Principles of Home Canning - Pinal County
Questions are often posed at the Pinal County Extension office regarding why anyone would want to can food at home and the process of how to do it. There has been a resurgence of this practice and the reasons are many on why we see this trend. Canning can be a safe and economical way to preserve quality food at home. Canning homegrown food may save you costs of buying commercially canned food and you know exactly what the ingredients are in your home canned product. Canning favorite and special products to be enjoyed by family and friends is a fulfilling experience and source of pride for many people.
How Canning Preserves foods
The USDA Complete Guide to Home Canning states fresh foods often contain a very high percentage of water. This makes it more likely that the food will easily spoil. There are four main reasons why foods spoil or lose their quality for several reasons:
- growth of undesirable microorganisms — bacteria, molds and yeasts,
- activity of food enzymes,
- reactions with oxygen,
- moisture loss
Microorganisms live and multiply quickly on the surfaces of fresh food and on the inside of bruised, insect - damaged and diseased food. Oxygen and enzymes are present throughout fresh food tissues (USDA, 2015). USDA recommended canning practices include:
- carefully selecting and washing fresh food
- peeling some fresh foods
- hot packing many foods
- adding acids (lemon juice or vinegar) to some foods using acceptable jars and self - sealing lids
- processing jars in a boiling water or pressure canner for the correct period of time
Collectively, these practices remove oxygen; destroy enzymes; prevent the growth of undesirable bacteria, yeasts and molds; and help form a high vacuum in jars. Good vacuums form tight seals which keep liquid in and air and microorganisms out (USDA, 2015).
Ensuring safe canned foods
Growth of the bacterium Clostridium botulinum in canned food may cause botulism—a deadly form of food poisoning. These bacteria exist either as spores or as vegetative cells. The spores, which are comparable toplant seeds, can survive harmlessly in soil and water for many years. When ideal conditions exist for growth, the spores produce vegetative cells which multiply rapidly and may produce a deadly toxin within 3 to 4 days of growth. Botulinum spores are on most fresh food surfaces. Because they grow only in the absence of air, they are harmless on fresh foods (USDA, 2015).
Removing bacteria, yeasts and molds from most food surfaces is difficult. There are several things you can do to limit their numbers–washing the fresh food, peeling root crops and tomatoes. You can blanch the food product as well. The vital controls are the method of canning and making sure to use the recommended research-based process times. These times are provided in the USDA Complete Guide to Home Canning or the Ball Blue Book Guide to Preserving.
More information will be forthcoming on the popular topic in future newsletters. Additional resources can be found at the National Center for Home Food Preservation website and by contacting the Pinal County Cooperative Extension, Lori Lieder, Program Coordinator, Sr. (520-836-5221, x216)
(Resources: USDA Complete Guide to Home Canning, updated 2015, Ball Blue Book Guide to Preserving