The purpose of this work was to study the structural changes of the cell wall during the storage of 'Orange Flesh' melon submitted to postharvest treatment with CaCl2. The content of cellulose, hemicellulose, pectic substances and their degree of esterification, proteins and calcium was determined in the cell wall of the flesh of the fruits stored under ambient temperature and refrigeration. The hot-water treatment for immersion in CaCl2 of 'Orange Flesh' melons stored under ambient temperature determinated, apparently, an increase in the concentration of calcium bound to cell wall of the flesh of the fruits, besides partially inhibiting the breakdown of pectic substances and their de-esterification and to promoting the solubilization of proteins of the cell wall, although it did not influence the changes of the cell wall compounds except that of the polyuronides, in the fruits stored under refrigeration at 6ºC. In spite of calcium treatment, the storage of 'Orange Flesh' melon for 28 days at ambient temperature showed a decrease in the levels of cellulose and protein and a substantial de-esterification of the pectins, although it did not affect, apparently, the content of hemicellulose and promoted a relative increase in the polyuronides and calcium bound to cell wall. The fruits stored under refrigeration showed a few changes of the cell wall compounds, despite the fact that a reduction in the degree of esterification was noticed during the 31 days of storage.
melon cell wall; melon postharvest; calcium postharvest treatment
