Alternan as a glucan with miscellaneous applications: Properties, preparation, and health efficacies

Alternan is an extracellular α-D glucan produced by lactic acid bacteria and characterized by its unique structure of alternating α-(1 → 6) and α-(1 → 3) glycosidic bonds. Herein, we comprehensively and systematically summarized the advances in alternan research. The molecular features and physicochemical property of alternan, including its linkage components, and hydrocolloid behaviors, are thoroughly analyzed are discussed. Approaches including fermentation and enzyme engineering are estimated for producing alternan which can be modified by enzymatic or ultrasonic treatments with special properties. Alternan exhibits multiple properties including nanoparticle and film formation, thermal stability and immunochemistry, serving as texturing agent, prebiotics, and emulsifiers as well as ingredients for developing new commercial products. The alternan application across foods, medicine, healthcare, and cosmetic formulations is systematically reviewed with both commercial prospectives and challenges. This review aims to provide valuable insights and a perspective to support the expanded range of applications of alternan across multiple fields.