8 BULLETIN 196, U. S. DEPARTMENT OF AGRICULTURE. 
by machines. The filling may be done by hand or by machine. There are many | 
products, especially fruits, which can not be successfully filled by machine because i 
of crushing or otherwise injuring them. When filled by hand, the contents should 
be regulated by weight rather than by volume, so that the finished product will be | 
uniform. If the filling be done by machine, care should be taken to get the best I 
results possible. It is illogical to use care in peeling a 3-inch tomato and then have | 
it squeezed through a 2-inch opening in front of a crude plunger, or that great care | |! 
should be exercised in washing and blanching peas which are to be run through a ||! 
filler that will cut or crush enough to make a muddy liquor. Machines should be }! 
designed to fill with reference to the nature of the product and not to be merely “‘can }- 
>) 
stufiers. 
given weight, and for most products this method is very satisfactory. In all cases, 
whether the can be filled by weight or volume, the amount of material used should 
be all that can be put in the can in first-class condition. Brining and siruping have | 
also been improved, the old-fashioned unsanitary dip box giving way to a sanitary | 
filler. 
In filling the cans head space equivalent to at least one-fourth of an inch for No. 2 | 
cans and about three-eighths of an inch for No. 24 and No. 3 cans should be left. The | 
amount of head space needed depends in a measure upon the nature of the product, 
but without some space the production of a small amount of gas will destroy the | 
vacuum. In the hole and cap cans this space is available, because the sealing can 
not be done without some room, and as a result springers are raré. The tendency © 
is to overfill the open-top cans. If the product is poured in the cans very hot, 180° F., 
the expansion which it has undergone will insure sufficient space. In general, any 
fruit or vegetable sealed at a temperature of 160° F., or higher, will have sufficient 
head space to prevent springers or flippers. The later types of sanitary capping 
machines are provided with plungers to squeeze out the overfill of cans. This works 
well upon such products as have liquids, but fails upon all solids, as sweet potatoes. 
EXHAUSTING. 
After the cans are filled they should be exhausted—that is, heated until the con- 
tents are hot and as much as possible of the air driven out. This process is not con- 
sidered necessary for articles that are subjected to forecooking, as corn, or for those 
that are kettle cooked and filled hot, and it is not generally employed with such 
products as peas and beans, which receive a hot brine, although it is advantageous 
even under these conditions. 
The time required for exhausting depends upon the degree of heat required in the 
product and the rate at which it penetrates. For such products as corn, peas, beans, 
pumpkin, squash, and sweet potatoes, a temperature of 180° F., or higher, is desirable. 
For fruits and tomatoes a temperature of 135° F. will suffice. With good equipment, 
the work can be done in from one and one-half to eight minutes. For products which 
will stand the high temperature the steam is turned into the heater under a fairly 
strong head and the perforated pipe made to spray directly against live steam pipes, 
so that it may have the effect of superheating. With fruits the heating should be 
less vigorous and the time rather extended. Too high a temperature causes fruit to 
swell and float on the top of the sirup, as well as to soften and break open, and it is 
better to take four or five minutes, rather than two minutes, in reaching 135° F. For 
hard pears or peaches an eight-minute exhaust will give a better article on the ‘“‘cut- 
out’! than is obtained by so much extra cooking in the can. For tomatoes a rather 
1 The “eut-out” is the finished product and is judged by appearance, color, consisrcy, odor, flavor, 
and weight of contents as a whole and of the solids and liquids separately. 
Vast improvements have been made in filling machines in the last few | 
years, so that most of the work can be done with nicety and precision. All filling | 
machines operate upon the principle of delivering a certain volume rather than a | 
