Thursday, Aug. 16, 2012
Food Matters: Canning's fun, but prepare and process food safely
By Chuck Newcomb
It's been a long time since I helped can food. When I was a kid in Wisconsin, my family had a backyard garden. We grew just about anything you could think of, from corn to tomatoes, rhubarb to carrots. Even with eight children in the house, we couldn't eat everything before it got over- ripe, so my mom would can much of it. I couldn't understand why they called it canning when all she used were glass jars.
At that time it seemed that most houses in the neighborhood had gardens, big and small. Getting fresh vegetables in the north central United States was really a luxury. We never got fresh vegetables in the winter, so canning during the summer was a way we could extend the life of our garden.
Living in California, and especially the Central Valley, many residents take the abundance of fresh produce for granted. The diverse climate and ecology of the state provides growers a unique opportunity to produce a large variety of fruits and vegetables throughout the year. Seasonal produce is also relatively inexpensive and shoppers are not confined to only grocery stores.
Farmers markets provide a chance for anyone to buy directly from the farmers themselves. Some of the items sold are very unique and not commonly found at regular stores. Don't worry if you are skittish about trying something new and different. They usually allow shoppers to taste their products. Not sure about how to use something in cooking? Farmers at the markets can provide recipes or some ideas on preparation.
The principle of canning at home is a pretty simple process. The jars and lids used for canning must be adequately heated to kill any bacteria, mold or yeast that can grow and contaminate the food inside. Heating or blanching foods also deactivate enzymes that cause the continued ripening and degrading of the food to be preserved. In addition, all oxygen must be removed and the final product must be vacuum sealed. Adding salt, sugar or acid (lemon juice or vinegar) to different foods also helps preserve the product to be canned.
The big danger for improper canning techniques is the growth of the bacterium Clostridium botulinum that causes the dreaded botulism. The spores can survive in soil and in water for many years. When ideal conditions exist for growth, the spores produce cells that rapidly multiply and may produce a deadly toxin within three to four days. Ideal conditions include a moist, low-acid environment with temperatures between 40 and 120 degrees and no oxygen.
Reheating the contaminated food doesn't help at all since it is the toxin causes the food poisoning. Adequate heat during the canning process kills any of the bacteria that could cause problems. Peeling vegetables also helps getting rid of bacteria that may be otherwise difficult to remove.
Home canning is certainly not for everyone. It takes some planning and the initial investment in a large pan or pressure cooker, jars and lids can end up being more than any money saved on commercially processed foods. Canning can be fun and can be a good motivation to grow your own garden.
Chuck Newcomb, MS, RD, CDE is a consulting registered dietitian providing medical nutrition therapy services for Memorial Hospital, Los Banos. He has a masters of science in clinical nutrition from New York University.
Email questions to the Attention of ChuckRD at: MHALosBanos@SutterHealth.org or on his website MySmartRD.com.