Brown rice syrup, also known as rice syrup, is a sweetener derived by culturing cooked rice with enzymes (usually from dried barley sprouts) to break down the starches, then straining off the liquid and reducing it by cooking until the desired consistency is reached. The final product is 45% maltose, 3% glucose, and 52% maltotriose.
Glucose, the most simple of sugars, is used as the reference food in constructing the Glycemic Index, with a glycemic index of 100. It quickly passes through the stomach into the small intestine where it is absorbed into the bloodstream.
Maltose, which has a higher glycemic index of 105, is digested and absorbed as blood glucose even faster.[1]
The more complex Trisaccharide, maltotriose[2] , has a glycemic index in the high-60s [3] about the same as whole, cooked brown rice.
The exact glycemic index for brown rice syrup appears to be unknown, as none of its manufactures have funded the simple blood sugar testing over a 3 hour time frame required to determine it. However, since all three of its components have GIs higher than table sugar, (sucrose) the mix of the three must also have a GI higher than table sugar. Diabetics should manage its consumption accordingly.
Rice syrup has a shelf life of about a year, and once opened, should be stored in a cool, dry place.
Brown rice syrup is produced commercially by cooking brown rice flour or brown rice starch with enzymes. The final carbohydrate mix can be adjusted, depending upon the desired sweetness and application. The syrup is filtered, and excess water is evaporated to thicken it. The product is produced on a commercial scale by several companies in the United States, Europe, and Asia.
Brown rice syrup is the sweetener found in some drinks, such as rice milk.