Simultaneously enhanced stability and biological activities of chlorogenic acid by covalent grafting with soluble oat β-glucan

Chlorogenic acid (CA) has a wide range of biological activities but the chemical structure is extremely unstable. In this study, CA was grafted onto a soluble oat β-glucan (OβGH) to improve the stability. Although the crystallinity and thermal stability of CA-OβGH conjugates reduced, the storage stability of CA significantly improved. The DPPH and ABTS scavenging ability of CA-OβGH IV (graft ratio 285.3 mg CA/g) were higher than 90 %, which is closed to activities of equivalent concentration of Vc (93.42 %) and CA (90.81 %). The antibacterial abilities of CA-OβGH conjugates are improved compared to the equivalent content of CA and potassium sorbate. Particularly, the inhibition rate of CA-OβGH for gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes) are significantly higher than that of gram-negative bacteria (Escherichia coli). The results demonstrated that covalent grafted CA with soluble polysaccharide is an effective strategy to enhance its stability and biological activities.