Characterization of iron, copper and zinc levels in the colostrum of mothers of term and pre-term infants before and after pasteurization

Abstract

Pasteurization is a thermal treatment applied to the milk used in human milk banks so as to provoke the thermic inactivation of pathogenic micro-organisms, with the aim of avoiding contamination of milk that will be offered to new-born infants in clinical conditions very often demanding special care. The literature has very little data available relating to the effect of pasteurization on the concentration of oligo-elements in human milk. The objective of this study was to evaluate the effect of pasteurization on the concentrations of iron (Fe), copper (Cu) and zinc (Zn) in the colostrum of mothers of pre-term (PT) and term (T) infants. Samples were collected from the day of birth to the seventh day after birth. The oligo-elements were analyzed using the total reflection X-ray fluorescence technique with synchrotron radiation. The following results of Fe, Cu and Zn (means±SD) were obtained for the PT and T colostrum samples, non-pasteurized and pasteurized, respectively: PT: 1.96±0.73 mg/l Fe/1.71±0.70 mg/l Fe, 0.67±0.28 mg/l Cu/0.64±0.28 mg/l Cu, 5.55±2.71 mg/l Zn/5.39±2.73 mg/l Zn; T: 1.71±1.01 mg/l Fe/1.46±0.99 mg/l Fe, 0.54±0.29 mg/l Cu/0.49±0.19 mg/l Cu, 6.97±2.82 mg/l Zn/6.75±2.62 mg/l Zn. There was a significant reduction in the levels of Fe, Cu and Zn in the samples of pasteurized colostrum. These results suggest that, despite the observance of a diminution in the levels of Fe, Cu and Zn in the samples of pasteurized colostrum, the values fell within the acceptable range for the specific nutritional needs of new-born infants during this period of lactation.