Bj. Pogson et Sc. Morris, CONSEQUENCES OF COOL STORAGE OF BROCCOLI ON PHYSIOLOGICAL AND BIOCHEMICAL-CHANGES AND SUBSEQUENT SENESCENCE AT 20-DEGREES-C, Journal of the American Society for Horticultural Science, 122(4), 1997, pp. 553-558
In most broccoli (Brassica oleracea L. var. italica) cultivars studied
, the loss of chlorophyll was marginal after 5 weeks cool storage (1 d
egrees C) + 2 days at 20 degrees C, but there was significant loss of
chlorophyll from some poor-storing cultivars, particularly after 10 we
eks cool storage (+2 days at 20 degrees C). Soluble sugars were deplet
ed rapidly during cool storage (especially sucrose) and were essential
ly exhausted after 10 weeks at 1 degrees C. Losses of total proteins w
ere only 20% after 10 weeks cool storage. There is preferential catabo
lism of carbohydrates (sucrose, glucose, and fructose) at low temperat
ures, whereas, at 20 degrees C, protein and carbohydrate levels declin
e concomitantly. The patterns of sugar and protein depletion suggest t
hat all soluble sugar is potentially accessible for metabolism, but pr
otein catabolism is targeted to specific tissues or organs. After 5 we
eks at 1 degrees C and placing at 20 degrees C, ethylene production an
d respiration increased to steady-state levels. Peak production of wou
nd ethylene usually occurs 4 to 6 flours after harvest at 20 degrees C
. After 5 or 10 weeks cool storage, this peak of production was not de
tected at 20 degrees C. After 10 weeks at 1 degrees C, recovery of eth
ylene production was delayed and the respiration rate only partially r
ecovered to the steady level. However, chlorophyll loss is the major d
eterminant of marketable life without cool storage, and, after 5 weeks
at 1 degrees C, postharvest decay is the major determinant of marketa
ble life after cool storage, particularly after 10 weeks at 1 degrees
C.