Ms. Tian et al., CHANGES IN COLOR AND CHLOROPHYLL FLUORESCENCE OF BROCCOLI FLORETS FOLLOWING HOT-WATER TREATMENT, Journal of the American Society for Horticultural Science, 121(2), 1996, pp. 310-313
Hot water treatments (HWTs), at a range of temperatures (43 to 55C) an
d durations (10 sec to 30 min), were applied to floret groups of 'Shog
un' broccoli (Brassica oleracea L. var italica) directly after harvest
, Floret groups were then stored at 20C in the dark for 3 days. A rang
e of optimal treatments was found in which yellowing was markedly redu
ced, acid heat damage (water soaking and decay) did not occur. Chlorop
hyll fluorescence measurements indicated that in the optimum treatment
that prevented yellowing the FvFm ratio following HWT decreased immed
iately and was maintained at a constant level for the next 3 days. A f
urther experiment examined the effect of HWT durations up to 20 min at
47C on fluorescence and yellowing, Longer durations of HWTs (>5 min)
progressively reduced yellowing and the F-v/F-m ratio. From these thre
e experiments a HWT of 47C for 7.5 min was selected as the best treatm
ent, This treatment consistently reduced yellowing for up to 5 days. A
decrease in the FvFm ratio may be a useful indicator of broccoli flor
ets response to hot water treatments.