The Atlantic blue crab (Callinectes sapidus) is an invasive species widely distributed in the Mediterranean Sea, causing significant ecological and economic impacts. Despite its low commercial value and the limited utilization of undersized and non-marketable specimens, whole blue crab biomass represents a promising resource for the production of value-added compounds within a circular bioeconomy framework. In this study, whole blue crab biomass, including undersized individuals and non-marketable fractions, was directly valorized through enzymatic hydrolysis for the production of protein hydrolysates. Three commercial proteases (Alcalase, Neutrase, and Papain) were comparatively evaluated for protein hydrolysate production, and the hydrolysis conditions were assessed based on soluble matter yield. The evaluation of hydrolysis conditions identified pH 8, 50 °C, enzyme-to-substrate ratio of 2500 U g−1, a solid-to-liquid ratio of 1:4, and a reaction time of 8 h as the most effective conditions for protein solubilization. Under these conditions, maximum soluble matter yields of 57.69% for Alcalase, 51.64% for Neutrase, and 48.44% for Papain were obtained. The obtained hydrolysates were subsequently characterized in terms of protein content and degree of hydrolysis (DH), both of which were significantly affected by enzyme type, following the order Alcalase (64.59 ± 0.75%) > Neutrase (62.29 ± 0.82%) > Papain (58.88 ± 0.65%). A similar trend was observed for degrees of hydrolysis (DH) of the products (43.20 ± 1.24%, 40.29 ± 1.05%, 37.26 ± 1.13%) respectively. Techno-functional properties of the hydrolysates were also enzyme-dependent and closely related to the extent of hydrolysis. Alcalase produced hydrolysates with higher DH, favoring the formation of smaller and more hydrophilic peptides, which enhanced water solubility (98.18 ± 0.51%) and antioxidant activity (77.08 ± 1.06%). In contrast, Papain-derived hydrolysates showed lower hydrolysis extent, likely preserving larger peptide structures and hydrophobic domains associated with higher emulsifying activity (16.10 ± 0.46 m2 g−1) and foaming capacity (30.47 ± 1.40%). Neutrase displayed intermediate behavior across most parameters. Overall, the results demonstrate that enzymatic hydrolysis of whole blue crab biomass is an effective valorization strategy, and that enzyme selection plays a key role in modulating hydrolysis efficiency and techno-functional properties. This approach provides a sustainable pathway for the management of invasive species while generating functional ingredients for food and nutraceutical applications.
Falciano et al. (Mon,) studied this question.