Comparative studies on physicochemical properties of bovine serum albumin-glucose and bovine serum albumin-mannose conjugates formed via Maillard reaction

• Extent of reaction in MBSA was higher than the one in GBSA.
• Decreased surface hydrophobicity in GBSA and MBSA led to reduced foaming stability.
• Different secondary structure in GBSA and MBSA led to their differences in foaming ability.
• Relative flexible and loosened conformation in GBSA resulted in its improved foaming capacity.

Glucose and mannose are important factors and ingredients in glycation of bovine serum albumin (BSA). We aimed to study the effect of glucose and mannose on the physicochemical properties of BSA. In this research BSA-glucose conjugate (GBSA) and BSA-mannose conjugate (MBSA) were prepared by Maillard reaction under neutral pH at moderate temperature (45 °C). Our results showed the conjugation ratio between mannose and BSA was significantly higher than the ratio between glucose and BSA. All foaming stability and emulsifying activity were substantially-decreased in GBSA and MBSA. However, an increase in foaming capacity was observed in GBSA. The fluorescent spectra of both GBSA and MBSA indicated their decreased surface hydrophobicity. These changes were attributed to their reduced emulsifying activity. In addition, circular dichroism spectra shown GBSA presented a relative flexible and loosened conformation, whereas MBSA remained compact and rigid conformation. These alterations in molecular structure were responsible for their different foaming capacity. Our study provided principle knowledge to understand the structure-functions relationships of BSA glycation by mannose and glucose. These results can be used to provide theoretical guidance for protein modification.