Calcium uptake and efflux, ion leakage, internal air space and cation exchange capacity in relation to mealiness in nectarine tissue

Abstract

Abstract Cool stored nectarine (Prunus persica) fruit (6 weeks at 0°C) ripen abnormally and develop a dry, mealy texture with low levels of extractable juice. Effects of mealiness on calcium uptake and efflux, cation leakage and internal air space of the tissue as well as the cation exchange capacity of the cell wall material have been investigated. Mealy fruit tissue had higher rates of calcium uptake and efflux, internal air space and cation exchange capacity than that from normally ripened fruit. In both normally ripened and mealy nectarines, ion leakage increased during the ripening period, although leakage of individual cations showed differences between ripe and mealy tissue. It is suggested that differences between properties of normally ripened and mealy fruit are due to changes in the cell wall character and can be expressed in terms of calcium binding and retention properties possibly involving the binding of water into the cell wall in a calcium pectate gel.