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15 Canning Mistakes to Never Ever Make

The sight of jars stacked in neat rows redolent with the taste of summer bounty will be inspiring for those who want to start canning their produce.  Before your start though there are a few mistakes to avoid if you want flavorsome, tip-top quality canned goods through the winter.

#1. Using sub-standard produce

When the recipe says choose ripe fruit or vegetables ensure they are crisp and firm. Carrots that still look good but have lost that crack when you break them are not going to make good pickles. Similarly fruit that is just that bit past ripe is going to result in a poor jam. The secret is getting the pectin right so the jam will set – slightly under ripe and perfectly ripe fruit are better than over ripe fruit which have a lower pectin content.

So, what is pectin and why do you need it? Pectin is a starch (a heteropolysaccharide) that occurs naturally in the cell walls of fruit and vegetables and in combination with the sugar and acid in lemon juice when making jams will cause the mixture to gel. Quince and apples are particularly high in pectin, as are the skins of citrus fruit.

If you need to add pectin it can be obtained in dry or liquid form but many traditional homesteading recipes use apple or quince to up the pectin content when making strawberry jam for instance – strawberries being soft and fairly low in pectin. As soft fruits are lower in pectin, generally they will benefit from added pectin.

#2. Using a boiling water bath instead of a pressure canner

For those new to canning one would think that a boiling water bath would do the same job as a pressure canner – but it doesn’t – the heat in the bath will reach 212 while the pressure canner will reach up to 425 Fahrenheit. The boiling water bath is fine for food that has a high acid content, as botulism will find it difficult to survive the pH level of around 4.5 to 4.6.

Food that can safely be processed with a boiling water bath are pickles, tomatoes – to which vinegar has been added, sweet preserves like berry jams as berries have a high acid content and other fruit. You will notice lemon juice is often introduced in the recipe raising the acid level.

Food that is not acidic like vegetables (not pickled), soup, and meat must be done in a pressure canner to kill all traces of organisms that could spoil the food. This article explains the dangers of botulism which is fortunately fairly rare – but will only remain so if proper hygiene and sterilization is carried out in home canning situations. The high temperature of the pressure canner will kill off the organisms that can cause food to spoil.

#3. Not putting enough water into the boiling water bath

Once in the boiling water bath the jars must be covered– that includes the lids – so make sure the water is deep enough so there is an inch or more of water covering the lids at all times during the processing. This is important as all the produce needs to be heated equally during the process – you can’t have the bottom half of the produce heated to kill organisms while the part near the top is not sufficiently heated, allowing organisms to proliferate once the product is stored on a shelf.

This video gives the basics on using a boiling water bath:

#4. Doubling the recipe for jam making

Especially when you are making batches of jam or canning produce, it is tempting to simply double the recipe. After all you have the produce to use up, a large pot, the space in the pressure canner so there shouldn’t be a problem – should there?

Yes, it can be a problem. Once you double a recipe you spend longer getting the ingredients to the right temperature – that can destroy the pectin, which is what you need to make the jam or jelly set. When making jam you are usually advised to use a pot with a large surface area. The reason is it leads to evaporating the water in the fruit faster. When the recipe is doubled, fruit will take longer to process and can become mushy under the weight of the rest of the fruit in the process.

Cooking the jam quickly leads to fruit retaining its texture and shape – think lovely strawberry jam where you can identify the individual chunks of strawberry. If you have a lot of produce what you can do is take two pots and make two batches at the same time, making sure to tend to them carefully so the jam doesn’t catch on the bottom and burn, then use that extra space in the pressure canner or boiling water bath.

If you are using commercial pectin then you can double recipes as there is sufficient pectin to make the product set without having to lengthen the cooking time – but be careful of adding too much otherwise you end up with jam that is more like rubber.

#5. Not testing for set in jams and preserves

If you follow the instructions, prepare the fruit, add the sugar and do not test whether it is forming a gel you my end up with fruit syrup instead of jam or a liquid that is too thick meaning the fruit you pack in the jars will tend to want to float to the top. This is because fruit will vary in pectin levels depending on the time it was picked, the climate conditions, and between various cultivars, among other factors.

The way to get the set right is to keep testing –keep 4 to 5 tablespoons chilled in the freezer and put a teaspoon of the jam or syrup onto the chilled spoon, wait a few seconds and see if it sets. If it doesn’t, keep cooking a little longer and test again with another chilled spoon until you are happy that the consistency is right.

Because you cooked the jam for 20 minutes the last time and it turned out perfect does not necessarily mean you can simply repeat – always test to avoid a disappointing batch. If the result does turn out too runny watch this video  to learn how to reprocess your product:

#6. Not using a canning rack

It happens – kids get hold of the canning rack and use it for something else and when you get out your pressure canner there’s no rack. You may be tempted to simply put the jars in without a rack. This is not advisable – the direct heat from the metal base and the bubbling and boiling heated water can cause the jars to bump against the base and crack in the high temperatures of up to 425 Fahrenheit in a pressure canner, and of 212 Fahrenheit in the boiling water bath.

If the rack has been misplaced, you can take a clean dishcloth twist it into a sausage and coil it to fit inside the canner. This will provide a buffer between the glass and the metal.

#7. Using a reactive pot

Recipes will call for a non-reactive pot. Specifically you should use stainless steel or an enameled cast iron pot. Do not use untreated cast iron or an untreated aluminum pot – the acids in the preserves will react with the pot imparting a metallic taste to the produce – also aluminum pots, particularly, will discolor due to the acid in the batch.

If the pot is made from anodized aluminum, it will probably be fine – many people cook in these and claim there is no metallic taste. The acid content keeps the food in the jars preserved by not allowing yeasts and molds to grow in the low – pH levels of around 4.6. Personally though, I prefer not to use aluminum pots for any cooking at all.

You will often see people preparing their batches in copper pots. Although copper is a reactive metal is does not give a metallic taste to the batch cooked in it.

#8. Forgetting to check for imperfections in the canning jars and lids

Once the shiny new jars and lids are delivered check each jar and lid carefully for imperfections – there may be a slight nick on the rim, a hairline crack that occurred during transportation, a part of the lid where the sealing material is thinner or non-existent, a buckled lid. These should not be used. You run the risk of seals not forming properly and in the case of cracked jars, them bursting in the canner.

#9. Not sterilizing jars and lids properly

The jars and lids are all new and clean when they arrive in their boxes so one may be tempted to skip the sterilizing step. The problem is that if you do this, figuring the hot water bath or pressure-canning process will get rid of all the organisms that can cause spoilage you are putting whoever eats your produce at risk. Rather be 100% safe and sterilize those jars and lids.

Once the hot food is placed into the jars, organisms may have snuck in from being exposed to the air, hence the boiling water bath or pressure canning step to ensure the last of the baddies is killed off.

After all who wants to be featured in the news as the person whose produce caused death or paralysis due to botulism? The trouble with botulism is you can’t see, smell or taste it in comparison with molds that announce their presence with a whitish, green or sometimes orange growth on the surface of preserved goods. This video shows how to sterilize jars:

#10. Not leaving the correct amount of headspace

Quality recipes will tell you how much headspace to leave – this will vary depending on what you are canning as some produce may swell. Leaving the correct amount of headspace allows a proper vacuum seal to form in the pressure canner or boiling water bath. If you have a little extra product that won’t quite fill the next jar, don’t be tempted to distribute it among the other jars and overfill them. You need the headspace for a proper seal to form with no product touching the seal area. Rather take the extra produce and put into a container you can keep in the fridge for use over the next two to three days.

#11. Forgetting to wipe the rims of jars where the lid and canning ring will fit

Omitting this step could mean small particles of product stop the formation of a good seal – the result being wasted food. Always keep a clean sterilized cloth at hand. You can pop it into boiling water after you have wiped a couple of jars to prevent air borne organisms settling on it while you are working with large batches.

#12. Forgetting to remove the canning rings

Once all the jars are all processed and filled with the bounty of summer it’s tempting to leave the rings on the jars. Don’t! They mask what is happening on the surface of the product so you won’t see mold growing in the headspace. They keep the lid in place if a seal hasn’t formed properly, so you are unaware of the problem until months later when you fetch a jar from the storeroom to find it has spoiled. The canning rings need to be removed, cleaned and stored for use with another batch.

Check each jar to ensure a proper seal has formed. If you do this immediately you have time to reprocess the contents before organisms proliferate to ensure you have a good seal the second time around.

#13. Reusing old lids

The seal has a red rubbery type substance on it that ensures no air can get in. Once it has been used and opened the seal can be damaged and the will have started degrading over time. Be safe and order new lids – you can reuse the jars and the canning rings provided they are in good condition. It is cheaper to spend on the new lids than to have to throw away produce, which has taken time, effort and money to process.

#14. Fiddling with jars while they are cooling

When jars are being removed from the boiling water bath or the pressure canner use canning tongs to avoid burns and place the jars in the spot where they are to be cooled. Keep jars upright as you remove them. Once the cooling process has started avoid moving them around – tilting the jar allows the hot produce to come into contact with the seal and may result in a seal not forming properly.

#15. Stacking jars directly on top of each other.

This is a big no-no. The weight of the jars on top of each other can cause the seals to pop as this video explains:

Rather, design shelves for storage that will accommodate the height of the jars or use a thin piece of plywood over the first row of jars to distribute the weight.

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About Jeanie Beales

Jeanie Beales
Traveler, photographer, writer. I'm eternally curious, in love with the natural world. How people can survive in harmony with nature has fueled my food safety and survival gardening practices. Over the years on numerous trips to wild places and cities I've learned all sorts of survival hacks, but there is always someone out there who can teach you a new trick so I remain an eternal student and forever humble.

2 comments

  1. Wiping the rims of the jars with a rag dipped in vinegar is a better way to go then to use a rag with water.

  2. #2. 15psi in a canner is 240F. 425F is created with over 300psi (http://www.tlv.com/global/US/calculator/steam-table-pressure.html).

    #9. Unless you are sterilizing jars in a 350F over or higher, you can achieve the same level of food/jar sanitization by washing your jars and then filling them, then can them. If you doubt that, how will you sanitize the lids to the level of the jars without melting the rubber ring on the lid? Lids will have the same amount of germs as the jars.

    Otherwise, lots of good info.

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