How to choose food preservatives

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FREUND’s food preservatives that prevent the deterioration of foods are broadly divided into three types.

  • Ethanol evaporation agent

    Ethanol gas is subject to evaporation in sealed packaging to prevent the growth of mold and also retain “softness” and “moistness” of foods.

  • Ethanol evaporation agent + Oxygen absorber

    The strongest bacteriostatic effect is exerted by combining the two functions.

  • Oxygen absorber

    Oxygen in sealed packaging is absorbed to prevent the growth of mold and also prevent deterioration by oxidation.

Choose by water activity value (Aw) and typical examples of foods

Ranges of food preservatives that are compatible with water activity values (Aw) are shown below. Choose by referring to typical examples of foods.

Choose by water activity value (Aw) and typical examples of foods

What is water activity (Aw)?

There are two main types of water contained in foods: “free water” and “bound water.”
“Free water,” easily evaporates and migrates, and can be used to propagate microorganisms.
“Bound water” binds to proteins and carbohydrates in foods.
Water activity is expressed as a numerical value showing the amount of “free water” and is an indicator of preservability of foods.

* The water activity value is defined as the relative humidity on the surface of foods.

Free water
Contained water

As an example, jam is a food containing a high moisture content, but its water activity is not so high because much of the water is bound to sugar.
On the other hand, white bread is fairly high in water activity because it contains little sugar and salt.

As an example, jam is a food containing a high moisture content, but its water activity is not so high because much of the water is bound to sugar.


The EZ-200, which enables high-precision and short-time measurements and includes a color touch panel, is the only made-in-Japan water activity meter.

             Water Activity Meter

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