Emulsifying Properties of Proteins of Yeasts Grown on n-Paraffin

Abstract

To evaluate the emulsifying properties of single-cell proteins from the standpoint of food uses, the emulsifying capacity(EC)and emulsion stability(ES)of the proteins extracted from yeast of the Candida family grown on n-paraffin were determined, and the following results were obtained:
1) The EC and ES of the proteins in a water extract of yeast were hardly affected by pH, concentration of sodium chloride and heat treatment of the extract.
2) The EC and ES of the proteins precipitated from unheated alkaline extract decreased slightly in the isoelectric region(around pH 4.5). The EC decreased and the ES increased respectively with the increase of protein concentration.
3) The behavior of the ES and EC of the heated alkaline extract was similar to that of the supernatant obtained by precipitating proteins from the extract, and they showed maximum values in the isoelectric region. On the contrary, the EC and ES of the acid precipitated proteins exhibited minimum values in the same isoelectric region.
4) The fact that the emulsifying properties of the yeast proteins were superior to those ofsoybean proteins, and exhibited higher values in a slightly acidic to neutral pH range, seemed toexhibit possibilities as an excellent emulsifier in food processing.