Milk provides the newborn (neonate) with nutrients and an array of antimicrobial factors.  These are believed to help protect neonates from infection until their own immune system has developed.This section of the dairy science website reviews the properties and potential nutritional and industrial significance of the major antimicrobial systems of milk, with particular reference to the lactoperoxidase system.

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The LP system can be used to prevent bacterial deterioration of milk when refrigeration is not available.  It can also be used to prolong the safe storage life of refrigerated milk.  Arguably the LP-system, immunoglobulins and lactoferrin have potential to be of value in neonate nutrition.  The remaining section largely concerns the exploitation of the LP-system in the protection of neonates.

Manufacture of milk powders containing a functional LP system

That milk provides neonates with nutrients and  various protective antimicrobial factors has been discussed previously.  Because many of these factors are denatured by the heat treatments used in milk replacer manufacture commercial products, unless specially produced, generally do not contain antimicrobial proteins in active form.

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Peroxidases catalyse reactions in which hydrogen peroxide is reduced and a suitable electron donor is subsequently oxidised.  A wide variety of organic and inorganic substances can serve as electron donors, but substrate specificity varies between various peroxidases.

Most assays are based on the principle that the electron donor in oxidised form absorbs light and can be determined by a spectrophotometric assay.

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Details

Written by Emily Haque and Rattan Chand

Milk is an excellent source of well balanced nutrients and also exhibits a range of biological activities that influence digestion, metabolic responses to absorbed nutrients, growth and development of specific organs, and resistance to disease. These biological activities are mainly due to the peptides and proteins in milk. However, some of the biological activity of milk protein components is latent, and is released only upon proteolytic action. Bioactive peptides are produced during digestion of milk in the gastrointestinal tract, and also during fermentation and food processing.

Bioactive peptides have been defined as specific protein fragments that have a positive impact on body functions or conditions and may ultimately influence health. Upon oral administration, bioactive peptides, may affect the major body systems—namely, the cardiovascular, digestive, immune and nervous systems. The beneficial health effects may be classified as antimicrobial, antioxidative, antithrombotic, antihypertensive, antimicrobial or immunomodulatory (FitzGerald and Meisel, 2003; Korhonen and Pihlanto, 2003a).

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