Milk, trace elements

Byrne AR, Camara-Rica C, Cornelis R, de Gobi JJM, Iyengar GV, Kirkbright G, Knapp G, Parr RM, and Stoeppler M (1987) Results of a co-ordinated programme to improve the certification of IAEA milk powder A-ii and animal muscle H-4 for eleven difficulf trace elements. Fresenius Z Anal Chem 326 723-729. 

De Goeij JJM, Kosta L, Byrne AR, and Kucera J 1983) Problems in current procedures for establishing recommended values of trace-element levels in biological reference materials, illustrated by IAEA Milk Powder A-ii. Anal Chim Acta 146 161-169. 

For example trace elements in milk powder are not consumed as milk, and moisture in transformer oil is not used in transformers, yet matrix reference materials based on milk are imported as food and are subject to health certification requirements and sometimes import quotas. Likewise a matrix based on oil is identified as fuel or lubricating oil and is both classified as a hazardous material and subject to mineral oil tax. These problems arise because RMs are frequently incorrectly classified by specific title of their matrix (as Reference Material of Trace Elements in Rice is classified as rice) and not as reference material which is the intended use. 

Standard solutions, a solution of nickel in acid with a quoted mass/volume concentration, a solution of sodium hydroxide with a quoted concentration as a molarity and a solution of pesticides with quoted mass/volume concentrations. Matrix RMs - natural materials, river sediment with quoted concentrations of metals, milk powder with a quoted fat content and crab paste with quoted concentrations of trace elements. 

Matrix RMs - spiked materials, lake water fortified with trace elements and milk powder spiked with organic contaminants. 

Zinc is an important trace element required for all healthy plants and animals. Zinc is found in proteins, such as meats, fish, eggs, and milk. About 10 to 15 miUigrams of zinc is required per day, and it may be taken as a dietary supplement. Zinc helps the blood in our bodies move the waste gas—carbon dioxide—to the lungs and helps prevent macular degeneration (loss of vision). 

Ustundag, B., Yilmaz, E., Dogan, Y., Akarsu, S., Canatan, H., Halifeoglu, L, Cikim, G., and Aygun, A. D. (2005). Levels of cytokines (IL-lbeta, IL-2, IL-6, IL-8, TNF-alpha) and trace elements (Zn, Cu) in breast milk from mothers of preterm and term infants. Mediators Inflamm. 2005,331-336. 

Report of Joint World Health Organization/International Atomic Energy Agency (WHO/ IAEA), Collaborative Study, Minor and Trace Elements in Breast Milk, World Health Organization, Geneva, 1989. 

Apart from the analysis of blood serum and urine, there are different applications of trace element analysis by ICP-MS, for instance on milk samples.24-28... 

Folate is a relatively unstable nutrient processing and storage conditions that promote oxidation are of particular concern since some of the forms of folate found in foods are easily oxidized. The reduced forms of folate (dihydro- and tetrahydrofolate) are oxidized to p-aminobenzoylglutamic acid and pterin-6-carboxylic acid, with a concomitant loss in vitamin activity. 5-Methyl-H4 folate can also be oxidized. Antioxidants (particularly ascorbic acid in the context of milk) can protect folate against destruction. The rate of the oxidative degradation of folate in foods depends on the derivative present and the food itself, particularly its pH, buffering capacity and concentration of catalytic trace elements and antioxidants. 

In 1935, the Committee was renamed the Analytical Methods Committee (AMC) but the main analytical work was carried out by sub-committees composed of analysts with specialised knowledge of the particular application area. The earliest topics selected for study were milk products, essential oils, soap and the determination of metals in food colourants. Later applications included the determination of fluorine, crude fibre, total solids in tomato products, trade effluents and trace elements, and vitamins in animal feeding stuffs. These later topics led to the publication of standard methods in a separate booklet. All standard and recommended methods were collated and published in a volume entitled Bibliography of Standard, Tentative and Recommended or Recognised Methods of Analysis in 1951. This bibliography was expanded to include full details of the method under the title Official, Standardised and Recommended Methods of Analysis in 1976 with a second edition in 1983 and a third edition in 1994. 

For the purpose of this discussion, milk salts are considered as ionized or ionizable substances of molecular weight 300 or less. Ionizable groups of proteins are not included here, although, of course, they must be taken into account in a complete description of ionic balance and equilibria. Trace elements, some of which are ionized or partially so in milk, are considered in a later section of this chapter. Milk salts include both inorganic and organic substances thus they are not equivalent to either minerals or ash. The principal cations are Na, K, Ca, and Mg, and the anionic constituents are phosphate, citrate, chloride, carbonate, and sulfate. Small amounts of amino cations and organic acid anions are also present. 

In addition to the major salt constituents discussed up to this point, the elements listed in Table 1.3 have been detected in normal bovine milk by spectroscopic and chemical analyses. They include a large number of metals, the metalloids As, B, and Si, and the halogens F, Br, and I. The subject of trace elements in milk has been reviewed comprehensively (Archibald 1958 Murthy 1974 Underwood 1977). Their significance for human nutrition is discussed in Chapter 7. 

Reported concentrations of the trace elements exhibit large ranges. For some of them (e.g., I, Mo, Zn), the concentration in the milk depends markedly on that in the diet consumed by the cow. The concentrations of some of them are increased by contamination by utensils... 

The distribution of trace elements among the compounds and physical phases in milk has not been elucidated completely. Molybdenum appears to be found exclusively in xanthine oxidase and Co in vitamin B12. Iron is an essential component of xanthine oxidase, lactoperoxi-dase, and catalase. About half of the total Fe and 10% of the Cu are in the fat globule membrane. Copper has been studied extensively in relation to oxidation of milk lipids. The trace metal present in highest con-... 

Murthy, G. K. 1974. Trace elements in milk. CRC Crit. Rev. Environmental Control 4, 1-37. 

Although new analytical techniques with greater sensitivity have been employed to determine the levels of trace elements in dairy foods, the values obtained must be considered approximate. The trace element content of milk and other dairy foods can vary as a result of the stage of lactation, season, milk yield, amount of trace element in the... 

Trace elements. g per gram MSNP Hg per 100 g Fluid whole milk... 

The metal ions of major biological significance are indicated in Figure 1, which shows part of the Periodic Table. Some information on the distribution and concentration levels of these metals in living systems is shown in Table 1. The transition metals and zinc are usually regarded as trace elements, as they are present in very small amounts. Of the transition elements, iron is the most abundant metal, and probably the most well studied. Iron is essential for all living systems with the exception of certain members of the lactic acid bacteria, which grow in environments notoriously low in iron, such as milk. Lactic acid bacteria are devoid of cytochromes, peroxidases... 

Nonbacterial milk components and components produced from milk fermentation may also contribute to the immunostimulatory activity of yogurt. Peptides and free fatty acids generated by fermentation have been shown to enhance the immune response. Milk components such as whey protein, calcium, and certain vitamin and trace elements also can influence the immune system. 

Cobalt is used in the manufacture of alloys and in nuclear technology. Cobalt compounds are also included in trace element supplement preparations for ruminants. The cobalt concentrations in vegetables and other foods have been found to be between < 0.01 and 0.83 mg/kg, while levels in milk are between 0.0002 and 0.06 mg/kg.40 Cobalt concentrations in dietary supplements ranged between <0.005 mg/kg to 4.1 mg/kg.26 The mean and 97.5th percentile dietary exposures to cobalt for adult consumers in 1994 were 0.11 mg/day and 0.019 mg/day respectively.10... 

Scholz-Ahrens, K.E. and Schrezenmeir, J. 2000. Effects of bioactive substances in milk on mineral and trace element metabolism with special reference to casein phosphopeptides. Brit. J. Nutr. 84(suppl. 1), 147-153. 

A method to prepare milk powder, bovine liver, and bovine muscle samples for analysis by ET-AAS was proposed by Martins et al. [9]. Samples were mixed with a small amount of TMAH and a stable and homogeneous slurry was produced in ca 2h with heating at 60D70G. After such sample preparation and dilution with water, trace elements (Ag, Cd, Cr, Cu, Ni, and Pb) were determined in CRMs. External calibration was used for every analyte. 

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