The collection and storage of human milk : report / of a Working Party on Human Milk Banks, Panel on Child Nutrition, Committee on Medical Aspects of Food Policy.

  • Great Britain. Working Party on Human Milk Banks.
Date:
1981
Catalogue details

Licence: Open Government Licence

Credit: The collection and storage of human milk : report / of a Working Party on Human Milk Banks, Panel on Child Nutrition, Committee on Medical Aspects of Food Policy. Source: Wellcome Collection.

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    3.5 Microbiological safety in relation to the preservation of protective anti-microbial factors in human milk 3.5.1 The aim of heat treatment of human milk is to make it bacteriological- ly ‘safe’, that is to say, not harmful to the infant, without at the same time causing undue destruction of protective anti-microbial factors and of nutrients. 3.5.2 For any bacterial species, there is a linear relationship between the logarithm of the number of surviving organisms at a given temperature and the length of time for which the organisms were exposed. Because the rate of thermal destruction is exponential, the point at which all the organisms in the milk are destroyed is, in theory, never reached. The time required to reduce the microbial count to a satisfactorily low figure will depend on the temperature and the number of organisms initially present in the milk. 3.5.3 A similar linear relationship between surviving activity and time at a given temperature exists for the heat inactivation of the many anti-microbial factors in milk. The rate of destruction of these factors, however, differs from that of most bacteria. Baum (1979c) has shown that, for milk IgA, the rate of destruction of the immunoglobulin is slower than that of most micro- organisms. Thus when almost all micro-organisms have been destroyed, there is still an appreciable amount of IgA left. Rates of destruction vary between the different anti-microbial factors, as they do between different micro- organisms, but present evidence indicates that Holder pasteurization, in which milk is subjected to a temperature of 62.5°C for 30 minutes, results in adequate bacteriological safety without undue destruction of anti-microbial factors. Holder pasteurization conditions were, however, defined for the commercial treatment of cows’ milk, and further investigation might show that for the processing of human milk for milk banks a different combination of time and temperature would be more appropriate. It