This method is based on a multi-enzymatic hydrolysis of proteins:

• Successive hydrolyses by pepsin (gastric phase of digestion) and then by pancreatin (intestinal phase of digestion);
• Acid precipitation of non-hydrolysed proteins;
• Filtration on a filter crucible and drying of the residue;
• Determination of the proteins amount in the residue;
• Expression of the result as the ratio of proteins in the residue to the initial protein content, thereby determining the percentage of digestibility.