The safe Preservation of food has always been crucial to Human survival. From the most remote periods of antiquity people have sought methods to render food resistant to spoilage.
The preservation of food supplies was a critical factor in the development of early civilization. The inability to store foods from bountiful harvests, for times of famine and drought led to the downfall of many early societies.
Pickling, smoking, drying, and salting are some of the methods utilized. Preserves, such as Jams, Jellies, Marmalades, and Conserves are the form of canning this page deals with.
Jelly is a clear preserve from strained fruit juices , generally with added sugar.
Jams are thick spreads, and are less firm than jelly. They are made from crushed or chopped fruits with added sugar.
Marmalades are generally made from citrus fruits. they are essentially soft jellies containing small pieces of fruit and/or peel.
Preserves are made from small, whole fruits or uniform-size pieces in a clear, thick, slightly jellied syrup.
Conserves are jams made from a mixture of fruits, nuts, raisins ,coconut and so forth.
Equipment <PageTopGlass jars with lids and bands. Jars, undamaged, can be re-used, but the lids cannot.
A large pot for boiling the jars. A steam pressure cooker may also be necessary.
A jar lifter for safely removing the hot jars from the boiling water. It's special design securely grips around the jar.
A lid wand that safely removes the lids from boiling water.
A funnel for easily pouring liquid into the mouth of the jar.
A bubble spatula for removing air bubbles in the filled jars.
Cheesecloth , Jelly bag and stand, Colander,
Jelly or Candy thermometer. Many of these items can be purchased within Canning kits
Do not use copper, brass, iron or galvanized utensils . These metals may react with acids or salts and cause undesirable flavors, or even form toxic compounds in the mixture.
Wash glass jars.
Prepare lids according to manufacturer's instructions.
Fill jars uniformly with product.
Discard any cracked or chipped jars and any lids with blemished sealing surfaces.
Wash and rinse all fruits thoroughly before cooking.
Pectin, Acid and Sugar in Preserving
<PageTop*Pectin is a naturally occurring substance found in most fruits, it is necessary for gel formation. The level of pectin varies amongst various fruits and their degree of ripeness.
Soft fruits such as grapes ,strawberries and most berries contain very little pectin, while harder fruits such as Apples and Citrus contain larger quantities. Under ripened fruit [harder] has a higher pectin content. As fruit ripens, the pectin is changed to a nongel-forming substance.
Jams and jellies can be made from fruit that is not suited for canning or freezing so long as the fruit isn't overripe, moldy or spoiled.
Use 3/4 ripe-firm and 1/4 under-ripe fruit to make jams and jellies without adding pectin. Use fully ripe fruit to make jellied products with added pectin.
*Sugar, in addition to being a flavor enhancer also serves as a preserving agent, and aids in gelling. Cane sugar is the most common source. Corn syrup and honey may replace part of the sugar in some recipes, but too much will alter the flavor and the gelling process. The same is true of artificial sweeteners. Use tested recipes for replacing sugar with other products. Do not try to reduce the amount of sugar in traditional recipes. Too little sugar prevents gelling and may allow yeasts and molds to develop.
The acidity of food influences processing. Foods are grouped as "acid" and "low-acid" for purposes of selecting the correct processing method.
Acid protects against the growth of unwanted organisms, such as botulinum a/k/a botulism. Thus, heat treatments need not be as intense for foods in the "acid" group as opposed to foods in the "low-acid group.
The level of acidity is critical in gel formation. If there is too little acid, the gel won't set. If there is too much , the gel will lose liquid and separate. For fruits low in acid, add lemon juice or other acidic ingredients as directed. [Most commercial pectin products contain adequate acids to ensure gelling.]
When preserving low acidic foods, such as tomatoes, the USDA recommends that acid should be added to lower the pH level. This can be done by adding 1 tablespoon of lemon juice or 1/4 teaspoon citric acid per pint of product. For quarts, add 2 tablespoons of lemon juice or 1/2 teaspoon citric acid.
Foods with a pH below 4.6 are classified as "acid," while foods with a pH between 4.6 and 7.0 are classified as "low-in-acid." It might be more appropriate to describe the latter group as "low-in-acid." Foods in the "acid" group can be processed by the boiling water bath method.
Heat Treatments for Preserving, Canning
Boiling water bath canning is recommended for processing high-acid foods
Pressure Cooking under high heat for longer periods is recommended for low acid foods
Process jars in a boiling water canner or use the low temperature pasteurization treatment.
If you decide to do extensive home canning, it would be advisable to purchase a steam pressure canner or water bath canner. A steam pressure canner is basically a large pressure cooker which is used to process foods under high temperature and pressure. It will destroy bacteria that can cause sickness and spoilage.
A Water bath canner is a deep kettle with a wire insert that holds yourcanning jars. It's used to preserve pickles and other foods high in acids , such as fruits and berries.
To process foods in a boiling water canner, fill canner halfway with water and preheat to 180 F for hot packs or 140 F for raw packs.
Load sealed jars into the canner rack [Jar rack] and lower with handles or load one jar at a time with a jar lifter onto rack in canner.
Cover canner and turn heat to high. Add water if needed to a level of 1 inch above jars. When water boils vigorously, lower heat to maintain a gentle boil and process jars for the time given in manufacturers instructions,
To process using low-temperature pasteurization treatment, place jars in a canner filled halfway with warm (120 F to 140 F) water. Add hot water to a level 1 inch above jars. Heat the water and maintain 180 F water temperature for 30 minutes. Use a candy or jelly thermometer to be certain that the water temperature is at least 180 F during the entire 30 minutes.
After processing is completed, remove jars from canner with a jar lifter and place on a towel or rack. Do not retighten screw bands. Cool jars 12 to 24 hours and remove screw bands. Check lid seals. If the center of the lid is indented, the jar is sealed. Wash, dry, label and store sealed jars in a clean, cool, dark place. If the lid is unsealed, examine and replace jar if defective, use new lids, and reprocess as before. Wash screw bands and store separately. Home canned foods are best if used within a year but are safe as long as lids remain vacuum sealed.