Like water icings, glazes set as they cool to room temperature.

Water icings and glazes are visual accessories to baked goods, typically applied in a thin layer over the whole product or in a decorative pattern such as stripes or swirls. Applications include Danish, coffee cakes, puff pastries and honey buns, as well as colorful holiday-themed cookies.

“The typical application would be upon a cooled product with the water icing slightly heated,” said James Jones, vice-president, customer innovation, AAK USA, Inc. The water icing sets once ambient temperatures are achieved.

“A glaze, on the other hand, tends to be a simple transparent topping applied to a baked good to impart a shine or a thin veneer,” he continued. “The glaze can protect and seal the baked good, as well as impart sweetness or flavor and improve visual appeal. The typical physical application would be upon a hot product.”

Like water icings, glazes set as they cool to room temperature. Applications include donuts, hand-held pie snacks and simple butter cookies. “Glazes can be poured or brushed on, or the baked good can be dipped into these confectionary coatings,” said Jean Bacardi, regional market segment lead, bakery and beverage, ICL Food Specialties. “When either glazes or icings are scaled up to industrial proportions and long distribution channels, desired texture and stability become more challenging to achieve. The product developer must consider machinability, extended shelf life and freeze-thaw stability, as well as consistent quality.”

The main formulation difference between icings and glazes is the water-to-sugar ratio. This influences viscosity and appearance once applied to the baked good. “A glaze will contain 20 to 25% water and 70 to 75% sugar, while an icing will be closer to 15% water and 80% sugar, plus other ingredients,” said Bill Gilbert, certified master baker and principal food technologist, Cargill.

This difference in water-to-sugar ratio has an impact on appearance. “The higher water content of glazes gives it a transparent appearance compared with the more opaque look of water icings,” said Eric Shinsato, senior project leader, Ingredion, Inc.

The opaque look of water icings can be emphasized or down-played, if desired. Water icings often contain titanium dioxide for opacity and white color, according to Michael Saulsberry, vice-president, baking division, Watson. The company offers stabilizing systems that yield very clear to opaque toppings. Usage levels vary depending on the degree of stability required and the amount of shelf life desired.

Stabilization is paramount with icings and glazes. Unless properly stabilized, they can either pull moisture from the baked good causing it to stale while the topping runs off, or the topping can release moisture into the product, causing it to become soggy.

For example, donuts have a water activity greater than 0.90 aW, while that of a common glaze is around 0.70 aW. Unless properly stabilized, there will be moisture migration from the donut to the glaze, which will cause it to weep.

“Stabilizers maintain the two-phase system of dissolved and suspended sugar in water,” said Janae Kuc, principal technologist at Ingredion. “They protect the desired texture, appearance and volume against temperature and humidity over the shelf life of the baked good. The stabilizer achieves this by controlling water migration to and from the icing or glaze and the product.”