516 10 Milk and Dairy Products
Table 10.22.Mineral composition of milk
Constituent mg/l Constituent μg/l
Potassium 1500 Zinc 4000
Calcium 1200 Aluminum 500
Sodium 500 Iron 400
Magnesium 120 Copper 120
Phosphate 3000 Molybdenum^60
Chloride 1000 Manganese^30
Sulfate 100 Nickel^25
Silicon 1500
Bromine 1000
Boron 200
Fluorine 150
Iodine 60Table 10.23.Vitamin content of milk
Vitamin mg/l Vitamin mg/lA (Retinol) 0. 4 Nicotinamide 1
D (Calciferol) 0.001 Pantothenic acid 3. 5
E (Tocopherol) 1. 0 C (Ascorbic acid) 20
B 1 (Thiamine) 0. 4 Biotin 0. 03
B 2 (Riboflavin) 1. 7 Folic acid 0. 05
B 6 (Pyridoxine) 0. 6
B 12 (Cyano-
cobalamine) 0. 00510.1.2.7 Enzymes
Milk contains a great number of enzymes which
are not only of analytical importance for the de-
tecton of heat-treated milk, but can also influence
the processing properties. The rate of heat inacti-
vation of the enzymes indicates the type and ex-
tent of heating (cf. 2.5.4).
Hydrolases identified include: amylases, lipases,
esterases, proteinases and phosphatases. Protein-
ase inhibitors have also been found. Important
oxidoreductases in milk are aldehyde dehydro-
genase (xanthine oxidase), lactoperoxidase and
catalase. A general idea of the occurrence and lo-
calization of enzymes in boving milk is given in
Table 10.24
10.1.2.7.1 Plasmin
The serine endopeptidase plasmin is of special in-
terest in milk technology.
Table 10.24.Enzymes in bovine milkEC Name Localizationa
Number1.1.1.27 L-Lactate dehydrogenase P
1.1.1.37 Malate dehydrogenase
1.1.3.22 Xanthine oxidase F
1.4.3.6 Amine oxidase
(copper-containing)
1.6.99.3 NADH dehydrogenase F
1.8 Sulfhydryl oxidaseb S
1.8.1.4 Dihydrolipoamide F
dehydrogenase
1.11.1.6 Catalase L
1.11.1.7 Lactoperoxidase S
1.15.1.1 Superoxide dismutase
2.3.2.2 γ-Glutamyltransferase F
2.4.1.22 Lactose synthase S
2.4.99.1 β-Galactoside-α-2,6-
sialytransfersase
2.6.1.1 Aspartate aminotransferase P
2.6.1.2 Alanine aminotransferase
2.7.1.26 Riboflavin kinase
2.7.1.30 Glycerol kinase
2.7.7.2 FMN adenyl transferase
2.8.1.1 Thiosulfate sulfurtransferase
3.1.1.1 Carboxylesterase S
3.1.1.2 Arylesterase
3.1.1.7 Acetylcholine esterase F
3.1.1.8 Choline esterase S
3.1.1.34 Lipoproteinlipase C
3.1.3.1 Alkaline phosphatase F
3.1.3.2 Acid phosphatase F
3.1.3.5 5′-Nucleotidase F
3.1.3.9 Glucose-6-phosphatase F
3.1.3.16 Phosphoprotein phosphatase P
3.1.4.1 Phosphodiesterase I F
3.1.27.5 Pancreatic ribonuclease S
3.2.1.1 α-Amylase S
3.2.1.2 β-Amylase
3.2.1.17 Lysozyme S
3.2.1.24 α-Mannosidase
3.2.1.31 β-Glucuronidase
3.2.1.52 β-N-Acetylglucosaminidase
3.4 Acid peptidases
3.4.21.7 Plasmin C
3.6.1.3 Adenosinetriphosphatase F
3.6.1.9 Nucleotide pyrophosphatase
4.1.2.13 Fructosebiphosphate
aldolase
5.3.1.9 Glucose-6-phosphate
isomerase
aC: casein micelle, F: fat-globule membrane, L: leuco-
cytes, P: plasma, S: serum.
bNot thiol oxidase EC 1.8.3.2.