One thing zebras know is that when we don’t know something we want to know, it’s time to start asking lots of questions.
Case in point: the other day, I overheard some scientific humans discussing “freeze-drying” as a good way to preserve fresh fruit. Supposedly, when you freeze-dry fruit, it will keep its great taste and color for years and years!
Well, I’m a huge fan of fruit, so that sounded totally cool to me (pun totally intended)! But how the heck would a zebra go about freeze-drying?
My zebra buddies and I decided to get some frosty advice from our coolest friends: the SnowDudes and the Penguin Brothers. They said they were pretty sure they’d seen a polar bear freezing-drying his own food, so how hard could it be?
We figured we’d give it a try. The first thing we did was round up some of our favorite fresh fruits: melons, tangerines, apples and a pineapple.
Okay, so what’s the logical first step to freeze-drying? Freezing, right?
So we put our fruit in the freezer. Just to be adventurous, I tried to hang out in the freezer to watch the action, but as zebras are not the most cold-weather creatures in the world, I only lasted a VERY short while.
After the fruit was frozen, what do you suppose we did? Yup, we took it over to our dryer – but there didn’t seem to be a setting for fruit.
My cousin ZoeBot, who is super-brainy, said we should try doing some research.
After looking through a whole bunch of science books, we figured out that we’d sort of mixed-up the freeze-drying concept. To clear up all ZeConfusion, we decided to ask our food scientist friend Angela to explain it to us.
Besides being an amazing scientist and very cool human, Angela is the founder of a company called Crispy Green, which specializes in turning fresh fruit into healthy freeze-dried snacks.
She’s also very fond of zebras, so she was happy to explain the science of freeze-drying in a way that we could understand.
And now, here is ZeInterview:
First of all, Angela: why is freeze-drying a good way to preserve foods like fruit?
“Freeze-drying removes the water from fresh fruit, while naturally preserving the fruit’s structure (fiber), nutrients and flavors. This process also makes the fruit a lot lighter in weight, so it’s very easy to carry. That’s why everyone from hikers and backpackers to soldiers and astronauts tend to appreciate freeze-dried fruit.”
What exactly IS freeze-drying – and how is freeze-dried fruit different than regular dried fruit?
“When you simply dry fruit (say, turning grapes into raisins), you put the grapes into a heated environment that causes water inside the fruit to evaporate.
When you freeze-dry fruit, you preserve it by drying without applying enough heat to cause the evaporation process. Instead, freeze-drying converts ice (which is solid water) directly into water vapor. The shift from a solid directly into a gas is called ‘sublimation.'”
Wow, that’s pretty technical! So exactly how do you do it?
“Well, you and your friends started out with the right idea, ZeBot — it does involve frozen fruit. But instead of putting it into a clothes dryer, the way you thought it might be, you use a freeze-drying machine.
First, the fruit is frozen solid. Heat is then applied to the shelves inside the drying chamber, where the fruit is. This causes the water inside the fruit to evaporate, while the fruit itself remains frozen (that’s the sublimation process). The evaporated water vapor is then condensed onto freezer coils at the bottom of the chamber. What’s left is freeze-dried fruit!”
How much fresh fruit does it take to make freeze-dried fruit?
“Typically, it takes more than ten pounds of fresh fruit to produce one pound of freeze-dried fruit, because water makes up 80-90% of the fresh fruits’ weight.”
Why does fruit work so well for freeze-drying?
“It works especially well because of its texture. Fruits tend to be high in complex carbohydrates and cellulose—these allow fruit to retain its cellular structure during drying. Think of it as being a bit like the skeleton in your body: the cellular structure keeps the fruit from collapsing.”
How come freeze-dried fruit doesn’t taste hard and cold and sort of wet like regular frozen fruit?
“Because the water inside freeze-dried fruit evaporates from ice crystals directly into vapor–this gives the fruit a uniquely light, crispy texture with a very bright taste.”
Cool! So can you freeze-dry any kind of food — how about ice cream?
“You can, but what you end up with is powdered cream – that’s what ice cream is reduced to when the water component is removed. You’re left with a small amount of protein and lots of fat, which combine to give the ice cream powder its shape. It tastes a bit like chalk—and, of course, you lose the coldness that you associate with ice cream.”
What would happen if you freeze-dried snow?
“It would disappear. Snow is frozen water (that is, 100% water molecules), so it would evaporate into nothing.”
What about fire?
“Well, this may sound a bit complicated, but you need to consider the chemical makeup of fire: fire itself is a physical state of transformation of energy – you can’t capture the energy of fire to put it into a freeze-dryer.”
You’re right: that’s WAY too complicated! What if you tried to freeze-dry an actual zebra?
“Let’s just say that I do not recommend it, ZeBot—you would definitely not be a pretty sight!”
Yikes! Let’s think of something that WOULD be a pretty sight, then. What about using freeze-dried fruit as a crunchy topping for a healthy, frosty dessert like homemade frozen yogurt?
“Now THAT is a very cool idea, ZeBot – and one I can happily recommend!”
You’ve read ZeInterview. You’ve seen ZePhotos.
Before you make ZeFroYo, check out ZeVideo!
RECIPE: ZeBestEver Frozen Yogurt with Crispy Freeze-Dried Fruit
If you’re in the mood for frosty fun, you’ll love this creamy honey-vanilla frozen yogurt! The freeze-dried fruit adds a light, delicate crunch — but fresh fruit also tastes amazing. Anyway you make it, you’re in for a super-cool (and super-healthy) treat!
WHAT YOU NEED:
3 cups of Greek yogurt (either whole-milk or reduced-fat yogurt is fine)
1/3 cup honey
1 tbsp. pure vanilla extract
1 cup freeze-dried fruit (any kind) or cut-up fresh fruit (whatever you like)
WHAT YOU DO:
1. Put the yogurt, honey and vanilla into a medium-sized mixing bowl, then stir everything together until all you see is a perfect blend of creamy goodness!
2. Spoon the honey-vanilla yogurt into the pre-chilled container of an ice cream maker.
3. Switch the ice cream maker to “on” and let it run for about 15-20 minutes (or until the yogurt is billowy and frosty — just like the soft-serve frozen yogurt you could get at your favorite fro-yo shop).
4. Scoop the frozen yogurt into serving dishes and top with bits of freeze-dried or fresh fruit (or add both).
5. Eat happily and enjoy being really, really cool!