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[Biological value of a yeast isolate]
Voprosy Pitaniia
|May 1, 1978
Summary
Food yeast protein isolate has low biological value due to amino acid imbalance, specifically low sulfur-containing amino acids and excess lysine. The separation method did not impact protein quality.
Area of Science:
- Nutritional biochemistry
- Food science
- Protein chemistry
Background:
- Food yeast is a potential protein source.
- Assessing protein quality is crucial for nutritional applications.
Purpose of the Study:
- To determine the biological value of protein isolated from food yeast.
- To evaluate the impact of protein isolation methods on its nutritional quality.
Main Methods:
- Chemical, enzymatic, and biological assays were used.
- Protein isolate was tested using growing male rats (initial mass 45 +/- 1.0 g) over 28 days.
- Protein content in balanced rations was 10% (excluding nucleic acids).
Main Results:
- Food yeast protein isolate showed a Protein Efficiency Ratio (PER) of 1.8, Biological Value (BV) of 49.1%, and Net Protein Utilization (NPU) of 40.3%.
- These values are lower than the control (casein: PER 2.1, BV 79.0%, NPU 60.2%).
- The isolate's biological value was 71% of casein, attributed to low sulfur-containing amino acids and excess lysine.
Conclusions:
- Food yeast protein isolate has a suboptimal anabolic effect due to amino acid profile limitations.
- The isolation process itself does not adversely affect the protein's biological value.
- Further supplementation or processing may be needed to enhance the nutritional profile of food yeast protein.