ment, especially after 14 days of storage (L
⁄
35.00 ± 0.52,
36.06 ± 0.37, 36.31 ± 0.40, and 36.65 ± 0.47 in control samples
and those exposed to ozone at 0.45, 0.9 and 2 lmol mol
1
, respectively), suggesting that characteristic dark green colour could be
bleached by ozone, due to accelerated chlorophyll degradation.
This was further confirmed by hue angle being significantly
reduced from 132.2 ± 0.6 in control to 128.6 ± 0.3, 129.4 ± 0.2,
127.8 ± 0.2 in chilli peppers exposed to ozone at 0.45, 0.9 and
2 lmol mol
1
. However, these differences were not always visually
obvious.
It has previously been reported that continuous exposure to
ozone at 0.1–0.3 lmol mol
1
had no significant effect on skin colour of red bell peppers (Glowacz et al., 2015b). Similarly, the colour
was not affected in minimally processed peppers treated with
ozone at 0.7 lmol mol
1
for up to 5 min (Horvitz & Cantalejo,
2012). The findings from this study, however suggest that: i) there
is a threshold in the ozone dose, i.e. continuous exposure at above
1 lmol mol
1
, that would affect colour of red chilli peppers; ii)
green chilli peppers are more sensitive to ozone than red ones.
3.4. Firmness
Both, green and red chilli peppers showed softening during
storage (Table 2). In red chilli peppers firmness was reduced during
storage in all treatments, but was less pronounced in samples
exposed to ozone, being highest at 0.9 lmol mol
1
. In the case of
green chilli peppers no significant difference was observed
between control samples and those exposed to ozone, regardless
of the dose used. However, firmness maintenance seemed to be
improved in ozone exposed chilli peppers at day 10, i.e. the loss
of firmness was reduced/delayed. Improved firmness maintenance
in ozone exposed chilli peppers is in agreement with findings previously reported for chilli peppers exposed to ozone at
30 lmol mol
1
for 10 min prior to storage at 8 C (Chitravathi
et al., 2015).
It has been suggested that in the commodities, where the exposure to ozone can significantly reduce water loss during storage,
firmness maintenance would be improved (Glowacz et al.,
2015b) and in agreement with this, weight loss was also found
to be reduced in ozone exposed chilli peppers (Chitravathi et al.,
2015).
Several studies have already reported better firmness retention
in ozone exposed fruit, e.g. in cucumbers and courgettes continuously exposed to ozone at 0.1 lmol mol
1
(Glowacz et al.,
2015b), in tomatoes cyclically exposed to ozone at 4 lmol mol
1
for 30 min every 3 h (Aguayo, Escalona, & Artes, 2006), and continuously exposed to ozone at 0.05 lmol mol
1
and 1 lmol mol
1
(Tzortzakis, Borland, Singleton, & Barnes, 2007).