Safe Preserving of Fruits, Tomatoes, Salsa, Pickles and Relishes

Introduction to Canning FoodEquipment, ingredients, time and temperature are crucial factors in safe preservation of food. For food safety, use good quality ingredients and modern recipes, equipment and processing techniques. The level of acidity and the concentration of sugar and salt in the food will determine the correct processing method and time. Fruit, tomatoes with added acid, salsa, pickles and relishes can all safely be processed in a boiling water bath.


Use mason jars that are manufactured for canning. Made of a heavier weight glass than commercial food jars, they can withstand high processing temperatures in a boiling water canner or pressure canner. Check for cracks and nicks in the rims that might prevent a good seal.

If your recipe calls for a processing time of less than 15 minutes, sterilize jars in boiling water for 10 minutes immediately before filling them. Otherwise, wash jars with hot soapy water and rinse well.

Different brands of metal lids require different preparation before use to form an airtight seal. Read and follow instructions on the label. Don’t mix brands. And don’t reuse these lids as the sealing compound becomes too brittle to form a good seal.

The vinegar and salt in these recipes will react with some metals. So never use utensils or cooking equipment that’s galvanized, copper, brass, iron or aluminum.

The boiling water canner should be large enough to hold 2 to 4 inches (5 to 10 cm) of water above the top of the jars to allow for a rolling boil.


Always follow the recipe exactly. These recipes require a specific acid balance and changing the ingredients could make the product unsafe.

Use fresh, ripe, firm, blemish-free vegetables and fruits. Never use fruit which has dropped on the ground or been shaken from a bush. These are on the verge of rotting and could contaminate good fruit. Unless they are going to be peeled, cucumbers should be unwaxed. Refrigerate fruits and vegetables that cannot be used within 24 hours of harvest, especially cucumbers which deteriorate rapidly.

Wash produce carefully to remove dirt and bacteria. Cut 1/8 inch (3 mm) from blossom end of cucumbers and discard. Enzymes contained in the blossom will soften the pickles.

Use commercial vinegar with a minimum acidity of 5%. Pickling vinegar has 7% acidity. Vinegar is a critical ingredient so measure carefully. If a less sour pickle is desired add sugar rather than reducing the amount of vinegar.

Hard water reduces the acidity of pickling solutions and can affect the growth of bacteria. So only use soft drinking quality water or distilled water.

Use only pickling salt in pickles and pickled products. Iodine in table salt can cause brine to darken and anticaking agents can cause a cloudy appearance.

Garlic cloves in pickles may turn bluish green. This may be caused by pigments in the garlic reacting in an acid environment or reacting with iron, tin or aluminum cookware. If the pickles were properly prepared and processed and the jars are sealed, the pickles are safe to eat.

Old recipes sometimes call for the addition of alum to make pickles crisp. Such chemicals are not necessary because high acid levels in commercial vinegars make pickles crisp.

Modern varieties of fresh tomatoes have acidity values that fall close to the dividing line between high and low acid foods, so precautions must be taken to can them safety in a boiling water canner. To be sure the acidity level is high enough to prevent growth of harmful and potentially fatal bacteria, put 1 tbsp (15 mL) of commercially bottled lemon juice or 1/4 tsp (1 ml ) citric acid per pint (500 ml) and 2 tbsps (30 ml) lemon juice or 1/2 tsp (2 ml) citric acid per quart (1 L) directly into each jar before adding tomatoes.


Leave the required headspace for expansion and bubbling-up of liquid during processing. If there is not enough space, food will be forced out with the air leaving particles on the sealing compound which prevent a good seal forming. At higher elevations steam in the headspace expands more than at sea level. So if you live at an elevation higher than 1,000 ft (305 m) increase headspace by 1/8 inch (3 mm) for every additional 1,000 ft (305 m). But do not exceed 1 3/4 inch (4.5 cm) for quarts 1 inch (2.5 cm) for pints, 3/4 inch (2 cm) for 1/2 pints.

Remove trapped air bubbles by sliding a rubber spatula between glass and food. Adjust headspace, if necessary.

Time and Temperature

The processing time given in each recipe is based on the acidity level, density of the food, jar size and time required to exhaust the oxygen. Do not adjust the time or use different jar size as this can affect the safety of the product. At higher elevations water boils at a lower temperature so processing time must be extended. If you live at an elevation higher than 1,000 ft (305 m) check the following chart.

Increase Processing Time
1,001 – 3,600
306 – 915
3,001 – 6,000
916 – 1,830
6,001 – 8,000
1,831 – 2,440
8,001 – 10,000
2,441 – 3,050

After Processing

The day after pickling, check the seals of jars and prepare them for storage. If during the 24 hours following processing you find any imperfect seals, dump contents into the preserving kettle, bring back to a boil, repack into clean hot canning jars with new closures, and reprocess for the required time. This is the only period when it is safe to do this. If only one or two jars are imperfect, pop those into the refrigerator and use within a week.

Resist temptation to retighten screw bands on jars after processing. You may damage the sealing compound and prevent an airtight seal.


Put jars with questionable seals in a special place so you can use them first and keep an eye on them for signs of spoilage.

These home-preserved foods can be stored for one year in a cool dark and dry place. Containers must not freeze or the food will expand and break the seal.

In excessively warm temperatures, bacteria can reactivate and grow causing spoilage. Dampness and humidity will cause metal closures to corrode or rust.

Check periodically for signs of spoilage. If you see any of the following do not taste. Discard so the contents cannot be eaten by people or animals:

  • a jar that was sealed and then loses its seal
  • seeping seams, seeping around seal, bulging lids
  • mold around seal or in contents
  • gassiness (small bubbles) in contents
  • cloudy or yeasty liquid
  • shriveled or spongy-looking food
  • unnatural color often very dark

When the can is opened look for these additional signs of spoilage:

  • liquid spurts from pressure inside can
  • food is slimy or texture too soft
  • musty or disagreeable or downright nasty odor


The production of this fact sheet has been supported by Agriculture and Agri~Food Canada, Agriculture and Food Council of Alberta, and the Canadian Adaptation and Rural Development Fund.