Abstract
Summary
The proteins of whole egg, whole egg white, and yolk, were prepared and analyzed for cystine, methionine, phenylalanine, tryptophane, threonine, arginine, histidine, lysine, sulfur, and nitrogen. These proteins were incorporated into diets at a 10% level and fed to young rats. The protein efficiency ratio (gain in weight per gram of protein ingested) was determined after a 2-week feeding period. Commercial preparations of wmole egg and whole white protein were similarly analyzed and their PE ratio determined. The PE ratio of the whole white protein was higher than that of either the whole egg or the yolk proteins. The PE ratio of the commercial whole white protein was almost as high as that of the laboratory prepared sample. The PE ratio of commercial whole egg protein was markedly lower than that of the laboratory prepared sample. The amino acid content of all the whole egg proteins wTere quite similar with the exception of the cystine content of the commercial samples which was lower than that of the laboratory samples. When the commercial whole egg protein II was reenforced with 0.25% cystine the PE ratio was not improved. Other factors in addition to the amino acid content apparently play a role in the biological value of proteins.
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