CANNING SARDINES 143 
in at one end and out the other, so that they will be subjected to the 
average temperature. These conditions will give the desired results. 
Time.—As high air velocity and temperature as practicable have 
been recommended in order that the fish can be cooked and dried in 
the shortest possible time. Economy of time is important. It leads 
to many savings, among which the saving in quantity of equipment 
required is very important. About 15 minutes is sufficient even for 
very large pound-oval fish and for quarter-oil fish when prepared 
with air at the velocity and temperature recommended above. Here, 
again, exact recommendations can not be made for reasons already 
stated. It will be found, however, that the time can not be extended 
much over 15 minutes without undesirable changes taking place in 
the fish, unless the temperature is lowered. 
Some canners may not wish to remove as much water from their 
fish as will be taken out in 15 minutes under the above conditions. 
In this case the time can be shortened sufficiently to give the desired 
result. Itis to be remembered, too, that cooked fish lose considerable 
water when they stand on flakes exposed to the air for several hours 
(p. 108). Under some circumstances advantage can be taken of this 
fact to shorten the cooking period a little or to increase total moisture 
loss. If the trucks of cooked fish are allowed to stand a few hours 
they will cool and also dry to an appreciable amount. In fact, these 
effects can be accelerated by forcing a good draft of air through the 
cooling room. 
Humidity.—In commercial operations, in order to conserve heat, 
a large part of the air that passes over the fish should be recirculated; 
that is, it should be returned to the fan, mixed with more hot air, and 
again sent over the fish. This will increase the moisture content of 
the air in the cooker. Part of the air (probably not more than 10 
per cent) must be discarded, however, to carry out of the cooker the 
water that evaporates from the fish. The exact amount that can be 
recirculated will vary with different conditions and must be deter- 
mined by experience. It will be very easy to control recirculation, 
and no difficulty will be met. 
Moisture loss—Average size pound-oval fish and three-quarters 
mustard fish, prepared according to the recommendations given 
above, will lose about 13 to 16 per cent in weight. This is about 
right for fish that are to be packed in fairly thick sauce. Average 
size quarter-oil fish will lose about 20 to 25 per cent in weight. 
In practice a packer should vary his drying conditions some in order 
to get the exact results desired. In doing this it will pay ‘to deter- 
mine what loss in weight occurs, as this gives a good index to actual 
results. The loss is easy to determine, using ordinary kitchen 
scales. Weigh a flake of fish before and after cooking and from these 
weights subtract. that of the flake. This gives the weight of the fish 
before and after cooking. The difference between these is the loss. 
The loss divided by the weight of fish taken, multiplied by 100, gives 
the per cent loss in weight. 
Drippings from the fish.—Drip pans are needed whenever large, 
fat fish are being cooked; although it may turn out that they are not 
needed for quarter-oil fish, it is much safer to include them in equip- 
ment for preparing the fish. 
Minimizing breakage——Raw fish can be handled quite roughly 
without injury; for instance, they can be dropped 8 to 12 inches from 
