Freezerbag Cooking

[Joe Gaffney]

I just read the email about cooking in freezerbags and the dangers from PE plastics and boiling water. I discovered freezerbag cooking about 15 years ago from Sarah Kirconnell’s website and it has changed my (backpacking) life. I make and dehydrate a lot of my meals and, when I buy commercial food, I repackage them in freezerbags. I even make up ramen lunches to carry when I go skiing because I don’t want to eat lodge food. My cooking is reduced to boiling water which saves a lot on fuel and cleanup.

I have had no issues with the PE and boiling water. After 15 years, I think I would have noticed something by now. I’ll continue using Ziploc freezerbags for my backpacking meals.

[Brad Rogers]

I too repackage all of my dinners into freezer bags and rehydrate them by putting boiling water in the bags.  I might not would want to do that for 365 days a year, but I figure the 10-15 days a year I do it backpacking isn’t likely to hurt me.

I also eat my backpacking meals with an aluminum spoon – I probably wouldn’t want to do that daily either, but for backpacking, I figure it’s OK.

[JCH]

Probably the same for high sodium commercial FD meals, brushing teeth with baking soda and many other things…no problem for a few days a year but not a good idea every day.

As a wise person once said, “Everything in moderation”.

[David D]

There are conflicting opinions out there, here’s all I could find after extensive searching in the past.  It would be nice to have conclusive evidence with citations.

Ziploc bags are a type of polyethylene start to soften at 195F or 149F depending who you believe, and melt with extended contact above 212F.  Ziploc (see faq) also recommended avoiding boiling water.   I don’t know why these claims differ.  Russbe doesn’t recommend using boiled water in their PE bags.  Packitgourmet provides a maximum contact time table with their bags (not exceeding 195F) but don’t provide a reference.  They recommend nylon/poly COEX for boiling applications.

To reduce risk I follow this protocol

1.  filter water to avoid an extended boil.  I prefilter because BPL and Gearskeptic disagree on boil time required to kill pathogens.  Gearskeptic recommends taking to 165F quickly is enough to pasteurize. BPL recently sent a newsletter calling for boing of ~ a minute.  Both claim to be science based, I don’t know why (yet) that they differ

2. Heat water to ~ 190F (large bubbles, not roiling boil) and pour water directly onto the food to get it a quick contact cool before it touches the sides.  The lower temp increases cook time 5-10mins but I do camp chores during the soak.  I could see this being more of a drawback for people that like to eat before reaching camp.  The lower temp also means fewer starches gelatinize in the carbs which some may have trouble digesting.  I use capellini to encourage faster gelatinization, and minute rice (which is already cooked).

3. I use Wallaby bags that are Mylar lined, a form of PET.    Wallaby claim them to be safe for adding boiled water to.  They have the added benefit of being a  highly effective odour barrier to protect your food from attracting bears and mini bears.  The drawback is their weight, 20g each but its worth it.   I’m able to reuse them several times but they will absorb strong spice scents.

 

 

[Dan]

I guess I’m ok. Water will never get  above 195 degrees F where I camp.  :-)

[Sarah Kirkconnell]

That’s a key take away: Once you boil water it’s done at it’s highest temp. By the time you go to pour…..it’s dropped already. Once you pour it into the dry ingredients you instantly lose temperature. And no one is doing FBC 365 days a week for years.

It isn’t any different than using mylar bags.

But as you all might notice: When I post new recipes on TrailCooking.com I list both cooking methods of One Pot and FBC (if applicable for that recipe) and over the years I have updated nearly all the recipes on our website in the FBC section :-) At the end of the day, any of my FBC recipes can be cooked in a pot.

There’s a certain person who LOVED to hate on me here, without ever having talked to me directly, or met me. I have no idea why that person doesn’t like me…but ya know, if you have haters, then you have succeeded. Lol. So I don’t really care that toooooo much and I have pretty thick skin.

[Sarah Kirkconnell]

Btw, might who wrote the email sent out? And oh, it’s not “cooking in plastic bags” – it is REHYDRATING in a plastic bag. That is a huge difference. People seem to get that confused over and over. Well, most people don’t, but a few over-thinkers do…..

Not shocking that no one contacted me. As a woman in the outdoor industry I always get mansplained and talked over. And have for the past 20 years. I am casually bitter of course. Had a person from the BP forums once tell my husband (after refusing to talk to me, and he had to talk to Kirk) that it was so awesome he set me up with a business to run…to keep me busy. Yeah. Two middle fingers to that man, who was not only a member here, but a business owner also. Kirk told him it was my business and he could talk to ME.

[Alan W]

I’ve over 40 years of manufacturing, engineering, and R&D in PE. (and more years backpacking)

Yes, the problem for “PE” for backpacking “cooking” is the softening and melting temperature of PE grades used in food baggies.

Melting of PE crystallites occurs through a range of temperatures beginning about 180F and extending above 250F, depending on the distributions of molecular architectures in a given type (grade) of PE.

PE is comprises aliphatic hydrocarbon molecules; it is a synthetic form of paraffin (wax) molecules though having much greater molecule sizes than kids juice drink bottles and Dracula teeth, or grandma’s paraffin put on top of homemade jelly jars.

(Also, one must also consider the scores of chemical additives, comprising hundreds to thousands of ppm typically, that are added to SOME – but not all – grades of PE used for various non-food end use applications.)

Some Grades of PE are specifically, individually approved by the US FDA (and similar foreign) for: Food Contact, Food Cooking, and even Medical Apparatus applications, both temporary bodily contact and permanent implantation.

Returning to the main point for backpacking “cooking”: the issues with using PE baggies are the risk of scalding safety and meal loss resulting from softening and possible gross containment failure (most likely at heat-sealed seams).

If your PE bag does not fail, it’s OK to eat from because it was made from an FDA approved grade of a super-MW-paraffin mixture.

Also, think about what polymer typically makes up the inside, food contacting lamination of the multilayer packaging constructs used for commercial freeze-dried meals.  Hint: It is laminated onto the aluminum foil barrier layer to provide an inert, palatable, safe, heat-sealable layer.

Yes, PET and polypropylene grades approved by the FDA for food usage are also OK and will have less risk of gross failure from adding hottest water, since their softening and melting ranges are above those of PE.

[David D]

Alan, thanks for sharing your expertise.  Do you know if Ziploc freezer bags and Russbe bags, 2 commonly used fbc bags, are food contacted rated but not cook rated?  Safe to add boiled water to with dehydrated food?    J&J and Russbe don’t share this info and it’s been stated second hand that they don’t recommend adding boiling water which is somewhere in between food contact and cooking.

I feel comfortable using the Wallaby because they do rate it for adding boiled water to.

[Sarah Kirkconnell]

Ziploc rates their bags for microwave use. Just pointing that out.

Also: When you add hot water to a bag….you are not pouring the water into the bag empty. It is going into the dry food. Which immediately lowers the temp of the water, before it touches the bag.

Last but not least: You can buy heavier mil bags such as the ones used in Food Vac bags or stand up ones that can be sealed like mylar bags. Those are often 6 mil or thicker, and are often rated for being SUBMERGED into boiling water (used in sou vise prep of food).

FBC meals are not submerged, nor are using actively boiling water to prepare them. I am happy to explain the method if one has questions. FBC came out of the ancient recipes from the 70’s and 80’s where they were prepared in turkey roasting bags (also known as crockpot liners now), which are rated for 400* and 4 hours of that. That is what Mountain House meals came in prior to the early 2000’s – yep, the meals were in a turkey bag….and then in a mylar outer bag. You added the water, sealed the bag with a cardboard collar and slid it into the mylar bag to act as a cozy. I used those meals in 2002…..it was literally my inspiration to develop 1000’s of recipes.

PS: You have far more to worry about if you drink coffee in a to go cup daily from Starbucks. Those cups have plastic liners and that coffee? It’s at boiling when poured into it black…..

[David D]

Then why do Ziploc and Russbe say they’re not rated for boiled water?  This is the conflicting info that needs to be resolved.

I Fbc in mylar lined bags comfortably and agree with the food contact lowering temps as I mention above.

[Greg Pehrson]

Sarah, I have a copy of your book Freezer Bag Cooking: Trail Food Made Simple Volume 1, and I find it fantastic. I really appreciate the vegetarian/vegan options and all of the tips you offer along the way (like how to make an insulated winter cozy bowl that won’t collapse from something you find in the hardware store–not reflectix). You were the first person I saw teaching about cold-soak meals (in the section about lunches) and how to have something more satisfying than a bar without having to take a big break in the middle of the day to prep and cook. I’ve also learned a lot from your forum posts here over the years. I’ll put out there that I’d  be very interested in hearing BPL do another podcast on the subject interviewing you.  Thanks again for your work!  -Greg

[Terran Terran]

Somebody would try to carry boiling water in an otherwise empty Ziplock, get burned and sue them. Ziplock have no reason to take on the liability, or to educate customers on safety, especially when the community is already aware of the process.

[David D]

Check out the links I provided earlier.  Really nothing to do with lawsuits.  Packitgourmet also claim ziploc informed them that the bags soften at 149F.

Lots of conflicting hearsay on this topic on the web, no substantive facts (test data).  Its why I’m sticking with Wallaby: one company sticking its neck out to say their bags are boiled water safe.

Not all PEs are equal and made the same.

[Terran Terran]

I just don’t repackage. It always seemed wasteful. There’s nothing that I be doing that is that important.

[David D]

I make all my FBC meals from scratch (except buying dehydrated ingredients in bulk), no repackaging.  No love for the $15 uninteresting sodium bombs from the outfitters

[Jerry Adams]

where do you buy dehydrated ingredients in bulk?

[David D]

Jerry, these are some of my dehydrated food shopping sources, but some availability may be regional:

• Walmart: Mushrooms (intense!   little goes a long way); great selection of instant Ramen (same as our best Vietnamese grocer, not the junky stuff)
• Bulk Barn (Canuckistan only?): TVP, dried onions (intense!), dried veg flakes (too much tater), dried fruit
• OM foods (will probably ship to US): nice assortment, especially like their green peas, black and pinto beans
• Costco: dried blueberries, Just Real Spuds (waaaay better than Betty Crocker); they sell dehydrated salmon skin that I’m tempted to try
• good2go: probably ships to US but haven’t tried, big selection

Amazon: Nido, instant polenta

Any grocer: usual minute rice, cappellini, instant couscous, sun dried tomatoes

EDIT: Forgot Yami-buy.  They look super interesting.  I’m especially curious to try their bean curd sheets that rehydrate in 10 mins vs the usual 30 mins for stick and knots

[Brad Rogers]

I don’t repackage my dinners for weekend trips for for week long trips I almost have to repackage my food or it wouldn’t fit in a bear canister.  Commercial food options are packed in very bulky (and heavy) packaging.

[Alan W]

What Sarah said: +1.

After massive legal settlements for scalding from hot coffee at McDonalds, corporate lawyers a understandably overly cautious about failure of containment with boiling water when labeling their products.

Yes, most paper coffee cups are laminated with a thin layer of FDA approved PE to provide waterproofness.

[Steve M]

Another option is to use oven bags.  These are very tough and are also a nifty multi-use item…(stuff sacks, water storage bag,  VBLs (feet), etc.   I cut down the smaller ones (“chicken bags”) and use these instead of zip-locks.

From their web site (ReynoldsBrands):

What are oven bags made of?
A heat resistant nylon that is FDA-compliant for cooking.

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