Hydrolysed vegetable protein (HVP) products are foodstuffs obtained by protein hydrolysis and are used as ingredients with an authentic bouillon (broth) taste. Almost all products rich in protein are suitable for the production of HVP. However today, it is mainly made from protein resources of vegetable origin such as soybean meal, wheat gluten or maize meal.
Proteins consist of chains of amino acids joined together by amide bonds, when subjected to hydrolysis, the protein is broken down into its component amino acids. In the industry, hydrochloric acid is used to perform this process, and the remaining acid is then neutralized by mixing with an alkali such as sodium hydroxide, which leaves behind table salt.
For the production of aHVP (acid-HVP), the proteins are hydrolysed by cooking with a diluted (15–20%) hydrochloric acid, at a temperature between 90 and 120°C for up to 8 hours. After cooling, the hydrolysate is neutralized with either sodium carbonate or sodium hydroxide to a pH of 5 to 6. The hydrolysate is filtered to remove the insoluble carbohydrate fraction (humin) and then further refined. The source of the raw material, concentration of the acid, the temperature of the reaction, the time of the reaction, and other factors can all affect the organoleptic properties of the final product. Activated carbon treatment can be employed to remove both flavor and color components, to the required specification. Following a final filtration, the aHVP may, depending upon the application, be fortified with additional flavoring components. Thereafter, the product can be stored as a liquid at 30–40% dry matter, or alternatively it may be spray dried or vacuum dried and further used as a food ingredient.
For the production process of enzymatic HVP, enzymes are used to break down the proteins. To break down the protein to amino acids, proteases are added to the mixture of defatted protein and water. Since no salt is formed during the production process, adding salt as an ingredient is common practice to meet the criteria as described in the European Code of Practice for Bouillons and Consommés. Due to the sensitivity of enzymes to a specific pH, either an acid or a base is added to match the optimum pH. Depending on the activity of the enzymes it, up to 24 hours are needed to break down the proteins. The mixture is heated to inactivate the enzymes and then filtered to remove the insoluble humic acid.
When foods are produced by canning, freezing, or drying, some flavor loss is almost inevitable. Manufacturers can use HVP to restore these lost flavors, bring out latent taste characteristics, and generally round off and improve the flavor of the food. Therefore, HVP is used in a wide variety of products such as in the spice, meat, fish, fine-food, snack, flavor, and soup industries.