Question

Given the following values for amino acid content of the proteins of egg and navy beans calculate the chemical score. Percentage composition of protein of:

Amino Acid Egg (%) Navy Beans (%) Lysine (EAA) 10 7 Methionine (EAA) 8 3.7 Tryptophan (EAA) 2 1.6 Isoleucine (EAA) 9 6 Alanine (NEAA) 10 1.9 *(EAA) designates an essential amino acid or combination **(NEAA) designates a non-essential amino acid
Calculate the chemical score of this protein compared to the egg protein.

Answer 1

The chemical score of navy beans protein compared to egg protein is 46.25%, determined by the lowest ratio of essential amino acid content in navy beans to that in egg protein, which is methionine with a ratio of 0.4625.

Step-by-step explanation:

The chemical score of a protein is calculated by comparing the content of essential amino acids in the test food protein with those in a reference protein, typically egg protein. To compute this score, we look at each essential amino acid individually. We divide the percentage of that amino acid in the test food by the percentage in the reference protein, and the lowest resulting value is the chemical score for the protein.

For navy beans compared to egg protein, the essential amino acid with the lowest ratio will determine the score:

• Lysine: 7% / 10% = 0.70
• Methionine: 3.7% / 8% = 0.4625
• Tryptophan: 1.6% / 2% = 0.80
• Isoleucine: 6% / 9% = 0.6667

The lowest value here is for methionine, which is 0.4625 or 46.25%. Thus, the chemical score of navy beans protein compared to egg protein is 46.25%.