Summer is here and that means fresh vegetables. If you are like me you probably plant more than you, your family and your neighbors can eat fresh. So what do you do with all of the “extra” vegetables? Food preservation is not terribly difficult and it allows you to enjoy your homegrown produce for the entire year. There are some things that you need to know before trying to can your own foods.
Organisms that cause food spoilage–molds, yeasts and bacteria–are present everywhere in the air, soil and water. Enzymes that may cause undesirable changes in flavor, color and texture are present in raw vegetables.
When vegetables are canned, they are heated hot enough and long enough in the jar to destroy organisms that can make people sick in addition to spoilage organisms. This heating (or processing) also stops the action of enzymes that can spoil food quality.
Pressure canning is the only safe method of canning all vegetables (except tomatoes). Jars of food are placed in a pressure canner which is heated to an internal temperature of at least 240°F. This temperature can be reached only in a pressure canner.
The Clostridium botulinum microorganism is the main reason pressure canning is necessary. Though the bacterial cells are killed at boiling temperatures, the spores they form can withstand very long boiling. In the soils, these bacteria are naturally found in the spore form. The spores grow out well in moist, low-acid foods in the absence of air, such as in canned low acid foods (vegetables and meats). When this happens, the spores change to growing bacterial cells which produce the deadly botulinum toxin (poison). This growth and toxin formation can occur without any noticeable signs of spoilage in the sealed jar.
These spores can be destroyed by canning the food at a temperature of at least 240°F. This temperature is above the 212°F. boiling point of water, so it can only be reached in a pressure canner at the appropriate pressure (10 pounds at sea level). Because most people do not can at sea level, use the pressure given with the directions for canning vegetables. The pressures are different for dial and weighted gauge canners, because the weighted gauge canners operate in a manner that provides some additional safety margin over dial gauges. Recommended pressures are different for different altitudes; be sure to check altitude corrections if canning at altitudes over 1000 feet.
For this and more on pressure canning and other ways to preserve foods you can visit this website https://www.fcs.uga.edu/extension/food-preservation or come by the office and purchase a “So Easy to Preserve” book. It is the bible when it comes to food preservation, written by food preservation specialists at UGA. If you have questions or comments you can get in touch with your County Agent Here.
