3.4. Changes in color
Color of mango skins is an important selection criterion for
buyers. It can give an indication of the state of fruit ripening. As
shown in Fig 2, noticeable changes in the skin color occurred
during storage. Uncoated mangoes lost their green color (a* > 0)
unlike coated fruit that maintained this color (a* < 0). Chitosan
concentration at 1.5% seemed the best to maintain green color.
The presence of LPOS did not influence color change, and thus the
action of the coating in slowing ripening was correlated with
the concentration of chitosan and was not dependent on the
presence of the LPOS.
3.5. Firmness
Mango is a soft fruit that suffers a rapid loss of firmness during
ripening which contributes greatly to its short postharvest life.
Fig. 3 shows the changes in flesh firmness of control and treated
fruit after eight days of storage. Initial flesh firmness decreased for
all treatments, however chitosan coatings retained more initial
flesh firmness of fruit in contrast to uncoated fruit. An overall
comparison showed that there was no significant difference
between chitosan at 1% or 1.5%. This same result was observed with
the use of chitosan incorporating LPOS or LPOSI. LPOS with or
without iodine did not influence chitosan protection against
firmness lost. These results indicate that fruit firmness is preserved
by chitosan coating and not by the presence of the enzyme system.
Reduction of respiration and water loss could be responsible for the
retention of firmness. Using a suitable coating could maintain that
strength .