Abstract: This study adopted an automatic amino acid analyzer to measure the amino acid composition of whey proteins in human milk, bovine milk and goat milk. The nutritional value was comprehensively evaluated by the fuzzy recognition method based on ratio coefficient of amino acid (RCAA) and score of ratio coefficient amino acid ratio coefficient score (SRCAA). The secondary structure of whey proteins was measured based on the amide I and amide III bands in Fourier transform infrared (FTIR) spectra. Results showed that the ratio of essential amino acids to total amino acids (EAA/TAA) in goat whey proteins was 0.450, showing a 0.919 7 and 0.925 0 similarity to whole egg protein and United Nations Food and Agriculture Organization/World Health Organization (FAO/WHO) reference protein, respectively, and the SRCAA values were 68.47 and 76.56, respectively in the two patterns indicating high nutritional value. The proportion of α-helix structure in goat whey proteins was 20.26%, which is much closer to that of human whey proteins (27.37%) indicating greater ease of absorption by the human body. Therefore, goat milk is a better source of functional foods for infants and young children.

Key words: amino acid, nutritional evaluation, whey protein, Fourier transform infrared (FTIR), secondary structure