Basic Canning Guide

This week our Blenheim apricots were fully ripe and ready for harvest. This variety is unquestionably the most delicious, but its delicate nature means it doesn't keep or transport well. Home gardeners have only a few days to enjoy these before they begin to over-ripen so it's best to enjoy as many as possible fresh and then preserve the rest. 

Blenheim Apricots

For the last few years we've been experimenting with a variety of food preservation methods for fruits and vegetables from our garden including canning, freezing, pickling, fermenting and drying. Unlike freezing which everyone has familiarity with today, the other forms of food preservation are a bit of a lost art. Something grandma may have done but not a skill that was transmitted to the next generation.

Many folks are fearful of canning because they are concerned about getting botulism or being scolded by hot water or steam. These fears are really exaggerated. Canning is safe and easy to do. You just need to follow a few rules. 

If you would like to give canning a try, here is our Basic Canning Guide. We'll discuss two methods of canning and the equipment you need to do both kinds. The objective is not to make you a canning expert in one article. Rather, this is to give you an overview of the process and equipment so that you can decide whether you want to give it a go.  

The Hot Water Bath Process

This is the easiest and requires the least equipment.  It is generally used for preserving fruit, jams and jellies, tomatoes and pickles.  You can preserve a lot with the hot water bath method, but not everything (I elaborate on this below)

To can using the "hot water bath" method:

·       Wash your vegetables and do the basic food preparation.  The prep. will vary depending on the vegetable or fruit you are preserving.  (For example, if you want to can tomatoes, you'll remove the skins by cutting an "X" into the bottom of the tomato with a knife and boiling for 1 minute.  The skin will then peel off easily)  

·       Put your fruits or vegetables along with the proper additives into jars.  The additives (lemon juice, vinegar/spices, or sugar syrup) aid in food preservation and allow you to can at lower temperatures.  The proper additive will vary depending on what you are preserving, but will be listed in your recipe.

·       Wipe of the lip of the jar with a clean paper towel and screw on the top.  (The lids should be sanitized by first boiling them in water)

·       Place the jars into a pot so that the water which completely covers the tops

·       Boil for 10-50 minutes depending on what you are canning and the size of the jar you are using.  You can find processing times listed in the USDA Complete Guide to Home Canning, your pressure caner instruction manual, or at cooking and caning web sites on the Internet.

Equipment for Hot Water Bath Canning

The only equipment you need to do hot water bath canning is a large stock pot, a pair of canning tongs to remove hot jars from the pot, and special canning jars.  

These canning jars are made of thick glass to withstand the heat of the canning process and a special lid with a rubber gasket seal.  Canning jars are manufactured by two companies (Ball and Kerr) and are widely available at hardware stores, Wal-Mart and other retail locations.

The Bad News about Hot Water Bath Canning

Now here's the rub... The hot water bath process is good for many, but not all, canning applications.  Specifically, it's good for jams and jellies (sugar syrup additive used), canned tomatoes (lemon juice additive used) and pickles (vinegar and pickling spice additive used).  

If you want to preserve green beans, but don't want to add vinegar and pickling spices which will alter their flavor, boiling water alone will not be sufficient to prevent your food from spoiling.  You'll need to heat the food you are preserving to a temperature above that of boiling water and will need a pressure caner to accomplish this.

Canned Apricots. Open during the Winter for a Taste of Summer

Pressure Canning

Pressure canning is a process which allows you to heat your canned vegetables and fruits above the temperature of boiling water (212 degrees Fahrenheit or 100 degrees Celsius).  As I mentioned above, by canning using higher temperatures, you're able to preserve a wider range of fruits and veggies and to forgo the use of additives in some cases.

Pressure canning works by using steam to do the preservation.  Under pressure, steam can reach much hotter temperatures than boiling water --generally temperature between 228 to 250 degrees Fahrenheit (107-118 degrees Celsius).   

I should also mention that pressure canning can be used to do all of the same foods that can be done using the hot water bath method, but to complete the canning process faster because you're using a higher temperature.

Pressure Caning Process

·       To do pressure canning, you prepare your fruits or vegetables according to the recipe you are following.  This will be very similar to the hot water bath process.

·       Fill the pressure canner with water so that the water level is about 1.5 inches above the bottom of the pot.  

·       Place your jars into the pressure canner.  You will put the jars onto a rack that sits just above the bottom of the pot in your pressure canner that prevents the cans from sitting directly on the hot bottom of the caner.

·       Lubricate the metal seal on the cover of the caner with a little Vaseline to prevent sticking and then screw down the lid being careful to gradually and evenly tighten opposite wing nuts.  This ensures that the cover will be properly sealed.

·       Bring the the water to a boil.  You'll see steam escaping from a small vent at the top of the pressure canner.

·       Place a weight (supplied with your canner) on the vent using a set of kitchen tongs so you don't get burned by escaping steam.  The weight will have settings for 5-15 pounds of pressure.  Use the setting specified in your recipe.

·       Steam for the time given in the recipe.

·       When the cooking time has elapsed, turn off the stove.  

·       Let the temperature/pressure gauge of your caner return to 212 degrees Fahrenheit/0 pounds of pressure.

·       Gradually remove the hot weight from the pressure canner using a kitchen tongs so you don't get burned.

·       Open the top and remove your preserved cans.  Allow to cool.

Pressure Canners & How They Work

There are two devices on the market - pressure cookers and pressure canners.  If you are canning fruits and vegetables, you want to buy a pressure canner.  Both devices work on the same principle of using steam to do the heating, but canners are larger and designed for caning jars.  Cookers are too small and the USDA warns against using them for canning.

A good brand of pressure canner is All American but there are other good brands on the market.  You can buy a variety of different sized pressure canners, but a 21 quart pressure caner is a good size for home caning applications.

The canner is basically a stock pot with a lid that can be screwed down to hold in pressurized steam. The lid of the canner has a gauge on it that will tell you the pressure in pounds per square inch (PSI) and the temperature within the pot.  There is also a small vent pipe on the top of the pot that allows steam to escape.  You control the pressure withing the pot (and hence the temperature) by regulating the amount of steam that is able to escape through this vent pipe.  You regulate the pressure by placing a small weight (supplied with your pressure caner) on top of the vent.  My weight has three settings on it and allows steam to escape so that the pressure in the pot is 5, 10 or 15 PSI.

All American brand pressure canner

Recipes & Instructions

If you want to can, I recommend that you purchase a copy of the Ball Blue Book on canning. This is widely available and will give you recipes and detailed canning instructions for almost every type of fruit or vegetable.... green beans, corn, tomatoes, cucumbers (pickles), strawberries, apricots, peaches etc. etc. It's well worth the $18.  You can find it at Amazon.com if it's not in your local store.