Monoglycerides (also: acylglycerols or monoacylglycerols) are a class of glycerides which are composed of a molecule of glycerol linked to a fatty acid via an ester bond. As glycerol contains both primary and secondary alcohol groups two different types of monoglycerides may be formed; 1-monoacylglycerols where the fatty acid is attached to a primary alcohol, or a 2-monoacylglycerols where the fatty acid is attached to the secondary alcohol.
Monoglycerides are produced both biologically and industrially. They are naturally present at very low levels (0.1-0.2%) in some seed oils such as olive oil, rapeseed oil and cottonseed oil. They are biosynthesized by the enzymatic hydrolysis of triglycerides by lipoprotein lipase and the enzymatic hydrolysis of diglycerides by diacylglycerol lipase; or as an intermediate in the alkanoylation of glycerol to form fats. Several monoglycerides are pharmacologically active (e.g. 2-oleoylglycerol, 2-arachidonoylglycerol).
Industrial production is primarily achieved by a glycerolysis reaction between triglycerides and glycerol. The commercial raw materials for the production of monoacylglycerols may be either vegetable or animal fats and oils.
Monoglycerides are primarily used as surfactants, usually in the form of emulsifiers. Together with diglycerides, monoglycerides are commonly added to commercial food products in small quantities as E471, which helps to prevent mixtures of oils and water from separating. The values given in the nutritional labels for total fat, saturated fat, and trans fat do not include those present in mono- and diglycerides as fats are defined as being triglycerides. They are also often found in bakery products, beverages, ice cream, chewing gum, shortening, whipped toppings, margarine, and confections. In bakery products, monoglycerides are useful in improving loaf volume and texture, and as antistaling agents.