Gardeners Exchange Group Meeting 16 May 2015
Location: Shenandoah Junction, “Moon on the Mountain” a Community Supported Agriculture Farm and home of Patricia Stevenson
Topic: Canning Food Safely presented by Judy Matlick M.A.
Submitted by Julie Neely
It was a beautiful Saturday in May at the picture perfect setting of Patricia Stevenson’s farm. Food Canning was presented by Judy Matlick from the West Virginia Extension Service, Department of Families and Health. In addition to the detailed lecture, Judy provided the attendees with a wealth of handouts and a free copy of the USDA Complete Guide to Home Canning. Canning and freezing information online is provided by the National Center for Home Food Preservation at the University of Georgia.
Highlights of the lecture include the following information:
- Altitude matters, your altitude will change cooking times. (Try What is my elevation?)
- Start with high quality foods, preserving foods will not improve the foods quality.
- Food to be canned should be placed into “approved for canning” jars (not imitation “Mason-like” jars) with 2-piece lids.
- Jars and lids are heated to a prescribed temperature to destroy microorganisms, not all jars can be safely heated to high temps.
- Heat can cause changes in the color, texture and flavor of your preserved food.
- Air is driven out of the food during the canning process, as the jar cools a vacuum seal is created.
- Creating the vacuum seal is very important; no seal = no preservation.
- Canning methods are either boiling water or pressure canning; the method to be used is determined by the food’s acidity.
- Boiling water method is safe for high acid foods like fruits, sauerkraut and sometimes tomatoes.
- Pressure canning method is advised for low acid foods including figs, most vegetables, meats, potatoes, mixed foods (low and high acid combinations) and sometimes tomatoes.
- Tomatoes are not consistently acidic so should be treated as neutral and be acidified with store-bought lemon juice. (Bottled juice is consistently acidic and was recommended over natural squeezed lemon juice). Tomatoes can be processed safely as a low acid food using pressure canning.
- Use canning jars that are not nicked, scratched or damaged on the inside.
- To remove air from the jars once they are filled (but before they are heat processed) run a plastic or wooden utensil around the inside. Avoid using metal because this may weaken the jar.
- Canning jar bands (the rings that screw on) may be reused.
- When screwing on the bands, screw them on only “fingertip tight” not super strong tight.
- Each food has its own processing time, follow reliable instructions or go to the National Center for Home Food Preservation website for cooking times.
- Always process your canning jars on a rack in your cooking pots (pressure canners or other pots). Canning rings can be used as a rack on the bottom of the pots, don’t use towels.
- Raw pack means that raw food is loosely packed into the canning jar and boiling hot liquid is poured on top of the food. Do not crush the food into the jar.
- Hot pack means that the food is cooked in the liquid and poured with its liquid into the canning jars.
- Head space refers to the amount of air space inside the canning jar from the level of the top of the food to the inside of the lid—follow directions for prescribed air space.
Boiling Water Method
- Use 6 inches simmering water.
- Place jars on the rack.
- Add boiling water to cover the jars with 1-2 inches of water.
- Time starts when full boil is reached.
- When the prescribed time is up, remove the lid of the pot, wait 5 minutes, remove the jars, place on a towel covered, flat surface to cool for 12-24 hours.
- Check the vacuum seal, remove the rings, wipe the jars clean, store in a cool, dry place, away from direct sunlight. Rings should be removed to prevent the jar from exploding if the food becomes spoiled—even though you did everything right…
Pressure Canning Method
- Uses only 2-3 inches of water in the bottom of the canner.
- Place jars on a rack in the canner, put the lid in the canner and heat the canner with the weight off/petcock open for 10 minutes then put the weight on.
- Time starts when the canner reaches the correct internal pressure (pounds per square inch-psi).
- After prescribed cooking time, turn off the heat and let the pressure dissipate to zero, then wait 10 more minutes. Open the canner with caution to avoid steam burns. Cool jars on towels as above check seals.
- Checking the vacuum seal means that the lid is bowed inward toward the food and won’t buckle when lightly pressed.
Food Canning Musts
- Food must be prepared in the correct way per the directions.
- It must be cooked for the prescribed amount of time.
- It must be cooked at the prescribed temperature.
- It must be packed hot or cold as directed.
- Follow your areas altitude recommendations.
- Changing the sugar content, more fat, larger chunks of food or adding thickeners all change the cooking parameters.
- Follow preheating and prescribed cooling times.
There are a variety of organisms that cause “food poisoning.” However, improper canning techniques create the correct growth environment for Clostridium botulinum, i.e. Botulism.
- Botulinum is a very dangerous bacteria that must be destroyed during the canning process.
- Botulinum is a spore-forming, anaerobic soil bacterium that will germinate under the right conditions and form potentially lethal neurotoxins. C. botulinum will produce its neurotoxin in the low oxygen, low acid conditions of improperly canned low acid foods.
- Botulinum spores will not germinate under acidic conditions and are destroyed by long, high heating temperatures.
- Food contaminated by C.botulinum may appear normal, it is usually not detectable by smell, sight or taste. Symptoms of botulinum neurotoxin food poisoning include blurred or double vision, nausea, difficulty breathing and swallowing, and death which may occur within 12-72 hours. Botulism food poisoning is not always lethal if identified quickly and treated correctly in a hospital setting, although side effects can persist life-long.
Canning vs. Freezing
A short discussion of the pros and cons of canning vs freezing followed.
- Freezing is easier, may preserve color and flavor better.
- The texture of foods high in water will be changed by freezing. Textural changes are caused by ice crystal formation and subseqent thawing within the frozen food.
- Foods must be stored at zero degrees Fahrenheit for best storage length. If your freezer is warmer than zero or if your freezer temp fluctuates, the length of safe storage will be less.
- Use good quality packaging that is designed to prevent moisture loss of frozen foods. Freezer burn results from food not properly wrapped and protected from the desiccation that can occur when frozen. Freezer burn affects texture but not the safety of the food.
- Some foods benefit from quick blanching in boiling water prior to freezing
For information regarding Moon on the Mountain Farm/CSA please see the Moon on the Mountain website. Patricia also raises alpaca and sheep for fine quality fiber for handspinners and crafters.