Influence of Enzymatic Hydrolysis on the composition, nutritional quality, antioxidant activity, and technofunctional characteristics of lupin protein isolates

Abstract

Global protein scarcity highlights lupin as a sustainable, high-protein alternative for the European market. However, its storage proteins aggregate easily, so enzymatic hydrolysis is proposed to enhance their quality and technofunctional applications. This study investigated the modification of lupin protein isolates using three enzymes—papain and two multi-enzyme complexes—and the resulting effects on the final product’s properties, including nutritional quality, chemical composition, and antioxidant, antimicrobial, and technofunctional activities. The multi-enzyme systems were highly efficient, achieving a high degree of hydrolysis (≈25%) compared to papain (≈5%). A high degree of hydrolysis showed a strong positive correlation with antioxidant capacity across all assays. Crucially, extensive hydrolysis improved nitrogen solubility across the entire pH range, making the isolates pH-independent (> 85% solubility). However, excessive hydrolysis results in a deterioration of oil absorption capacity, and the foaming and emulsifying properties. Nutritionally, the hydrolysis did not compromise the excellent essential amino acid profile, which exceeded FAO/WHO/UNU requirements. Nevertheless, the inherent legume deficiency of methionine persisted as the primary limiting amino acid. In conclusion, enzymatic hydrolysis is an ideal tool for modifying lupin proteins, significantly enhancing both their antioxidant properties and solubility. Therefore, the use of enzyme complexes represents a superior strategy to unlock the bioactivity and functional versatility of lupin protein, and the potential application of lupin hydrolysates in food formulations.