Canning and Preserving

Home food preservation techniques using jars and cans

Canning in jars extends shelf life by killing microorganisms with heat and creating a vacuum seal that prevents recontamination. Two main methods: water-bath canning (for high-acid foods, pH < 4.6) and pressure canning (for low-acid foods).

⚠️ WARNING: Improper canning of low-acid foods (vegetables, meat) can cause botulism, which is deadly. Always follow tested recipes and the correct canning method.

Canning methods

1. Water-bath canning (85-100°C)

For acidic foods with pH < 4.6: fruits, jams, pickles, tomatoes with citric acid. Time: 10-45 minutes depending on product and jar size.

2. Pressure canning (121°C)

Mandatory for low-acid foods (pH > 4.6): vegetables, meat, soups, stews. Requires a pressure canner. Time: 20-90 minutes depending on product.

pH scale and safety

pH < 4.6 (acidic): safe with water-bath canning – fruits, tomatoes with lemon, pickles

pH > 4.6 (low-acid): requires pressure canning – vegetables, meat, fish

Step by step: water-bath canning

  1. 1. Prepare clean equipment and wash jars in hot soapy water
  2. 2. Prepare the product using a tested recipe
  3. 3. Fill hot jars, leaving 1-2 cm headspace
  4. 4. Wipe jar rims, place lids, screw bands fingertip tight
  5. 5. Place in boiling water (water 2-3 cm above lids)
  6. 6. Boil for recommended time, remove, and cool
  7. 7. Check seals: lid should be concave and not click

Storage and inspection

  • • Store in cool (10-15°C), dark, dry place
  • • Label jars with date and contents
  • • Inspect regularly: cracks, leaks, bulging lids, mold
  • • Typical shelf life: 1-2 years for fruit, 2-5 years for high-temp meats

When to discard

  • • Bulging or dome-shaped lid (may indicate gas production)
  • • Leakage, cracked jar, rusted lid
  • • Foam, mold, cloudy liquid (if it wasn’t cloudy initially)
  • • Off smell after opening
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