In our manufactory in Zielona Góra we dry natto using two different methods: freeze drying and convective drying, for which we hold a patent (PL 237235). These are two completely different physical processes. Here I describe exactly what freeze drying involves, how it works step by step and how it differs from our convective drying and from fresh natto.
⚠️ Are you taking anticoagulant medication (for example acenocoumarol or warfarin)? Freeze-dried natto, like fresh natto, contains vitamin K2, which may affect how these medicines work. Consult your diet and supplements with a doctor. See the important legal and medical information.
In short
- Freeze-dried natto is fresh natto, i.e. fermented soy, dried by freeze drying. It is a food, not a food supplement.
- Freeze drying freezes the product and then removes water from it by sublimation of ice under vacuum, bypassing the liquid phase, which preserves the structure and compounds sensitive to high temperature, including vitamin K2 (MK-7).
- Vitamin K contributes to normal blood clotting and to the maintenance of normal bones. Nattokinase, an enzyme produced during fermentation, has no authorised health claim in the European Union.
- The main differences from fresh natto relate to form, shelf life, taste and way of consumption, not to the composition itself.
What freeze-dried natto is
Freeze-dried natto is made from the same raw material as fresh: fermented soy, in which the bacterium Bacillus subtilis natto produces vitamin K2 in the MK-7 form and the enzyme nattokinase during fermentation. Freeze drying adds nothing to this composition; it only removes water.
It is worth distinguishing the legal categories. Fresh and freeze-dried natto are food, i.e. fermented soy in different forms. Only concentrated extracts enclosed in capsules or tablets are food supplements. Freeze-dried natto, despite its powdered form, remains a food.
Why fresh natto doesn’t taste good to everyone
The intense smell and stringy strands of fresh natto are no accident, but the result of the fermentation of soybeans by the bacterium Bacillus subtilis natto. During this process aromatic compounds are produced, including pyrazines and ammonia, responsible for the distinct odour. At the same time the bacteria produce a glutamic acid polymer, the famous stringy strands that wrap around chopsticks and a spoon.
For Japanese people, who have eaten natto since childhood, these are familiar and desirable characteristics. For someone who tries natto for the first time as an adult, the same sensory profile can be a real barrier. I prefer to name it plainly rather than pretend it is not there.
Freeze drying changes this experience at its root. Once the water is removed, most of the sensations that bother some people disappear, while the ingredients valued in fresh natto remain in the product.
How freeze drying works: sublimation drying
Freeze drying is another name for sublimation drying. Fresh natto first goes into a freezer and then into a vacuum chamber in which the frozen ice evaporates directly into vapour, bypassing the liquid phase. This phenomenon is called sublimation. Because the product remains frozen throughout the process, the process temperature is low, and the grain structure and compounds sensitive to high temperature are preserved largely intact. After drying, the freeze-dried product does not require refrigeration and retains its usability for many months.
Our second method: convective drying
In Zielona Góra we also dry natto using a different method: convective drying, for which we hold patent UPRP no. 237235. This is a completely different physical process from freeze drying. Instead of freezing and sublimation under vacuum, warm air with a controlled flow evaporates water from the natto, at a higher temperature than in freeze drying, though still gentle enough not to damage the product. Both methods produce a dry, durable product from the same fermented soy, just by a different physical process, and we choose them for different product lines.
What freeze-dried natto contains
Freeze-dried natto provides plant protein, fibre and vitamin K2 in the MK-7 form. Vitamin K contributes to normal blood clotting and to the maintenance of normal bones.
Natto also contains the enzyme nattokinase, which is produced during fermentation. In laboratory studies (in vitro) its activity towards fibrin has been described, but results from a test tube do not directly translate into effects in humans after oral intake, so we describe nattokinase as a natural component of fermentation, without attributing health benefits to it.
Natto also provides live cultures of fermentation bacteria Bacillus subtilis natto, originating from the fermentation process.
Fresh natto and freeze-dried natto. A comparison
| Feature | Fresh natto | Freeze-dried natto |
|---|---|---|
| Form | Moist, sticky grains | Powder or crushed grains |
| Shelf life | A few days in the fridge | Many months |
| Storage | Refrigerated | Room temperature |
| Taste and smell | Intense, characteristic | Milder |
| Way of consumption | A meal, most often with rice | Addition to dishes, a topping |
Both variants are food, not a food supplement.
How to eat freeze-dried natto
Freeze-dried natto tastes different from fresh: it is crunchy, slightly nutty, with a hint of umami. There are no stringy strands and none of the strong smell, so it is easier to reach for. In practice I eat it in several ways:
- as an addition to natural yoghurt, porridge or curd cheese, it goes well with banana, strawberries, raspberries and nuts,
- with a little soy sauce and wasabi, in the Japanese style, but without the barrier of smell and texture,
- as a stand-alone snack, straight from the bag, with no preparation,
- as a topping on salads, creamy soups, pasta or rice dishes.
A serving of about 20 g is a real component of a meal, not just a garnish. It also provides about 9 g of plant protein from fermented soy. Thanks to its long shelf life and the fact that it needs no refrigeration, freeze-dried natto is a convenient way to include fermented soy in your diet, also when travelling.
Who freeze-dried natto is for
This form works especially well for three groups.
The first is people who wanted to include natto in their diet but were put off by its classic form. The smell, the strands and the texture can be a real obstacle. The crunchy form removes them and opens the product to a much wider audience.
The second is people who are travelling, at work or away from home. Fresh natto needs a fridge and has a short shelf life. Freeze-dried natto fits in a backpack on a trek, at the office or on a long journey, because it weighs almost nothing and needs no refrigeration.
The third is people for whom fresh natto is the first choice, but who also want a convenient backup form. When there is no fresh natto at home, the freeze-dried form waits in the cupboard, ready to use.
Freeze-dried natto in our range
The freeze-dried natto we produce in Zielona Góra is made from the same certified organic soy as our fresh natto.
See our freeze-dried natto set
Safety and precautions
Natto is a food product that is safe for most healthy people. Caution is advisable and including natto in the diet is worth consulting with a doctor in several situations: for people taking anticoagulant medicines (for example vitamin K antagonists such as warfarin or acenocoumarol), because of the vitamin K content, for people with clotting disorders and before planned procedures, and also for people with a soy allergy, because natto contains soy. Neither a food supplement nor any food product replaces a varied diet and a healthy lifestyle.
Will freeze-dried natto replace fresh
In short: it does not replace, it complements. These are two different forms of the same fermented soy, each with its own use.
For someone who has come to love classic natto with all its sensory character, the fresh version remains the first choice. The stringy strands and the intense aroma are a feature, not a flaw, for such a person, and no other form conveys it.
For someone who reacts to the smell or texture of fresh natto with aversion, the freeze-dried form can be an entry into the world of this product. It is the same fermented raw material served differently, with the composition preserved and a milder flavour profile. It is worth having both on hand and reaching for whichever fits the situation better.
Summary
Freeze-dried natto is fresh natto dried by sublimation, without changing the raw material composition: vitamin K2 and nattokinase remain. From fresh natto it differs in form, shelf life and way of consumption, not in origin. In Zielona Góra we dry natto using two methods, freeze drying and patented convective drying, choosing the technology for each product line.
Frequently asked questions
Is freeze-dried natto a food supplement?
No. It is a food, i.e. a dried form of fresh natto (fermented soy). Only concentrated extracts in capsules or tablets are food supplements.
What is freeze drying and does it destroy the components of natto?
Freeze drying is sublimation drying: frozen natto goes into a vacuum chamber where the ice evaporates directly into vapour, bypassing the liquid phase. The low process temperature allows the grain structure and heat-sensitive compounds to be preserved, including vitamin K2 MK-7.
How does freeze-dried natto differ from our convective drying?
These are two different technologies. Freeze drying freezes the product and removes water by sublimation under vacuum. Convective drying, for which we hold patent PL 237235, evaporates water using warm air with a controlled flow, at a higher temperature. Both produce a dry, durable product from the same fermented soy.
How to store freeze-dried natto?
At room temperature, in a sealed package, away from moisture. It does not require refrigeration.
How to eat freeze-dried natto?
Best as an addition to dishes. You can sprinkle it on rice, salads, soups and vegetables or add it to smoothies. Thanks to its long shelf life it also works well when travelling.
Will freeze-dried natto replace fresh natto?
It does not replace it, it complements it. These are two forms of the same fermented soy. Fresh natto remains the first choice for people who enjoy its intense sensory character, while the freeze-dried form is a convenient entry point for those who are put off by the smell and texture of fresh natto.
Who is freeze-dried natto for?
For people who wanted to eat natto but were put off by its classic form, for travellers and those working away from home, because it needs no refrigeration, and for fans of fresh natto who want a convenient backup form.
Does freeze-dried natto have a confirmed health effect in the European Union?
Partially. Vitamin K2 in natto has an authorised health claim in the European Union: it contributes to normal blood clotting and to the maintenance of normal bones (Regulation (EU) 432/2012). Nattokinase, the enzyme from fermentation, does not have such status.
Sources
- Shurtleff W., Aoyagi A., History of Natto and Its Relatives, Soyinfo Center, 2012.
- EFSA Panel, Scientific Opinion on the substantiation of health claims related to vitamin K, EFSA Journal, 2009.
- Regulation (EC) No 1924/2006 and Regulation (EU) No 432/2012.
- EU Register of Nutrition and Health Claims (European Commission).
Legal and medical note. This article is educational and does not replace the advice of a doctor or pharmacist. Freeze-dried natto is a food, not a food supplement or a medicine. Nattokinase has no authorised health claim in the European Union (Regulation (EC) 1924/2006), and vitamin K2 has claims limited to blood clotting and normal bones (Regulation (EU) 432/2012). Full information is on the Legal and medical information page.
