title: Hydrolytic activity and ultrastructural changes in fruit skins from two prickly pear (Opuntia sp.) varieties during storage.
abstract: The activity of four cell wall hydrolases, pectinmethylesterase (PME), polygalacturonase (PG), cellulase, and beta-galactosidase (beta-Gal), was measured in fruit skins of two prickly pear varieties, Naranjona and Charola, during storage at 18 degrees C and 85-95% relative humidity (RH). In Naranjona (Opuntia ficus indica), of short postharvest life (ca. 2 weeks), PG, cellulase, and beta-Gal increased their activity more than twice, whereas PME activity tended to increase only slightly during storage. In Charola (Opuntia sp.), of long postharvest life (ca. 2 months), only beta-Gal increased its activity (77%), showing a high PG activity from the beginning of storage. Transmission electron microscopy observations showed middle lamella dissolution at the end of storage for both varieties. Naranjona showed a higher cell wall enzymatic activity than Charola, in agreement with their storability differences. Our results suggest that PG and cellulase in Naranjona and PG and beta-Gal in Charola are the main enzymes responsible for cell wall hydrolytic and ultrastructural changes in skins of stored prickly pears.
authors.affiliation: Departamento de Biotecnología y Bioquímica, Unidad Irapuato, Centro de Investigación y de Estudios Avanzados del IPN, Libramiento Norte Km 9.6, Carretera Irapuato-León, Apdo. Postal 629, 36500 Irapuato, Gto., México.
authors.forename: Armando
authors.initials: A
authors.lastname: Carrillo-López
authors.forename: Andrés
authors.initials: A
authors.lastname: Cruz-Hernández
authors.forename: Alfonso
authors.initials: A
authors.lastname: Cárabez-Trejo
authors.forename: Fidel
authors.initials: F
authors.lastname: Guevara-Lara
authors.forename: Octavio
authors.initials: O
authors.lastname: Paredes-López
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000032:analysis; D002473:Cell Wall / Q000201:enzymology / Q000648:ultrastructure; D002480:Cellulase / Q000032:analysis; D005519:Food Preservation; D005638:Fruit / Q000201:enzymology* / Q000648:ultrastructure; D006867:Hydrolases / Q000032:analysis*; D008854:Microscopy, Electron; D029747:Opuntia / Q000201:enzymology*; D011096:Polygalacturonase / Q000032:analysis; D013997:Time Factors; D001616:beta-Galactosidase / Q000032:analysis
chemical_list: D006867:Hydrolases; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D011096:Polygalacturonase; D001616:beta-Galactosidase; D002480:Cellulase