With regard to Ca changes with time of storage, the free Ca
concentration in fresh-cut melon reached a maximum at day 3
but it decreased when time of storage was extended to 8 days
(Fig. 6B). As in experiment 1, this could be due to diffusion from
external to internal tissues, binding to pectin galacturonic acid
residues or the presence of Ca gradients. However, the lowest
bound Ca concentrations were measured on day 0, and they
increased on day 3 and were maintained with time of storage
(Fig. 6B). This could indicate that Ca needs less than 3 days to
interact with the pectic acid in the cell walls to form Ca pectate.