Home Forums Hunting & Shooting Backpack Hunting Boiling Water to Rehydrate Freeze-dried

How long do you wait for freeze-dried food to rehydrate.?

Water at sea level boils at 212 degrees Fahrenheit,
at 5,000 feet above sea level, the boiling point is 203 degrees F.
I live at 6,400' elevation and water boils at about 101 degrees F.
at 10,000 feet, water boils at 194 degrees F.

The lower boiling point means that the water is not as hot at 10,000' so you have allow freeze-dried food a longer time to rehydrate. As a rule of thumb, I double the time required. So if the freeze-dried bag says to rehydrate for 9 minutes at sea level then I wait for 18 minutes at higher altitude.

I like to backpack into timberline lakes in the Sangre de Cristo mountain and camp at about 11,200' elevation. Doubling the wait time seems to eliminate the major burps that can occur if I don't wait long enough.

What has been your guys' experience?

Double is a good rule of thumb that I often follow.

KC- Have you ever tried one of the insulated pouches to help heat meals faster? I will be trying out on this season. I usually just add a few minutes to the time but it seems these coozies help a lot.

Good rule of thumb. I use the taste test method. If its crunchy it needs more time.

Sounds reasonable. How much does an insulated pouch weigh? Let us know how your experiment works.

I haven’t purchased one yet. There are a few companies that sell them for about $15-$25 and they weigh about 2oz.
You can also just make your own from some Reflectix insulation/tape. I’ve seen a few threads on it on the Rokslide forum. Seems to work very well.

I usually dump my next meal in a water bag as I finish the one I am eating. That way lunch is soft and will take less time to rehydrate then supper goes in the water bag and and breakfast gets to soak overnight makes for a quicker heat an eat time

I happen to have a bunch of insulated reflective "material" for just such a use. Weve been getting Blue Apron meals and they come in a big box lined with the stuff for insulation. I've been saving it. I'd be willing to send a piece for you to try and craft one. They are about 18" box shaped. The catch: you need to report on here how it worked and how you made it. I'll even cover the shipping......

Wing it. Mountain House times are usually pretty decent for my elevation (hike between 4000 and 7000 feet for the most part). Some of the other brands are such that you could double the time they call for and still chip a tooth. For the most part, if the yellowjackets aren't bugging me I'll wait 10-12 minutes rather than the 8-9 the package calls for. If the 'jackets are bad, dinner is in 6-7 minutes. Sometimes it depends on the camp location, how comfortable it is to just lounge around vs how much discomfort is pushing me towards bed.

For a while I had some terrible acid reflux with the freeze dried stuff. Turns out if I chug down a canteen of water after I eat that doesn't happen.

Same here. I also usually add a little more water than they call for.

dinner bivy from AHE

I've bought a lot from AHE, mainly hammock stuff, but they're gtg

The ones I used most recently were backpackers pantry. Their instructions said they were calibrated for 5000’ and to double for every additional 5k. We were at about 6500’ and found an additional 5 minutes on the suggested time to be pretty dead on.

It's true that water boils at lower temperatures under lower atmospheric pressures and that limits how hot we can practically get it. However, it's not the heat that rehydrates the freeze-dried food, but the water. You can rehydrate it with cold water. As long as the water is penetrating the solid particles, it will rehydrate. So larger pieces of food take more time to soak than smaller ones and stiring or mixing can help speed rehydration by breaking up large clumps.

You asked about my experience. I have been long-time backpacking/trekking/thru-hiking/mountaineering and eating Mountain House (aka Oregon Freeze Dry which is the one that won the initial contract to provide freeze-dried C-ration alternatives back in '66). Cold water works fine.

What you noted about water boiling at lower temperatures could be more relevant to making food and water safer from microorganisms. The EPA publishes a guideline recommending boiling potentially contaminated water for 1 minute at lower altitudes and for 3 minutes at over 5000'. If you "can" food (as in preserving it in mason jars), you know that processing times at atmospheric pressure are longer at higher altitudes because the boiling water temperature is lower and it takes longer to heat the jar's contents through. Using a pressure cooker allows higher water temperatures at higher altitudes or just for low-acidity foods that need higher temperatures to ensure they become uninhabited by microorganisms before sealing the lids.

At higher altitudes (say over 10,000') and in the winter, I'm often melting snow or ice for drinking water. I'm going to prefer boiling drinking water so my filter does not ice up and because it will pretty rapidly cool to a palatable temperature. Most savory freeze-dried foods are more palatable warm than they are cold, but there are some I prefer cold, particularly the sweeter rather than savory ones.

There is no harmful organism that can survive above 160F. Getting it to 180 is plenty. Boiling is an easy way to make sure it's hot enough but you don't have to boil it beyond just getting it there. Anything else is a waste of time and fuel.

Simply This ^.




GR

Last year I started adding about 1/4- 1/2 the amount of water the meal called for to the pouch about 15 minutes before I started boiling the rest of the water. It really helped to rehydrate the meal and the food was still very hot from the boiling water. I usually double the time on the bag also. I take that time to do some camp chores and make a cocktail.

freeze dried cocktails?

World's driest martini....

That would be perfect! What’s your recipe?😁

Speaking of Mountain House (Oregon Freeze Dry) in particular, what I have noticed is more people griping about the change of some recipes to "gluten free" and how that or a concurrent change ruined the those meals. I haven't eaten one of the meals altered to gluten free yet because I keep a stock (nothing extreme) and have been eating older ones from years ago first. I did just resupply (about 50 bags) and what I noticed is that they seem to have switched to "2 servings" in every bag (except the 1 serving bags). There are no more 2.5 or 3 serving bags. I believe they reduced the effective size of the portions and for sure the price has gone up as one would expect with the dollar ever marching out of fashion.

I do have some cans rather than bags but when I shopped last week I wasn't able to find cans at a volume discount unless buying 6 cans of the same type. Even then, the discount was paltry. Six cans (about 60 servings) of the same thing gets pretty tiring. I know this stuff lasts 30 years, but I wasn't willing to buy especially far into the future. I was able to find mixed variety pouches for as low as $3.10 per serving. I found cans ranging from around $2.10 to $3 per serving but only in 6-packs without variety.

I have not tried reconstituting a portion of the canned food while backpacking. I've always used the foil pouches. If I used the cans it was in a metal pot vehicle camping. Anyone use their own bags or other method? I'm thinking of trying gallon zip lock bags or possibly a reusable bag. I just want to reduce the trash I have to haul. I've been backpacking with a couple other people so we're using at least two sometimes four bags per meal and the trash accumulates after a few days.

Ziplocks would be lighter weight and could possibly hold four or five servings each instead of only 2, so no more than half as many bags to carry out. They're just not as sturdy when filled with boiling water.

I see mylar/aluminum bags for sale and I could pack gallon bags from the can with 5 servings (about what it takes to feed 3 people with modest appetites and supplemental food).

A washable and reusable reheating bag would allow me to use lighter ziplocks for carry. The foil bags are reusable but not very easy to clean in the cracks.

I typically carry only a 1.7L pot (MSR Reactor, coated aluminum) which I prefer to use only for water. Back in the Whisperlite days, I'd use a bulkier 2.0L stainless pot but I'm trying to get slimmer. In the summer, my Trangia is looking better. But to reconstitute 5 or 6 servings of freeze-dried food, I'd need a pot that's too bulky. Hence, looking for a reusable bag.'


PS. I've had frequent zip-lock failures on the Mountain House bags lately. I see similar complaints on aftermarket foil bags. If I was going to get one for reuse, I think I'd want to pass on ziplock and maybe just have it fold over or close some more reliable way.