Canning Foods At Home-The Basics
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Why is heat application important during canning?
- Destroy microorganisms
- Inactivates enzymes that can cause changes in color, flavor, and texture.
- Air is driven from the jar during heating (cooling vacuum seal is formed)
What is the vacuum seal important?
- Holds the lid on the jar
- Prevents re-contamination of the food
- Prevents air from drying out the food
What pH determines an 'Acid Food'? Provide Examples.
- Generally all fruits
- Tomatoes and figs are borderline.
- Food to which large amounts of acid are added
What must be done to 'borderline' acid foods, such as tomatoes and figs, before canning?
Specific amounts of citric acid or lemon juice must be added to increase acidity.
What is the pH of 'low acid foods'? What are some examples?
- pH > 4.6
- Generally all vegetables
- Mixtures of acid and low acid foods (spaghetti sauce-meat, veg and tomatoes)
What are the two approved methods of canning foods at home? Which is each method used for?
- 1. Boiling Water Canning (212 F at sea level). Used for acid foods
- 2. Pressure Canning (at least 240 F). Used for low acid foods and acid/low acid mixtures.
Why do low acid foods have to be pressure canned to be safe?
What is C. botulinum dangerous?
It forms protective, heat resistant spores. These spores require higher temperatures for destruction in reasonable period of time.
What can happen if low acid foods are not pressure canned and conditions become favorable?
- Conditions become favorable:
- 40-140 degrees F
- High moisture
- No air in jar
- Leads to: Spore germination and the formation of toxin-producing cells-BOTULISM
What are the signs and symptoms of Botulism? How long until symptoms occur?
- Food can contain toxin without showing signs
- Symptoms usually occur within 12-72 hrs and include:
- -Digestive upset (In some cases)
- -Blurred, double vision
- -Difficulty swallowing, speaking and breathing
How do you prevent botulim in home canned foods?
- Spores won't germinate in acid environments
- Spores are destroyed when heated long enough at a specific temp.
- USDA recommends a canner temp of at least 240F at sea level for canning low acid foods.
- Pressure canner must be used for all low acid foods.
What are the important 'musts' for canning?
- 1. Food must be properly prepared and processed at the correct amount of time.
- 2. Canner must be accurate and operated correctly.
- 3. You may need to make altitude adjustments
- 4. Directions from a reputable source must be followed (USDA)
- 5. Up-to-date methods and information should be used. (Beware of granny's method)
How are canning process times determined?
- 1. Foods are prepared by a specific procedure.
- 2. The length of time it takes to adequately heat the coldest spot in the jar is determined.
- 3. Size of the jar, size of the food, consistency of the canning liquid, etc. all have an effect on how heat penetrates though the product
What can slow heat penetration during canning?
- 1. Adding extra sugar or fat.
- 2. Having food pieces larger than called for in directions
- 3. Adding thickeners
What should canners not be 'quick cooled'?
Heat-up and cool down in pressure canners is counted towards hear penetration so don't quick cool the canner!
What are the methods of pack?
Explain Raw Pack. When is it often used?
- Often used for foods that lose shape when cooked.
- Place raw foods directly in jar. Boiling hot liquid is then poured over the food.
- Pack firmly, don't crush.
- Add jars carefully to canner.
What is Hot Pack? When is it often used?
- Preferred method for most foods.
- Food is cooked in liquid before packing. Cooking liquid poured over food in jar.
- Fewer jars needed.
- Less floating.
- Better color and flavor.
- Easier to pack, foods pilable.
What is headspace?
Space in the jar between the inside of the lid and the top of the food or its liquid. Directions will identify correct headspace.
What is the usual head space for the following products?
Jellied fruit products
Fruits, tomatoes and pickles
Low acid foods
- 1/4"- Jellied fruit products
- 1/2"- fruits, tomatoes and pickles
- 1" to 1-1/4" low acid foods
What happens when there is too little headspace?
- Food may bubble out during processing
- Deposit on rim may prevent proper sealing
What happens when there is too much headspace?
- Food at the top is likely to discolor.
- Jar may not seal properly, because not all air may be forced from jar during process.
What happens if you allow to little processing time?
What are the boiling water procedures during canning?
- Have about 6" of water simmering or hot in canner.
- -Hot packed jars-Simmering water
- -Raw packed jars-hot water
- Place jars on rack in canner.
- Water must be over the tops of the jars by at lease one or two inches. (Add more water if necessary).
(Canning) When should you start timing 'processing time'?
Begin timing the process when a full boil is reached.
(Canning) What should be done after processing time? Removal from canner?
- 1. Turn of canner.
- 2. Remove lid and wait 5 min before removing jars.
- 3. Remove jars sstraight up out of canner and place on padded surface away from drafts.
- 4. Cool 12 to 24 hours, undisturbed.
- 5. Check seals
- 6. Remove rings
- 7. Wipe of jars before storing in a cool, dry, dark place.
Pressure Canning Procedures?
- 1. Have 2" to 3" of water simmering or hot in canner.
- Hot Packed jars- Simmering Water
- Raw Packed jars- Hot Water
- 2. Place jars on rack in canner
- 3. Put lid on canner with weight off or petcock open
- 4. Exhaust 10 min - Steady stream of steam escaping
- 5. Close vent or petcock
- 6. Count time when correct pressure is reached
- 7. Turn off heat at end of processing
- 8. Let pressure drop to 0.
End of pressure canning process?
- 1. Wait about 2 min after pressure drops to 0 to make sure no pressure remains.
- 2. Remove weight or open petcock. Wait 10 min
- 3. Open canner.
- 4. Remove jars to padded surface or rack
- 5. Cool jars 12 to 24 hours, undisturbed.
- 6. Check that jars have sealed.
How do you test seals?
- 1. Listen for a "pop"
- 2. Lid curved inward, wont move when pressed
- 3. Clear ringing sound when tapped.
How do you store home canned food?
- 1. Store in a cool, dry, dark place
- 2. Avoid temperature extremes
- 3. Use within 1 yr. for best quality
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