Protein Quality Determination of Delipidated Egg-yolk

The efficiency of nitrogen utilization of egg-yolk protein, which was produced by delipidation of henʹs egg yolk with ethanol, was evaluated in terms of protein efficiency ratio and nitrogen balance in rats. Enzymatic digestion with pepsin and pancreatin in vitro demonstrated that egg-yolk protein was digested faster than milk casein. Using the bioassays of protein efficiency ratio, biological value and net protein utilization, egg-yolk protein was compared with milk casein. Egg-yolk protein showed a protein efficiency ratio value of 3.64±0.17, which was significantly higher (P<0.05) than that of milk casein (3.20±0.11). The values of biological value and net protein utilization in the egg-yolk protein group were 92.1±1.9 and 91.1±1.8%, respectively. These values were significantly higher (P<0.05) than 85.7±2.3 and 81.6±3.1%, that were obtained in the milk casein group. The present findings suggest that there is no adverse effect of delipidation of yolk protein on nitrogen utilization, therefore, egg-yolk protein provides an excellent nutritional value.