Detection of glycomacropeptide content in breast milk and comparison with varieties of newborn infant formula / 中华实用儿科临床杂志

ABSTRACT

Objective To detect the glycomacropeptide (GMP) content of human breast milk,and take it as reference of newborn infant formula milk powder to optimize the nutritional content of infant formulas.Methods Thirty primiparas who fit the following conditions were selectedhealthy,no special diet habits,living stably,having adequate milk,aged between 25 to 39 years old,and term delivery,were selected.Then they were divided into 2 groups,the colostrum group and mature milk group,and each group had 15 cases.Each case had been collected of breast milk 5 mL(front milk).The gathering time of colostrum group was the 2nd day postpartum and mature milk group was the 42nd day postpartum.Hydrolyzing the breast milk by chymosin at 37 ℃,then the sialic acid(SA) content was detected by a sialic acid detection kit,and GMP content was represented by SA content.In addition,6 brands of formula milk powder were detected in the same way as breast milk after being made into standard liquid milk.The differences between groups were compared by analysis of variance (ANOVA).Results Best conditions for enzymolysis werechymosin concentration 0.25 g/L,hydrolysis time 120 min.SA content of colostrum group was (3486.98 ± 406.70) mg/L,while mature milk group was (2687.95 ± 375.85) mg/L,as the former was significantly higher than the latter (P ＜ 0.01),but the differences between individuals within each group were small (CVco1 =0.12,CVma ilk =0.14).The average level of SA content of various infant formulas was (1196.93 ± 608.40)mg/L,which was significantly lower than colostrum and mature milk(all P ＜ 0.01).SA contents of various brands of formulas were various,and the difference among these brands was relatively big(CV =0.63).Conclusions The content of GMP in human colostrum was higher than that of the mature milk.The contents of the GMP in different brands of infant formula milk powder were uneven,and the measured values were quite different with human milk.However,because of the difference of the molecular weight of GMP and the number of amino acid residues between human milk and bovine milk,the amount of GMP required to achieve the same physiological effects may be different in breast milk and bovine milk.In order to optimize the nutritional content of infant formula,and make it even closer to human milk,it is necessary to further explore the best GMP content relative to human milk.