The wet process for producing infant formula milk powder requires multiple heating processes, which can cause some nutrient loss. Mixing uniformity is an important indicator for measuring the effectiveness of the mixing process, which is used to measure whether various nutrient indicators are evenly dispersed in infant formula milk powder. When designing infant formula milk powder, the loss rate and mixing uniformity of nutrients should be taken into account to ensure that the quality of products meets the requirements of the national food safety standards. This study analyzed nutrient loss rate and mixing uniformity in the wet processing of infant formula milk powder. The results showed that the nutrient that was most lost in the wet process was vitamins. Vitamin A (VA), vitamin B1 (VB1), vitamin B12 (VB12), and vitamin C (VC) were lost by 19.2%, 20.4%, 33.9%, and 20.3%, respectively, while the other vitamins were not significantly lost. Minerals were relatively stable in the wet process, and no significant loss of inositol, taurine or galactooligosaccharides was observed; the mixing uniformity of VB1 was less than 95%, while the mixing uniformity of the other nutrients was above 95%.

The composition and content of amino acids in infant formula sold in China were investigated in comparison with human milk at different lactation stages. An amino acid analyzer was used to detect the contents of free and hydrolyzed amino acids in commercial infant formula, and total amino acid content and the proportion of individual amino acids were calculated. The results showed that free amino acids were detected in some of the 12 samples, while hydrolyzed amino acids were detected in all these samples. The average concentration of most amino acids was close to that of human milk at 1 to 60 d of lactation, and higher than that of human milk at 61 to 180 d. The average ratio of essential to total amino acids was 46.43%, which was close to that of human milk. The proportions of methionine and tryptophan to total amino acids were higher than those of human milk, the proportions of arginine and cystine to total amino acids were lower than those of human milk, and the proportion of other amino acids to total amino acids was close to that of human milk. This study reveals the difference in amino acid content between commercial infant formula and human milk.

The composition and content of amino acids in infant formula sold in China were investigated in comparison with human milk at different lactation stages. An amino acid analyzer was used to detect the contents of free and hydrolyzed amino acids in commercial infant formula, and total amino acid content and the proportion of individual amino acids were calculated. The results showed that free amino acids were detected in some of the 12 samples, while hydrolyzed amino acids were detected in all these samples. The average concentration of most amino acids was close to that of human milk at 1 to 60 d of lactation, and higher than that of human milk at 61 to 180 d. The average ratio of essential to total amino acids was 46.43%, which was close to that of human milk. The proportions of methionine and tryptophan to total amino acids were higher than those of human milk, the proportions of arginine and cystine to total amino acids were lower than those of human milk, and the proportion of other amino acids to total amino acids was close to that of human milk. This study reveals the difference in amino acid content between commercial infant formula and human milk.