Monday, August 2, 2010

Cooking in plastic -- how safe is it?

When I wrote about using zip-lock bags for the sous-vide cooking method, one of my wonderful readers warned me about the possible danger of cooking in plastic.  The responsible person that I am, I decided to investigate the issue.  I called SC Johnson, the company that makes Ziploc® bags and asked them if their products are safe to use for sous-vide cooking. I explained that this involves heating the food in a bag in a 140F water bath for about 2 hours. They said they'll investigate and get back to me.  Here is the reply that I got:
Our official position is that our Ziploc® bags are not recommended for cooking, only for reheating and defrosting.
But let's be realistic.  Heat is heat whether you are "reheating" or "cooking".  With further prodding I was able to find out that Ziploc® bags start to melt at 230F and no, they don't contain BPA (the chemical that made us all throw out our water and baby bottles).  So, what does all this mean?  Are they officially safe?  No, because they were never tested at low temperatures for long periods of time like the vacuum seal bags -- those are officially safe for sous-vide cooking.  However, I don't see any big red flags here telling me bad things might happen if you occasionally use Ziploc® bags to cook something sous-vide.  That's my personal conclusion and you need to use your own judgement when making this decision.

This closer look at cooking in plastic made me take a loser look at cooking WITH plastic too.  When I looked at my plastic spatula, I didn't like what I saw.  It was easy to see with a naked eye that it was melted.  After inspecting it carefully, I found tiny little letters on the back of its handle (black on black) that read "Safe up to 400 degrees."  That's like making a car that is safe to drive up to 30 miles an hour.  What if you ever want to get on a highway?  Any time you are cooking in a skillet, you are likely to get way above 400F.  Saying that you shouldn't use it on "high" heat is way too vague.  Even on the same stove, medium of one burner is not the same as medium of another burner.  A lot also depends on how long the pan was sitting on the burner, what was in the pan and how the food was positioned.

What makes us question Ziplock bags more than the spatula?  I am guessing it's the novelty of it.  Very few households cook anything sous-vide, yet I can't think of any household that don't have a spatula. It's just like driving vs. flying.  I haven't met many people afraid of driving, but many that are afraid of flying.  Statistically, you are way more likely to die while driving than while flying, but the fact that you drive every day takes all the fear out of it.

The plastic spatula is now safely residing in my trash.  I replaced it with metal.  Technically, you shouldn't use it on non-stick pans, but I'll take my chances with that.  I found that if I am gentle and don't scrape the pan with a spatula, nothing terrible happens.


~M said...

There's also silicone and wooden utensils, which are non-stick safe.

Helen said...

All my cooking spoons are wood, but I've never seen a wood or silicon spatula that is thin enough to slip under things like fish fillets.

Alaskan Dave Down Under said...

I've completely moved to wood and metal cooking utensils. If the wooden spatula is shaped properly I can even flip omelets in a wok with them.

I also don't cook with any coated pans anymore. Have a look at them and you'll see scratches. There's only one place for that teflon to go!

You have a wonderful blog, btw and thank you muchly for the "crab grip" video. Practiced with it the other day while cutting some okra, very handy.

Helen said...

Hi Dave,

Can you send me a link to your wooden spatula?


Ed said...

You can buy high-temperature silicone spatulas that are good up to 800 degrees. I have a set from LeCreuset that have survived years of constant use.

Thailand said...

Hmm, never crossed my mind. I usually just use my wooden spatula. Thanks for the information thought = )

~M said...

I wonder if this silicone-covered metal spatula would do the trick for you.

Helen said...

Hi ~M,

Thanks so much for the link. This looks like a great alternative to plastic. I am using metal for now, which is working fine since I use teflon pans extremely rarely and the one I have has a very sturdy teflon lining. But if I see the metal spatula causing damage, I'll try the silicon wrapped one that you suggested.


Alaskan Dave Down Under said...

G'day Helen,

My wooden spatula actually came from a local grocery store for 3 dollars. The key is the shape: It's completely flat, the blade part is 3 inches wide and 1/4 deep. The leading edge of the blade tapers to about 2 mm. It was labeled as a "Wok Spatula" and it is very nice. It pretty much lives with my high carbon steel wok.

Helen said...

Thanks Dave!

Titanium Rat said...

Great post. Informative.

I built my own sous vide setup, using a PID and a water circulator using air stones.

I'm going to try sous vide experiment (ham) in a pressure cooker 242F . . . but perhaps my bags will melt at that temperature.

Helen said...

242F? That's really high for sous-vide. Did you mean 142? I don't think 242F works for even real vacuum seal bags.

Amanda said...

Thanks for posting this, I was curious myself, and about BPA as well. Good on you for doing the legwork for us.

Ed said...

I think its wise to reduce the number of (unnatural) chemicals we're exposed to, especially the ones that are easy to eliminate. My general sense is that there probably a link between all the various chemicals we use and generally high rates of cancer in the U.S.

That said, we've switched to all pans that have stainless steel interiors -- gone are all the non-stick pans except one for very limited use.

We stir with wooden spoons, etc.

We store in glass in the refrigerator -- especially acidic foods.

And we never, ever microwave or cook in plastic. Glass or ceramic only for the microwave.

(Essentially, we agree with Alaskan Dave Down Under...)