Best Storage for Maple Syrup and Honey
We've occasionally left maple syrup out on the countertop, only to find it spotted with mold a few weeks later, while a jar of honey sitting right next to it remained perfectly fine. Because of its high moisture level and lack of preservatives, maple syrup is a perishable food product that is susceptible to the growth of yeasts, molds, and bacteria. Refrigeration not only helps maple syrup retain its flavor but prevents microorganisms from growing as well. Unopened, maple syrup will last several years stored in a cool, dark place. Once opened, it will keep six months to a year in the refrigerator.
Honey, unlike maple syrup, is highly resistant to microbial growth because of its naturally low moisture content and slightly acidic nature. According to Harold McGee in his book On Food and Cooking (2004), when bees turn nectar into honey, an enzyme in the bees' saliva oxidizes some of the glucose (a simple sugar) to form gluconic acid (which increases the honey's acidity, making it less hospitable to microbes) and peroxides (which act as an antiseptic).
If kept tightly capped in a moisture-tight container, processed (that is, pasteurized) honey can be safely kept at room temperature (the National Honey Board recommends a range of 64 to 75 degrees Fahrenheit) for about two years. In the test kitchen's experience, however, it can be stored for even longer without flavor degradation. Refrigeration can cause processed honey to crystallize, or become cloudy, a phenomenon that can be reversed by heating the portion to be used in a water bath in a saucepan on top of the stove.