Glucans

Glucans are polysaccharides composed entirely of glucose units linked by glycosidic bonds. They represent a diverse family with both energy-storage and structural roles in living organisms. The two major categories are alpha-glucans and beta-glucans, distinguished by the configuration of the glycosidic linkage and by their biological functions.

Alpha-glucans include starch components in plants, namely amylose and amylopectin, and the storage polymer glycogen in animals. These polymers are primarily energy reserves and exhibit branched or linear structures that affect solubility and digestibility. Beta-glucans encompass a broad range of polymers such as cellulose, which is a beta-1,4-linked glucose chain forming rigid plant cell walls, and various beta-glucans found in fungi, yeasts, and cereals. Cerebral and cereal beta-glucans used in foods typically contain beta-1,3 and beta-1,4 linkages with substantial branching, contributing to soluble dietary fiber.

The properties of glucans depend on linkage type and branching. Solubility ranges from highly soluble beta-glucans to insoluble cellulose. Beta-glucans from fungi and cereals are notable for biological activities, including immunomodulation and cholesterol-lowering effects, and they are widely used as dietary fibers and food additives. Alpha-glucans primarily fulfill energy storage roles and influence texture and caloric content in foods.

Occurrence and applications: glucans occur in plants, fungi, bacteria, and yeast. They are exploited commercially as thickeners, stabilizers, and texturizers in the food industry, and, in health contexts, beta-glucans are studied for immune support and prebiotic effects. Safety profiles are generally favorable when consumed as part of a balanced diet.