Plastic safety

Hello everyone,

I just recently received my Anova cooker and started doing some research into which plastic bags are safe to cook in and after reading through a dozen websites or so, I’m pretty confused. On the one hand, it seems like there is a consensus on the safety of many (perhaps most) types of plastic bags used by vacuum sealers. However, I don’t have a vacuum sealer and am not interested in buying one at this point. Some people use silicon bags but they have so-so reviews on Amazon. I know that a lot of people use Ziploc bags but I was surprised to see that even Jason Logsdon (who mostly uses Ziploc bags) writes the following in his book, “Modernist Cooking Made Easy: Sous Vide: The Authoritative Guide to Low Temperature Precision Cooking”: “I find it hard to believe that we know everything about how plastic reacts to heat, water, our bodies, and the environment. As such, I encourage you to read up on the safety of plastic in sous vide and plastic in general then come to your own conclusions about the safety of using these techniques or consuming products packaged or shipped in plastic.”
I wrote to Ziploc asking for advice on which of their bags are safe to cook in (for sous vide specifically) and am waiting to hear back from them.

What type of bags does everyone use?


I just got the following reply from Ziploc:

"Hi Roman – thank you for your interest in Ziploc® brand Bags.

It means a lot to us that you use Ziploc®; unfortunately, our bags are not designed nor tested for Sous Vide, nor any type of water bath cooking. Even with their 110° C/230° F° softening point, we cannot recommend them for such use. We formulate and test every product for specific household tasks, and can only recommend using them according to their label directions.

If you’d like to know more about Ziploc® brand Freezer and Storage Bags and their make-up, please check our ingredient website:

If you have any additional concerns about the safety of our bags, feel free to call our product safety specialists at 866-231-5406. They will be happy to assist further and are available 24 hours a day.

Kind regards,

Consumer Relationship Center
SC Johnson, A Family Company

USA 1-800-558-5252 |
Canada 1-800-558-5566 |"

@Roman - Thank you for taking the time to get in touch with the team at ZipLoc! This is very helpful and will serve as a great reference for the rest of our community.

@saluki - I thought you might find this interesting following our conversation a few weeks back :smile:

Thanks, @JordanHouston . So I guess not too many people are worried about the type of plastic they use for sous-vide cooking :smile: I’m still hoping to find an inexpensive and safe alternative to buying a vacuum sealer.

@Roman Yep, but it’s a great questions! The cook temps are low for sous vide cooking though so it shouldn’t be an issue. There are some great vacuum sealers that run pretty cheap, I’ve also seen the ZipLoc freezer bags at the store that might be worth trying:

Thanks @JordanHouston! I’ll continue doing some research into this and if I find anything new or interesting I will post it here. In the meantime, I would appreciate any information that other people might have on this question.

more info on ziploc bags:

Thanks @humminglion that is helpful information!

@Roman No problem! Will add anything else I find as well.

@Roman, you don’t need a vacuum sealer to use the vacuum sealer bags, most of which are designed and safe for sous vide. For example, Weston makes a zipper-lock sealer bag as well as pint, quart, gallon, and something called “extra large” sealer bags. Just clip the non-zipper bags to the edge of your container so water doesn’t get in. Like everything else, these are available on Amazon, as well as from Weston.

1 Like
What type of bags does everyone use?

I received my anova precision cooker yesterday, and whilst this is my first immersion circulator, I've been researching since I was first introduced to the technique at a restaurant in new york during restaurant week way back either 2007 or 2008. I thought I had read enough that I wasn't going to be surprised and was really looking forward to finally getting to use the technique at home.

I've seen two temperatures mentioned above which it might not be a good idea to use ziploc bags. For my first meal I prepared with the precision cooker, I decided to use foodsaver vacuum bags for the vegetables (183F), and as I hadn't tried the displacement method to seal a bag before, I decided to cook the chicken (at a lower temperature, 143F) in zip lock bags.

It wasn't until after cooking the chicken that I realised that the "ziploc" bags I had used weren't actually ziploc, but glad. 1 quart Glad freezer bags to be specific.

The vegetables turned out fine, I was quite pleased with the results.

The chicken however, was a little alarming. The chicken was prepared following one of the suggested anova recipes, chicken lemon and rosemary. The recipe suggests 1.5 hours, I cooked it closer to 2 hours, and raised the temperature slightly for the last 45 minutes (145) (erring on the side of caution). As I had been working on preparing the vegetables while brining the chicken, brining was closer to 2 hours instead of the suggested 45 minutes.

When I opened the bags (I had one chicken breast in each 1 quart freezer bag), the first thing I noticed was that the seeds in the lemon had turned blue. Closer inspection of the chicken showed that there were blue jelly like deposits on the chicken as well.

Evidently, the blue from the freezer bags had leached into the contents.

Are Glad bags safe to use for sous vide cooking?

Has anyone else experienced the food turning blue with freezer bags?

I tried numerous google searches and couldn't find any evidence of someone else having seen this.

  • Mark

@mark Hmm, I don’t think the issue is due to the brand but it’s possible. I am curious and would like to take a look at it to give you a better answer. Do you have any photos?

I’ll pick up some of these at the store and try to do a little testing over the weekend. Will see if anyone on the team has seen this before.

@Roman Yep, but it's a great questions! The cook temps are low for sous vide cooking though so it shouldn't be an issue.

You shouldn’t be posting statements like this. My research shows leaching does occur at these temps. I’d like to see the data you’re using to support your statements.

Well, for the record I have had the blue from ziploc bags stain food just in the freezer. I haven’t worried too much about it. The broader question of the relative safety of cooking in plastic, however, is much more complex and at this point, each person may have to make an informed decision based upon what research they trust and their capacity for risk. I believe the following:

  • Ziploc doesn't have any ziploc-based bags they specifically qualify for boiling in but do make a product for steaming in the microwave. Ziploc bags all seem to be made of LDPE (#4) plastic.
  • Some vacuum bags (both commercial cavity bags and home bags) are designed for cooking and declared safe by the manufacturer.
  • Almost everyone claims their product that touches food is BPA free.
  • Nathan Myrhvold is fine with it (
I continue to use ziploc freezer bags personally but I am totally not qualified to tell anyone else that it is perfectly safe. The fact is I just don't know.

@combustication Sorry if it seemed definitive, I’d shared the link to another thread to provide others’ insight as well on the quote you’re referencing above to ensure others’ thoughts and findings were taken into account as well. As you’ll notice through others’ responses, we’ve all continued to do our own research and share any information we can find to help each other out.

You mentioned your research, we’d all love to see it! Would you mind sharing with everyone on the thread here so we can all be better informed? After all, that’s the goal of this thread :slight_smile:

@mark Hmm, I don't think the issue is due to the brand but it's possible. I am curious and would like to take a look at it to give you a better answer. Do you have any photos?

I’ll pick up some of these at the store and try to do a little testing over the weekend. Will see if anyone on the team has seen this before.

Hi Jordan,

No, unfortunately I didn’t take any photos. I’ll likely cook this again in the food saver bags

Interested to hear if you see the same result.


  • Mark

@adnewman Thank you for sharing - I enjoyed the story you linked to from Nathan Myrhvold, hadn’t read that one before.

@mark I haven’t had issues with the blue jelly yet but started with lower temps, will try to crank it up to see what I get with a few other foods, too. I need to take some pics of my little experiments, too.

@adnewman how long was the food bagged in the freezer before it turned blue? Did you end up eating it still? Had it been cooked before? Sorry for the millions of questions :slight_smile:

@jordan I stand corrected in that the bag wasn’t a ziploc brand but another (maybe Glad) that had a blue area on the outside of the bag to write a date (or other information) on. I had bagged one item (raw meat) in a bag and then double bagged it with a second item that touched the outside of the first bag. This caused the ink on the blue area to transfer. I just wiped it off before cooking the food and treated it like the old blue butcher marks that used to be on meat years ago. I assumed (perhaps foolishly) that the company used safe ink. For the record, the transfer didn’t come from the plastic material itself… sorry if I confused folks.

I would say not to use zip loc or glad bags for sous vide, even if it’s low temperature. The lowest I cook is 131 and I can taste plastic when using freezer bags for long cooks (12 hours). I got a Foodsaver vacuum sealer on Meh for $22 and use generic bags (cost $20 for two big rolls which will last well over a year).