1. Botulism:

While home preserving is very popular and great fun, we need to be conscious of the particular risk of Botulism. This bacteria which can cause serious food poisoning, is guarded against in home preserving by:

  • High-acid foods such as pickles, chutneys, jams or rhubarb are quite resistant to bacteria, and only require the “boiling water bath” method.
  • Low-acid foods — including most vegetables, meats and seafood have little acid and are therefore more prone to the risk of Botulism and must therefore be processed at higher temperatures, that only a pressure canner can attain.

2. Proper seals:

If proper vacuum seals are not achieved between the jar and lid, air can enter the preserve and spoil the product. It is possible to re-use jars once there is no damage, however safe preserving requires new lids every time as the seal integrity is critical to ensure the preserve remains safe.

3. Hygiene:

The other safety factor to keep in mind is cleanliness. All work surfaces should be kept clean during all stages of processing. The food being preserved must itself be rinsed clean. It is particularly important to clean the jars, lids and seals before use.


Many free on-line recipes and home preserving methods are available, some examples are given below:


Ball Complete Book of Home Preserving: 400 Delicious and Creative Recipes for Today. Edited by Judi Kingry and Lauren Devine

The Complete Book of Year Round Small-Batch Preserving: 250 Delicious Recipes. By Ellie Topp and Margaret Howard.


There are two basic methods for home preserving and these depend on the acidity of the food you are preserving.

1. High acid foods, e.g.; pickles, chutneys and jams: ‘Boiling Water Method’:


You will need a large pot to use as your hot water bath. This pot will need to be big enough to stand 4 or more jars in and then fill with water till the jars are completely submerged.

As you will be standing glass jars in this pot, you need to create a space between the jars and the bottom of the pot. To do this you can use a trivet from a pressure cooker or a shaped wire cake rack. It does not need to be much of a space, but enough so that the glass jars are not sitting directly on the bottom of the pot and bubbles from boiling are not trapped under the jars.

You will also need a pair of tongs, some clean towels and a wide mouth funnel.


Select a recipe and prepare your batch of preserve/sauce.

Wash the jars you are going to use in hot, soapy water and then rinse well. Leave them in a sink of hot clean water, without detergent to await being filled with your preserves. Do the same to the lids and leave them in a sink of hot water waiting to be placed on the jars once full.

Spread a towel out on your counter and when you are ready to fill your jars, place the jars on the towel, right by the pot of preserves. (This is where you need the tongs, so as not to burn your hands getting the jars out of the hot water.) You want the jars to be still hot when you are putting the hot preserves into them. Hot liquid into cold glass can cause the glass to break so be sure that your jars are left in the hot water right up until you are ready to start filling the jars.

Fill each of the jars with the preserve, using a wide mouth funnel, leaving approx. 2.5cm (one inch) space at the top. Once the jars are full, wipe off the rims with a clean cloth. Be sure that there is no preserve on the rims of the jars as anything that gets between the rim of the jar and the lid can stop you from getting a good seal.

Once you have cleaned off the rims of the jars you are ready to put on the lids. Using the tongs, get the lids out of the hot water and place them on the jars, tightening them all the way.

Vacuum sealing:

Now you are ready to process the jars to get the vacuum seal to ensure freshness.

Get the large pot and place the article you have chosen into the bottom to create a space between the bottom of the pot and the jars. As mentioned before, this can be a cake rack or something similar. Then place the jars into the pot ensuring they are not touching each other. Then using a jug, begin to fill the pot with warm to hot water. Do not use boiling water, but do not put cold water in as the glass is hot and once again you do not want to risk any jars breaking due to rapid temperature change. Fill the pot till the jars are completely submerged.

Turn the stove on low to medium and slowly bring the pot of water with your jars in it to the boil. This should be a gentle boil, (simmer) not a hard rolling boil. Process the jars at this gentle boil for the time required in the recipe and depending on the jar size. Larger jars should be processed for longer.

Once the time for processing specified in the recipe has been reached, turn the stove off and leave the jars in the water to cool down. You want them to cool down slowly. There is no reason for you to risk trying to get the jars out of hot water and burning yourself. Once the water has cooled sufficiently for you to safely remove the jars you can do so. Place the jars in a safe place to continue cooling if necessary.

As the jars cool down, a vacuum is created by the contents of the jar cooling.

Check the vacuum:

Push the pop-top button down as they cool. They will not stay down if the jars have not cooled sufficiently. If this happens just wait a little longer and push them down again. Continue to do this until all your pop tops stay down. If the pop tops do not stay down that is an indication that you do not have a vacuum seal.

If any of the jars do not seal, you can process them again or simply decide that this is the jar you are going to use right away. There are several reasons why a jar may not seal. There may have been some preserve left on the rim of the jar, or there may be a defect, such as a chip in the rim of the jar. Also if you do not leave enough empty space at the top of the jar, you could prevent a vacuum being created.

Labeling and storage:

Now your jars are cool and the vacuum seal has been created, you need to label the jars with their contents and the date. This is important as no matter how good your seal is, you do not want to leave a jar at the back of the cupboard for years with no date on it. Always eat the oldest jar first. Even preserved foods that you purchase in your supermarket are dated with a use by date.

2. Low acid Foods: for food items such as vegetables, meats and seafood.

A specialised ‘pressure canner’ is required for the safe preserving of ‘Low Acid’ foods.

A pressure canner is a large, cast-aluminum pot with a locking lid and a pressure gauge. By cooking under pressure, you can bring the temperature of boiling water up to 116ºC (240ºF). This is the minimum temperature necessary to destroy botulism spores, and the only way to guarantee safe canning for food items such as vegetables, meats and seafood. Your pressure canner should come with complete instructions. Always follow them carefully. Keep these pointers in mind:

  • Ten pounds is the minimum safe pressure;
  • Processing time — will vary depending on the type of food being preserved and the size of the jar. Never shorten the cooking time that is recommended in the instructions.
  • Once the right pressure is reached during cooking, it must be kept constant throughout the cooking step;
  • Both “weighted” gauges and “dial” gauges should be checked for accuracy. Read the manufacturer’s directions carefully for recommended testing/frequency procedures, to make sure your canner is being operated safely and correctly.