Abstract
Yellowing and wilting are the major postharvest losses of Chinese kale (Brassica oleracea
var. Alboglabra) during storage. This research aimed to investigate the effects of pre-treatments including i) hot water (HW) dipping at 45°C for 30s, ii) ultraviolet C irradiation (UV-C) at dose of 1.82 kJ m-2 and iii) a combined treatment between HW and UV-C (HW+UV-C) on the quality of Chinese kale compared with the control treatment during cold storage. After that,
all the samples were packed in perforated polyethylene bags before putting into storage at
10°C, 80-85% RH for 7 days. The results showed that leaves of the Chinese kale in the control
group become yellowing faster than other treatments. The control samples had a higher trend
in L*, b* values and Chroma compared with other treatments during storage periods of 7 days.
The control samples had the lowest hue angle (h° = 95.7) after 7 days of storage. However,
there was no significant difference in the changes of h° in all treatments during storage
periods. The samples pre-treated with HW+UV-C had the highest percentage of weight loss
(8.1 and 10.8%) while the control treatment or the samples treated with HW or UV-C alone
had significant (p < 0.05) less weight loss which was in the ranges between 2.3-3.5% and
3.0-5.1% after 5 and 7 days of storage, respectively. There was no significant difference in the
changes in chlorophyll content for all treatments during storage. In conclusion, the UV-C
treatment significantly (p < 0.05) delayed yellowness (especially, b* value), had less weight
loss compared with other treatments. The quality of Chinese kale was maintained by the UV-C
treatment during storage periods of 4-5 days.