Bacteriological, biochemical, and immunological modifications in human colostrum after Holder pasteurisation.

OBJECTIVE: The objective of this work was to evaluate the effect of Holder pasteurisation of human colostrum on a variety of microbiological, biochemical, and immunological parameters.
METHODS: Colostrum samples from 10 donors, and 8 samples of mature milk used as controls, were heated at 62.5°C for 30 minutes. Bacterial counts and the concentration of furosine, lactose, myoinositol, glucose, lactulose, cytokines, and immunoglobulins were determined before and after the heat treatment.
RESULTS: Mean bacterial counts in nonpasteurised colostrum samples oscillated between 2.72 and 4.13 log10 colony-forming units per millilitre in the agar media tested. Holder pasteurisation led to the destruction of the bacteria originally present in the samples. Furosine was detected in all samples before pasteurisation and increased significantly after the heat treatment (from 6.60 to 20.59 mg/100 g protein). Lactulose content was below the detection limit in nonpasteurised colostrum, but it was detected in all samples and quantified in 7 of them (from 10.68 to 38.02 mg/L) after Holder pasteurisation. Lactose, glucose, and myoinositol concentrations did not change after Holder pasteurisation. The concentrations of most cytokines and immunoglobulins were significantly higher in colostrum than in mature milk samples. Immunoglobulin content, both in colostrum and in milk samples, was reduced during pasteurisation, whereas, among cytokines, only macrophage inflammatory protein-1β, interleukin-7, and granulocyte-macrophage-colony-stimulating factor concentrations were affected by this heat treatment.
CONCLUSIONS: Lactulose and furosine content could be used as heat treatment indicators in colostrum samples. Holder pasteurisation modified the immunological profile of both colostrum and mature milk.