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Effect of edible coatings on enzymes, cell-membrane integrity, and cell-wall constituents in relation to brittleness and firmness of Huanghua pears (Pyrus pyrifolia Nakai, cv. Huanghua) during storage

Zhou, Ran, Li, Yunfei, Yan, Liping, Xie, Jing
Food chemistry 2011 v.124 no.2 pp. 569-575
Pyrus pyrifolia, cell membranes, cellulose, coatings, cold storage, edible films, endo-1,4-beta-glucanase, enzyme activity, firmness, hemicellulose, pears, pectinesterase, pectins, permeability, peroxidase, polygalacturonase, sucrose polyester
To investigate the effects of edible coatings, such as shellac and Semperfresh™ (sucrose-polyester based coating) on the brittleness and firmness of Huanghua pears (Pyrus pyrifolia Nakai, cv. Huanghua), the changes in the cell-membrane permeability and cell-wall constituents, such as total pectin (TP), Na₂CO₃-soluble pectin (NSP), CDTA-soluble pectin (CSP), water-soluble pectin (WSP), hemicellulose and cellulose were periodically measured, for up to 60days of cold storage (4°C) after harvesting. The activities of peroxidase (POD), pectinesterase (PE), polygalacturonase (PG), and cellulose were also assayed. The data suggested that high POD activity and low activity of cell-wall-degrading enzymes, such as PE, PG, and cellulase in the coated pears were associated with a high integrity of the cell membrane and few changes in the cell-wall constituents, which contributed to high levels of brittleness and firmness in the pears during storage; further, the shellac coating provided a better effect than Semperfresh coating.