Brown rice syrup is made by cooking rice, then fermenting it with special enzymes. These enzymes break down the starch in the rice, turning it into sugar. The syrup is only moderately sweet, with a texture similar to that of molasses. It has a light brown color and a mild caramel taste. Brown rice syrup is often considered to have a lower glycemic index and higher mineral content than more processed sweeteners. Minimal processing gives brown rice syrup a shorter shelf life than corn syrup and other highly refined products.
Unopened brown rice syrup has a relatively long shelf life. According to Briess Malt and Ingredients Company, clarified brown rice syrup can be stored for at least 24 months after its date of manufacture. The syrup does best in a cool, dry place without access to sunlight, which can degrade the product. It can expire early if stored in direct sunlight or allowed to reach temperatures above 90 degrees Fahrenheit.
After opening, brown rice syrup still keeps very well. You can store it at room temperature, as long as you don't allow any other foods to contaminate the syrup. Under these conditions, brown rice syrup keeps for several months. Exposing the syrup to light or moisture can shorten its shelf life, however.
Many brown rice syrup brands recommend refrigeration to prolong their shelf life. Since this kind of syrup does not crystallize like honey, keeping it in the refrigerator is a good way to make it last longer. According to The Complete Vegetarian Handbook, refrigerated brown rice syrup lasts about six months.
If your brown rice syrup comes into contact with moisture, it can grow mold on the surface. This can occur when liquid from dirty utensils splashes into the syrup or from condensation in humid environments. Keeping the syrup in the refrigerator reduces the risk of this problem. If you live in an area that experiences humid weather conditions, refrigeration should be your first storage choice.