in place by a metal screw band during processing. The flat lid is crimped around its bottom edge to form a trough, which is filled with a colored gasket material. When jars are processed, the lid gasket softens and flows slightly to cover the jar-sealing surface, yet allows air to escape from the jar. It is best to buy only the quantity of lids you will use in a year. Never reuse lids. To ensure a good seal, carefully follow the manufacturer’s directions in preparing lids for use. Examine all metal lids carefully. Do not use old, dented, or deformed lids or lids with gaps or other defects in the sealing gasket. Follow the manufacturer’s guidelines enclosed or on the box for tightening the jar lids properly.
•If screw bands are too tight, air cannot vent during processing, and food will discolor during storage.
•Over-tightening also may cause lids to buckle and jars to break, especially with pressure-processed food.
•If screw bands are too loose, liquid may escape from jars during processing, seals may fail, and the food will need to be reprocessed. Do not retighten lids after processing jars. As jars cool, the contents in the jar contract, pulling the self-sealing lid firmly against the jar to form a high vacuum. Screw bands are not needed on stored jars. They can be removed easily after jars are cooled. When
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removed, washed, dried, and stored in a dry area, screw bands may be used many times. If left on stored jars, they become difficult to remove, often rust, and may not work properly again.
3.Canning methods: There are two safe ways of canning, depending on the type of food being canned: the pressure canning method and the boiling water bath method.
PRESSURE CANNING METHOD: With the pressure canning method, the jars of food are placed in 2 to 3 inches of water in a pressure cooker and heated under pressure at a temperature of 240 °F or above for a specific length of time, which differs for every recipe. Pressure canning can be used to can all types of food. It is also the only safe method of canning low acid foods, which have a ph greater than 4.6. Low- acid canned foods are not acidic enough to prevent the growth of the bacterium Clostridium botulinum, which may cause botulism. To destroy the bacteria, foods must be processed at a temperature
of at least 240ºF, which can only be reached in a pressure cooker. Processing foods under pressure at a temperature of 240 ºF during an adequate time ensures the destruction of the largest number of heat-resistant microorganisms in home-canned foods. Low-acid foods include all vegetables, meats, poultry, and seafood. This method is also recommended for canning such items as soups, stews and chili.
Note: Although considered fruit, tomatoes have a ph value close to
4.6.Therefore, you should typically process them in a pressure canner. WARNING: 240 ºF can only be reached in a pressure cooker/canner. Never attempt to can low acid foods using the boiling water bath method.
Instructions for pressure canning method:
Processing Instructions: Fill the jars. Allow the proper headspace according to processing directions for specific foods. This is necessary so that all the extra air will be removed during processing, and a tight vacuum seal will be formed. To make sure that air bubbles have not been trapped inside the jar, run a bubble freer or any plastic or rubberlike utensil around the edges of the jar, gently shifting the food, so that any trapped air is released. After the air bubbles have been removed, more liquid may need to be added to the jar to ensure proper headspace. Wipe off the rims of the jars with a clean, damp cloth. Screw on the lids, but not too tightly — air needs to escape during processing. Set the jars of food on the rack and lower the rack into the pressure cooker so steam can flow around each jar. Add 2-3 inches of boiling water to the bottom of the cooker (pour it between the jars, not directly on them, to prevent breakage). Put the lid on the cooker. Once pressure is reached, keep the pressure constant by regulating the heat under the pressure cooker.
Do not lower the pressure by raising or lowering the heat during the processing. Keep drafts from blowing on the pressure cooker. Fluctuating pressure causes loss of liquid from jars and underprocessing. When the processing is completed, carefully remove the pressure cooker from the heat. If the pressure cooker is too heavy, simply turn it off.
WARNING: Let the pressure in the pressure cooker drop to zero using the natural release method. Do not use the cold water pressure release method for pressure canning.
Never use the automatic release method to hasten the reduction in pressure when canning foods. When the pressure cooker is depressurized, unlock the lid and tilt the far side up, so the steam escapes away from you. Use a jar lifter to carefully remove the jars from the pressure cooker. Place the hot jars on a rack, dry towels, boards or newspaper, right side up to prevent the jars from breaking on contact with a cold surface. Leave at least 1inch of space between the jars. Do not tighten the lids. Allow the jars to cool, untouched for 12 to 24 hours.
BOILING WATER BATH METHOD: The boiling water method is
safe for high-acid foods such as fruits and pickles, as well as pie filling, jam, jellies, marmalade and other preserves. In this method, jars of food are heated by being completely covered with boiling water (212 ºF at sea level).
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