Heating-induced Bacteriological and Biochemical Modifications in Human Donor Milk After Holder Pasteurisation
The objectives of the present study were to enumerate and characterize the pathogenic potential of the Bacillus population that may survive holder pasteurisation of human milk and to evaluate the nutritional damage of this treatment using the furosine and lactulose indexes.
Milk samples from 21 donors were heated at 62.5°C for 30 minutes. Bacterial counts, lactose, glucose, myoinositol, lactulose, and furosine were determined before and after the heat treatment. Some B cereus isolates that survived after pasteurisation were evaluated for toxigenic potential.
Nonpasteurised milk samples showed bacterial growth in most of the agar media tested. Bacterial survival after pasteurisation was observed in only 3 samples and, in these cases, the microorganisms isolated belonged to the species B cereus. Furosine could not be detected in any of the samples, whereas changes in lactose, glucose, and myoinositol concentrations after holder pasteurisation were not relevant. Lactulose was below the detection limit of the analytical method in nonpasteurised samples, whereas it was found at low levels in 62% of the samples after holder pasteurisation. The lactation period influenced myoinositol content because its concentration was significantly higher in transition milk than in mature or late lactation milk samples.
Holder pasteurisation led to the destruction of bacteria present initially in donor milk samples, except for some B cereus that did not display a high virulence potential and did not modify significantly the concentration of the compounds analyzed in the present study.
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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.
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.
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.
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.
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ABSTRACT: Donor human milk has emerged as the preferred substrate to feed extremely preterm infants, when mother's own milk is unavailable. This article summarizes the clinical data demonstrating the safety, efficacy, and cost-effectiveness of feeding donor human milk to premature babies. It describes the current state of milk banking in North America, as well as other parts of the world, and the differing criteria for donor selection, current pasteurization techniques, and quality control measures. A risk assessment methodology is proposed, which would allow milk banks globally to assess the safety of their process and respond appropriately to differing risk environments.
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