7 - part

(F.W. Liu)
The purpose of building caves for storage is to conserve coldness in rock or soil when ambient tem­
peratures are low, andi use this coldness to keep produce cool when ambient temperatures are high.
Japan uses underground storage systems that are already there, it is not building new ones. In Mainland
China, the labor cost is so low that they can afford to build new underground storage caves.
Northwest China haF a very heavy clay soil, with a texture that makes it very suitable for cave
construction Some well constructed caves can maintain a,temperature 5-6'C lower than the mean
temperature at that particular site. in higher altitudes in hotter climates, where nights are cold,
building caves can conserve this coldile:S in the ';nil.
In a true tropical clinia te, unless there ire "'old nights :)r a cool season, this type of storage is not
very useful. In a temperate ')rsubtropical co.itry, cave storage can save energy the primary
cost is labor, so vhere labor is cheap it can be very useful.
(W. Grierson)
Forty or fifty years ago in Canadwi, onyone who had a slope on his farm would have what was called
a 'common storage' dug back into the hill. Then, would he vents in the upper side, to trap cold air
rolling down the hill, while heat would rise straight tp. We hive tried to use the same principle to
build storage facilities in Jamaica, where an immense iniount of cold night air comes rolling down
from the hills. It k i:;, .ed ill California. in storage facilities locatedr etween the hills ard the
sea where sevral million ,x -,f lemons are kept it i steady 51 C, year i:l-ind year out.
2. Fumigation 'l'cl1ti(Ju(s Ii l0pItLUe I)K1l
One problem which re'ccie, coulhid'rahh (falfionl in the General l)iseti.ision was the recel banning
lit both IS.I and Jlapan 0 th, 1t1he ) ,i' nerall'r used ;r)jimflgne f'uil agailst ft'uit J'. As 'et tin
cheap replaceineut le, beenjfnnld,(nd iriou possible alternalive treatments were discussed.
(S C. Lin)
This morning I discusseci with fDr. Griersoit die possihle use of irradiation as an alternative to EDB,
but it seems to be too expensive. We have tried irradiatin'i lychee in Taiwan, and found that 15
kilorads was sufficient to kill all fruit flies. lowever, the cost was too high for us to be able to
use the treatment commercially.
(W. Grierson)
One problem in costing irradiation treatment i,to achieve sufficient volume. Our tests in Florida
have all involved pilot models which handle only a small quantity of fruit. Our first model could
handle only two grapefruit! Gradually we worked up t- one that could handle a carton of fruit.
However, in actual practice we would be dealing with a whole shipload of several hundred thousand
cartons of fruit, all needing to be processed within a (lay cr two. A pilot model to handle this volume
of fruit would ccsi US$2 million.
We should note that 15 kilorads were enough to kill fruit flies only when the fruit were laid out in
a singie layer for exposure to radiation. More kilorads would be needed if the layers of fruit were
deeper, and the outside fruit might then get too high a dose.
- 127 ­