Salt Equilibria and Protein Glycation in Young Child Formula

Young child formula (YCF) products are important sources of nutrients for children 1–3 years of age. Salt equilibria and protein glycation are two of the crucial aspects affecting nutritional properties and digestive behaviors of YCF, but detailed insights into these two aspects of YCF products remains limited. This study analyzed the distribution of salts and the level of protein glycation in 25 commercial YCF products from the retail market in China. The YCF products were reconstituted (12 g of powder per 100 g of water) and the distribution of calcium and phosphorus between the sedimentable (at 200× g), protein-associated and soluble (10 kDa-permeable) fractions were determined. Blocked lysine and 5-hydroxymethylfurfural were analyzed using reversed-phase high-performance liquid chromatography. Varying proportions of calcium (3.0–39.3%) and phosphorus (1.2–29.8%) were sedimentable for the products. Notable proportions of calcium (28.9–62.7%) and phosphorus (27.4–57.9%) were associated with the proteins. The remainder of the calcium (24.9–41.4%) and phosphorus (34.2–62.1%) were soluble. When expressing the protein-associated calcium as a function of casein, i.e., casein mineralization, large differences (~1.7 fold) were found among products. Variation in blocked lysine (7.4–19.2% of total lysine) and 5-hydroxymethylfurfural contents (3.0–7.0 mg/100 g protein) among products was also observed, suggesting notable differences in heat-load during processing. This study revealed notable variation in salt distribution and protein glycation among the YCF products. These findings underscore the critical need for manufacturers to optimize formulation and processing approaches, e.g., using milk with a low level of casein mineralization and using milk protein sources as concentrated liquid rather than powder to reduce protein glycation, to improve nutritional properties of the products.