Many people do a lot of unnecessary sterilization of jars and lids for home canning. Validated research has shown that it’s not needed in many circumstances, so you can save yourself some cooking fuel energy money — and carbon emissions at the same time!
Summary of new rules for sterilizing canning jars and lids
Here are the modern, up to date rules for sterilizing jars and lids for home canning, as of 2015 onwards.
- You don’t need to sterilize jars anymore if your water-bath processing time will be over 10 minutes, or, if you are pressure canning. You can if you want to, but it’s wasted time that is best spent on ensuring safety in other ways;
- Don’t sterilize or boil the canning lids. Since 1970, you haven’t needed to heat or sterilize the canning lids. You don’t even need to warm the lids anymore, you can just use them room temperature;
- It’s still recommended that you heat the jars, so you are not risking breakage by exposing the cold glass of the jar to hot contents and a hot canner. There are a variety of methods by which you can heat them, provided the end result is a heated jar;
- You never needed and still don’t need to sterilize the canning screw-band rings. They don’t touch any food.
- 1 Summary of new rules for sterilizing canning jars and lids
- 2 What the experts are saying
- 3 Get lazy — increase processing times from 5 minutes to 10 minutes
- 4 Sterilizing jars when not needed is a waste of energy
- 5 How to sterilize jars when needed
- 6 Can a steam canner be used to sterilize jars
- 7 Altitude adjustments for sterilizing jars for home canning
- 8 But you’ve still got to wash jars and lids
- 9 Do not boil canning lids, not even to sterilize them
- 10 Should you heat the lids anyway?
- 11 What about sterilizing the canning rings?
- 12 Heating the jars
- 13 Oven sterilization of canning jars is expressly recommended against
- 14 Timeline of recommendation changes
What the experts are saying
Mississippi State University Extension Service says,
Jars do not need to be sterilized before canning if they will be filled with food and processed in a boiling water bath canner for 10 minutes or more or if they will be processed in a pressure canner. Jars that will be processed in a boiling water bath canner for less than 10 minutes need to be sterilized by boiling them in hot water for 10 minutes before they are filled.” [1] Mississippi State University Extension Service. Canning. Accessed January 2015 at https://msucares.com/health/food_preservation/canning.html
The USDA Complete Guide (2015) says,
Empty jars used for vegetables, meats, and fruits to be processed in a pressure canner need not be presterilized. It is also unnecessary to presterilize jars for fruits, tomatoes, and pickled or fermented foods that will be processed 10 minutes or longer in a boiling-water canner. — USDA [2]United States Department of Agriculture (USDA). 2015. Complete guide to home canning. Agriculture information bulletin No. 539. Available at: https://nchfp.uga.edu/publications/publications_usda.html (Accessed March 2015). Page 1-15
It’s redundant for you to sterilize in advance because the process will do it, (and probably better than you could in the first place given that your jar could get contaminated again from the air while filling). The National Center for Home Food Preservation says,
When a process time is 10 minutes or more, the jars will be sterilized DURING processing in the canner. — NCHFP [3] Burning Issue: Pre-Sterilizing Jars before Canning. National Centre for Home Food Preservation. 19 March 2014. Accessed March 2015 at https://nchfp.uga.edu/publications/nchfp/factsheets/sterilizing.html
To be clear:
- Pressure canning: Sterilization is not needed for either jars or lids. No amount of hot boiling water or soap or scrubbing could sterilize the jars as much as the pressure canner will anyway, so don’t even bother trying. Just wash and make sure the jars and lids are clean. They will get sterilized, along with the food, during the processing;
- Water-bath (and steam) canning 10 minutes and over: Sterilization is not needed for either jars or lids. Just wash and make sure they are clean. They will get sterilized, along with the food, during the processing;
- Water-bath (and steam) canning 9 minutes and under: Sterilization is needed for both jars or lids.
Get lazy — increase processing times from 5 minutes to 10 minutes
Avoid recipes that call for 5 minute processing, or, increase processing time to 10 minutes, and you won’t need to sterilize your jars.
The National Centre for Home Food Preservation says,
Sometimes people choose to increase a 5-minute process time for certain jams and jellies to 10 minutes so that they do not have to pre-sterilize the jars. The extra process time is not harmful to most gels and spoilage should not be an issue as long as the filled jars get a full 10-minute treatment in boiling water. (And remember your altitude to increase this process time as needed.)” [4]Burning Issue: Pre-Sterilizing Jars before Canning. National Centre for Home Food Preservation. 19 March 2014. Accessed March 2015 at https://nchfp.uga.edu/publications/nchfp/factsheets/sterilizing.html
Bernardin says the same,
Heat processing time recommendations for jams and jellies was been increased from 5 minutes to 10 minutes in 2003, thus eliminating the need to pre-sterilize mason jars before filling. Tests have shown that increasing the processing time does not adversely affect the product.” [5]https://www.bernardin.ca/pages/faq/33.php#19
Sterilizing jars when not needed is a waste of energy
Basically, sterilizing jars and lids when not needed is a waste of energy and effort. The National Centre for Home Food Preservation says,
When process times are 10 minutes or more, pre-sterilization of jars is not needed. It doesn’t hurt your product to do it anyway, but it does require additional time and energy and is unnecessary.” [6]Burning Issue: Pre-Sterilizing Jars before Canning. National Centre for Home Food Preservation. 19 March 2014. Accessed March 2015 at https://nchfp.uga.edu/publications/nchfp/factsheets/sterilizing.html
By sterilizing jars when not needed, you are increasing your carbon footprint and causing more energy-generation pollution for no reason.
Instead, you can use the time you save to give your produce an extra thorough rinse to more greatly reduce the bacterial load going into the jars — that will do more concrete good.
How to sterilize jars when needed
If, however, you do need to sterilize jars, or want to, the National Centre for Home Food Preservation says this is how you do it:
To pre-sterilize jars, place the cleaned jars right-side-up on a rack in a canner and fill the jars and canner with water to 1-inch above the tops of the jars. Bring the water to a boil and then boil for 10 minutes at altitudes less than 1,000 feet elevation. Add 1 additional minute for each additional 1,000 feet of elevation. When you are ready to fill the jars, remove the jars one at a time, emptying the water from them back into the canner. This will keep the hot water in the canner for processing filled jars.” [7] Burning Issue: Pre-Sterilizing Jars before Canning. National Centre for Home Food Preservation. 19 March 2014. Accessed March 2015 at https://nchfp.uga.edu/publications/nchfp/factsheets/sterilizing.html
You can save energy by re-using the sterilizing water for water-bath canning the filled jars in. Or, by using a steam canner (see below.)
Can a steam canner be used to sterilize jars
We asked Dr Barb Ingham (who did the steam canner research at Wisconsin) directly if steam canners could be used the same as water bath canners to pre-sterilize jars (when required) for home canning purposes; she said yes. [8]Dr Barb Ingham to Randal Oulton. 23 October 2017. Email on file.
Follow the same jar sterilization procedures as recommended by the National Center (and discussed on this page), remembering to adjust sterilization times for altitude.
Altitude adjustments for sterilizing jars for home canning
Note that the sterilization time increases based on your altitude.
The National Center says, “Add 1 additional minute for each additional 1,000 feet of elevation [above 1,000 feet / 300 metres.]” [9] Burning Issue: Pre-Sterilizing Jars before Canning. National Centre for Home Food Preservation. 19 March 2014. Accessed March 2015 at https://nchfp.uga.edu/publications/nchfp/factsheets/sterilizing.html
Here’s the math done for you:
Altitude feet | Altitude metres | Sterilizing time... |
---|---|---|
0 - 1000 | 0 - 300 | 10 |
1001 - 2000 | 301 - 600 | 11 |
2001 - 3000 | 601 - 900 | 12 |
3001 - 4000 | 901 - 1200 | 13 |
4001 - 5000 | 1201 - 1500 | 14 |
5001 - 6000 | 1501 - 1800 | 15 |
6001 - 7000 | 1801 - 2100 | 16 |
7001 - 8000 | 2101 - 2400 | 17 |
8001 - 9000 | 2401 - 2700 | 18 |
9001 - 10000 | 2701 - 3000 | 19 |
But you’ve still got to wash jars and lids
Even brand new jars and lids out of the box from the store need to be washed. They’ve been through a factory and countless warehouses en route to you. They could have been exposed to minute broken glass shards, dust, fumes, and let’s face it, mouse and pest droppings as well. Wash by hand or just whiz them through the dishwasher:
New canning jars out of the box are not sterile. Being in a box or covered in plastic wrap is not the same as a sterile environment. In addition to contamination by microorganisms that cannot be seen with our bare eyes, packaged jars may accumulate dust, small bits of debris, and even chips of glass in the case of breakage.” [10] Burning Issue: Pre-Sterilizing Jars before Canning. National Centre for Home Food Preservation. 19 March 2014. Accessed March 2015 at https://nchfp.uga.edu/publications/nchfp/factsheets/sterilizing.html
Do not boil canning lids, not even to sterilize them
The USDA Complete Guide was last updated in 2015. It says to sterilize lids that will be on jars being processed less than 10 minutes.
Other than that, though, the guide has has no preference in how you prepare lids. In fact, the USDA defers to the private sector in this aspect and simply says: “follow the manufacturer’s instructions.” [11]United States Department of Agriculture (USDA). 2015. Complete guide to home canning. Agriculture information bulletin No. 539. Available at: https://nchfp.uga.edu/publications/publications_usda.html (Accessed March 2015). Page 1-15
The maker of Ball, Bernardin, Kerr and Golden Harvest lids has said that they DO NOT want you boiling the canning lids
The National Center for Home Food Preservation also says to do what the manufacturer tells you: “…then you prepare your canning lids and ring bands or rubber rings whichever lid style you are using by the manufacturer’s instructions..” [12] Andress, Elizabeth. “History, Science and Current Practice in Home Food Preservation.” Webinar. 27 February 2013. [1:14:00] Accessed January 2015 at https://nchfp.uga.edu/multimedia/video/nchfp.wmv
In the fall of 2014, Jarden, the largest manufacturer of mason jar canning lids in North America, clarified its directions about lids. Through its spokesperson Jessica Piper at Ball, the maker of Ball, Bernardin, Kerr and Golden Harvest lids has said that they DO NOT want you boiling the canning lids. Instead, they are saying that to ensure your lids are sterilized, consider extending the processing time of your product to 10 minutes so that the lids get sterilized on the jar. [13] New Changes in Canning Lid Procedures? https://www.livinghomegrown.com/changes-in-canning-lid-procedures/
The reason apparently is that if the metal lid is overheated by boiling separately, the plastic of the gasket ring on it will spread out prematurely. It’s only supposed to spread out over the surface of the rim of a jar during canning processing, to grip the rim and get a good seal as it cools and hardens. Any premature softening and spreading of the material in the gasket ring could cause issues that become apparent when lids fail to seal, or later on the shelf when lids come lose:
…if you boil your lids, they can get a false seal, or seal too early, and maybe there was an issue with the pressure and later down the road they can come unsealed.” [14] Jessica Piper. Video: Canning Lids 101. 2 October 2014 [27:00] Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/.
Ball says this is not a new recommendation, that they have said it for some time. Jessica Piper of Ball says,
We have always recommended that you do not boil your lids. Boiling can over soften that compound and cause lid failures or your seals to not seal at all.” [15]Jessica Piper. Video: Canning Lids 101. 2 October 2014. [3:07] Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/
She says this recommendation dates from 1969:
The pre-warming was recommended for that red gasket. A long time ago, they were made of latex. So back in those days, you did have to pre-warm that latex to soften it up to get a good seal but with the plastisol, which is that red ring that you see now, there’s no longer a need for pre-warming, and that was something we changed all the way back in 1969. The plastisol itself has had zero changes for decades upon decades upon decades.” [16] Jessica Piper. Video: Canning Lids 101. 2:16. Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/.
Ball now also says that it’s not even necessary to heat the lids at all:
After many years of research, it was determined that preheating Ball® and Kerr® lids is no longer necessary. The sealing compound used for our home canning lids performs equally well at room temperature as it does pre-heated in simmering water (180 degrees Fahrenheit / 80 C). Simply wash lids in hot, soapy water, dry, and set aside until needed. Instructions on lid, cap, and jar packaging is changed. However, retail stores may stock packaging having either instruction.” [17]Ball. Water-bath canning step by step. Accessed March 2015 at: https://www.freshpreserving.com/tools/waterbath-canning
Ball was telling people in writing to go ahead and heat lids as recently as the 36th edition of the Blue Book in 2013:
Home canning lids with sealing compound must be heated for 10 minutes before using to help lids achieve a vacuum seal. Place lids in water to cover and bring water to a simmer (180 F / 80 C), keeping lids in simmering water until ready for use. Remove lids one at a time for caning. Lids can be heated in a saucepan on a cook-top. Or, in a slow cooker that has a temperature control that can maintain 180 F / 80 C. Note: Overheating lids by boiling can result in seal failure.” [18]Ball Blue Book Guide to Preserving. Daleville, Indiana: Hearthmark LLC. Edition 36. 2013. Page 11.)
It’s only in 2014 that their written advice in the Blue Book (37th edition) changed:
Wash lids and bands in hot, soapy water. Do not use abrasive materials or cleansers that might scratch or damage the coatings applied to the lids and bands. Rinse them under hot water. Dry lids and bands and set aside until they are needed.” [19]Ball Blue Book. Muncie, Indiana: Healthmark LLC / Jarden Home Brands. Edition 37. 2014. Page 12.
Ball’s sister company, Bernardin, gives somewhat conflicting advice, even though their lids are the same lids as Ball, made in the same factory in Muncie, Indiana, except they have a different logo stamped on them.
As of May 2015, Bernardin tells you not to boil their lids, but they do want you to heat them:
Boiling lids prior to placement on jars is no longer required for home canning. This recommendation has been changed to “Bring SNAP LID® to a boil and leave in hot water until ready to use. [20] https://www.bernardin.ca/pages/faq/33.php#19
Should you heat the lids anyway?
Ball says that heating the metal lids is no longer necessary; Bernardin advises you to still heat them. Old-time canners are very nervous and suspicious about not at least heating the lids.
The University of Minnesota Extension Service says,
For many years, we were told to heat lids to soften the sealing compound. Today, Ball® home economists are saying that heating is optional. Wash the lids and set aside until you are ready to put them on filled jars. Today, Ball® does not include directions for heating lids on the box. If you want to continue to heat lids, it is okay. Keep them in water below boiling. [21] Home Food Preservation Newsletter. University of Minnesota Extension. June 2014. Page 3. Accessed May 2015 at https://www.extension.umn.edu/food/food-safety/home-food-preservation-newsletter/docs/home-preservation-june-2014.pdf
Ball says they no longer recommend warming the lids. They don’t recommend against doing it, but they don’t encourage you to do it, either:
We no longer recommend pre-warming the lids. You certainly can go ahead and simmer if you choose to, but we’ve done thorough testing, our quality assurance team has been testing for quite some time, and believe it or not, you don’t have to. You no longer have to pre-warm those lids. Which is great because .. not having to use an extra pot to pre-warm your lids is quite helpful. And it just takes out one more step. [22]Jessica Piper. Video: Canning Lids 101. 2 October 2014 [1:05] Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/.
You never have to pre-warm your lids, which is exciting. It’s not necessarily a change, it’s just an update to processing methods. So what we found with thorough testing from our quality assurance team is that our lids are going to work just as great… and all you have to do is wash with hot soapy water, just wash your lids in hot soapy water, set them aside, you’re done, no need for another pot on your stovetop, one more burner going, another pot to clean, you don’t have to worry about that anymore. If you choose to simmer.. that is absolutely still fine, you just never want to boil.” [23] Jessica Piper. Video: Canning Lids 101. 2 October 2014 [29:15] Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/.
Some people do continue to warm the metal lids in hot water out of habit. The question then arises, if you end up with more lids ‘heated’ than you need for that canning session, are those extra lids that you heated still good for a future use? Ball says:
If you do choose to simmer [the lids], people sometimes worry if they can use them again now that they’ve simmered them. Absolutely. You can still use those again. You’ll just want to make sure they are thoroughly dried [before] they are stored.” [24] Jessica Piper. Video: Canning Lids 101. 2 October 2014 [6:40] Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/.
There was indeed a time when the pre-heating was required. Before 1970, the gasket on the underside of the metal lids was made of a different material, and pre-heating before canning was required for that material. But, they changed the material in 1970, and since then, heating hasn’t been necessarily, and boiling has been deleterious.
The pre-warming was recommended for that red gasket. A long time ago, they were made of latex. So back in those days, you did have to pre-warm that latex to soften it up to get a good seal but with the plastisol, which is that red ring that you see now, there’s no longer a need for pre-warming, and that was something we changed all the way back in 1969. The plastisol itself has had zero changes for decades upon decades upon decades how to sterilize lids. That being said, do not boil the mason jar lids anymore. They realized that not only was it not necessary, but that it was often damaging the rubber on the lid and causing seals to fail on the shelf when jars were in storage for a while. The old way was to simmer / boil the lids and pull them out of the boiling water one by one and put them on the jar piping hot.” [25] Jessica Piper. Video: Canning Lids 101. 2 October 2014 [2:16] Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/.
At the end of 2012, Jarden reformulated its lids for Ball, Bernardin and Kerr to remove the BPA from the coating on the undersides of the lids. Some people guessed (wrongly) that the new instructions to not boil or heat the lids relates to that change. That is incorrect. Instead, it turns out that since 1970, it’s the advice to boil or heat the lids that has been outdated / incorrect. Jarden has been honest enough to look at its ongoing research findings, and admit that, gosh, its companies made people take an unnecessary step all those decades:
That BPA free coating is that cream coloured coating on your lid, so that was the only thing that changed, the red plastisol ring that goes around, that has been the same since 1969, but it’s just been in recent time that we’ve done all this testing to realize, oh my word, we don’t have to pre-warm those anymore. Prior to the plastisol, with a latex lid, those absolutely had to be pre-warmed and softened, but we haven’t manufactured with latex in literally decades. So that was the only change that was made with the BPA free coating. We haven’t changed the lid, we haven’t changed the plastisol – I will say that the colour of the lids has changed, many years ago they were gold, now they are silver, they’ve been silver for quite some time to kind of go more in trend with stainless steel appliances a lot of folks have in their homes, but we also have green lids now, and we have blue lids….” [26] Jessica Piper. Video: Canning Lids 101. 2 October 2014 [30:49] Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/.
If you really do want to heat the lids even though it’s not necessary anymore, do it in simmering water no hotter than 80 C / 180 F. [27] “Heat SNAP LID® sealing discs in hot water, not boiling (180°F/82°C).” https://www.bernardin.ca/pages/recipe_page/51.php?pid=113
What about sterilizing the canning rings?
You never hard to sterilize or heat the canning rings (aka screw bands.) They don’t touch the food and are not exposed to the inside of the jar. Though lay people often regard them as part of the lid, they aren’t really.
Heating the jars
It’s still recommended that you work with heated jars. Cold glass can crack when you pour hot contents into it, or, when you place it into a canner with boiling water.
You can usually heat them up enough sufficiently with quite hot tap water.
We do still recommend pre-warming your jars, just to prevent jar breakage and thermal shock.” [28] Jessica Piper. Video: Canning Lids 101. 2 October 2014 [32:50] Accessed March 2015 at https://ball.yourbrandlive.com/c/lids/.
One exception apparently to heating jars is when you are packing your canning jars with chilled fish. Bernardin advises,
“If packing jars with chilled fish, do not preheat jars or water prior to filling jars. When mason jars are filled and pressure canner is filled, add room temperature water to depth recommended by pressure canner manufacturer.” [29]Bernardin FAQ. Accessed May 2015 at https://www.bernardin.ca/pages/faq/33.php#19
Oven sterilization of canning jars is expressly recommended against
See here: Oven sterilization of Mason jars
Timeline of recommendation changes
- 1970 – Ball says boiling lids no longer necessary
- 1988 – USDA Complete Guide says jar sterlization not needed for processing over 10 minutes, or for pressure canning
- 2003 – Bernardin increases all processing times to a minimum of 10 minutes
- 2014 – Ball Blue Book drops recommendation to warm lids, changing it to just wash lids
References
Cari Jo
I bought jars at my local grocery store. I needed large mouth quarts. There was one box. I could see that the box was a faded blueish green. Knowing that was still Ball brand, I figured what could be wrong with them? Well after canning several batches of stuff in an evening……the lids turned a cloudy off color. Since everything sealed I hated to throw out 12 qrts of goodness. I do “share” my canned goods. My question is, is the metal in the lids tainted with some chemical that is going to hurt my products?
Healthy Canning
If there are Ball lids, they are fine. A cloudy off colour — did you remember to put a splash of vinegar in the canning water before you started?
Rose
Why should you take the rings off of the canned foods when storing.
Healthy Canning
Hi Rose, a lot of careful, safe, good canners still store their jars with the rings on. More and more, though, it’s becoming considered good practice to store with rings off as a final, extra bonus safety step. Here’s a discussion of that: https://www.healthycanning.com/store-your-home-canned-food-without-the-canning-rings/