Changes in interfacial behaviour, emulsifying and foaming properties of faba bean legumin after modification with dimethylsuberimidate

The effect of a rising rigidity and surface hydrophobicity of the 11S stora ge protein from faba beans - legumin - induced by chemical modification wit h dimethylsuberimidate (DMS) on some surface functional properties was stud ied. Short-time adsorption kinetics using a droplet-volume tensiometer, pre ssure transformation and desorption behaviour of monolayer using a film bal ance, and emulsifying and foaming properties were determined to characteriz e surface activity and interfacial film forming behaviour. Tensio-active pr operties at the air-water interface, i.e. decay in surface tension and pres sure transformation in monolayer, were improved by modification. However, a decrease in emulsifying activity, foam capacity and foam expansion after m odification of the legumin points to an overall deterioration of energy-ind uced film forming behaviour. The results support the view that surface acti vity is generally governed more by molecular flexibility than by surface hy drophobicity.