Many candies have a distinctive texture–chewy, crunchy, smooth, grainy, sticky, or soft. Confectionery flavors are similarly distinctive. These two things come together to form the customer experience. Moisture plays a key role in the texture of confectionery products. In fact, there is an ideal range of water activity—a sweet spot—that maximizes texture and quality. Getting the moisture measurement right is critical for nearly every product. Water activity is the most powerful way to measure and monitor moisture.
Water activity makes choosing the right specifications easy
Water activity affects the physical properties of foods. Foods with a high water activity have a texture that is moist, juicy, tender, and chewy. When the water activity of these products is lowered, undesirable textural attributes, such as hardness, dryness, staleness, and toughness occur. Low water activity products have texture attributes described as crisp and crunchy, while these products at higher water activity levels change to a soggy texture. Because water activity is closely correlated to product texture, it’s easy to set specifications that relate to important texture characteristics.
Critical water activities determine where products become unacceptable
There are two ways texture can go wrong: it can be wrong as soon as your product is made, or it can go wrong over time as your product sits on the shelf. If a chewy chocolate chip cookie rolls off the production line already crispy, it’s likely too much water has been taken out in the baking process. Another complication occurs if products undergo phase change during storage. These changes, including glass transition and crystallization, make smooth products into grainy ones, or soft products into hardened bricks.
Crackers, potato chips, puffed corn curls, and popcorn each lose their sensory crispness with increasing water activity. The crispness intensity and overall hedonic texture of dry snack food products are a function of water activity (Katz and Labuza, 1981). Critical water activities illuminate where the product becomes unacceptable from a sensory standpoint. These fall into the range where amorphous to crystalline transformations occur in simple sugar food systems and mobilization of soluble food constituents begins. Excessive and rapid drying or moisture reabsorption by a glassy material can cause product loss by cracking and excessive breakage.