Handbook of Food Science and Technology 3

1.1.4.
 Milk minerals 
Although the mineral fraction of milk is relatively small, it is very 
important from a structural, nutritional and technological point of view. 
Calcium phosphate nanoclusters, associated with casein phosphoserins 
α
S1
, 
α
S2
and 
β
, contribute to the structure and stability of casein micelles (see 
section 1.1.3.2). The solubilization of colloidal calcium phosphate in the 
presence of a calcium complexing agent such as EDTA (
ethylene diamine 
tetra-acteic acid) results in disintegration of the micelle. Milk and milk 
derivatives are the main supply of calcium and phosphorus in the diet. In 
cheese-making, the rheological properties of cheese strongly depend on the 
retention of these elements in the curd. Table
 
1.6
 
shows the average 
concentrations of the main minerals in cow’s milk. 
Minerals 
Concentration (mg kg
-1
) 
Concentration (mmol kg
-1
) 
Calcium 
1,043–1,283 
26–32 
Magnesium 
97–146 
4–6 
Inorganic phosphate
1,805–2,185 
19–23 
– (total phosphorus) 
930–992 
30–32 
Citrate 
1,323–2,079 
7–11 
Sodium 
391–644 
17–28 
Potassium 
1,212–1,681 
31–43 
Chloride 
772–1,207 
22–34 
Table 1.6.
 
Mineral composition of cow’s milk (according to [GAU 05])
 

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16 Handbook of Food Science and Technology 3 
Milk also contains many trace elements. The concentration of mineral 
elements is not influenced by diet, even though differences are observed for 
citrate. However, there are more variations during lactation or with 
pathological conditions (mastitis). 
Mineral elements are distributed differently between the soluble phase and 
the colloidal phase, depending on their respective affinities for proteins and 
organic solutes. Monovalent ions (sodium, chloride, potassium) are found 
exclusively in the soluble phase of milk, while divalent or polyvalent ions are 
distributed between both phases. The mineral balance between the colloidal 
phase and the soluble phase is rather complex, since many different types of 
minerals are involved. Figure 1.4
 
shows the main mineral balances of milk.
Figure 1.4.
 Main mineral balances of milk (salt concentrations
shown are for milk under physiological conditions) 
Calcium phosphate is poorly soluble and is saturated in the soluble phase 
of milk (0.59 mM) over a wide pH range. In milk at pH 6.7, the natural 
content of calcium phosphate is far greater than its solubility limit. Micelles 
increase the solubility of calcium phosphate by the integration of calcium 
phosphate nanoclusters with a core-shell structure: calcium phosphate clusters 
stabilized by the phosphorylated caseins 
α
S1
, 
α
S2
and 
β
. In addition, a fraction 
of calcium is directly linked to casein phosphoserines. Under physiological 
conditions, approximately two-thirds of calcium and half of the inorganic 
phosphate are associated with micelles and are in equilibrium with the serum 
phase. Any physicochemical change in milk will affect the concentration of 
minerals in the soluble phase of milk, causing a shift in the mineral balance 
and an alteration in the structure and stability of micelles (see section 1.2.2).
(Citr Ca)
-
Ca
2+