From time to time, we get questions about cold rehydration of backpacking food. The reason for this is that someone wants to reduce weight and leave the stove and fuel behind. There is only so much you can eat of bars and trail mix before you get rather grumpy, so cold rehydration offers another option.
Cold rehydration of backpacking food is possible but requires a bit of planning since it takes considerably longer than using boiling water to rehydrate. Depending on the type of meal, water temperature, and the ambient temperature, it will take 15 minutes to an hour to rehydrate your food.
Rehydration times depend on the temperature conditions and the type of ingredients (Dehydrated or Freeze Dried - See our Blog post: Why Freeze Dried Ingredients). The timing also depends on your hunger level and whether you don't mind some crunchy or chewy pieces of food…..sometimes you just can't wait!
So how do I do this?
Simply add the same amount of cold water as directed on the package, mix and securely zip the bag closed. Some people do this while they are hiking and carefully stow the bag in their pack so the meal is ready when they stop hiking. Or you may want to start your cold rehydration before setting up camp or while packing up in the morning. In any case, plan on a lot of wait time before your meal is ready.
Here are some guidelines for cold rehydration:
Freeze Dried meals rehydrate faster and more complete than dehydrated meals (see Why Freeze Dried Ingredients blog post).
Dinner Entrees typically take the longest to rehydrate and have the most varied list of ingredients. Most dinner entrees will rehydrate in 40 to 60 minutes.
Desserts: some desserts already use cold water, but others like the Fruit Crisp desserts will rehydrate in about 20 minutes.
Some ingredients just don't rehydrate well in cold water or take way too long, this includes Kidney beans. So that Chili Mac that you might be craving is probably not a good candidate for cold rehydration.
Keep in mind that while cold rehydration is doable, there are some risks of bacterial growth in the food if you leave it sit too long. You wouldn't eat cooked food at home that was left out overnight because it could go bad (grow bacteria that can make you sick). Use some common sense and be cautious when doing cold rehydration.
Some pros and cons of going stoveless:
Keeping it simple: No need to set up a stove, cook pot, measure fuel and cook your food. Just eat your bars, trail mix, dried fruit, etc. Alternatively, you can cold soak/rehydrate your backpacking food, this can take 15 min to 60 minutes.
Traveling: You don't have to worry about procuring fuel if traveling by plane or during resupply stops if you are on a long hike. You also eliminate the need to dispose of empty canisters.
Weight Savings: You do eliminate the weight of the stove, cook pot, and fuel but your weight savings may not be that much if you don't use easily rehydrated Freeze Dried food. If you carry more bars, trail mix, dried fruit and jerky the weight savings may be a wash.
Environmentally Friendly: No stove = No Hydrocarbons, so yes its more environmentally friendly though the impact is extremely small.
Keeping warm: Cold food will not have a big impact on your body temperature as its more about the nutrition (fuel) that your body needs to keep itself warm. Although, there is the physiological effect of having a hot meal or simply using your bag of food as a hand warmer on those cold mornings or evenings.
My morning coffee!: Personally I love a hot cup of coffee in the morning and hot tea in the evening but there are some great instant options, Starbuck Via coffee and Cusa Tea, that work just fine in cold water. There are lots of Ice coffee and Ice Tea lovers out there!
Going stoveless is not something that you do in every situation. It's just another option that an experienced hiker can use depending on your situation. It can somewhat simplify your trip and has the potential to save some weight.
Want to try cold rehydration for yourself? Use the code coldsoak for 12% off your order of any Trailtopia Meals!