weight of pectin corresponds with changes in viscosity. A substantial portion of the cell wall polysaccharides was hydrolyzed to soluble sugars in the early pha se of ripening.