Comment by jadence | Hacker News Reader

Comment by jadence | Hacker News Reader

What temperature-safe bags are out there?

I did some digging into this a few months ago and couldn't find anything conclusive. All I found were blogs, quotes, etc by wannabe scientists.

Of note:

• http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222987/

Nearly all plastics (even the BPA-free ones) leach estrogenic activity chemicals

• http://pprc.org/index.php/2013/networking/p2-rapid/do-plasti...

Basically said that there is little evidence in either direction

• http://www.codlo.com/faq.html#.Ux5Ly-ddWlg and http://www.chow.com/food-news/107898/cooking-sous-vide-in-pl... and http://www.sfgate.com/food/article/Author-says-use-of-plasti...

Says that bags made from polyethylene (PE) are safe while bags made from polyvinyl chloride (PVC) are not.

• http://www.beyondsalmon.com/2010/08/cooking-in-plastic-how-s...

SC Johnson (Ziplock manufacturer) themselves do not recommend cooking w/ their bags. Note their bags are made w/ the supposedly safe (per the links in the previous bullet) polyethylene (PE)

Right now I'm very intrigued by sous-vide but am too paranoid about the plastics to make the jump.

Hey jadence,

The bottom line: No one knows how safe HDPE sous-vide is in the long run. There's nothing conclusive out there, though what little evidence there is points to it being safe. Nathan seems so think so, too: http://modernistcuisine.com/2013/01/why-cook-sous-vide/

In the end you have to make a personal call. For me, the risk of undiscovered effects is vastly outweighed by the awesome food I serve.

I respect your concern, even if I don't share it, and I'm hoping to solve it soon enough, too. Be on the look out for a new product from us in the coming year.

I don't know a lot about sous-vide, I am more of a wood fire and smoking kinda person, but what would prevent you from using a stainless steel canister? That would eliminate the risks from plastic. Perhaps, a ceramic would also work?

You still need to put the food in something that keeps it out of direct contact with the water while not leaving enough space for air to insulate the food.

I see. So a hard sided container won't trasfer heat properly? Sounds like I need to talk to a friend in polymers to really get a grasp on the right approach because I can't really think of a non-polymer material that would meet the flexibility requirement.

In general it seems like sous-vide would result in food similiar to a braise but without the browny bits and the pan sauce? (saying it that way makes it sound unappetising but I understand it is quiet nice) That said, I think while it doesn't have the asthetic of a wood fired smoker, a device like the op's could replace the slow cooker.

Noooooooo. Food is not similar to a braise. The point of low-temp cooking (sous vide is low temp under a hard vacuum) is that the cook locks in a perfect temperature for the food and the water bath never exceeds that temperature. In practice, you aim never to exceed the temperature at which the protein expels all the water from the food; think: absolutely perfectly cooked steak --- or, more magically, think a short rib, cooked to the doneness of a perfect steak, but with all the collagen converted to gelatin as if in a braise; it's the best of both worlds. Because a short rib cooked to the temperature of a perfect steak in an oven would be tough as nails, it's something you can really only achieve in a water bath.

There are other tricks too; you can simultaneously cook a dozen eggs to perfect running or "walking" yolk, without paying any attention; you can cook veg to a temperature between the breakdown of pectin and cellulose; you can heat-temper carnaroli or arborio rice and set the starches, so that you can make bulletproof risotto in a pan by dumping all the liquid in at once.

It's a pretty nifty tool.

Sounds neat I will definitely do some research on it. Smoking is a similar process but without a fancy rig you can't get control very precise (+/- 30°f is what I can achieve over an 8 hour smoke. pros can do much better). The idea is similar, low temperature forea long time, until the meat hits the desired temperature.

I've been cooking sous-vide for years and somehow missed the risotto trick - thanks for that!

It's worth noting that sous-vide can also cook meats that are somewhere between "a right pain" and "almost impossible" to cook another way. In particular, sous-vide and a bit of time transforms mutton into one of the tastiest, cheapest meals imaginable. I had real trouble going back to lamb after a few months of sous-vide mutton.

Can you elaborate a bit on the risotto? I've never gotten a clear answer on how that's supposed to work.

The premise is amylopectin retrogradation. Heat a starch to the point where it breaks up and liberates its network of amylopectin. Cool it, and the starch crystallizes in a much stronger structure. Heat it again, or (in the case of, say, potatoes) beat the hell out of them in a blender, and they'll retain their structure; they become somewhat bulletproof.

Retrograded arborio is stable enough that you can dump boiling liquid onto it, stir it, reduce the liquid, and end up with perfect risotto --- rather than carefully tempering the rice with small amounts of slowly stirred liquid. Hence: 7 minute risotto.

It turns out you can also simply hydrate risotto rice (soak it in cold liquid for a couple hours) and do the same thing to it, but it doesn't hold long term the way the retrograded risotto does.

These ideas are due to Ideas in Food, a really amazing blog. The authors have published a couple of books; their first (I think it's just "Ideas In Food") is one of my favorite cooking books.

Thanks for the reply zemvpferreira.

How are you planning to solve the concern of plastic leaching while maintaining the benefits of sous-vide?

Ah, there's a question I'm going to sneak away from. I shouldn't have hinted, sorry for being a tease, but it's just not ready for show-and-tell yet :)

Fair enough.

For the interim what do you and Mellow recommend customers use for a "temperature-safe bag" (per instructions on your website)?

On food-safe bags; we can't make a better recommendation than what the manufacturers make themselves. Personally, I've used ziploc when I've been able to afford it.

Dave Arnold talked to (IIRC) someone from SCJ and below boiling, the Ziplock freezer bags supposedly won't leach plasticizers or anything like that.

Thanks for the reply tptacek!

I tracked down Dave Arnold's report to 9:28 here: https://itunes.apple.com/us/podcast/cooking-issues-episode-1...

In summary: SC Johnson (SJC) told Grant Achatz and others chefs not to use their bags for sous-vide so Dave Arnold contacted SJC and asked specifically about using the bags for sous-vide and explained why he believes the practice is safe. The SJC representative replied with "Ziplock brand bags are designed to withheld being held in high temperature water including being used up to 82 degree Celsius for up to 72 hours." (quote at 12:05 of podcast)

I'd feel better if there was a specific statement about the safety of the food being held in the bag rather than an implication that since the bags withstand the bath the food isn't tainted.

Cooking Issues is so great. If any of this thread interests any of you, you should be listening to Cooking Issues.

Thanks for the recommendation! Looks like it's time to prune my podcast list so I can make room...

Right now I'm very intrigued by sous-vide but am too paranoid about the plastics to make the jump.

FYI, immersion circulators are fairly common in restaurant kitchens, since it's so much easier to get predictable results with them compared to traditional means of cooking meat. So if you dine out, it wouldn't be surprising if you're already unwittingly exposing yourself to the plastics risk.

Thanks for the heads up, pcl.

I was already aware but it's a great point and one of the many reasons I try to limit how often I dine out.

Awesome dinner out tonight with a great sous vide duck breast or a 1 in a billion chance I will die from the plastic in the bag in which it was cooked? I choose duck.

Would vacuum sealed glass jars work?

For some foods, yes, perfectly.

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