Guide to Home Canning

Processing and preserving your own food has many advantages. Like any other form of food preservation, home canning is perfectly safe if practiced properly. Being careful to follow recommended guidelines and recipes will ensure that your family enjoys healthy, delicious home preserved foods. This method of food preservation is my personal favorite because there is so much you can do. 

Some people have the opinion that modern food preservation methods have largely reduced the need for home canning. They also question why it is even necessary. Furthermore, many people are concerned about the safety of home canning. With all of these concerns in mind, why would you do it when you can simply purchase canned food from the supermarket? 

Continue reading to find out the answer to that question.

TABLE OF CONTENTS

1) 15 REASONS TO HOME CAN YOUR FOOD

2) DISADVANTAGES TO HOME CANNING

3) HOW DOES CANNING PRESERVE FOOD

4) CANNING METHODS

5) PREPARATION FOR CANNING

6) BOILING WATER BATH CANNING METHOD

7) PRESSURE CANNING METHOD

8) HANDLING OF UNSEALED JARS

9) PROPER STORAGE

10) SHELF LIFE

11) SIGNS OF SPOILAGE

12) 22 CANNING MISTAKES AND PROBLEMS AND HOW TO AVOID THEM

13) ADDITIONAL REFERENCES

14) ADDITIONAL POSTS OF INTEREST

15 Reasons to Home Can Your Food

1) Health

Canning your own food is one way to ensure that your food is free of contaminates. Commercially grown food always seems to have an “acceptable level” of pesticides. However, processing your own food ensures that it is free of pesticides and preservatives. Furthermore it is also free of excess salt and sugar.

2) Saves Money

Produce that is in season is plentiful and cheap. Consequently, canning it for later use will save you a considerable amount of money. 

3) Preserves Your Excess Produce

Active gardeners are commonly over run with various types of fresh produce.  Canning is a perfect way to preserve the excess.

4) Quality and Taste

There is a huge difference in the quality and taste of home canned food compared to commercially processed food. Home canned food tastes so much better. I know this from personal experience. 

5) Necessity

This scenario is much less common these days.  However, this is actually how I grew up.  Families in rural areas still have a large garden and can food during the warmer months in order to feed themselves throughout the winter.  

6) Nutritional value

Most studies agree that home canned food retains all of its nutritional value for up to a year. Additionally food processed at the peak of freshness and properly preserved is much better for you than commercially prepared food.  

7) Environmentally Friendly

If you are processing your own food, there is much less waste relative to using prepackaged foods.  The jars are reusable as well as the rings.  Additionally, you are not consuming food that was transported for thousands of miles on a truck.  You simple transport the food from your kitchen counter to your storage closet.  

8) You Control the Taste

When making your own canned food, you are in control of whatever flavors or spices you want to add.  You also get to relive your harvest in the middle of winter. 

9) Variety in your diet

When you preserve food that is available seasonally, you have the added benefit of keeping that variety in your diet year round. You also have the ability to make a huge variety of recipes not typically available with commercially canned food.  

10) Saves time

Canning food can be labor intensive.  However, if you process food in larger quantities, it actually saves you time in the long run. For example, you do not have to take the time to make a recipe from scratch if you home canned it the first time. 

11) Convenience

With home canned foods you simple open it, heat and eat.  Fresh canned fruit can be consumed directly out of the jar. 

12) Self sufficiency

Home canning puts you one step closer to being in control of your own resources. It makes you more independent from a huge infrastructure over which you have no control. 

13) Energy free storage

Home canning requires the use of electricity or gas. However, after the canning process is complete no additional energy is needed for storage.

14) Gifts

Home canned food makes wonderful gifts during the holidays. 

15) Personal Satisfaction

Similar to many other things that you do yourself, preserving your own food gives you a great sense of accomplishment.  

Disadvantages to Home Canning 

1) Labor Intensive

There is no doubt that home canning food is a lot of work. There are numerous steps involved compared to freezing food. 

2) Equipment intensive

It takes a small investment in equipment to can your own food. Purchasing a hot water bath canner and a pressure canner cost a few hundred dollars. This does not include the initial investment in jars as well as cooling racks, tongs, etc.  However, you will save a little money by simply purchasing a pressure canner.  It can double as a hot water bath canner.

3) Learning curve involved

It is easier to learn how to freeze and dehydrate food. Home canning takes a bit more knowledge. Like so many other things, you need to practice and experiment a little. You are going to have failures as well. Everyone does. However, in my experience this method of food preservation is worth the effort. 

4) Shorter shelf life?

Home canning is not the ultimate method of long-term food storage. The general recommendation on shelf life is one year.  However, I’ve stored home canned food for much longer under certain conditions.  By contrast, freeze dried food keeps for up to 25 years.  Although I am not sure I see the point in 25 year food storage.  But then again, I am not a prepper.  

How Does Canning Preserve Food?

Home canning requires  heating the food to a temperature that destroys the microorganisms responsible for causing illness and food spoilage.  This process involves placing the food inside jars or other containers for processing.  Home canning also inactivates the natural enzymes in foods that if left uncheck would result in decay. Furthermore, the heating and canning process drives air from the jars. As the jar cools a vacuum seal is formed. This prevents recontamination of the food.

Because of the infamous bacteria Clostridium botulinum survives boiling temperatures, pressure canning is necessary to preserve low acid foods.  Temperatures as high as 240 ℉ are needed to inactivate the spores.  These temperatures cannot be reached in boiling water. A higher pressure is necessary. That is achievable in a pressure canner.

Canning Methods 

The two most common canning methods are the boiling hot water bath and pressure canning. Which method you use depends on the type of food you are processing.

Boiling Hot water bath method: This method of canning is safe for high acid foods, meaning a pH 4.6 or less. This includes fruits, tomatoes, pickles, jams, jellies, and other preserves. Jars of food are immersed in boiling water which is 212 ℉ at sea level. If foods have a pH approaching 4.6, that pH is lowered by adding a small amount of lemon juice. If canning above 1000 ft elevation, processing times need to be adjusted since water boils at a lower temperature at higher elevations.

Pressure canning method: This method is needed to safely can low acid foods, meaning a pH of 4.6 or greater.  This includes meat, seafood, and most vegetables. Pressure canning involves placing jars in 2 to 3 inches of water and sealing them in  the canner for processing.  Because the canner is sealed, a higher internal pressure is achieved. A higher pressure means higher internal temperature. That higher temperature is what kills the Clostridial spores. 

Preparation for Canning

Equipment, jars, and lids. 

Assemble all the needed equipment and make sure it is clean and ready for use. This simply makes your processing more efficient. Inspect all canning jars and lids prior to use. Any lids or jars with nicks or cracks are discarded since they will not form an air tight seal. Wash them thoroughly with hot soapy water and keep them hot until the processing begins. 

Food that is processed in a hot water bath for less than 10 minutes, must be placed in sterilized jars. These jars are sterilized by boiling them for 10 minutes. At an altitude of 1,000 feet or greater, add one minute of processing time for each 1,000 feet in elevation.  For food processed for greater than 10 minutes, or processed in a pressure canner,  sterilization is accomplished during the processing.  Consequently, there is no need for pre-processing sterilization.  

Lids and rings are processed according to the manufacturer’s instruction.  Most of them need to be boiled. Some need to be left in hot water.  

One last thought on preparation.  Always think in terms of being as clean and sterile as possible. The more careful you are with your processing techniques the more successful you will be in your home canning.  

Methods of packing jars 

Raw packing: This is where raw food is placed directly into the jars.  Boiling hot water, syrup, or juiced is then poured into the jar enough to surround and cover the food.  Be sure to leave the appropriate amount of head space, which is a small amount of open space at the top of the jar. Food is packed tightly because there is a certain amount of shrinkage during processing.  

Hot packing: Food is heated or slightly cooked prior to placing it in the jar.  Then it is covered with boiling water, syrup, or juice. When hot packing food be sure to pack loosely because some shrinking has already taken place.  

When packing jars by any method it is important to complete cover the food with liquid.  Otherwise the exposed food at the top will change color and possibly take on a different flavor. 

Boiling Water Bath Canning 

Very simply stated, you are submerging sealed jars of food in a “bath” of hot water and processing  (boiling) them for a specified amount of time. The water must be boiling {(212 degrees Fahrenheit (F), 100 degrees Celsius (C)}. This amount of heat is sufficient to drive the air out of the jars and form a tight seal during the cooling process. It also kills any vegetative bacteria and prevents further growth. There are variations in processing time depending on the type of food, how it is packed and the size of the jar. It is important to consult your canning reference manual. Allow one minute additional processing time per 1000 feet elevation above sea level.   

Any large metal container with a wire rack, and a tightly fitting lid can be used  as a water bath canner.  It needs to be of sufficient size to allow 1 to 2 inches of hard boiling water to cover each jar. The wire rack prevents the jars from touching the bottom and allows hot water to freely flow around the jars.  To be more frugal with equipment purchase, keep in mind that a pressure canner can be used as a hot water bath canner provided it is large enough.  Simply place the lid on the canner to maintain heat and prevent evaporation. Just do not seal it. You should also open the petcock (safety value) to prevent pressure build up in the canner.  

Only high acid foods, those with a pH of less than 4.6, are appropriate for processing with the hot water bath method.  High acid foods naturally prevent the growth of Clostridium botulinum, which is infamous for causing a deadly form of food poisoning.  The temperatures and pressures reached with water bath canning are not significant to kill the Clostridial spores. 

Examples of high acid foods:

• Apples
• Applesauce
• Apricots
• Berries
• Cherries
• Cranberries
• Fruit juices
• Peaches
• Pears
• Plums
• Tomatoes
• Pickles
• Relishes
• Preserves

Steps for Boiling Water Bath Canning

• Filled the hot water bath canner about half way full of water and start heating the water.  Filling it half way allows for placing the jars in the canner without over flowing.  
• If vegetables are raw packed into cool jars do not allow the water in the canner to boil before submerging the jars. If it is, placing the cooler jars in boiling water may cause them to break. This is the advantage of heating the jars prior to packing. With hot packed jars the water can be boiling.  
• Pack jars according the the instructions above. Be sure to allow for appropriate head space.  Use a small wooden or rubber utensil and run it along the edges of the jar to free up any air bubbles. Add more fluid as needed. 
• Proper head space is important.  Food in the jars may start to boil during the processing.  Proper head space accounts for this and prevents the food from leaking during processing.  If this happens, a proper seal will no form.   
• Carefully clean the edges and rim of the jars from any liquid or food particles.  Use a clean rag or sponge or damp cloth.  If food material remains on the rim or in the threads, it may prevent a proper sea from forming during processing.  
• Fill jars one at a time. Place the appropriate sized lid and rim. Snug the lid down very slightly.  You do not want to over tighten because air needs to escape during the processing. Fill jars and place them in the canner one at a time.  
• When loading the canner be sure there is at least one inch of water covering all of the jars. 
• Place the lid on the canner and turn up the heat.
• When the water reaches a rolling boil, begin the processing time.  If the water ceases to boil during processing, return it to a boil and start the processing time over from the beginning
• After processing for the appropriate time, turn off the heat and remove the lid from the canner.  
• Set out some strong wire cooling racks for the jar.  You do not want to place the hot jars on a cool surface. 
• Remove the jars with a jar lifter and place on cooling racks. Allow sufficient space between the jars for air flow.  This helps with cooling.  
• Allow the jar to sit untouched for at least 12 hours. DO NOT tighten the lids during this time.  
• After cooling to room temperature, remove the ring bands from the tops of the jars. Do not leave them on or tighten them for any reason.  In the event of spoilage during storage, gas will accumulate inside the jar and will pop the lid off or will leak around the edge. Tightening the lid may prevent this from happening. 
• Inspect the edges closely for any leaking. 

Pressure Canning Method

Pressure canning is essential to preserve foods with a pH of greater than 4.6, which means they are more basic.  It is this low acid content that allows for the growth of bacteria. Processing food under pressure achieves a higher temperature. That high temperature kills bacterial spores, especially Clostridium.  Pressure canning is a little more complicated and you truly need to pay attention to details. It is necessary to have a good reference manual on canning. It will contain important charts with recommended temperature, pressure, and processing times. 

Examples of low acid foods:

• Beans
• Beets
• Carrots
• Corn
• Meat
• Potatoes
• Okra
• Seafood

Keep in mind that a pressure canner is not the same as a pressure cooker.  A pressure canner is thicker, heavier, and typically has a lid with multiple threaded handles for sealing the lid in place when under pressure. It also has several important features such as a pressure gauge, petcock (safety valve), and a safety plug or over pressure plug.  This is designed to release pressure from the canner if the temperature or pressure becomes too high.  

A lot of people find pressure canning intimidating and view it as a dangerous process. People tend to envision large pots filled with boiling water exploding on the stove. Although this is possible, I have been pressure canning for most of my life and have never had an issue. 

There are a number of very good pressure canners on the market. It is important to follow the specific instruction manual for your particular model or brand because procedures may vary.  Some of the more popular brands on the market are All American, Presto, Fagor, Mirro, and Granite Ware. 

I have used several different models. Although it is a matter of personal choice, I have never been a fan of trying to care for the rubber gaskets on some models.  They can be difficult to source and expensive to replace especially if you have had your canner for a number of years.  I’ve had an All American model for over 20 years.  It is a precision ground aluminum model with a lid that does not have a gasket.  It has given me years of service and still going strong.  

Do not spare any expense on purchasing a high quality pressure canner.  My personal preference is a canner that is precision milled and does NOT require a rubber gasket on the lid for proper sealing. Canners with dial gauges must have those gauges checked yearly for accuracy.  You are depending on this canner to preserve healthy food for you and your family. So, take this one extra step as a precaution. 

Steps for Pressure Canning

• Place 2 to 3 inches of water in the canner. The water should be hot but not boiling. 
• Pack the canning jars using the same steps as described in the Boiling Water Bath Canning Method above.  
• Be sure to allow for appropriate head space, remove excess air bubbles, and wipe rims and threads with a clean cloth or sponge prior to placing on lid. 
• Snug the lid slightly. Do not over tighten. 
• Place a rack in the bottom of the canner prior to loading the jars. 
• After filling the canner, make certain there is at least 2 to 3 inches of water around all the jars. 
• Place the lid on the canner and tighten it down. Steam should only be escaping from the vent. 
• Increase the heat until steam steadily escapes from the vent.  Allow venting for 10 minutes. This venting time forces out all the remaining air in the canner.  If air is still present, the internal temperature may not reach the appropriate level.  This will result in under processing. 
• Close the vent using the valve, weight, or screw depending on the type of canner.  
• If using a dial gauge canner, allow the pressure to quickly rise to about 8 to 10 pounds. Then turn down the heat so that the pressure slowly rises to the appropriate level for processing.  Begin your processing time once the appropriate pressure is reached. 
• If using a weighted gauge canner, slowly increase the pressure until the weight begins to “jiggle” several times per minute. Once this occurs, start your processing time. 
• For best results with pressure canning, it is important to slowly change the pressure. Any rapid pressure changes can easily cause the jars inside the canner to over flow. 
• During processing, if the canner pressure drops below the recommended lever, adjust it back to the appropriate pressure and start your processing time over from the beginning. 
• Once the processing time is complete, turn off the heat. Allow the pressure to drop to zero.  This may take 30 minutes to an hour.  Do not be tempted to vent pressure manually. This could result in the jars in the canner over flowing. 
• Open the vent or remove the weight when the canner is depressurized.  
• Open the lid very carefully so that the steam escapes away from you.  
• Remove the jars with a jar lifter and place on the cooling rack.  
• Cool jars for 12 to 24 hours. Once cooled, remove the rings.  

Handling of Unsealed jars

Even if you are a master of canning, you are occasionally going to have a jar that does not seal properly.  If this happens, there are three things you can do. 

• Refrigerate the food and consume it within a couple of days. This is typically what I do because it is not worth the time and effort to process only one jar of food.
• Remove the food from the jar and freeze it. 
• Reprocess the food within 24 hours.  

Proper storage 

Proper storage of your canned goods will ensure a longer shelf life. Storage in an area that maintains a near constant temperature is best. In fact, the cooler the better. Storage in a dark area prevents exposure to natural light which can cause deterioration of color and taste. The storage area can be a large walk-in closet, a room in the basement, well sealed cabinets, or in a root cellar, which is what I use. 

After the jars have cooled, it is actually better to store canned goods without the rings on top. The reason is that if there is a deterioration of the food, or spoilage, most of the time the lid will pop open. The presence of mold on the rim of the jar or an odor alerts you the spoilage problem.  

Label each jar with the name of the contents and the processing date.  This helps greatly with proper rotation.     

Shelf life

The shelf life of home canned goods seems to be a matter of opinion. The official answer from the National Center for Home Food Preservation(see the reference section below)  is “For highest quality, properly stored preserved foods are best eaten within a year of canning.” Some other sources will say 12 to 18 months. 

The reality is that properly stored home canned foods last for several years.  However, keep in mind that the longer they are stored there is a greater possibility of the loss of quality. I have stored canned goods in my cellar for 4 to 5 years, even meat products, and have had great luck doing this.  It is up to you to use your own best judgement on this issue.    

Signs of Spoilage  

Your best safe guard against spoilage of home canned goods is proper processing technique and storage.  When I process foods at home, I am meticulous with sterility and cleanliness.  That said, I still occasionally have a jar of food go bad.  However, that almost always occurs when I kept it longer than I should.  

Proper processing, proper storage, and rotation will prevent most problems. The number one rule about using home canned goods: If in doubt throw it out. Throwing out one jar of food is far better than taking the risk of food poisoning.  

Here are some things to watch for:

• Total loss or change in color. Some change in surface color is okay.  But a total loss in color is suspect.  
• Significant loss in the amount of fluid in the jar. This is a good sign of a leak.  
• Liquid or mold around the edge of the lid.  This is also a sign of a leak.  
• Mold or scum on the inside of the lid or on the surface of the food.  
• Odd odor
• Bubbles forming inside the jar.  This is a sign of gas formation that occurs with fermentation and spoilage. 

22  Canning Mistakes and Problems and How to Avoid Them

1) Improper Processing Method

The biggest mistake you can make is processing food in a hot water bath canner when you should have used a pressure canner. Hot water bath canners are only suitable for high acid foods. For example tomatoes, pickles, and fruit.  If in doubt about proper processing of specific foods, consult a reference manual on home canning. 

2) Not removing air bubbles 

Excess air bubbles can add to the head space. If this happens, there may be too much pressure in the top of the jar resulting in the jar not sealing.  

3) Not measuring head space 

Head space is the unfilled space in the canning jar between the top of the food and the underside of the lid. Head space allows for food expansion during the heating process.  It is also important for the formation of a vacuum seal as the jars cool.  

4) Leaking during processing

This seems to be a more common problem with beginners.  Leakage can happen for several reasons: not allowing enough head space, not removing all the air bubbles from the jars before processing, varying the pressure in the canner too quickly. 

5) Jars not Sealing

This can happen for several reasons. If food leaks during processing, it accumulates on the rim and under the lid preventing the formation of a vacuum seal. Attempting to reuse an old lid is a common mistake.  It will not form a seal on the second use. Nicks in the rim of the jar, dents in the lids, or any other defect prevents a proper seal. 

6) Over filling the jars

This results in too little head space.  The food will expand during processing and the jar will fail to seal. Always, always, measure head space.  

7) Jars Unsealing During Storage

This is generally a processing problem.  There may have been some mild leakage that was undetected. The jars, lids, or rings may have been defective. This can also result from a head space problem or from not processing the food properly.  These problems can be avoided by simply following the recipes closely.  

8) Rusted or Moldy Lids and Rings During Storage

After processing, thoroughly clean the jars, lids, and rings and dry them. Any debris, food material or even excess moisture on the outside of the jar or lids will promote the growth of mold and the formation of rust. This can and will eventually break down the seal on the jar.  

9) Food Discoloration

Some food discoloration can always occur.  This can also be the result of exposure to too much heat or sunlight.  It is best to store foods in a cool, dry, dark place with a fairly constant temperature.  However, complete loss of coloration is suspect and may indicate spoilage.  

10) Reusing Canning Lids

Never do this. The lids will form a nice vacuum seal only once. The only time I reuse a lid is when I want to store food with only a semi-airtight seal.  For example, placing dehydrated foods in the jar.

11) Not Completely Submersing Jars During Processing

When processing food in the hot water bath canner, the jars have to be covered with 1 to 2 inches of boiling water.  Otherwise, they will not process properly.  

12) Improper Cooling of Jars

After the food is processed, leave the jars undisturbed to cool for 12 to 24 hours. The majority of the time a complete vacuum seal will form prior to this.  However, moving the jars around may result in breaking the seal.  

13) Not Adjusting Processing Time for Altitude

Water boils at 212 ℉ at sea level.  At higher altitudes the boiling point of water decreases.  Consequently, the food processing time needs to be adjusted. If you fail to do this, food will be under processed. Increase processing time by one minute for every 1,000 feet increase in elevation. So, at 1,000 feet, increase the processing time by one minute. At 2,000 feet increase the processing time by two minutes.  

14) Using Inferior Ingredients

You only get out what you put in. Your canning will be much more flavorful if you only use the best ingredients.  Only use products at the peak of freshness.  

15) Not Following the Recipe

Follow canning directions precisely in order to ensure proper safety.  Do not experiment with processing time or directions.  

16) Over Tightening the Lids 

I know it is tempting to firmly screw the lids down. But doing so will prevent air from escaping during the processing.  Consequently, you only need to screw them down finger tight.  

17) Not Using the Correct Jars

Proper canning jars are a must. The lids and rings are designed to form a vacuum seal. Using the correct sized jars called for in the recipe is also important.  Larger jars require more processing time.  You can always use a smaller jar than called for and process at the same amount of time. 

18) Using Fresh Lemon Juice

Some fruits and vegetables require a little more acid content for proper processing. If this is the case, do not use fresh squeezed lemon juice. You have no way of knowing if it is at the proper pH. The prepackage lemon juice has a consistent pH and is better to use for canning.  

19) Poor Sterile Technique

Some canning sources recommend that all jars be sterilized prior to use. This is not necessarily true.  If the food is processed for less than 10 minutes in a hot water bath canner the jars must be sterilized. Simply boil them in water for 10 minutes and adjust the time according to altitude.  Processing food for greater than 10 minutes or processing in a pressure canner, sterilizes everything during the processing.  Personally, I sterilize everything anyway just as an added precaution.  

20) Jars Breaking in the Canner

This can happen for several reasons: 1) placing hot jars in a cool canner, 2) Putting hot food in cold jars, 3) Placing food jars directly on the bottom of the canner instead of on a rack, 4) Using commercial food jars instead of jars made specifically for canning 5) Placing unheated jars of food into the boiling water in the canner, 6) Using jars with hairline cracks.

21) Open Kettle Canning

With his method food is cooked in an open pot or kettle and placed directly into hot food jars without processing. This is not recommended. Cooking food in this manner does not achieve temperatures sufficient to kill the bacteria that causes spoilage and food poisoning.  

22) Discoloration of Metal Lids

The underside of the metal lids can discolor to some degree due to the natural compounds found in foods, particularly the acid content.  Some discoloration on the lid of properly sealed jars is harmless.

Additional References

In the interest of being as complete as possible, I wanted to provide these additional references. I have read all of these publications and the information on basic canning principles are similar to what I have provided here.  The additional benefit of these publications are the recipes provided.  There are numerous easy recipes for you to try.  Enjoy!

The USDA webpage, called the  National Center for Home Food Preservation , is packed with information. They have a 196 page PDF for downloading.  

Ball has a very nice webpage on Canning 101. 

Mother Earth News has an informative Guide to Canning  with numerous recipes.  

Penn State Extension Program has a great article on the Basics of Home Canning. 

Additional Posts of Interest

Guide to Pickling Vegetables

Guide to Fermenting Foods

Guide to Smoking Meat

Guide to Dehydrating Foods

Go off grid and live well,

Patrick