Firmness is one of the important parameters reflecting the postharvest storage characteristic of fruits. It is related to tissue softening. Loss of firmness caused by the loss of integrity of cell wall structure leads to wilting and shrinking of fruits (Qi et al., 2011).
As shown in Fig. 1b, firmness of the initial samples was 3.19 N before
any treatments. After 1 day of coating processing, firmness of calcium treated groups was significantly (P < 0.05) higher than untreated control group. With calcium salt treatment, the firmness of fruit increased slightly in the first couple of days of storage; this might be due to chelate effect of calcium ions on pectin and other
related macromolecules within fruit flesh, leading to increased
firmness.