SPOILAGE. 29 



therefore more likely to be associated with rush operations and flat 



H MI iv with ;iii overwork <>r delay in getting at the raw material. It 

 is not intended to give the impression that swells and sours may not 

 occur under other conditions, such as changes in the consistency of 

 the corn, nor that s\vi-ll> may not occur in material which has stood, 

 and sours result from underprocessing, but only to state a general 

 rule. 



Swelling or souring may take place shortly after processing or 

 the spoilage may be delayed for weeks or even months. Swelling 

 is more likely to occur and be detected early, while souring is apt to 

 be delayed, though it may occur early. The heat used in processing 

 may have been insufficient to kill the vegetative forms or spores, but 

 may have injured them to such an extent that time was necessary for 

 recovery and subsequent development. A microscopic examination 

 of the material a few days after processing, or of the incubating cans 

 during a short period, might not show anything wrong. It is only 

 by incubating samples for a number of days that early recognition 

 can be made of some cases of spoilage or possible spoilage. The 

 canner often sends his goods from the factory with full confidence 

 in their condition, and it is not until after they have been in the 

 broker's warehouse or upon the grocer's shelves many weeks or even 

 months that he becomes aware that anything is wrong. The spoilage 

 may amount to only one can to the case, or the percentage may be 

 high; but in either event the goods are rejected with loss. 



Spoilage from the use of improper material i. e., material which 

 has been allowed to stand until fermentation has begun is generally 

 more or less sour to the smell and taste, but is sterile, the heat of 

 processing having killed the bacteria. 



Can leaks may occur along the side, " seam leaks " ; at either end, 

 "end leaks"; at the cap, "cap leaks"; at the tip, "tip leaks"; or 

 may be due to defective tin plate. Can making has reached such a 

 point of perfection that manufacturers guarantee all above two to 

 the thousand. These imperfect cans are usually due to the solder 

 not making a perfect union or to defects in crimping or double seam- 

 ing. With the use of the automatic capping and tipping machines 

 there are fewer leaks than formerly occurred when the work was done 

 by hand; leaks in sanitary cans are generally due to poor adjustment 

 of the rollers. Leakers are recognized, as a rule, by inspection in 

 the hot bath, few getting into the wareroom. Leaks may be very 

 small, even microscopic in size, and, therefore, difficult to detect, or 

 pieces of the can content may be driven into the opening and seal it 

 for the time. Leaks invariably cause swells. A check on spoilage 

 can be kept by placing a few cans from each day's run in a room kept 

 at a high temperature (98) , as these will incubate much more rapidly 

 than if kept in a storeroom. 



