Reduced-fat products contain higher levels of water than their full-fat counterparts. In these products, higher levels of hydrocolloids can “control the increased water and to replace some of the mouthfeel imparted by the milkfat,” says Klemaszewski. “Products with reduced fat have different whipping properties than full-fat products, and adjustments to the emulsifiers may be needed.”
High sugar levels in the formulation might compete for water in the system. “Furthermore, too high a level of mono- and diglycerides might render the stabilizers less functional,” cautions Joshua Brooks, vice president of sales, Gum Technology Corporation.
As the trend moves toward healthier, lower-calorie frozen desserts, stabilizers face different challenges. Tim Carter, dairy program manager, TIC Gums, Belcamp, MD, has found that sugar alcohols in the formulation can negatively affect the batch by increasing the viscosity.
“Reduced-sugar products contain higher-molecular-weight carbohydrates, such as polydextrose and maltodextrin, along with higher levels of milk proteins. This combination imparts a higher viscosity to the ice cream mix,” Klemaszewski explains. Therefore, a lower hydrocolloid level is needed to prevent excessive viscosity during processing.
In frozen desserts, fat or sugar reduction corresponds to increases in water or overrun. Ice creams with lower solids and/or higher overrun require additional functionality from stabilizing ingredients.
A hard-pack ice cream mix will be in a liquid state for less than 24 hours and frozen for up to one year. “By contrast, an aseptically processed soft-serve mix can be stored for months before freezing and be consumed less than one hour after freezing,” says Klemaszewski. “Controlling ice-crystal growth is critical to maintaining product quality in the hard-pack product, given it will see a number of temperature cycles. Mix separation is not typically seen in a manufacturing plant. In the aseptically processed mix, the proteins need to be stabilized to prevent coagulation during the high-temperature processing. Cream and serum separation are a concern as the mix is shipped and stored. Ice-crystal growth over time is not a concern, but the churning properties of a soft-serve freezer are different from the continuous freezer used in a plant. Mixing in a soft-serve freezer experiences higher levels of shear, and an emulsifier level and type typically used in a hard-pack product can result in the milkfat churning out of the soft-serve mix. This is especially prevalent in full-fat mix and is described as small pieces of butter in ice cream.”