Laccase-induced structural remodeling of cottonseed protein for improving its emulsion stability and curcumin bioaccessibility.

BACKGROUND: Cottonseed is an important byproduct of cottonseed processing and is rich in proteins. A literature review indicated that cottonseed protein isolate (CPI) demonstrated a compact structure because of its limited exposure of hydrophobic groups, leading to poor emulsifying performance. This limited the functional performance and practical application of CPI in food systems. This study aimed to enhance CPI interfacial functionality through laccase-induced structural remodeling and to evaluate its performance in curcumin (Cur)-loaded emulsions. RESULTS: This study designed a control group (0%) and laccase-treated groups (0.3%, 0.5%, and 0.8%, w/w). It was found that protein aggregation and network formation became more pronounced following laccase treatment and followed a dose-dependent pattern. Importantly, this investigation revealed that free sulfhydryl and free amino groups decreased, whereas random coil content, hydrophobic residue exposure, surface hydrophobicity, emulsifying activity, foaming capacity and oil-holding capacity increased, in which surface hydrophobicity increased by 61.09%, and emulsifying activity, foaming capacity, and oil-holding capacity increased by 30.55%, 57.24%, and 10.94%, respectively. Pearson correlation analysis showed that surface hydrophobicity was closely related to functional improvement. Compared with the control, 0.8% laccase-modified CPI produced smaller, more uniform Cur-loaded droplets. Encapsulation efficiency increased from 74.04% to 81.97%, and Cur bioaccessibility increased from 26.84% to 40.88%. CONCLUSION: These findings indicated that laccase modification improved the functional properties and interfacial characteristics of CPI by altering its molecular conformation, thereby enhancing the encapsulation and bioaccessibility of Cur. This study provided a promising strategy for improving the delivery of hydrophobic bioactive compounds through enzymatic modified proteins. © 2026 Society of Chemical Industry.