3.4. Effect of edible coatings on i

3.4. Effect of edible coatings on initial respiration rate
The physical damage or wounding caused by peeling and cutting
increases respiration rate within minutes, thus the need to reduce initial
respiration rate is critical in extending shelf-life of minimally processed
fruits. Fig. 5. shows the effect of chitosan edible coatings on initial
respiration rate. All formulations tested reduced initial respiration rate,
and 2%AA+0.5%CaCl2 +1% chitosan had a significantly greater effect
than others. Initial respiration rate showed a decrease by about 5% and
20% in the 2%AA+0.5%CaCl2+1% chitosan apple slices, Their waterinsolubility
and oxygen barrier properties made them suitable as coating
to achieve internal modified atmospheres (MA) within a fruit system.
Another possible reason for the large reduction of initial respiration rate
in chitosan-coated apples is the effect of calcium ion contained in the
aqueous chitosan solution. Calcium ion is known to inhibit respiratory
activity and ethylene production. Wong, Tillin, Hudson, and Pavlath
(1994) investigated that polysaccharide/lipid bilayer formulation reduced
respiration and ethylene production of cut apples due to the
diffusion barrier properties of the lipid layer and the inhibitory effect of
the ascorbate buffer containing calcium. However, considering the 1 g/
100 mL concentration of CaCl2 in the 1% chitosan solution, the observed
large reduction of initial respiration rate seems to be due to oxygen
barrier properties of chitosan coating rather than the effect of calcium ion.