Agriculture Reference
In-Depth Information
Fig. 7.17.
Percentages of leeks cv. 'Acquisition' in top-quality grades, based on
weight at input, after 5 months' storage at 0°C in different O
2
concentrations in 0.5
or 10% CO
2
(averages of 3 years' data) (from Hoftun, 1978b. Courtesy of
Meldinger
fra Norges Landbrukhogskole
).
prolonged storage at 15% CO
2
, some internal damage to leeks occurs, and
storage at 20% CO
2
causes the tissues to collapse.
In terms of practical conclusions, these trials have shown that it is possible
to maintain trimmed leeks at a high quality for about 2 months when they are
stored upright at -1 to 0°C and at 95% RH. This duration of storage can
probably be approximately doubled by using, in addition, a near-optimal
controlled atmosphere, like 10% CO
2
and 1% O
2
. Leeks should be cooled down
to the storage temperature as soon as possible after harvest. They should be
slowly warmed up after storage, using a temperature around 5°C, and should
be kept at low temperature and high RH during marketing.
Green, leafy onions cut for fresh salad use are at the opposite end of the
vegetable storability spectrum to the naturally dormant onion, shallot or garlic
bulb, being a highly perishable commodity with much in common with other
leafy salad vegetables. For example, the data of Hong and Kim (2001) show
that at 20°C green
A. fistulosum
respired approximately 20 times faster than
dormant bulb onions, while at 10°C the difference was a factor of eight and at
0°C a factor of seven.
After harvesting, green onions are prone to rapid water loss leading to
limpness and loss of turgor. They have a high respiration rate typical of young,
growing plants and therefore internal reserves of carbohydrate decline rapidly.
