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I often see confusion when people try to compare measurements of dehydrated and freeze dried foods to fresh equivalents. In fact, it reminds me of those math problems that circulate social media and essentially boil down to whether people remember the order of operations. Remember, volume is the amount of space the item takes up, NOT the weight of said item.
1. If you have 1 cup of dehydrated strawberries and rehydrate with 1/3 cup of water, how many cups of strawberries do you have?
2. If you have 1 cup of freeze dried strawberries and rehydrate with 1/3 cup of water, how many cups of strawberries do you have?
What do you think? Do you know?
1. Don’t do it. In most cases, dehydrated foods really don’t rehydrate to anything like their original form. You can use them in cooking, but don’t expect it to be something you’ll want to sit and snack on unless you just like the dehydrated form (like fruit leathers or banana chips). However, remember that foods tend to shrink during the dehydration process so 1 cup of dehydrated strawberries was probably 2 cups worth of volume when fresh.
2. Freeze dried foods may ‘plump’ slightly when refreshing, but they don’t have a meaningful change in volume even though the freeze dried process means they lose (water) weight. Additionally, the amount of calories and nutrition in 1 cup fresh versus 1 cup freeze dried will be roughly the same.
You’ll find a lot of health and dieting sources that act like dehydrated and freeze dried both have higher calories per cup than the fresh equivalents but this is due to the misconceptions regarding those processes. You CAN however end up consuming more than you intend to simply because without the water weight it can take more before you start feeling full – even though your body has had plenty. This isn’t because it’s more calories per volume, but just because it’s easier to get carried away. To combat this make sure you’re consuming plenty of water or other beverage while eating if not rehydrating the food before eating.
That is a good idea anyway because our bodies depend on our food for most of our water intake, which we aren’t getting when snacking on food in dehydrated or freeze dried form. That’s why I specifically advise keeping more water on hand in your stock pile if dehydrated and freeze dried foods are a significant portion of your stores.