CANNING The same principles and methods are used in canning as bottling, the chief difference being that metal, and not glass, containers are used, and the method of sealing is therefore different.
Canning has the advantage that it occupies less time than bottling and less care is necessary as there is no risk of breakage. It has not been widely practised by housewives, chiefly owing to the fact that until recently soldering was necessary, a process which the majority of women found difficult. This drawback no longer exists, for a small hand sealing machine is now available which eliminates soldering. Numerous tests with the machine have been carried out and the results are invariably extremely satisfac tory and reliable. In conjunction with the hand sealer, special straight sided sanitary cans with open ends must be used. The cans may be either plain or lacquered. The latter are preferable, as they prevent the acid fruit coming in contact with the tin. The outer rim of the lid has a groove which is treated with rubber solution and which acts in the same way as the flat rubber band used when fruit bottling.
position and with the aid of the sealing machine close the can. As the escape of steam exhausts the air it is important to seal the can whilst very hot ; therefore only two or three should be filled with boiling syrup at one time, otherwise they cool down before there is time to seal them. (3) When all the cans have been sealed, place them in any large container, such as a clothes boiler, large pan or zinc bath containing sufficient boiling water to cover them completely. (4) Bring to the boil and boil gently for 15-40 minutes, according to the fruit. Small soft fruit requires 15 min utes only, and pears from 35 to 4o minutes. The time must be calculated from the moment the water boils again after all the cans have been put in. Small bubbles rising from the can whilst it is in the water indicates that it is not airtight, and has been sealed im perfectly. The contents must be removed, put into a new can and resealed. (5) When sterilizing is complete, cool the cans quickly by placing them in a bath or sink of cold water. When cold, dry and label. (See also FOOD PRESERVATION.)