New Insights into the Mechanisms of Bitterness and Astringency in Chitosan Oligosaccharide Complexes

Chitosan oligosaccharides (COS) possess valuable bioactive properties but exhibit undesirable bitter and astringent tastes that severely restrict their applications in functional foods. This study comprehensively elucidates the formation mechanisms of these taste defects by systematically investigating COS fractions with varying molecular weights. It was found that COS astringency intensifies with increasing molecular weight, while bitterness increases with decreasing molecular weight. The astringency mechanism primarily involves COS binding to salivary proteins via electrostatic interactions, hydrogen bonds, and van der Waals forces. This binding alters the structure of salivary proteins, causing them to precipitate and impairing mucosal lubrication, thereby triggering astringency. These fundamental insights establish a theoretical framework for developing innovative strategies to modulate COS taste attributes through precise molecular weight control or structural modification, thereby facilitating broader utilization of COS in the food industry.