Human milk properties

But we must appreciate how the phosphate group acts much like the anion from a weak acid (see Chapter 6), so its exact composition will depend on the pH of solution. The pH of cow s or human milk is about 7 (see Table 6.4). If the pH decreases much below about 6 (e.g. by adding an acid in the form of orange juice), the phosphates become protonated. The emulsifying properties of casein cease as soon as its structure changes, causing the milk to separate. 

The IL-1 receptor antagonist (IL-lra) is present in human milk. IL-lra limits inflammation by competing with IL-1 (pro-inflammatory cytokine) for receptor binding (Dinarello, 1995). The reduced inflammatory response in rats with colitis fed human milk compared to chow or formula was similar to the inflammatory response in rats fed infant formula supplemented with IL-lra (Grazioso et al., 1997). These results suggest that the IL-lra content of human milk contributes to its anti-inflammatory properties. 

Goldman, A. S. (1993). The immune system of human milk Antimicrobial, antiinflainmatory and immunomodulating properties. Pediatr. Infect. Dis. ]. 12, 664-671. 

Kunz, C., Rodriguez-Palmero, M., Koletzko, B., and Jensen, R. (1999). Nutritional and biochemical properties of human milk. Part I General aspects, proteins, and carbohydrates. Clin. Perinatol. 26, 307-333. 

Cousins, R. J. and Smith, K. J. 1980. Zinc-binding properties of bovine and human milk in vitro Influence of changes in zinc content. Am. J. Clin. Nutr. 33, 1083-1087. 

While bovine milk is a rich source of xanthine oxidase, milks from some species do not necessarily contain appreciable amounts of enzymatically active xanthine oxidase. For example, human milk contains only traces of xanthine oxidase activity as measured by oxidation of xanthine or hypoxanthine (Zikakis and Treece 1971 Zikakis et aL 1976), yet a band corresponding in electrophoretic mobility to xanthine oxidase is a major constituent of human milk lipid globule membrane (Freudenstein et al. 1979 Murray et cd. 1979). Evidence that the membrane-bound form of xanthine oxidase in bovine lipid globule membrane contains small amounts of tightly bound fatty acid has been obtained (Keenan et al. 1982). Whether this property promotes attraction between the membrane or membrane-associated coat and the surface of the globule core remains to be determined. 

Milk proteins are subdivided into random coiled caseins, which can be precipitated by acidification of raw skim milk to pH 4.6 at 20°C, and into more globular whey proteins, which remain in the serum after precipitation of the caseins (42). In Table 8, an overview is given of the molecular structure and basic properties of the major protein fractions present in milk. Some specific properties that might be of importance for their determination in foods and food products are also listed. For the young of mammals, including humans, milk is the first and, for most, the only food ingested for a considerable period of time. With the domestication of animals, it became possible to include milk in the diet of adult humans as well. For much of the world, particularly in the West, milk from cattle (Bos taurus) accounts for nearly all the milk processed for human consumption (43). 

Michalski, M.-C. and Januel, C. 2006. Does homogenization affect the human health properties of cow s milk Trend Food Sci Technol 17 423 -37. 

Milk composition is not constant and is influenced by the timing of feeding and duration of nursing postpartum. Human milk contains about 2-3% fat and a large number of proteins. The pH of milk tends to be lower than that of plasma. Most water-soluble substances are excreted into the milk by simple diffusion, and lipid-soluble compounds are transported along with lipid molecules from plasma into the mammary gland. The amount of a certain substance transferred to the milk depends on the physicochemical properties of the... 

Lysozyme (LZM) is a potent antibacterial enzyme acting against a range of bacteria, especially Gram-positive, but due to its low concentration in bovine milk (in contrast to human milk), LZM may not contribute significantly to the overall antimicrobial properties of cow s milk and colostrum. However, LZM is known to add to the antimicrobial activity of LF and specific antibodies (Reiter, 1985 IDF, 1991 Shah, 2000). 

G. Harzer, J. G. Bindels, Changes in human milk immunoglobulin A and lactoferrin during early lactation, in J. Schaub (ed.), Composition and Physiological Properties of Human Milk, Elsevier Science, Amsterdam, 1985, pp. 285-295. 

Garza, C., Schanler, R.J., Butte, N.F., Motil, K.J. 1987. Special properties of human milk. Clin. Pathol. 14, 11-32. 

Guinea pigs milk contains a high level of LPL (20-50-fold that of cows milk), with more than 90% in the skim (Hamosh and Scow, 1971). Guinea pig LPL has been purified and found to be very similar in molecular structure and properties to the LPLs of cows and human milks (Wallinder et al., 1982 Bengtsson-Olivecrona et al., 1986). 

The recombinant whole molecules are both expressed in glycosylated form, although the glycosylation patterns differ from the proteins isolated from natural sources. The recombinant human transferrin binds to receptors both in its glycosylated form and as a nonglycosylated mutant, showing that the carbohydrate is not required for receptor binding (230). Recombinant human lactoferrin shows identical spectroscopic properties and shows an identical profile of pH-dependent iron release when compared with human milk lactoferrin (231). 

It has been reported that the early Romans used egg white in the treatment of eye infections, and some mothers are reputed to have used human milk for the same purpose both media contain appreciable amounts of lysozyme. Later, andbacterial properties of leukocytes (Met-schnikoff, 1883), cow milk (Fokker, 1890), Boa ws swifoVd (Nicolle, 1907), domestic hen egg-white (Laschtschenko, 1909), and nasal secretions (Bloomfield, 1919, 1920) were described from 1880 to 1920. It has been stated (e.g., Fleming and Allison, 1922) that none of the workers prior to 1920 considered bacteriolysis in their publicadons. Nevertheless, Nicolle (1907) does discuss faction bactiriolysente in his paper. While Laschtschenko (1909) does not consider bacteriolysis, he does attribute the spore-destroying properties of egg white to proteolytic enzymes. ... 

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