pH and water activity in food products
pH and water activity are two of the most important factors affecting food safety, shelf-life, and product quality. Water activity is commonly abbreviated as aw. Understanding how these measurements work together can help food businesses make informed decisions about product formulation, packaging, processing, and storage.
This guide explains what pH and water activity are, why they matter, and how they influence the safety and stability of food products.
What is pH?
pH is a measure of how acidic or alkaline a food product is. The pH scale ranges from 0 to 14:
- Below 7: Acidic
- 7: Neutral
- Above 7: Alkaline (basic)
The lower the pH, the more acidic the product is. The higher the pH, the more alkaline the product.
Why is pH important in food?
The pH of a food product plays an important role in:
- Food safety
- Microbial growth
- Product stability
- Shelf-life
- Preservation methods
Many microorganisms grow only within specific pH ranges. Managing the acidity of a product can help reduce food safety risks and improve product stability throughout its intended shelf life.
What is water activity?
Water activity measures the amount of water available within a food for microbial growth and chemical reactions. It is different from moisture content, which measures the total amount of water present in a product. Understanding water activity helps manufacturers evaluate how a food product will behave during storage and distribution.
Why is water activity important?
Water activity affects several characteristics of a food product, including:
- Shelf-life
- Food safety
- Texture
- Product stability
- Microbial growth
Lowering water activity can help slow microbial growth and improve the stability of many food products.
pH and water activity work together
Although pH and water activity are measured separately, they are often evaluated together during food product development.
Understanding both measurements helps determine:
- Appropriate processing methods
- Packaging requirements
- Storage conditions
- Shelf-life expectations
- Whether formulation changes or additional ingredients may be needed
By managing both pH and water activity, food businesses can improve product safety, maintain quality, and extend shelf life.
Frequently asked questions
No. Moisture content measures the total amount of water in a food, while water activity measures how much of that water is available for microorganisms and chemical reactions. Two products can have similar moisture content but very different water activity values.
Both measurements influence food safety, shelf-life, and product stability. Evaluating them together provides a better understanding of how a product should be processed, packaged, and stored.
Measuring pH and water activity helps businesses evaluate food safety risks, determine appropriate preservation methods, optimize packaging, and support product shelf-life.
Continue exploring
Interested in learning more? Explore additional resources from CFRIL:
Need help evaluating your food product?
Whether you’re developing a new product or improving an existing formulation, CFRIL can help assess pH, water activity, and other factors that influence food safety, quality, and shelf-life. Contact our team to learn more.
This is intended for general informational/educational purposes only and does not replace professional food safety training, regulatory guidance, or legal advice. For comprehensive support, contact our team.