ELECTROLYTE AND MINERAL COMPOSITION OF TERM DONOR HUMAN MILK BEFORE AND AFTER PASTEURIZATION AND OF RAW MILK OF PRETERM MOTHERS

ABSTRACT Objective: To determine and compare the concentrations of electrolytes and minerals in three different types of maternal milk samples: term donor milk before pasteurization, term donor milk after pasteurization and raw milk of mothers of preterm newborns at bedside. Methods: Descriptive cross-sectional study. Concentrations of calcium (Ca), phosphorous (P), magnesium (Mg), sodium (Na) and potassium (K) were measured in random samples of three human breast milk groups. Samples were analyzed using acid mineralization assisted by microwave radiation and further analysis by inductively coupled plasma optical emission spectrometry. Concentrations were expressed in mg/L, described as mean and standard deviation. The one-way ANOVA and Tukey’s post-test were applied to determine the variability between the means of each group. Significance level was set at 5%. Results: There was a significant reduction in the content of Ca (259.4±96.8 vs. 217.0±54.9; p=0.003), P (139.1±51.7 vs. 116.8±33.3; p=0.004) and K (580.8±177.1 vs. 470.9±109.4; p<0.0001) in donor maternal milk before and after pasteurization. Samples of raw milk presented higher contents of Na than the donated milk (twice). The elements P and Ca would only reach the daily intake levels recommended by the European Society of Pediatric Gastroenterology, Hepatology and Nutrition if at least 60 mL of milk could be offered every 3 hours. Mg levels were not different between the three groups. Conclusions: There was a significant reduction in Ca, P and K levels in samples after pasteurization. The Na value in raw milk, collected at bedside, was higher than in the samples of donor’s milk before pasteurization.

摘要
目的：测定并比较三类母乳样本的电解质与矿物质浓度，分别为巴氏灭菌前的足月捐赠母乳、巴氏灭菌后的足月捐赠母乳，以及床旁采集的早产新生儿生母的原乳。
方法：本研究为描述性横断面研究。对三组母乳的随机样本中的钙（Ca）、磷（P）、镁（Mg）、钠（Na）及钾（K）浓度进行检测。样本采用微波辅助酸消解处理，随后通过电感耦合等离子体光发射光谱法（inductively coupled plasma optical emission spectrometry）进行分析。浓度以mg/L为单位，以均值±标准差进行描述。采用单因素方差分析（one-way ANOVA）与Tukey事后检验（Tukey’s post-test）比较各组均值间的差异，检验水准设定为5%。
结果：巴氏灭菌前后的捐赠母乳中，钙（259.4±96.8 vs 217.0±54.9；p=0.003）、磷（139.1±51.7 vs 116.8±33.3；p=0.004）及钾（580.8±177.1 vs 470.9±109.4；p<0.0001）的含量均显著降低。早产新生儿生母的原乳样本钠含量为捐赠母乳的两倍。若每3小时喂哺该母乳至少60mL，其中的磷与钙含量才能达到欧洲儿科胃肠病学、肝病学与营养学会（European Society of Pediatric Gastroenterology, Hepatology and Nutrition）推荐的每日推荐摄入量。三组样本的镁（Mg）水平无显著差异。
结论：巴氏灭菌后的捐赠母乳样本中钙、磷及钾水平显著降低。床旁采集的原乳样本钠含量高于巴氏灭菌前的捐赠母乳样本。