Photo courtesy of FMC Foodtech Inc.

Cooling is a standard part of any baking process. Proper cooling is important to the integrity of finished baked foods and can truly impact a product's shelf life. Residual heat can cause a buildup of condensation after packaging, which negatively affects product texture and may become a catalyst for mold growth. “Bread needs to be uniformly cooled to a crumb temperature of 86°F to 95°F (30°C to 35°C) to avoid condensation in packaging and improve the slicing operation,” says Chris Hanssen, freezer sales support and business development manager, FMC FoodTech Inc., Northfield, Minn.

In some cases, bakers who primarily market fresh products have expanded their portfolios with frozen items. Freezing offers many advantages, chiefly among which is cost savings. Freezing also allows the bakery to become more dedicated to longer runs, eliminates peak demands, extends storage stability and gives the bakery far more leverage over its distribution area, notes Tim Sieloff, baking instructor, AIB International, Manhattan, Kan., who presented a seminar on freezing at the American Pie Council's Pie Industry Seminar in Orlando last month.

As with cooling, freezing requires a good measure of control; perhaps even more so, since frozen products are subject to far more environmental changes than those that are cooled. “Anytime the environment temperature changes, product is a recipient of that temperature change,” Sieloff says. As a result, using the proper equipment and freezing method is critical to ensuring finished product quality.

Maximizing quality

While moving from fresh to frozen processing might seem straightforward, freezing technology is far more complex than anyone might think. Any baker considering such a move should run small-scale shelf life testing through various freeze/thaw cycles before taking on full- scale production.

When a product is frozen, its water phase effectively changes from a liquid to a solid state. A product's freezing point is affected by its formulation and chemical composition. For instance, the amount of solutes in the formula, such as sugar, will affect the freezing point. The higher the sugar amount, the lower the freezing point. Thus, there can be as much as 10 percent water left unfrozen if the product is not frozen properly. Sieloff recommends freezing leaner products at 20°F to 25°F (-4°C to -7°C) and richer products, or those containing higher levels of solutes and fat, at 13°F to 18°F (-8°C to -11°C).

“In freezing, two types of heat must be removed: sensible heat and latent heat,” Sieloff explains. “Sensible heat is the heat that must be removed to lower the core temperature of the product closer to the freezing point, and once cooled, latent heat is the heat that must be removed to change the physical state of the product from liquid to solid form.” If product isn't through its latent heat phase before it is placed in a holding freezer, where the temperature may not be sufficiently cold enough to drop its temperature further, it may increase in temperature. When the temperature rises back above the freezing point, water within the product remains in a liquid state. This free water can cause a variety of quality issues.

Any amount of water left unfrozen can damage the product, particularly during freeze/thaw cycles that occur throughout storage and distribution. Residual unfrozen water left in the product can create problems with moisture migration, dehydration and crystallization during storage. Moisture loss of 0.8 percent to 1 percent is typical, but it can be as high as 2 percent, Sieloff notes.