Thursday, April 19, 2012
Canning and Drying Part 4 - Methods of Processing
(From the Women’s Institute Library of Cookery 1925)
Methods of Processing:
Canning Methods can be broken down into two steps:
1) The Preparation of the food to be canned – sterilizing the jars and lids, preparing the food, filling the jars, and covering them.
2) The Processing of the jars to be sealed – whether by pressure or water-bath
Open Kettle Method Processing
In the old days, housewives began preserving food using the open-kettle method.
· Preferred method of canning during the late 19th and early 20th Centuries
· Requires on minimal, common, equipment
· Cooking the food to be canned, transferring it into jars, and sealing the jars
· Does not process the jars, but uses heat from the food to seal the jars
· Exposure of food without sterilization, liable to contamination between cooking and filling the jars.
· Danger of contaminating contents before the jar is closed and sealed – mortally dangerous botulism poisoning because botulism spores are pervasive in the air.
· No longer used, considered to be unsafe
Equipment (All utensils touching the food must be sterilized):
1) Large enamel or metal saucepan to cook food
2) Measuring utensils
3) Large pot to sterilizing jars, rubbers, and lids,
4) Large spoons
1) Sterilize jars, rubbers, and lids. Wash them thoroughly and boil them in clear water for 15-20 minutes
2) The food to be canned should be picked over, with bruised, damaged, and decayed parts, removed. Seeds, leaves, roots, stems, etc. should be removed too. Then the food should be washed free of dirt and grime.
3) Cook the food. Fruit is usually prepared with syrup until softened. Vegetables are usually cooked with salt and water until soft.
4) Transfer the food to sterile jars, filling them well, and seal them with the jar lids and rubbers. Invert the jar for the food to cool and the jar to seal properly. Make sure it has sealed, and does not leak.
· Jars are sterilized and filled with food, placed in a pan of shallow water in the slightly warm oven. The jars with the food in them are not sealed but the jar lids without the rubber seal is placed on loosely. The oven temperature is raised until the water in the pans boil and then baked for another 30-45 minutes. After the food is cooked in the oven, the jars are removed, filled to be brim with boiling water or syrup, and sealed tightly.
· Similar to the open-kettle method, also subject to serious contamination but slightly less dangerous.
· May be difficult and dangerous to handle hot jars in the oven
Water Bath Processing
· Water bath processing is sterilized the filled jars of food in a large stock pot covered by 1-2 inches for water for a time, so that the interior temperature of the jar is raised and unwanted dangerous bacterial spores are eliminated.
· Today, water-bath canning, though safer than open-kettle processing, is generally discouraged by professionals in the food safety industry especially with regards to low-acid foods, because the temperature during processing cannot be high enough to completely eliminate bacterial spores. A large concentration of acids in certain foods contributes to the elimination of bacterial spores and are thus (still) condoned (but not encouraged) by food safety experts.
· The Amish have been canning foods using the waterbath method for generations just like all housewives in the early 20th did. They suffer no ill-consequence because of their simple meticulous hygiene. They do not follow modern fads and advise of modern “professionals” but keep doing things the old way. Their simple values include disposing of any canned food that is questionable, such as food with the lids unsealed or with a bad odor. If you are careful, the water-bath method can work. This is a decision you have to make for yourself. Take care to learn from someone who still follows the old ways and can help you. Do not take risks if you are ignorant.
Pressure Cooker Processing
· Pressure canning is by far the most efficient way to can food if you have the proper equipment. It heats food using pressure, and thus saves on gas/coal heating because it uses steam pressure. It also saves cooking time, because it heats and sterilizes food to higher temperatures in a quarter of the time compared to water-bath canning. It produces the safest and most sterile food of all the methods.
· You need the proper processing equipment to do pressure-cooker canning. You need a tall, sturdy, and safe pressure cooker. You also need new, strong jars without blemishes like chips that can withstand pressure. You need jars specifically made for canning, like Ball’s. These jars can be reused, but you cannot reuse mayonnaise or tomato sauce jars any more for pressure canning as they will crack under the heart.
· The preparation and sterilizing of the food and jars for pressure-cooker processing is exactly the same as the water-bath method.