Effects of protein level and type of heat treatment of milk formulas on growth and maturation of infants

Four formulas designed to provide two levels of protein density and sterilized by two different methods (autoclaved and flash sterilized) were assigned to four groups of 27 infants for consumption from birth to 16 weeks of life. In the flash sterilized formulas, corn oil replaced butter fat. The weight gain and anthropometric performance were not significantly different among the various groups. The cholesterol levels in infants receiving formulas with butter fat (autoclaved) were higher than those receiving formulas with corn oil (flash sterilized). Blood urea nitrogen was higher in the infants consuming high-protein formulas. Infants receiving high-protein formulas consumed more calories. The caloric and protein efficiency ratios of low-protein formulas were significantly higher than those of the high-protein formulas, as were the ratios of the low-protein flash sterilized milks in comparison with the low-protein autoclaved ones. This latter difference could be evidence of protein injury resulting from autoclaving in the lower protein formulas.