Respiration rate
Table 1 shows O2 consumption and CO2 produced from
uncoated and coated mangoes with 1 and 1.5% of chitosan
incorporated with LPOS or LPOSI. Significant differences (p < 0.05)
were found with the lowest O2 consumption and highest CO2
production observed for coating mangoes. These results indicated
on the whole that chitosan coating reduced the respiration rate of
mangoes by decreasing O2 and increasing CO2.
Regarding the O2 consumption, there was no significant
difference between mangoes treated with chitosan at 1% and 1.5%. The presence of the enzyme system (LPOS or LPOSI) did not
affect O2 consumption. These results confirmed these obtained by
Cissé et al. (2012), who demonstrated that the diffusion of O2 could
be reduced by a chitosan film. The addition of the LPOS with or
without iodine did not alter the permeability of the film. Other
work has also highlighted the reduction of O2 permeability in
coated fruit by chitosan films; Thumula (2006) showed that
chitosan could reduce the oxygen consumption of tomatoes.
Concerning CO2 production, there was no significant difference
observed between coated and uncoated mangoes after two days,
with production from coated mangoes increasing sharply to the
sixth day. The increase in CO2 production of coated fruit may be a
stress response due to the treatment (El Ghaouth et al., 1992). The
strong CO2 production caused by chitosan coatings has been
demonstrated by other authors (El Ghaouth et al., 1992; Thumula,
2006). No significant difference in CO2 production was observed
between mangoes treated with two concentrations of chitosan
(1% and 1.5%) combined or not with LPOS or LPOSI.