8 BULLETIN 196, U. S. DEPARTMENT OF AGRICULTUEE. 



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 

 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 

 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 

 stuffers." Vast improvements have beeii made in filling machmes 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 

 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. 2 J and No. 3 cans should be left. The 

 amount of head space needed depends in a measure u^Don the natm-e 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 rare. 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 suflacient 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 worka 

 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 temperatui'e 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 sii-up, 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 "cut-out" is the finished product and is judged by appearance, color, consist^iicy, odor, flavor, 

 and weight of contents as a whole and of the solids and liquids separately. 



