Influencing emulsifying properties of egg yolk by enzymatic modification by phospholipase D from Streptomyces chromofuscus Part 1: technological properties of incubated egg yolk

Abstract

Impact of a direct incubation of egg yolk with phospholipase D (PLD) from Streptomyces chromofuscus was investigated with respect to its effect on rheological and emulsifying properties. Egg yolk has been shown to be a suitable substrate for incubation with PLD after a slight dilution with water (70/30, w/w). A considerable increase of egg yolk viscosity during incubation was observed correlating with formation of phosphatidic acid due to enzymatic activity. Emulsions prepared with such an incubated egg yolk showed a higher viscosity, in particular at high egg yolk concentration. Especially in the case of lower concentrations, smaller droplets indicating better emulsifying activities were detected in emulsions prepared with the incubated egg yolk compared to the application of untreated egg yolk. Stability after heat treatment of the emulsions could be significantly improved by the application of egg yolk incubated with PLD.