R&D RADIO: How Water Activity Keeps Shelf-Stable Food Safe, Crunchy, and Fresh

In this episode of R&D Radio, host Adam Yee sits down with Zachary Cartwright, Principal Food Scientist at AQUALAB by Addium, to break down one of the most important but least understood metrics in food science: water activity. They cover what water activity is, what the numbers mean, how it affects safety, texture, and shelf life, and how brands of any size can start testing for it.

Zach holds a PhD in Food Science from Washington State University, where he also serves as adjunct faculty in the School of Food Science. Over the past seven years at AQUALAB, he has worked with thousands of food scientists across low-moisture food categories, and has applied moisture science to pharmaceuticals, cosmetics, cannabis, and even gunpowder and batteries. AQUALAB provides water activity, moisture analysis, and moisture sorption solutions that help food companies improve product quality, stability, shelf life, and food safety.

Adam and Zach dig into the 0.6 water activity threshold for microbial growth, critical water activities that cause caking, sogginess, and sticky gummies, the difference between moisture content and water activity, and why packaging, temperature, and humidity matter so much. They also share practical ways for smaller brands to access testing, what to look for in a water activity meter, and how large manufacturers use water activity from incoming ingredients through production.

Listen in as they discuss:

What water activity really measures: the capacity of water to cause biological, chemical, and physical changes in a productWhy a water activity above 0.6 creates an environment where mold, yeast, and bacteria can growHow critical water activities drive caking and clumping in powders, lost crispness in snacks, and sweating in gummiesHow a water activity test works, from closed-chamber equilibrium to readings in as little as 60 secondsThe difference between moisture content and water activity, and how a moisture sorption isotherm helps predict shelf lifeWhen water activity matters less, like beverages, and where it still plays a role, from condiments to ice cream inclusionsWhy packaging should be decided before shelf life testing, and how sustainable packaging can change water vapor transmission ratesHow brands can access testing through universities, testing labs, or AQUALAB, and why in-house testing is idealWhat to look for in a meter: direct versus indirect sensors and temperature controlWhy clean label and preservative-free trends make wate