Chocolate is Man’s unquestioned favorite sweet treat. At one time, the wisdom of eating chocolate was in question. Carob was proffered as a suitable replacement, though it never truly caught on. Despite that, carob is of commercial importance. In fact, a derivative of the carob seed or carob bean is probably familiar to you—locust bean gum. What is locust bean gum?
What It Is
Locust bean gum is a food additive—a thickener—derived from the carob tree (Ceratonia siliqua), prevalent in the region of the Mediterranean. The elongated pods of C. siliqua are coarsely ground, then separated as two fractions, pulp and seed. Locust bean gum, or LBG, is derived from the seed fraction.
Seeds first have their skins removed by acid treatment or by roasting and mechanical removal. Then the seeds are split and milled. The rugged yellowish endosperm portion is collected and fine-ground into “flour.” This flour can be used to form a sol—or—it can be modified to form a gel, by combining with carageenan. Although LBG is not very soluble in water at ambient temperatures, it is dissolved by hot water.
Chemistry and Structure
The chemical structure of locust bean gum consists of linked sugar units—specifically two hexose sugars (sugars containing six carbon atoms), mannose and galactose, in a ratio of about 4 to 1. The mannose units are bonded linearly—end to end—with galactose units attached at the side. The LBG structure is immense, with a molecular weight of from fifty thousand to two million!
LBG in Food Use
Although it can be employed in a number of other applications, the most familiar use of carob bean gum or locust bean gum is for food. Dairy products, sauces, and salad dressings contain locust bean gum. Meat products, breads and breakfast cereals may contain it, as well. LBG can be used to replace fat, and lower cholesterol—it has even been associated with decreased diarrhea in infants.