α-Lac is a major component of breast milk protein, it has good foaming properties, but poor emulsifying and gel properties. Hence, it is necessary to improve the functionality of α-Lac. Superfine grinding is a new physical treatment method, it can improve the utilization rate, and little damage to nutritional characteristics of materials. Laccase (EC.1.10.3.2) is considered as a green catalyst because the only by-product of the cross-linking reaction between laccase and protein is water. However, whether superfine grinding might improve the functionality of laccase-treated α-Lac is still unclear. The main purpose of this study was to confirm the impact of superfine grinding treatment on physicochemical, functional properties, and in vitro digestibility of laccase-treated α-Lactalbumin (α-Lac). Throughout the experiment, α-Lac was treated by superfine grinding, then the laccase was added to the α-Lac solution to catalyze the crosslinking reaction at 40 °C for 10 h. After that, the reaction mixture was heated at 70 °C to inactivate laccase. The sample solution was placed at room temperature, cooled and lyophilized, and the superfine grinding α-Lac was treated as a control group. With the grinding time ranging from 0 to 12 h, the high molecular weight polymers, relative dityrosine, and surface hydrophobicity of laccase-treated α-Lac increased significantly (P ＜ 0.05). After superfine grinding treatment (12 h), compared with α-Lac, the emulsifying activity and emulsifying stability of laccase-treated α-Lac were increased by 24.78% and 10.50%, and its gel strength and water holding capacity were enhanced by 19.92% and 21.78%. Superfine grinding treatment reduced α-helix and β-sheet content and increased β-turns and random coils of α-Lac and laccase-treated α-Lac. The in vitro digestibility of α-Lac and laccase-treated α-Lac was improved after being treated by superfine grinding. These results indicated that superfine grinding could promote laccase cross-linking of α-Lac and improve its functional characteristics.

Structure, functional characteristics and in vitro digestibility of laccase-crosslinked α-lactalbumin: Impacts of Superfine grinding pretreatment

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