A sugar and milk glaze is one of the simplest cake toppings you can make. It requires only two ingredients and additional flavorings, if you want. Because this sweet glaze is made with milk, it does require refrigeration to keep it from turning sour. If it completely dries on your cookies or cakes, they don't necessarily need refrigeration, though.
Keeping It Cool
While the powdered sugar used to create your milk and sugar glaze has an indefinite shelf life, the milk does not. Dairy products such as milk or cream require refrigeration at 40 degrees Fahrenheit or below to prevent spoilage. Even when combined with sugar, milk may spoil if left out at room temperature for more than two hours. Pour any extra glaze into an airtight container to keep it from drying out when you store it in the refrigerator. Before using it again, take it out and bring it to room temperature.
Storing the Goods
Although milk-based glazes themselves require refrigeration, refrigeration isn't necessary if you allow it to dry completely on baked goods. The glaze should stay good for the life of the cookies, cakes or doughnuts that it is used on. This means that glazed doughnuts or cakes will usually last two to three days in the pantry, while hard cookies can last as long as two weeks. The reason that these goods don't require refrigeration is because the glaze no longer contains any liquid, much like powdered milk. It's the liquid content of milk that encourages the growth of mold, bacteria and other spoilage microorganisms that affect dairy products.
Once you mix a sugar and milk glaze, you can store it in the refrigerator in an airtight container for as long as a week. Once you bring it to room temperature, stir it and pour it over your cake or cookies. To thicken the glaze, add additional powdered sugar, likewise, to thin it, simply add a bit of milk until you reach the desired consistency. Allow the glaze on baked goods to dry completely, which can take as long as two hours at room temperature. If the glaze isn't dry after two hours, allow it to dry in the refrigerator before wrapping the goods in plastic and storing in a cool, dark pantry.
To Freeze or Not to Freeze?
While baked goods covered with a milk-based glaze can last for a couple of days or weeks in your pantry, they will last longer in the refrigerator or freezer. The hardened glaze on the baked goods is safe to freeze, although it may become somewhat watery and sticky when thawed. While you can also freeze the glaze itself, the texture may change when it thaws, making it undesirable to use on baked goods. For best results, mix up a glaze just before icing a fresh-baked treat.