460 TWENTY-SECOND ANNUAL YEAR BOOK— PART VI 



The question of swelled goods is a more serious problem, 

 and where such goods are found, they should be condemned 

 and if possible, thrown on the dump in the inspector's presence. 

 The slightest bulge in the end of a can is just cause for condem- 

 nation, as this is due to pressure from the inside from gases 

 produced by fermentation or bacterial action, especially is this 

 true in the case of such foods as peas, corn, etc. However, in 

 acid fruits, swelling is often caused by the action of the fruit 

 acids on the tin which liberates hydrogen gas in sufficient 

 amounts to bulge the ends of the can, except where the can is 

 leaky in which case the swelling is due to decomposition. The 

 action of the fruit acids on the tin is also influenced by the 

 temperature, being hastened when the goods are stored in a 

 hot climate or under a metal roof during the hot summer 

 months in this climate and retarded when held in a cool store 

 room or during the winter months. It can be easily seen then 

 how under certain conditions cans may be normal and under 

 others ''springers". Where there is doubt in the inspectors' 

 mind regarding canned goods, an inspection of the contents of 

 the can will solve the matter. 



The number of vent holes in the top of a can is one which 

 might be misleading. More than one vent hole is no proof that 

 the goods have been reprocessed as some canners still seal the 

 can before cooking and when the cans are removed from the 

 kettles they are punctured to allow the air to escape, resoldered 

 and put into the kettles and cooked the second time. Even a 

 third vent hole is sometimes made when the second hole has 

 failed to give the proper exhaust, due to particles of the con- 

 tents stopping the hole. With the sanitary can whose use is 

 becoming so common it is possible to find a vent hole although 

 this is unusual and occurs when by mistake the brine or 

 liquid has been left out and is placed in the sealed cans by 

 means of a vent hole. Also some salmon and crab canners 

 still prefer to vent the sanitary cans and give them a short 

 cooking in the retorts before sealing. Sometimes upon open- 

 ing a can of beans or peas there is a discoloration on the 

 sides of the can and even on top of the food. This color 

 which is usually black or nearly so is due to a very thin 

 film of metallic sulphide in colloidal form. There is not enough 

 of these materials present, however, to be injurious while they 

 present a suspicious appearance and usually result in com- 



