Effect of Preparation Methods of Yeast Protein Isolate on Emulsion Stability

Abstract

In the previous report, emulsifying capacity of yeast protein isolates prepared with three different methods(Yeast protein isolate I, II, III)was studied in comparison with those of soy protein and caseinate at various pH's, ionic strengths and leicthin contents(%). In the present study, emulsion stability of these three yeast protein isolates was compared with the results of previous reports and the particle sizes of these emulsions were measured with a microscope. Emulsion stability of yeast protein isolate I was far superior to that of soy protein or caseinate, especially in the acidic and alkaline region. However, yeast protein II and III gave low emulsion stabilities, which were similar to those of soy protein or caseinate. It was suggested that emulsifying properties of the yeast protein isolates were largely influenced by preparation methods of the protein. The particle sizes of the emulsions which have good emulsifying properties were smaller than those of poor emulsions and yeast protein isolate I had the smallest particle sizes.