Hydrolysed protein is protein that has been broken down into smaller peptides and amino acids — usually by controlled hydrolysis with water at high temperature, acids, or enzymes — to create intensely savoury flavour compounds. It is the basis of yeast extracts (Marmite), hydrolysed vegetable protein seasonings, and the deep umami of soy sauce, where fermentation does the hydrolysing naturally; even ordinary cooking hydrolyses proteins to a limited extent. The liberated glutamic acid and peptides deliver the meaty, brothy notes food manufacturers prize for soups, snacks, and ready meals. Because hydrolysis can unmask or create allergenic fragments unpredictably, allergen labelling of hydrolysed proteins — especially from wheat, milk, or soy — is strictly regulated.