WHITE LUPIN PROTEIN ISOLATE AS A FOAMING AGENT

In this work the foaming ability of white lupin protein isolates was i nvestigated in order to evaluate the potential use of these isolates a s functional additives in food products and to find a vegetable altern ative to egg-white foams. Lupinus albus protein isolate, modified in o rder to improve its foaming ability, was tested. Thermal denaturation, chemical treatment (acylation) and enzymatic hydrolysis (with vegetal proteases) were used, and the best results were obtained by using an optimised thermal denaturation method. A series of additives was tried out in order to further improve foam stability; xanthan gum gave the best results. Prior heat treatment of the protein and the conditions u nder which foam was generated were optimised using response surface me thodology. Texture and microstructure of the optimised lupin foam were objectively evaluated. The lupin foam, when boiled in water for 5 min became very similar in texture and microstructure to uncooked egg-whi te foams. This shows, therefore, some promise as a substitute of the l atter for products like fruit and chocolate ''mousses'', with the adva ntage of being able to withstand heat treatments.