Slow softening of Kanzi apples (Malus×domestica L.) is associated with preservation of pectin integrity in middle lamella.
Kanzi is a recently developed apple cultivar that has an extremely low ethylene production, and maintains its crispiness during ripening. To identify key determinants of the slow softening behaviour of Kanzi apples, a comparative analysis of pectin biochemistry and tissue fracture pattern during different ripening stages of Kanzi apples was performed against Golden Delicious, a rapid softening cultivar. While substantial pectin depolymerisation and solubilisation was observed during softening in Golden Delicious apples, no depolymerisation or increased solubilisation was observed in Kanzi apples. Moreover, tissue failure during ripening was mainly by cell breakage in Kanzi apples and, in contrast, by cell separation in Golden Delicious apples. Kanzi apples had lower activity of beta-galactosidase, with no decline in the extent of branching of the pectin chain. A sudden decrease in firmness observed during senescence in Kanzi apples was not due to middle lamella dissolution, as tissue failure still occurred by cell breakage.
KU Leuven, Division MeBioS, Department of Biosystems (BIOSYST), W. de Croylaan 42, bus 2428, B-3001 Leuven, Belgium.
Sunny George
SG
Gwanpua
Flanders Centre of Postharvest Technology, W. de Croylaan 42, B-3001 Leuven, Belgium.
Bert E
BE
Verlinden
KU Leuven, Division MeBioS, Department of Biosystems (BIOSYST), W. de Croylaan 42, bus 2428, B-3001 Leuven, Belgium.
Maarten L A T M
ML
Hertog
KU Leuven, Division MeBioS, Department of Biosystems (BIOSYST), W. de Croylaan 42, bus 2428, B-3001 Leuven, Belgium; Flanders Centre of Postharvest Technology, W. de Croylaan 42, B-3001 Leuven, Belgium.
Bart M
BM
Nicolai
KU Leuven, Laboratory of Food Technology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Department of Microbial and Molecular Systems (M(2)S), Kasteelpark Arenberg 22, PB 2457, B-3001 Leuven, Belgium.
Marc
M
Hendrickx
KU Leuven, Division MeBioS, Department of Biosystems (BIOSYST), W. de Croylaan 42, bus 2428, B-3001 Leuven, Belgium. Electronic address: annemie.geeraerd@kuleuven.be.
Annemie
A
Geeraerd
D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D005030:Ethylenes / Q000737:chemistry / Q000378:metabolism; D005638:Fruit / Q000737:chemistry / Q000378:metabolism*; D027845:Malus / Q000737:chemistry / Q000378:metabolism*; D010368:Pectins / Q000737:chemistry / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism*
D005030:Ethylenes; D010936:Plant Extracts; D010368:Pectins; C036216:ethylene
Cell wall pectin; Depolymerisation; Ethylene; Softening; Tissue failure