OVEN METHOD
51. The OVEN METHOD of canning is thought to be very satisfactory by many housewives, but, as it is necessary to remove the covers after cooking the contents of the jars, food canned in this way is subjected to contamination, just as in the open-kettle method. In addition, the jars are difficult to handle in the oven, owing to the extreme heat that is required to cook the food in the jars.
52. In canning by the oven method, proceed by preparing the food as for the cold-pack canning method; also, fill the jars with fruit or vegetables and with liquid or sirup as in this method. Put the covers on the jars loosely, omitting the jar rubbers. Place the jars in a shallow pan of water, as in Fig. 21, and set the pan containing the jars into a stove oven, which should be only slightly warm. At the same time place the jar rubbers in a pan of boiling water, so that they may be sterilized as the food cooks. When the jars are in the oven, increase the heat gradually until the food in them boils. Then keep up a temperature that will allow the food to boil quietly for a period long enough to cook it soft and sterilize it. Usually, 30 to 45 minutes after boiling has begun will be sufficient. During the cooking some of the liquid in the jars evaporates. Therefore, when the jars of food are ready to be removed from the oven, have boiling water or sirup ready, remove the cover of each jar in turn, and fill the jar brimful with the liquid. Then place a sterilized rubber in place and fasten the cover down tight. The procedure from this point on is the same as in the other canning methods.
CANNING VEGETABLES AND FRUITS
PREPARATION FOR CANNING
53. In canning, as in all other tasks related to cookery, the housewife's aim should be to do the greatest amount of work, and do it well, with the least effort on her part. The results she gets in canning, then, will depend considerably on the orderly arrangement of the utensils and materials with which she is to do the work. But of greater importance is the preparation she makes to eliminate as much as she can the possibilities of contamination, for, as has been repeatedly pointed out, success in canning depends on the absence of dangerous bacteria.
54. From what has just been mentioned, it is essential that everything about the person who is to do the work and the place in which the work is to done should be clean. Clean dresses and aprons should be worn, and the hands and finger nails should be scrupulously clean. The kitchen floor should be scrubbed and the furniture dusted with a damp cloth. Any unnecessary utensils and kitchen equipment should be put out of the way and those required for canning assembled and made ready for the work. The jars should be washed and the covers tested by fitting them on without the rubbers. If a glass cover rocks, it does not fit correctly; and if a screw cover will not screw down tight, it should be discarded. Without the rubber, there should be just enough space between the cover and the jar to permit the thumb nail to be inserted as is shown in Fig. 3. The edge of each jar and each glass cover should be carefully examined every time it is used, so that none with pieces chipped off will be used, as these will admit air. This examination is made by running the finger over the edge of the jar and the cover, as is shown in Fig. 4. The jars, covers, and rubbers should be put into pans of cold water, and the water should be brought to the boiling point and allowed to boil for 15 minutes or more while the fruit or vegetables are being prepared for canning. They should be kept in the hot water until the food is ready to be placed in them. In the one-period cold-pack method, it is not necessary to boil the jars, rubbers, and covers, but this may be done if desired.