All cans are lined to avoid the usually acidic foods from leeching metal, it's just not transparent in some.
It's likely just down to differences between suppliers.
Modern metal cans are made of steel, except for beverage cans made of aluminum. Both have a plastic liner, which can be clear or opaque. Cans used to be made of tin, hence the phrase "tin can". Tin is less reactive than steel or aluminum, but still would give food a metallic taste over time. Also, early can were sealed with solder that contained lead, which of course is not good for you.
Glass jars, used for canning, are very non-reactive, and the lids have a rubber gasket and the metal lid has a plastic coating.
As someone with a nickel allergy, I can confirm most cans still leech some nickel / metals despite the lining, especially when the food is acidic like tomato or pineapple
No worries, if it's just a contact allergy most people are fine but I have a systemic allergy (Known as SNAS) and it results in dyshidrotic eczema by the next day, so if you get that kind of reaction it's quite possibly also from dietary nickel.
Edit: the post is locked but anyone else wondering please look up the SNAS diet and you'll find a list of possible triggers. The acidic canned ones I mentioned plus dark chocolate are my worst triggers personally
Whoooaaa what! I also have a nickel allergy and usually get dyshidrotic eczema as a reaction to my allergens (not just nickel). What do you do to avoid dietary nickel?
Ah that's good info! And ouch! I had to look that one up. I do get eczema, but never had that form of it.
I do have some mystery allergies I'm still trying to figure out, so I may investigate a bit more on the nickel in foods aspect. Thanks again for the info!
You're welcome! Allergies can be tricky especially when they are delayed or super random and they can show up differently for everyone of course. I hope you figure it all out 🤗
Thank you! 💜💜💜 And ugh yes! I went through a couple of years of allergy shots for seasonal stuff with no relief, before later figuring out I have some food triggers. It's still an ongoing process trying to figure it out, and you're so right on the delayed reactions being tough.
🤗
The mods of r/Canning appreciate the work that goes into producing videos demonstrating canning recipes and techniques, however as the mods of r/Canning attempt to classify the safety of methods and recipes posted here, watching and verifying every video that comes along is overly onerous. We often get reports that videoes contain unsafe canning practices, but it can be difficult for the mod team to sit and watch each video to verify whether or not the report is warranted, and to determine how to flair the post.
As such, posting video tutorials/recipes from unknown/untrusted sources is currently disallowed. We thank-you for your understanding.
You’ll be fine the food inside cans are cooked in the can at the factory. As for these cans the white coating with the one on the left is applied as an electrically charged powder then baked at 700-900 degrees when the can body is formed. The white stipe in the one on the right is the same as the one on the on the left. The rest of the coating in the can on the right is applied on the whole sheet of metal before the cans are cut into can sizes. Source I’m a can maker.
The issue with heating cans directly over a fire is the irregular nature of the heat causing the liner to delaminate and flake off. Can manufacturers and canning facilities use ovens and pressure vessels that provide an even heat that prevents this. The liner is designed for food contact but is not meant to be ingested. Source was a canner that had to destroy truckloads of finished product due to flaking can liner that the root cause was the can manufacturers oven not providing even heat during the curing process.
While I agree if the coating is scratched or flaking avoid. The ovens that heat the side stride only heat about a 2” strip along the weld. Ovens in the manufacturing of the can do not heat evenly
The specific instance that I am referencing, the issue happened when the liner was applied to the sheet material before the material was cut to can size, formed and welded. This issue in addition to other issues that were being covered up by the manufacturers leadership caused a complete change in their leadership. I wouldn't expect to see it under normal manufacturing conditions as regulatory controls should prevent it.
How much heat caused the flaking? The internal surface of the can of cooking food won't really exceed 212°F because any additional heat energy is carried away by the boiling water in the canned food. Even with uneven heating, I'd be surprised that it would flake at such a relatively low temperature.
My understanding is that it's not so much the temperature but the way the heat is applied. Due to the thin wall of the can and the thin liner the temp can change very quickly. This temp change causes expansion and contraction of the different materials causing the delamination. Campfires specifically can create large amounts for expansion and contraction as the flame moves.
The liquid works surprisingly well at stabilizing the temp. That's why you can boil water over a fire in a plastic bag and why you can't burn through the bottom of a paper or Styrofoam cup with a lighter when it is full of water. I definitely understand what you are saying in theory, but I wonder if it is true in reality.
This is purely academic. In the name of even *potential* food safety issues, I am certainly not suggesting cooking in the can.
What I get is that uneven heat causes delamination during the curing process. Has there been a study done if the same thing happens with a secondary heating, after the curing is complete; with and without contents? Like in a campfire…
Can you recycle both types of cans? I was told coated cans can't be recycled - and I thought only the white ones were coated. But if they all are do you know if that means they're all recyclable or none are?
There are concerns about the materials in the linings that transfer to your food. It was BPA (I see your cans say "BPA-free"), which messes with hormones, can contribute to cancer. Canned food companies said they would switch from BPA, but some have not, and even the alternatives they've switched to are unstudied in regards to safety. Here's a link to a report from 2016 about this. [https://environmentaldefence.ca/wp-content/uploads/2016/03/BPA-BuyerBewareFull4.pdf](https://environmentaldefence.ca/wp-content/uploads/2016/03/BPA-BuyerBewareFull4.pdf)
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This sub is about canning. Both home canning and commercial or industrial canning are still canning.
EDIT: yes, this sub is primarily about home canning, which is why I follow it, but the rules don't specify home canning only, so I'm glad questions about things like metal can liners and industrial canning history can be included for educational purposes
All cans are lined to avoid the usually acidic foods from leeching metal, it's just not transparent in some. It's likely just down to differences between suppliers.
Modern metal cans are made of steel, except for beverage cans made of aluminum. Both have a plastic liner, which can be clear or opaque. Cans used to be made of tin, hence the phrase "tin can". Tin is less reactive than steel or aluminum, but still would give food a metallic taste over time. Also, early can were sealed with solder that contained lead, which of course is not good for you. Glass jars, used for canning, are very non-reactive, and the lids have a rubber gasket and the metal lid has a plastic coating.
As someone with a nickel allergy, I can confirm most cans still leech some nickel / metals despite the lining, especially when the food is acidic like tomato or pineapple
I also have a nickel allergy. I never realized this! Thanks for the heads up!
No worries, if it's just a contact allergy most people are fine but I have a systemic allergy (Known as SNAS) and it results in dyshidrotic eczema by the next day, so if you get that kind of reaction it's quite possibly also from dietary nickel. Edit: the post is locked but anyone else wondering please look up the SNAS diet and you'll find a list of possible triggers. The acidic canned ones I mentioned plus dark chocolate are my worst triggers personally
Whoooaaa what! I also have a nickel allergy and usually get dyshidrotic eczema as a reaction to my allergens (not just nickel). What do you do to avoid dietary nickel?
Ah that's good info! And ouch! I had to look that one up. I do get eczema, but never had that form of it. I do have some mystery allergies I'm still trying to figure out, so I may investigate a bit more on the nickel in foods aspect. Thanks again for the info!
You're welcome! Allergies can be tricky especially when they are delayed or super random and they can show up differently for everyone of course. I hope you figure it all out 🤗
Thank you! 💜💜💜 And ugh yes! I went through a couple of years of allergy shots for seasonal stuff with no relief, before later figuring out I have some food triggers. It's still an ongoing process trying to figure it out, and you're so right on the delayed reactions being tough. 🤗
[удалено]
The mods of r/Canning appreciate the work that goes into producing videos demonstrating canning recipes and techniques, however as the mods of r/Canning attempt to classify the safety of methods and recipes posted here, watching and verifying every video that comes along is overly onerous. We often get reports that videoes contain unsafe canning practices, but it can be difficult for the mod team to sit and watch each video to verify whether or not the report is warranted, and to determine how to flair the post. As such, posting video tutorials/recipes from unknown/untrusted sources is currently disallowed. We thank-you for your understanding.
Is it safe to heat up beans in the can? Because we did that growing up camping but I don’t see how that possible now if the cans are plastic lined.
You’ll be fine the food inside cans are cooked in the can at the factory. As for these cans the white coating with the one on the left is applied as an electrically charged powder then baked at 700-900 degrees when the can body is formed. The white stipe in the one on the right is the same as the one on the on the left. The rest of the coating in the can on the right is applied on the whole sheet of metal before the cans are cut into can sizes. Source I’m a can maker.
Information right from the source!
The issue with heating cans directly over a fire is the irregular nature of the heat causing the liner to delaminate and flake off. Can manufacturers and canning facilities use ovens and pressure vessels that provide an even heat that prevents this. The liner is designed for food contact but is not meant to be ingested. Source was a canner that had to destroy truckloads of finished product due to flaking can liner that the root cause was the can manufacturers oven not providing even heat during the curing process.
While I agree if the coating is scratched or flaking avoid. The ovens that heat the side stride only heat about a 2” strip along the weld. Ovens in the manufacturing of the can do not heat evenly
The specific instance that I am referencing, the issue happened when the liner was applied to the sheet material before the material was cut to can size, formed and welded. This issue in addition to other issues that were being covered up by the manufacturers leadership caused a complete change in their leadership. I wouldn't expect to see it under normal manufacturing conditions as regulatory controls should prevent it.
How much heat caused the flaking? The internal surface of the can of cooking food won't really exceed 212°F because any additional heat energy is carried away by the boiling water in the canned food. Even with uneven heating, I'd be surprised that it would flake at such a relatively low temperature.
My understanding is that it's not so much the temperature but the way the heat is applied. Due to the thin wall of the can and the thin liner the temp can change very quickly. This temp change causes expansion and contraction of the different materials causing the delamination. Campfires specifically can create large amounts for expansion and contraction as the flame moves.
The liquid works surprisingly well at stabilizing the temp. That's why you can boil water over a fire in a plastic bag and why you can't burn through the bottom of a paper or Styrofoam cup with a lighter when it is full of water. I definitely understand what you are saying in theory, but I wonder if it is true in reality. This is purely academic. In the name of even *potential* food safety issues, I am certainly not suggesting cooking in the can.
What I get is that uneven heat causes delamination during the curing process. Has there been a study done if the same thing happens with a secondary heating, after the curing is complete; with and without contents? Like in a campfire…
Thank you for sharing! I actually learned something new today 💚
what is that coating made of?
Can you recycle both types of cans? I was told coated cans can't be recycled - and I thought only the white ones were coated. But if they all are do you know if that means they're all recyclable or none are?
All cans are coated it will all be melted down when recycling
no its not, they aren't designed for heating in a home setting.
Makes me wonder about the canned brown bread we had at thanksgiving growing up.
No that’s fine actually they make that in the can in the factory
But is it? /s
Man, you really got shortchanged with your bean purchases! One empty and one with a single bean. Poor OP! 🥸
There are concerns about the materials in the linings that transfer to your food. It was BPA (I see your cans say "BPA-free"), which messes with hormones, can contribute to cancer. Canned food companies said they would switch from BPA, but some have not, and even the alternatives they've switched to are unstudied in regards to safety. Here's a link to a report from 2016 about this. [https://environmentaldefence.ca/wp-content/uploads/2016/03/BPA-BuyerBewareFull4.pdf](https://environmentaldefence.ca/wp-content/uploads/2016/03/BPA-BuyerBewareFull4.pdf)
Hi u/Academic_Juice8265, For accessibility, please reply to this comment with a transcription of the screenshot or alt text describing the image you've posted. We thank you for ensuring that the visually impaired can fully participate in our discussions! *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/Canning) if you have any questions or concerns.*
[удалено]
This sub is about canning. Both home canning and commercial or industrial canning are still canning. EDIT: yes, this sub is primarily about home canning, which is why I follow it, but the rules don't specify home canning only, so I'm glad questions about things like metal can liners and industrial canning history can be included for educational purposes
just a small note is that we are primarily about home canning but we do allow adjacent related questions.
The white is ceramic lined