Enzymatic hydrolysis of the <i>Eisenia andrei</i> earthworm: Characterization and evaluation of its properties

<p>Some studies have carried out in order to retrieve proteins from the by-product of animal-processing industries. Earthworms are rich in protein and usually are used in animal feed. Thus, this study aimed to optimize the hydrolysis process of <i>Eisenia andrei</i> earthworms by employing Alcalase enzyme. Using the response surface methodology, we evaluated the following conditions: temperature, hydrolysis time, stirring speed, and enzyme/substrate ratio. The optimal conditions for the experimental design were determined through the analysis of the foaming and emulsifying properties, <i>in vitro</i> starch digestibility, and antioxidant activity. The results demonstrate that the highest degree of hydrolysis (i.e., 92%) was obtained under the following conditions: pH, 9.5; temperature, 25 °C; hydrolysis time, 2.25 h; stirring speed, 200 rpm; and enzyme/substrate ratio, 1.77%, using Alcalase enzyme. Evaluation of the amino acid composition under these conditions revealed higher concentrations of aspartic acid, glutamic acid, and leucine. The <i>in vitro</i> protein digestibility of the hydrolysate was approximately 73%. There were no significant improvements in either foam stability or emulsification after enzymatic hydrolysis. Additional studies on the antioxidant activity are required. This bioproduct could potentially serve as a promising supplementary food product.</p