OBJETIVE: The objective of the present work was to evaluate the centesimal composition, the amino acid profile and the the composition and nutritive value of three casein concentrates, obtained by different methods. METHODS: The casein concentrates were analysed according to the following methods: a commercial casein obtained by acid precipitation (pI) followed by neutralization; an enzyme coagulated casein obtained by rennet coagulation; and a casein micelles concentrate obtained by microlfiltration and diafiltration. The Centesimal composition was determined by the procedures described in the manual Official Methods of Analysis. The amino acid profiles were determined after the protein acid hydrolysis (HCl 6N, 105°C, 22h) in an amino acid autoanalyzer by cation exchange chromatography and post-column ninhydrin reaction. The essential amino acids were in accordance with Food and Agriculture Organization/World Health Organization recommendation for children 2 to 5 years of age. The nutritive value was determined on 21-day old rats of the Wistar strain through apparent net protein ratio, and protein efficiency ratio operational. RESULTS: Commercial casein presented higher protein concentration (92.0%) than micellar casein (86.0%) and casein clot (72.0%). The animals in the various protein diets did not show significant differences as to body weight gain and diet consumption. The highest digestibility was that of commercial casein (93.8%), compared to the other two concentrates (91.0%). CONCLUSION: The casein concentrates showed differences related to the centesimal composition, since the commercial casein presented a higher protein concentration. The casein clot was inferior to the other protein concentrates regarding net protein ratio and protein efficiency ratio operational.
coagulated casein; milk; casein micelles; nutritive value
