Powders are the unsung heroes of the food world. Although rarely consumed on their own, they play starring roles in millions of products by enhancing flavor, providing vitamins or minerals, and improving physical stability and shelf-life. Some products, like protein bars, are made up almost entirely of cold-formed powder paste. But powders can be tricky to work with.
One common problem: caking and clumping. Caking is a time-dependent reaction where the surface of particles that rub together become sticky and stop flowing nicely. Maybe you've seen this in a can of sports drink powder you left too long in the cupboard. Controlling water activity can stop caking and clumping by identifying aw levels that cause problems. For example, if you buy spray-dried lactose with a water activity of 0.470, chances are you'll have problems trying to make it move through your machinery.
As we noted above, powders nearly always get mixed with other ingredients to make finished product. When you make powder mixtures or spice blends, you're putting components together that have different water activity values. When combined with such a small particle size, this makes water move almost immediately from high water activity components to low water activity ones. I've seen spice blends solidify into rock-hard lumps within minutes because of this phenomenon. Knowing the water activity of your ingredients can help you avoid this problem.
All products have a finite shelf-life, even Twinkies. Most powders show a distinct point below which they are shelf stable for months or years. Above this point, they succumb to lipid oxidation, vitamin degradation, and other harmful reactions at a much faster rate. This "critical aw" is easy to find for any product. The most important clue is your product's isotherm, which can then let you set an aw spec that protects your ingredients.
If you can solve all these problems in your powders and spices, the next challenge is making sure they stay solved. Many quality control instruments are only useful in the lab - they're either too complicated or delicate to use anywhere else. AquaLab is different. It gives you +/-0.003 aw accuracy no matter where you are. The instrument is solid and easy to use, and doesn't require any special training or sample preparation. Water activity is as easy to measure on the factory floor as it is in the lab.