When we talk about preserving foods, we talk about canning. Canning is away of preserving foods for use later without that food spoiling. I think pretty much anyone born since 1858 understands the concept. But, what most people don’t know is that there are two types of canning processes used by the home canner. The hot water bath method, which is probably the most common and most used (and misused) method of canning and the pressure method. The other thing people may not know is that different foods require different canning methods.
This article will focus primarily on water bath canning, but we will touch on pressure canning as well.
What does water bath canning mean?
Water bath canning is preserving food by placing it in sterilized jars, usually mason jars placing a lid on the jar and submerging them into boiling water for a specified time period. The boiling water heats the contents of the jar causing the contents inside to expand creating an area of high pressure while pushing out gasses. Once removed from the hot water bath, the atmospheric pressure is lower on the outside of the bottle. It pushes in on the lid as the contents inside the jar cools. This creates a vacuum seal preserving the food inside. The heating process also kills mold, yeast, and other bacteria including the bacteria that causes botulism.
How does water bath canning prevent spoilage?
The heat is the key to preventing spoilage. Discussed earlier, the heat from the boiling water kills off a bunch of the nastys that cause food to spoil and spread food-born illnesses. That’s why it is important to choose the correct canning method for the food you are preserving. 212º Fahrenheit, the temperature of boiling water, will kill the bacteria that causes botulism. Botulism spores require a higher temperature but cannot survive in a high acid environment like jams and pickles. For low-acid foods such as meats and soups, you would need to use the pressure canning method in order to reach a temperature high enough to kill off the spores as well.
Is water bath canning necessary?
It seems this question may come down to a matter of risk. Canning is a labor intensive undertaking. First you must sterilize the bottles and lids, then you put your prepared food inside the jars. Then you dump boiling liquid over the food (Boiling Jam or jelly into the jars) and place the lids on them and boil them again. One would think that with all the boiling going on, the need for the final boil in the water bath is a bit of overkill. The thought behind the water bath is that “bugs” can still contaminate the jars between sterilization and filling and “bugs” can contaminate your liquid and your liquid could cool before you get the lid on.
A jar with a lid filled with a hot substance is still subject to the rules of science. The high pressure inside the jar will cool and the lid will seal. (most of the time) It may not be as tight of a seal, and this could lead to spoilage and possible illness. If you are going to be using the product quickly, this may not be an issue for you. It is all in the risks you are willing to take with your food. Cutting corners could lead to botulism and botulism could lead to death. I think I will use the hot water bath.
A process called inversion canning skips the water bath processing step altogether. In inversion canning, once the jars are filled with the hot liquid or jelly mixture, they are turned upside down on their lids to cool. The jars will usually seal due to the cooling process, but you can never be sure if all of the little baddies inside are dead. This is because there was never any actual processing of the product that took place. At best, you can say the food was bottled, but again, the risk factor is a lot higher.
Is water bath canning safe?
As long as you follow the rules, yes. Water bath canning is completely safe. High-acid foods like pickles and jams are the perfect products for a beginner to start with because of the high acid. What the hot water doesn’t kill off, the acid takes care of. Botulism cannot grow in a high acid environment, so, pickle your cukes and string beans to your heart’s content. Jam out the jams and jellies without hesitation. As long as you follow the recipe and get a good seal, you are completely safe.
How to can using a hot water bath
Canning your food using a hot water bath is pretty simple. Cleanliness of your work area and tools is the primary concern. The first step is to sterilize your jars and lids. You can do this by boiling the empty jars and allowing to dry or use your dishwasher’s sterilize cycle. Keep your sterilized lids in hot water until ready to use. Next, prepare your foods. Follow your recipe and prepare your pickles, jams, jellies and sauces. Put the product into the jars per the instructions.
Next, remove a hot lid from the water using tongs or a magnetic lid grabber and place the lid on the jar. Make sure there the rim is absolutely clean and free from any food that may have slopped over during the filling process. Place lid rings on the jars and hand tighten. Lower the packed jars into the boiling water and process for the time indicated on your recipe.
Should the lid be on or off the canner during processing?
Yes. Keep the lid on the canner during processing. This will help maintain the temperature within the water bath. During processing you can lower the heat a bit, but make sure the pot stays at a nice rolling boil for the entire processing time.
How long will foods last that have been canned using the water bath method?
In order to avoid health risks, foods canned at home should be used within a year to avoid any risks. There are also some precautions you need to follow in the storage of canned foods that will help the product last as long as it possibly can.
1. Do not store your canned goods in direct sunlight. The sunlight can heat the contents of the bottles and promote mold growth even if the food was canned properly. Ideally, canned foods should be stored in a cool dry place that averages about 72º Fahrenheit.
2. Properly washing and trimming all foods before canning will cut down on the possibility of spoilage. The fewer the contaminants the less chance of spoilage during storage.
3. Pack your food loosely in the jars. I know you want to make the most of the space, but packing loosely allows a more even heat distribution during the processing. This gives a better chance at killing off all of the bacteria that could cause problems and food spoilage down the road.
4. Follow the recipe guidelines for processing time. The USDA recommends at least 10 minutes processing time for food canned using the water bath method.
How to tell if canned food has gone bad
Not all of your jars are going to turn out the way you want them to every time. For some it may be as easy as spotting a lid that hasn’t sealed after the jar has cooled. Other bottles may unseal themselves during storage. Others will just go bad for reasons that you can’t figure out. Here are some signs to look for to tell if your canned food has gone bad:
- The lid is bulging or you can depress the lid.
- Mold on top
- Rusty lids
- Broken seals on the lids
- Any leaking fluids
- Your food has gone “mushy”
- Bubbles in the jars
- The food explodes from the can upon opening
- The food smells strange
Water bath canning troubleshooting
Sometimes despite our best attempts, things just do not go the way we planned. Luckily, there aren’t too many problems that can’t be fixed or mistakes that can’t be learned from. Let’s take a look at some common issues and some common causes.
Lids didn’t seal
Use jars that are made for canning purposes. You should never use leftover pickle jars or other jars of the like.
The rim of the jar may be chipped or uneven
Not enough head space in the jar causing food to seep between the lid and the rim during processing
The lid ring was bent or not tight enough
Jars were not processed long enough
Jars were not processed at the correct temperature
Not enough water in the water bath
Temperature fluctuation during processing
Jars cooled too rapidly
My foods darkened but didn’t spoil
Not processed long enough
Not enough water in the bath
loss of liquid during canning resulting in exposed food
My Jars didn’t seal. What should I do?
As stated before. Jars that don’t seal is one of the most common issues when it comes to canning. If you have jars that didn’t seal properly during processing and cooling, you have three options.
1. Refrigerate the food that didn’t seal and use it within seven days.
2. Check the rim of the jar and the lid for any nicks or imperfections. Replace the jar or lid as needed and reprocess within 24 hours. You should use the same processing time as before.
3. Remove some of the liquid to give the jar 1½” head space and freeze the product. The extra head space will allow for the expansion of the liquid as it freezes.
Special equipment needed for water bath canning
The equipment needed for water bath canning is simple, but necessary. First, you need a canning pot large enough to accommodate your bottles. This pot should have a lid to maintain the correct temperature throughout processing. Most of these pots will be aluminum or steel covered with porcelain. A few will made out of stainless steel. Pay attention to the bottoms of the pans as some work better on electric/flat cook top surfaces. There are also electric models that can by purchased and used as a stand alone unit. These pots will usually come with a rack that allows you to submerge the jars into the hot water bath gently and pull them out without burning your hands.
Jar lifter: To remove hot jars from the boiling water
Jar funnel: To get the food and liquids into the jars with minimal spillage.
Lid wand: This little guy snags hot lids from hot water
Clean cloths: clean-up and jar wiping. A clean work-space is a safe work-space
Narrow, flat rubber spatula: Helps remove air bubbles before sealing. Air is bad mmm-kay.
Timer or clock: Accuracy will give the best results.
Hot pads: Pans can be hot on your little fingers.
Cutting board: Don’t want to mess up that new counter top.
Water bath canning is a great way to preserve the foods from your garden. Follow proven recipes and process at the correct temperatures for the right amount of time and you will be able to safely enjoy the tasty fruits (and vegetables) of your labor for many months to come.