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RELATIONSHIP BETWEEN pH, AND WATER ACTIVITY

The following table illustrates the relationships between pH, water activity (aw), and current low-acid and acidified regulations. The table indicates whether a product is a low-acid or an acidified food and therefore must meet the registration and process filing requirements of FDA. To use the table, determine the finished equilibrium pH and water activity (aw) of the product. It is the relationship between pH and water activity that defines a product as either low-acid or acidified. Regardless of pH, a food product with a water activity of 0.85 or below, would not be covered by the low-acid canned food regulations or the acidified food regulations. Thus, the firm would not be required to file scheduled process information for that product.

NOTE: THIS TABLE DOES NOT APPLY TO FOODS WHICH ARE NATURALLY OR NORMALLY ACID, AS DEFINED IN THE PRECEDING PARAGRAPHS.

Final Equilibrium
pH		 Water Activity
(aw)		 Registration and Process Filing
Required as:
Low Acid*
(21CFR 108.35/113)		 Acidified**
(21CFR 108.25/114)
4.6 0.85 No No
4.6 >0.85 No Yes
>4.6 0.85 No No
>4.6 >0.85 Yes No

> greater than
less than or equal to

* A yes under this column defines the product as low-acid, subject to the requirements of 21 CFR 108.35 and 113, and it means that the establishment must register and file scheduled process information for that low-acid product.

** A yes under this column indicates that the product is an acidified food, subject to the requirements of 21 CFR 108.25 and 114, and if so, requiring the establishment to register and file scheduled process information for that acidified product.

 

    
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