title: Changes in cell wall composition associated to the softening of ripening papaya: evidence of extensive solubilization of large molecular mass galactouronides.
abstract: Papaya (Carica papaya) is a climacteric fruit that undergoes dramatic pulp softening. Fruits sampled at three different conditions (natural ripening or after exposition to ethylene or 1-methylcyclopropene) were used for the isolation of cell wall polymers to find changes in their degradation pattern. Polymers were separated according to their solubility in water, CDTA, and 4 M alkali, and their monosaccharide compositions were determined. Water-soluble polymers were further characterized, and their increased yields in control and ethylene-treated fruit, in contrast to those that were treated with 1-MCP, indicated a strong association between fruit softening and changes in the cell wall water-soluble polysaccharide fraction. The results indicate that the extensive softening in the pulp of ripening papayas is a consequence of solubilization of large molecular mass galacturonans from the pectin fraction of the cell wall. This process seems to be dependent on the levels of ethylene, and it is likely that the releasing of galacturonan chains results from an endo acting polygalacturonase.
authors: Laboratorio de Quimica, Bioquimica e Biologia Molecular de Alimentos, Departamento de Alimentos e Nutricao Experimental, FCF, Universidade de Sao Paulo, Avenida Lineu Prestes 580, Bloco 14, CEP 05508-900, Sao Paulo, SP - Brazil.
authors: Tânia Misuzu
authors: TM
authors: Shiga
authors: João Paulo
authors: JP
authors: Fabi
authors: João Roberto Oliveira
authors: JR
authors: do Nascimento
authors: Carmen Lúcia de Oliveira
authors: CL
authors: Petkowicz
authors: Lúcia Cristina
authors: LC
authors: Vriesmann
authors: Franco Maria
authors: FM
authors: Lajolo
authors: Beatriz Rosana
authors: BR
authors: Cordenunsi
mesh_terms: D029441:Carica / Q000737:chemistry* / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D005511:Food Handling; D008970:Molecular Weight; D010368:Pectins / Q000737:chemistry* / Q000378:metabolism; D012995:Solubility
chemical_list: D010368:Pectins; C003181:polygalacturonic acid