What is freeze-dried? A gentle explanation of the drying technology spreading to miso soup, vegetables, and strawberries

Chocolate-coated strawberry sweets are a common sight in online shops and souvenir stores. They're popular thanks in part to inbound tourism, and those light, crisp strawberries are made by Freeze-dried.

Freeze-drying is a drying technology used widely, not only for emergency food and outdoor use but also for instant miso soup, snacks and confectionery ingredients. However, even though both are "drying," hot-air drying (air drying) works in a completely different way and suits completely different products. As a manufacturer that dries domestic vegetables and fruit, Agriture decides every day which method a product should be made with.

How Does Freeze-Drying Work?

Freeze-drying is a processing method in which food is first frozen and then placed under vacuum to remove water. It uses sublimation, turning ice directly into gas without letting it melt back into liquid water. Because the water isn't driven off by heat, the cell structure of the ingredient is less likely to break down.

The spaces where the cells were remain as hollows, so when you add water or hot water it quickly returns to its original shape. This Speed of rehydration is the greatest strength of freeze-drying.

Comparing three drying methods

Here's how it differs from other common drying methods. The question isn't which is better; the answer depends on the product you want to make.

The row to note here is "how flavor comes through." Freeze-drying seals in the ingredient just as it is, whereas hot-air drying Releases flavor when simmered and blends easily into dishes. This difference determines which uses each is suited to.

A familiar example is the dried toppings in instant noodles. According to an industry association's explanation, hot-air drying accounts for the largest production volume among drying methods and is used mainly for vegetables. Freeze-drying, on the other hand, is used for protein-rich ingredients and aromatic vegetables. Rather than choosing by price, manufacturers change the method to suit the nature of the ingredient.

If you'd like to know more about how it differs from dried vegetables, see the following article as well.

Specialist manufacturer of domestic dried vegetables | Corp.…

Freeze-Dried vs. Dried Vegetables: A Guide to Choosing a Drying Method by Flavor, Lot Size and Cost What is the difference between freeze-dried and dried (hot-air dried) vegetables? Agriture, a drying manufacturer, explains. Along with a comparison of how flavor comes through, texture and cost, freeze-drying requires mass-production lots of 300–1,000…

What Makes Freeze-Dried Miso Soup Appealing?

The most familiar freeze-dried food is miso soup. Just add hot water and you have a bowl in which even the texture of the ingredients has come back. It needs no refrigeration and keeps for a long time at room temperature, so it has become a staple for stocking at home and in the office and as emergency food.

This is something unique to freeze-drying. Drying something liquid like miso soup directly into single-serving shapes is something hot-air drying can't do. The process goes as follows.

The key is Step 3, freezing. Because the block keeps its shape once frozen, drying it as is produces a single-serving block. Nothing is mixed in to make it set. When you put it in a bowl and add hot water, the shape loosens and spreads out.

• Just add hot water and even the texture of the ingredients comes back
• Keeps long-term at room temperature, suited to stockpiling and keeping in the office
• Liquids can be made into single-serving shapes, widening the scope of product design

In terms of being able to dry liquids into single-serving shapes, freeze-drying has the edge in the range of processing applications. There is also a method of drying the miso and the ingredients separately and combining them, and designs vary by manufacturer.

Freeze-Dry Processing That Seals in Vegetables As-Is

Freeze-dried vegetables are used as miso soup ingredients. Because they're dried while frozen, changes in color and shape from heat are less likely, and even leafy greens like Spinach,and Komatsuna return to a state close to freshly boiled when rehydrated in hot water. burdock and root vegetables like carrots can be used as is in soups and simmered dishes.

However, freeze-drying isn't the right answer for every vegetable. In fact, from our standpoint as a company that dries food every day, there are many situations where hot-air drying is better suited to vegetables.

It may come as a surprise, but for uses such as kneading vegetable powder into sweets or dissolving it into drinks, we find that freeze-dried powder doesn't release much flavor. The strength of keeping the ingredient as it is works against it here, making the flavor fall flat. This comes from our experience in processing, and it's also why we choose hot-air drying for powders. The items we handle are Vegetable powder list.

Freeze-drying is often assumed to be "the superior technology," but in reality it depends on the use. For products where you want flavor to come through, we choose hot-air drying.

When using our in-house stock of raw material: from 100g

Agriture's drying services, flexibly available from 10 kg

• Agriture's dry processing, flexible from
• Drying of brought-in raw materials also possible
• Support from processing to filling in one place

Handles everything from small to large lots

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The Potential of Freeze-Dried Strawberry

Among freeze-dried products, one of the most popular is strawberry. The sweet-tart flavor and aroma are concentrated, and it's finished with a light, crisp texture. Because the bright red color is retained, it's widely used in chocolate- or matcha-coated sweets and gift products.

High-sugar fruit is exactly what freeze-drying is suited to

The reason for freeze-drying fruit isn't just appearance or texture. High-sugar fruit sometimes never dries completely with hot-air drying, and that's the main reason.

High sugar content makes water hard to remove, so even after drying, the fruit stops at a semi-dried state. The sweetness is concentrated and the flavor itself turns out delicious, but the remaining moisture shortens shelf life. From a manufacturer's standpoint, this leads to the judgment that it becomes difficult in terms of best-before dates when considering export.

• The higher the sugar content, the harder it is to remove water, and the longer drying takes
• If it stops at semi-dried, designing for shelf life becomes that much harder
• For export products that require a long best-before date, this difference decides whether it's adopted

With freeze-drying, by contrast, water can be thoroughly removed even from high-sugar fruit, so it can even be processed into powder. This method is also what makes chocolate-coated strawberries possible.

While freeze-drying is strong for ingredients used in processed foods, if you're eating it simply as dried fruit, hot-air drying gives a better-tasting result. Our experience on the production floor is that freeze-drying doesn't automatically make something better.

Is Freeze-Drying Bad for You?

We sometimes see people ask, "Isn't freeze-dried food bad for you?" Answering as a company whose business is drying food:freeze-drying is a physical process that simply removes water, and the method itself poses no health problems.

Why can it be stored for a long time?

It doesn't keep because preservatives are added. Food needs water to spoil, and removing that water makes it less likely to spoil; that's all there is to it. It's the same principle that lets dried shiitake mushrooms and kiriboshi daikon be kept at room temperature.

What deserves attention isn't the drying itself but what has been added to the ingredient before drying. Some products are dried after sugar, fats or flavorings have been added. If you want to judge, the reliable way is to look at the ingredient label rather than the method.

• Check the ingredient label for seasonings and additives
• Eaten as is, it can get stuck in the throat, so rehydrate it in hot water for small children and older people
• After opening it absorbs moisture, so use it up soon

If anything, we consider it an easy food to handle, since it can be kept at room temperature without refrigeration or preservatives.

A Processing Technology Drawing Attention in Commercial and OEM Use Too

Freeze-dried products are also used as commercial raw materials. The range of applications is growing, including instant soups and zosui, confectionery ingredients, and shelf-stable products for export.

The first obstacle in product development is lot size

This is the point we most want to convey to anyone planning to make a product with freeze-drying.Freeze-drying equipment is large, and each production run requires a substantial volume. The production lots contract manufacturers quote are generally around 300–1,000 kg in terms of pre-drying raw material.Because the equipment runs in large units, it's a method that makes it hard to prototype just a small amount. In fact, commercial operations use large machines that process tens of thousands of servings at a time.

Hot-air drying, on the other hand, ranges from small to large equipment. Because it can be run from around 1 kg of fresh raw material, you can test a small amount first and see the response. The differences between the two can be summarized as follows.

In other words, If you're making a product with freeze-drying, you need to move with a certain sales volume in view. At the stage of "just wanting to test 100 units first," it's more realistic to lean toward a product design that can be made with hot-air drying. If you build your business plan around freeze-drying, you may find yourself stuck because the lot sizes don't fit.

Our approach to small-lot product development is explained in detail in the following article.

Specialist manufacturer of domestic dried vegetables | Corp.…

What Is the Minimum Lot for Food OEM? How to Choose a Food Factory That Handles Small Lots | Specialist Manufacturer of Domestic Dried Vegetables | Agriture Inc.… Agriture, which knows both the commissioning and the manufacturing side, explains what the minimum lot in food OEM is. The pros and cons of small lots, our example of drying from 1 kg of raw material, 5 points for choosing a factory…

Agriture works with hot-air drying and low-temperature drying

At Agriture, we process domestic vegetables and fruit with hot-air drying in a low-temperature range. We set the drying temperature at around 45℃, aiming for a finish that retains the flavor of the ingredient itself. We can also handle powder processing and specified cut shapes, and we accept processing of raw materials you bring in.

The shortest route is to choose the method by use

Freeze-drying is a technology that goes beyond "drying = preservation": it can turn soup into a single-serving shape and transform high-sugar fruit into confectionery ingredients. Fast rehydration and the ability to dry liquids into solids are strengths no other method has.

On the other hand, hot-air drying suits products where you want flavor to come through and products you want to test in small quantities. It isn't a question of which is better; deciding the method by working backward from the product you want to make is the way to avoid detours.

As a drying manufacturer, Agriture takes consultations from the stage of deciding which method suits your product. Tell us the product you want to make and your expected quantities, and we'll help from choosing the method onward. For details, see our Drying OEM and contract processing page.

If you are considering product development with off-spec or your own farm's vegetables:From planning to processing, materials, package printing and novelties, you can consult us through a single point of contact. → Learn more about one-stop product development