Indexed on: 13 Dec '11Published on: 13 Dec '11Published in: Journal of the American Oil Chemists' Society
The aim of this study was to investigate soy protein recovery feasibility after lab- and pilot-plant scale oleosome isolation. The proteins were isolated by isoelectric precipitation and by ultrafiltration. The functional properties of the recovered proteins were compared to soy protein isolate produced in our laboratory. The residual lipid content in the aqueous supernatant affected the protein recovery yields and purities. Ethanol precipitation and ultrafiltration resulted in the best protein yields, which were 25 and 26% greater than protein yield obtained by isoelectric precipitation with distilled water dilution. The protein content of the isoelectric precipitated pilot-plant supernatant was higher (98%) than the protein content of ethanol-precipitated proteins (80%). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed similar peptide profiles for laboratory and pilot-plant supernatants. Protein solubility curves between pH 3 and 8 were typical for soy protein isolate with higher solubilities for proteins obtained from pilot-plant supernatant. The soy protein isolate and ethanol-precipitated protein had the highest emulsification capacity on a dry-weight basis. These desirable functional properties of proteins recovered as co-products after oleosome isolation suggest they are highly suitable for industrial application as food ingredients and their recovery would contribute to the economics of the overall oleosome fractionation process.