Water Activity As A Critical Control Point

Water activity can be used as a CCP (critical control point) for food production.

Water activity is a measure of the amount of water available for microbial growth and chemical reactions in a food product. It is represented on a scale from 0 to 1, with 0 being completely dry and 1 being pure water.

Water activity is a critical factor in determining the microbial stability and safety of food products for several reasons:

  1. Microbial Growth:

    Water activity influences the ability of microorganisms, such as bacteria, molds, and yeasts, to grow and proliferate in food. Microorganisms require water for metabolic processes and reproduction. Foods with high water activity (above approximately 0.85) provide an environment conducive to microbial growth, increasing the risk of spoilage and foodborne illness. Controlling water activity through drying, adding salt, adding sugar, evaporating, or other preservation methods can inhibit microbial growth and extend the shelf life of food products.

  2. Pathogen Growth and Survival:

    Certain pathogenic microorganisms, such as Salmonella, Escherichia coli (E. coli), and Listeria monocytogenes, can pose serious health risks if present in food. Water activity influences the survival and growth of these pathogens. Low water activity levels inhibit the growth of most pathogens, as they are unable to extract sufficient water from the food matrix to support their metabolic activities. However, some pathogens, such as Salmonella, have adapted mechanisms to survive and even proliferate at low water activity levels, highlighting the importance of other control measures, such as heat treatment or pH adjustment, to ensure food safety.

  3. Spoilage and Quality:

    Water activity also affects the sensory characteristics and quality of food products. Foods with high water activity are more prone to spoilage by microbial contamination, enzymatic degradation, and chemical reactions, leading to changes in flavor, texture, and appearance. Controlling water activity can help preserve the sensory attributes and overall quality of food products, enhancing consumer acceptability and satisfaction.

To increase the food safety protection of a low water activity, it may be pared with pH reduction and/or heat treatment.

In most cases, the pH must be below 4.2 to add additional protection, or the filling temperature must be above 175ºF.

Water activity plays a critical role in determining the safety and stability of food products. Understanding and controlling water activity levels is essential for minimizing microbial growth, preventing foodborne illness, and maintaining the quality and shelf life of food products. Food scientists use water activity measurements to assess the potential for microbial contamination and design effective preservation and safety strategies to ensure the safety and quality of food products throughout their shelf life.

These are basic guidelines, and we recommend that any decisions are reviewed by a process authority.