Pressure canning for the home gardeners
There certainly has been an upsurge of home gardening. More and more people want to know where their food comes from. And they want to preserve it by drying, canning, freezing and storing. This article is about safe pressure canning. Home canning has greatly advanced since it was first introduced as a way to preserve food.
The objective of pressure canning is to destroy microorganisms using high temperatures applied for a specified time period. The success of destroying all microorganisms capable of growing in pressure-canned food is based on the temperature obtained in pure steam, free of air, at sea level. At sea level, a canner operated at a gauge pressure of 10.5 lbs provides an internal temperature of 240 degrees Fahrenheit. Where a person lives determines the amount of pressure needed and processing time. Low acid foods such as meat, potatoes, greens, beans, beets and the like must be pressure canned to destroy clostridium botulinum. Each meat and vegetable has its own timetable and pressure requirements. It seems daunting but if one follows the directions precisely, one will be successful.
After harvesting, fruits and vegetables do lose some of their vitamins. Nearly half may be lost within a few days of harvesting so the best plan is to to pick and pressure can the same day. The U.S. Department of Agriculture publication mentioned at the end of this article reports that between one to two weeks, refrigerated produce loses half or more of these vitamins, particularly vitamins A and C, thiamin and riboflavin. And for every year canned, 5 percent to 20 percent of these sensitive vitamins is lost. So pressure can only the amount you can eat in one year.
In planning to pressure can, carefully select ripe vegetables, cutting away any damaged parts. Wash very well, scrubbing dirt away; some may need to be peeled and be ready that day or the next, keeping the freshly picked vegetables refrigerated.
A word about safety: canning with a pressure canner is not to be trifled with. Do not multi-task, as your attention must be on the canner pressure gauge at all times and constant tweaking of the burner is needed to keep the gauge at the recommended pressure. Use a timer. I find it best to use gas as it can quickly be adjusted to more or less heat. If you have a flat top (ceramic top) stove, check the manual before starting to see whether canning is recommended or not.
I have been pressure canning vegetables and meat for more than 30 years. My initial lessons were from the antique Presto canning book and then the University of Minnesota canning guidelines from the '80s. Now there is a website I recommend canners refer to at http://nchfp.uga.edu/publications/publications_usda.html. It is USDA National Institute of Food and Agriculture research led by University of Georgia, among other universities and government agencies. This is where the research is conducted in principles of safe canning, new recipes, what canners to use and a bit about rings and lids. The graphics are splendid and very understandable. There are also many recipes to try as well. An update to the manual is done every few years. Good luck and enjoy the fruits of your labor.
Refer to the revamped and updated University Of Minnesota Extension Service website, www.extension.umn.edu/garden/yard-garden/> for more information on horticultural topics. In addition, local master gardeners will again answer your questions on home horticulture. Call (218) 444-7916, leave your name, number and question and you will receive a return call.