Hgeocities.com/canningafrica/readytocan.htmlgeocities.com/canningafrica/readytocan.htmlelayedxJqZ[OKtext/htmlZ[b.HSun, 17 Sep 2000 19:54:28 GMTsMozilla/4.5 (compatible; HTTrack 3.0x; Windows 98)en, *JZ[ The Canning Process


The Canning Process

     Getting Ready to Can

  Assemble and wash equipment and containers before gathering fruits and vegetables. Gather products early when they are at their peak of quality. Do not use over-ripe products. Gather or purchase only as much as you can handle within 2 or 3 hours. (See Table 2, Preserving Food for the approximate yields of canned foods from fresh.)

Wash the product carefully, small amounts at a time. Lift the food out of the water, drain the water and continue rinsing until the water is clear and free of dirt. Dirt contains some of the bacteria that are hardest to kill. Don't let the food soak; it will lose flavor and nutrients. The cleaner the raw foods, the more effective the canning process. Do not can decayed or damaged food items.


         Pre - Heating the Canner

  Fill the boiling water bath or pressure canner with the appropriate amount of hot water and begin heating it on the range. One to 2 inches of water above the tops of the jars is needed in a boiling water bath canner. Two to 3 inches of water are needed in the bottom of a pressure canner. This can be difficult to determine before the filled jars are placed in the canner. After using your canner you'll learn how much water to start with. Until then, be prepared by having an extra pan of water heating in case you've heated too little water in your canner. If you've heated too much, be prepared to remove some.

         Preparing Jars and Lids

  Examine jars and discard those with nicks, cracks and rough edges. These defects will not permit an airtight seal on the jar and food spoilage will result. All canning jars should be washed in soapy water, rinsed well and then kept hot. This could be done in a dishwasher or by placing the jars in the water that is heating in your canner. The jars need to be kept hot to prevent breakage when they're filled with a hot product and placed in the canner for processing.

Jars that will be filled with food and processed for less than 10 minutes in a boiling water bath canner do need to be sterilized. This can be done by boiling them for 10 minutes. NOTE: If you are at an altitude of 1000 feet or more, boil an additional minute for each 1000 feet of additional altitude. Jars processed in a boiling water bath canner for 10 minutes or more, or in a pressure canner will be sterilized during processing.

Be sure to use new two-piece lids. Follow the manufacturer's instructions for treating them. Some need to be brought almost to a boil and then left in hot water, while others need to be boiled for a period of time.

        Methods of Pack

  Fruits and vegetables may be packed raw or they may be preheated and then packed into canning jars. A jar filler will help when filling the jars with small foods. In this book, directions for both raw and hot packs are given for many foods. Others may have directions for only the type of pack most suitable for that product. Always use the type of pack that is specified for each food. If given a choice, the hot pack yields better color and flavor, especially when foods are processed in a boiling water bath.

Raw pack means putting raw, unheated food directly in jars. Boiling hot water, juice or syrup is poured over the food to obtain proper head space.

Fruits and most vegetables packed raw should be packed tightly because they will shrink during processing; however, corn, lima beans, potatoes and peas should be packed loosely because they expand during canning.

Hot pack means heating the food to boiling (or cooking it for a certain length of time) and then packing the hot food and boiling hot liquid in jars. Foods packed hot should be packed fairly loosely, as shrinkage has already taken place.

For both raw pack and hot pack, there should be enough syrup, water or juice to fill in around the solid food in the jar and to cover the food. If not covered by liquid, food at the top tends to darken and develop unnatural flavors. It takes from to l cups of liquid for a quart jar.

        Head Space

  Whether the boiling water bath or the steam pressure canner method is being used, a certain amount of "head space" must be allowed. This is the space in the jar between the inside of the lid and top of the food or its liquid. The amount of head space needed depends on the type of food being processed. Starchy foods for instance, tend to swell when heated and therefore require more head space.

If the jars are filled too full (leaving too little head space) the contents may boil out during processing. Solids or seeds may be caught under the sealing compound and prevent the jar from sealing.


If too much head space is left at the top of the jar, the processing time may not be long enough to drive out all the extra air from the top of the jar. This would mean that a tight vacuum seal may not be formed. Also, the air left inside the jar could cause the food to discolor.

For the correct head space for each food, check the processing directions for each specific food.


       Closing the Jars

  Air bubbles trapped inside the jar may rise to the top during processing, causing too much head space. This can result in the jars not sealing properly.

To make sure that air bubbles have not been trapped inside the jar, run a bubble freer or any plastic or rubber knife-like utensil around the edges of the jar, gently shifting the food, so that any trapped air is released. Do not use a metal knife to do this because the metal can scratch the glass inside the jar. Though these scratches may be difficult to detect, they weaken the jar and could cause it to break during later processing. After the air bubbles have been removed, more liquid may need to be added to the jar to insure proper head space.

Next, wipe off the rims of the jars with a clean, damp cloth. Any foreign matter such as food particles, seeds, grease, sugar, syrup or brine on the rims of the jar may prevent an airtight seal from forming.

When using two-piece lids place the treated lid on the filled jar, center it, and hold in place with fingers. Then screw the band down fingertip-tight. These lids will not require further tightening, after processing.

Do not use force or jar tighteners when applying the lids. Tightening the screw band too tight will prevent the air from escaping as is necessary during processing. This can result in buckled lids (lids that are deformed in some way by the air trying to force its way out). Buckled lids may not seal properly.

    Processing the Jars of Food

  Each food has its own processing time. These processing times are based on research that tells how long the product must be heated so that all of the food in the jar has reached the temperature needed to destroy all dangerous microorganisms. The length of time required varies with the denseness of the food, its packing liquid and its pH.

Because these processing times are based on research, they should be followed exactly. Under-processing can result in spoiled food, while over-processing results in overcooked food. Do not guess at the processing time if you can't find one.


     Boiling Water Bath Method

  The water bath canner is used to process foods at a boiling temperature (212 F at sea level). It is recommended for processing acid foods such as fruits, tomatoes, pickles and relishes. Heat from the boiling water is sufficient to destroy microorganisms which cause spoilage in acid foods. Jams, jellies, preserves, conserves, marmalades, butters, honeys and syrups are also processed in a boiling water bath canner.

The following are general instructions for using a boiling water bath canner:

  • Fill the canner about halfway with hot water. Turn on the burner and heat the water.
  • For raw packed jars, have the water in the canner hot but not boiling to prevent breakage of the jars when they're placed in the canner. For hot packed jars, use hot or gently boiling water.
  • Put filled glass jars on the rack in the canner. Add more boiling water or take out some as needed so that the water is at least 1 inch over the tops of the jars. (If you add more water, pour it between the jars, not directly on them, to prevent breakage.)
  • Put the lid on the canner.
  • When the water in the canner reaches a rolling boil, begin counting the correct processing time. (See specific directions for each food.) Boil gently and steadily for the recommended time, adjusting the heat and adding more boiling water as necessary.
  • Use a jar lifter to carefully remove the jars as soon as the processing time is up. Place the hot jars right side up on a rack, dry towels, boards or newspapers to prevent the jars from breaking on contact with a cold surface. Leave at least 1 inch of space between jars.
  • Do not tighten the lids.
  • Allow the jars to cool untouched for 12 to 24 hours.

     Pressure Canner Method

  The pressure canner is used to process foods under pressure. The temperature most often used is 240 F (10 or 11 pounds pressures, depending on the type of canner). A pressure canner is the only safe method for processing low acid foods such as vegetables, meat, poultry and fish. The pressure canner can supply enough heat to destroy spores of bacteria that cause botulism as well as other types of spoilage. Failure to properly process low acid foods in a pressure canner can result in botulism which is often fatal.

Read your manufacturer's instructions on the use of your pressure canner. The following are general instructions:

  • Have the 2 to 3 inches of water in your canner hot but not boiling if you are canning raw packed foods. The water can be hot or gently boiling for hot packed foods.
  • Set the jars of food on the rack in the canner so steam can flow around each jar.
  • Fasten the canner lid so that no steam begins to escape except through the vent.
  • Turn heat to high and watch until steam begins to escape from the vent. Let the steam escape steadily for 10 minutes.
  • Close the vent, using a weight, valve or screw, depending on the type of canner. If you have a weighted gauge canner that has a weight of varying pressures, be sure you are using the correct pressure.
  • For a dial gauge canner, let the pressure rise quickly to 8 pounds of pressure. Adjust the burner temperature down slightly and let the pressure continue to rise to the correct pressure. (If the burner were left on high, the pressure would be hard to regulate when the correct pressure is reached.) Start counting the processing time as soon as the pressure is reached. For weighted gauge canners, let the canner heat quickly at first and then adjust the heat down slightly until the weight begins to rock gently or "jiggle" 2 to 3 times per minute, depending on the type of canner you have. Start counting the processing time as soon as the weight does either of these.
  • Keep the pressure constant by regulating the heat under the canner. Do not lower the pressure by opening the vent or lifting the weight. Keep drafts from blowing on the canner. Fluctuating pressure is one cause of liquid loss from jars and under-processing.
  • When the processing time is completed, carefully remove the canner from the heat. If the canner is too heavy, simply turn off the heat.
  • Let the pressure in the canner drop to zero. This will take 30 to 45 minutes in a standard heavy-walled canner and nearly an hour for a larger 22-quart canner. Newer thin-walled canners depressurize more quickly. Do not rush the cooling by setting the canner in water or by running cold water over the canner. Never lift the weight or open the vent to hasten the reduction of pressure.
  • Older canners are Re-pressurized when the gauge on a dial gauge canner registers zero or when a gentle nudge to the weight on a weighted gauge canner does not produce steam or resistance. New canners are equipped with a safety lock. These canners are depressurized when the safety lock drops to a normal position. When a canner is depressurized, open the vent or remove the weight. Wait two minutes and then open the canner.
  • NOTE: Sometimes safety locks that are located in the handle of a canner will stick. If a nudge to a canner weight shows that it is depressurized, remove the weight, wait 2 minutes, and then run a knife blade between the handles to release the lock.
  • Unfasten the lid, and tilt the far side up, so the steam escapes away from you. Do not leave the canner un-opened, or the food inside could begin to spoil.
  • Use a jar lifter to carefully remove the jars from the canner. 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 1 inch of space between the jars.
  • Do not tighten the lids.
  • Allow the jars to cool, untouched for 12 to 24 hours.

All information Courtesy the "University of Georgia - So easy to Preserve Guide ".

CanninAfrica compiled and maintained

 by Rosalie Acornley Webmaster.