Changes on the cell wall composition of tree-ripened “Bartlett” pears (Pyrus communis L.)

• Autores: Raffo Benegas, Maria Dolores; Ponce, Nora M. Andrea; Sozzi, Gabriel Oscar; Stortz, Carlos Arturo; Vicente, Ariel Roberto
• Año de publicación: 2012
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Postharvest Biology and Technology 73 : 72-79 (November 2012)
• Materia: Pera; Variedades; Pared Celular; Maduramiento; Firmeza; Pears; Varieties; Cell Walls; Ripening; Firmness; Variedad Bartlett
• Institución: Instituto Nacional de Tecnología Agropecuaria

Most of the European pear cultivars fail to develop a desirable texture when ripening on the tree. In order to identify some biochemical anomalies that might be associated with this phenomenon, the main differences in cell wall polysaccharides occurring during “Bartlett” pear on-tree ripening were evaluated. Fruit was harvested at 3 different ripening stages (119, 147 and 161 days after anthesis, DAA) namely unripe (UR) mid-ripe (MR) both developing normal texture upon ripening, and late-ripe (LR), which did not result in buttery and juicy fruit. The characterization of cell wall structure was accomplished by determining the monosaccharide composition, yields, and solubility of uronic acids and neutral sugars in fractions extracted by water (WSF), 0.05 M CDTA (CSF), 0.1 M Na2CO3 (NSF), 1 M and 4 M KOH (1KSF and 4KSF). The size exclusion profiles in all the isolated fractions were also determined. In the transition from the UR to the MR stage, glucose from the 4KSF and Ara from all other fractions became markedly solubilized. A slight increase in water-soluble pectin content and depolymerization of the 4KSF and CSF were also found during this period. From the MR to the LR stage, a glucan probably originating in cellulose turnover was found in the 4KSF, and (though at a lower rate) Ara solubilization continued. In contrast, the depolymerization of all wall fractions after day 147 was minimal, and a shift of water soluble pectins toward the CSF was detected. An imbalance in polyuronide degradation, including decreased depolymerization of pectin backbones, together with continuing removal of Ara from RG I, and/or other modifications increasing ionic interactions, may lead fruit which yield an abnormal, mealy texture upon ripening.
EEA Alto Valle
Fil: Raffo Benegas, Maria Dolores. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Alto Valle; Argentina
Fil: Ponce, Nora M. Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentina
Fil: Sozzi, Gabriel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Stortz, Carlos Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentina
Fil: Vicente, Ariel Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Agroindustrias; Argentina