Whether you’re eating something you freeze-dried yourself or just thinking about trying something a friend freeze-dried, it’s totally normal to wonder about its nutritional content. Are these actually nutrient-deficient compared to their fresh counterparts?
Freeze-dried foods tend to be close in overall nutritional content to fresh food. Food preparation and storage impact nutritional content degradation more than freeze-drying. Freeze-dried foods have the closest nutritional value to fresh food while also giving the food the longest shelf-life.
Ready to talk about freeze-dried nutrition? Let’s do this.
What Does Freeze-Drying Do to Nutritional Value?
Freeze-dried foods can lose a small but imperceptible percentage of some nutrients, though the loss of nutrients doesn’t affect the taste. Freeze-dried food keeps longer and is as close to fresh as possible when compared to other methods of long-term food storage.
During the freeze-drying process, the food is dehydrated using freezing and sublimation. Okay, so technically it’s a repeating, three-stage process: freezing, sublimation (primary drying), and adsorption (secondary drying).
Translation and simplification: the freeze dryer freezes foods to a crazy-cold temperature. Then, it turns the vacuum pump on and pumps out the water while also slightly warming the food enough to keep pulling out more water. Then, it does it again (and again and again) until about 95% of the food’s total water content is removed.
The resulting food is devoid of its enzymes, which would otherwise promote its structural degradation over time. Due to this, the resulting food holds up its nutrients very well for a sustained interval of time.
Freeze-dried food is as close to its original nutritional content as it can be – while also being shelf-stable for up to 25 years (depending on the food).
So while freeze-drying does change the nutritional value of some things, it’s not by a lot. And it’s by a lot less than if you used a different processing method (like dehydrating or canning the food).
Of all of the foods we’ve freeze-dried, we haven’t noticed any differences in taste – just the texture. Freeze-dried foods are super dry! But once reconstituted? There’s no noticeable difference in taste. And we haven’t been able to measure or notice any differences in nutritional value.
Does Freeze-Drying Remove Nutrients?
Freeze-drying can remove a small percentage of some nutrients, though most nutritional loss comes during food preparation before freeze-drying and in storage after freeze-drying. Nutritional loss can be anywhere from imperceptible to measurable, depending on the nutrient in question. Some vitamins can see a loss between 3-23% in freeze-dried and stored foods.
From the research outcome across various food products, it is very well established that freeze-dried-based food products hold on to their nutrients quite efficiently. Since freeze-dried products are nearly moisture-free, the concentration of the nutrients will be high, which means that little bites of your favorite snacks provide you with the required vitamins and minerals to have a balanced supply of carbs and calories.
For example, research carried out at the Sultan Qaboos University of Oman suggests that freeze-dried capsicum could retain its vitamin C concentrations for an extended period of at least up to 150 days when maintained at five degrees centigrade. On the other hand, fresh capsicum maintained the required levels of vitamin concentration ratio only up to 13 days when stored under 20°C.
Another research project carried out by the Defense Science and Technology group of Australia studied the retention period of Vitamins B1, B2, B6 & E for the fortified military freeze-dried foods at different storage temperatures. Results suggest that the mean 24-month retention rate was about 94%, 97%, 86%, and 77% for Vitamins B1, B2, B6, and E respectively.
So let’s give you that data in a table – because tables are cool.
|Nutrient||Percent of Nutrients Removed in Freeze-drying||Percent Retained in Freeze-dried Foods|
Keep in mind that these studies are looking at two variables – both freeze-drying and storage. So how you store your freeze-dried foods will definitely impact their overall nutritional value, too.
If this were a scientific paper, I’d dive more into the whole idea that these studies ought to have looked at this in more depth – and measured all the variables separately. But this isn’t a scientific journal – even if I do translate ’em for you.
Does freeze-drying remove nutrients in fruits and vegetables?
Freeze-drying fruits and vegetables can have a reduction in nutrients and/or nutritional value for various vitamins and minerals, though the loss of nutrients seems to be more related to preparation and storage than the actual freeze-drying process.
Several types of research have been carried out on different kinds of vegetables.
Take leaf cabbages, for example. Anna Korus, a Poland based researcher from the Department of Plant Product Technology and Nutrition Hygiene of the University of Agriculture in Krakow, found that the retention of Vitamin B and E of leaf cabbages were relatively between 3 to 10% for B1, 1 to 4% for B2 and 1-16% for E for 12 months. This was significantly higher in comparison with the unblanched dry process. The same goes with Potatoes. Again it had a considerably higher retention rate of 92% to 94%.
What about the phenolic content in fruits and vegetables? Tomatoes, for example, had about two times the phenolic content than the usual drying methods.
- How about Persimmon? About 90%.
- Blueberries? Freeze-dried Blueberries retained their polyphenols and anthocyanins with higher antioxidant activity in the glycoside forms.
In other words, how you prepare your fruits and vegetables can affect the final nutritional value, too. Sure, freeze-drying will diminish it to some degree. But how you prepare and store the food will have a much larger effect on the final nutritional value.
Does freeze-drying remove nutrients in meat-based products?
It has been consistently observed that the total fat and the saturated fatty acids are reduced with the Freeze-drying process. Further, freeze-dried chicken, turkey, and ham have all been known to retain their rich source of minerals and protein.
In other words, you may lose some of the fat – especially if you’re actively removing the fat so that the meats will freeze-dry better. Otherwise, you’re not going to notice a huge loss in other nutrients.
Will freeze-drying coffee or tea remove any nutrients?
Freeze-drying has also been used to store coffee and tea. Instant tea produced with freeze-dried technology had a high concentration of volatile compounds such as alcohols, aldehydes, and lactones. Further, phenolic acids in coffee beans increased by 41%.
Does Freeze-Drying Increase the Sugar Content or Calories in Food?
Freeze-drying does not increase the total sugar content or calories in foods, but the loss of water does increase the total percentage of calories and sugar when compared to the now-decreased food weight. The lowered water content can also lead to eating more food than normal, resulting in an increased total sugar and calorie consumption count.
Short Answer: Freeze-drying doesn’t increase sugar or calorie count. At least not in the way you think.
Long Answer: it’s more complicated than that – and it’s due to some math. So let’s take a step back and go through it together.
Apart from the fear of loss of nutrients, another worry people have about freeze-dried foods is the increase in sugar content. So much so that people refer to freeze-dried foods as “Sugar Bombs.” While the cause is valid, the fact is quite far from actuality.
Fruits, for example, derive their succulent sweetness from the fruit sugars (namely fructose and glucose) produced by plants and trees during photosynthesis. It is a general consensus that these are often termed “good sugars” compared to refined sugars from the processing industries.
Now, put on your thinking hat and ask yourself a question. Can freeze-drying mysteriously increase the quantity of naturally formed sugar found in fruits? If not, then what is the fuss all about? And spoiler: the answer is no.
Why do freeze-dried foods taste sweeter?
The reason why freeze-dried food tastes sweetened is due to the increased concentration of sugar and not due to the increase in the amount of sugar. Confused? Well, to understand what it means, let’s get back to the actual freeze-drying process.
If you remember, it was understood that freeze-drying typically removes as much as 95% of the moisture content from the food. This shrinks the food size, no doubt, but the actual sugar content remains intact. However, at this point, something amazing happens. With the reduction in the size (by as much as 75%), the amount of sugar per unit volume in the freeze-dried food gets more concentrated.
Sounds strange? Well, it’s simple. An excellent way to explain this would be the classic example of grapes and raisins. A cup of grapes and a cup of raisins, both reserve the same amount of sugar content within them. So does it mean that eating a cup full of grapes is the same as eating a cup full of raisins?
Well, no. Not really. The difference lies in the serving.
Imagine being offered 20 grapes and 20 raisins after your meal. After 15 grapes, you feel relatively full between the consumption of each passing grape. This is primarily due to the water content in the grape, which adds up to the total food you are consuming, limiting further consumption.
Not so with the raisins!
In the absence of water, the 20 raisins will be gone in no time without you feeling full. This might lead to further cravings, and by the time you are finished with those tasty, nutrient-rich, Sun-Maid packs of California Raisins in one sitting, your calorie count would have comparatively increased.
So now you know where the real issue lies. Freeze-dried foods do not have higher sugar content. But due to the ease of consumption, they create an opportunity for excessive eating, which could very well lead to an increase in calories.
Can this be avoided? Absolutely. Pair the freeze-dried food with protein and healthy food (like almonds) to have a well-balanced meal. This way, you will restrict excessive intake of food of one kind.
So, the next time you enjoy those 20 raisins, put a check on your cravings. After all, as Bethenny Frankel rightly said, “Your diet is a bank account. Good food choices are good investments.”
Key Takeaways on Freeze-Dried Foods and Nutrition
It’s really fun (in a nerdy way) to keep an eye on the nutritional content of freeze-dried foods. And as more studies come out to give us a better idea of which nutrients don’t keep as well during any of the food preparation, freeze-drying, or storage steps? That information helps us make more informed decisions as prepared homesteaders.
So remember that freeze-drying itself doesn’t mess a ton with most of the nutrients overall. You’re more likely to degrade the various nutrients during any food prep (like blanching) or during long-term storage.
You can minimize any storage-related nutrient degradation by storing your freeze-dried foods in a cool, dry, and light-controlled environment.
But once you’ve done your best to prepare, freeze-dry, and store your food? Don’t worry too much about nutrient degradation. There’s still more than enough there to eat healthy during any scenario where you’re dipping into that food storage.
And eating a healthy, balanced diet can offset any minor nutrient degradation that may happen while you’re prepping and freeze-drying your food. So prep that food storage to your heart’s content.
Then make sure you read either my article on freeze-drying versus dehydrating or this article I wrote on freeze-drying versus canning next – so you can make sure that you’re picking the right food storage method for the right scenario.
Learning from your own experience is essential, but learning from others is also intelligent. These are the sources used in this article and our research to be more informed as homesteaders.
- Bhatta, S., Janezic, T. S., & Ratti, C. (2020). Freeze-Drying of Plant-Based Foods. 1–22.
- Korus, A. (2021). Effect of pre-treatment and drying methods on the content of minerals, B-group vitamins and tocopherols in kale (Brassica oleracea L. var. acephala) leaves. Journal of Food Science and Technology. https://doi.org/10.1007/s13197-021-05012-9
- Mishra, B., Mishra, J., Pati, P., & Rath, P. (2017). Dehydrated Meat Products: A Review. International Journal of Livestock Research, January, 1. https://doi.org/10.5455/ijlr.20170812035616
- Rahman, M. S., Al-Rizeiqi, M. H., Guizani, N., Al-Ruzaiqi, M. S., Al-Aamri, A. H., & Zainab, S. (2015). Stability of vitamin C in fresh and freeze-dried capsicum stored at different temperatures. Journal of Food Science and Technology, 52(3), 1691–1697. https://doi.org/10.1007/s13197-013-1173-x
- Rahman, M. S., Salman, Z., Kadim, I. T., Mothershaw, A., Al-Riziqi, M. H., Guizani, N., Mahgoub, O., & Ali, A. (2005). Microbial and Physico-Chemical Characteristics of Dried Meat Processed by Different Methods. International Journal of Food Engineering, 1(2). https://doi.org/10.2202/1556-3758.1016
- Coad, R., & Bui, L. (2020). Military Freeze-Dried Meal During Extended Storage. 1–11.
- Wang, R., Zhang, M., & Mujumdar, A. S. (2010). Effects of vacuum and microwave freeze drying on microstructure and quality of potato slices. Journal of Food Engineering, 101(2), 131–139. https://doi.org/10.1016/j.jfoodeng.2010.05.021
- Chang, C. H., Lin, H. Y., Chang, C. Y., & Liu, Y. C. (2006). Comparisons on the antioxidant properties of fresh, freeze-dried and hot-air-dried tomatoes. Journal of Food Engineering, 77(3), 478–485. https://doi.org/10.1016/j.jfoodeng.2005.06.061
- Jia, Y., Khalifa, I., Hu, L., Zhu, W., Li, J., Li, K., & Li, C. (2019). Influence of three different drying techniques on persimmon chips’ characteristics: A comparison study among hot-air, combined hot-air-microwave, and vacuum-freeze drying techniques. Food and Bioproducts Processing, 118, 67–76. https://doi.org/10.1016/j.fbp.2019.08.018