Formation of an Aminoreductone during the Maillard Reaction of Lactose with Nα-Acetyllysine or Proteins

When lactose is heated with N α -acetyllysine or other amines for a short time, e.g. 15 min under reflux, a main product can be detected by HPLC/DAD. The product has a UV maximum at 319 nm, indicating an aminoreductone structure (AR). AR was isolated and identified as 1-[ N ε -( N α -acetyllysinyl)]-1,2-dehydro-4-deoxy-3-hexulose. The analogous derivative of butylamine has previously been obtained from maltose. The product is the main UV absorbing material for several hours of heating and at various reaction temperatures. When lactose is heated with milk proteins, such as β-lactoglobulin, formation of AR can be observed by measuring a new UV maximum of the modified protein at 319 nm. Since AR can also be found after a short heating time and since it is the main product at various reaction conditions, it was concluded that the new product can be of importance for the Maillard reaction during milk processing.