Slide1: Food Preservation CANNING Canning Methods: 2 Canning Methods Determine by the pH:
Low acid foods
High acid foods Acid Foods: 3 Acid Foods pH < 4.6 (measure of acidity)
Generally all fruits
Tomatoes and figs are borderline – (specific amounts of citric acid or lemon juice must be added before canning to acidify)
Foods to which large amounts of acid are added (pickles) Low Acid Foods: 4 Low Acid Foods pH > 4.6
Generally all vegetables
Mixtures of acid and low acid foods (spaghetti sauce – meat, vegetables and tomatoes) Methods of Pack: 5 Methods of Pack Raw Pack
Place raw food directly in jars. Boiling hot liquid is then poured over the food.
Pack firmly, don’t crush.
Add jars carefully to canner. Slide6: 6 Hot Pack
Food is cooked in liquid before packing. Cooking liquid poured over food in jar.
What are the advantages? If directions only list hot pack instructions, then hot pack! Slide7: 7 Two Approved Methods of Processing canned foods 1) Boiling Water Canning (212°F at sea level)
2) Pressure Canning (at least 240°F) Why Do Low Acid Foods Have to be Pressure Canned to be Safe?: 8 Why Do Low Acid Foods Have to be Pressure Canned to be Safe? Clostridium botulinum!
C. botulinum forms protective, heat-resistant spores.
Spores require higher temperatures for destruction in a reasonable period of time (usually 240oF or above at sea level) Headspace: 9 Headspace * Space in the jar between the inside of the lid and the top of the food or its liquid. What happens if you do not leave the correct headspace?: 10 What happens if you do not leave the correct headspace? Too little
Too much Testing for Seals: 11 Testing for Seals * Listen for “pop”.
* Lid curved inward, won’t move when pressed.
* Clear ringing sound when tapped. Pickling: Pickling