Agriculture Reference
In-Depth Information
Table 14.3 Average concentrations of basic
nutrients, minerals, and vitamins in goat milk
(100 g) as compared with those in cow and
human milk.
tion. Some variations in composition can be related to
different production practices in the dairy goat industry
and diffi culty in procuring representative milk samples
from pooled bulk milk from various herds and farms
(Chandan et al., 1992 ).
On average, goat milk contains 12-13% total solids,
consisting of about 3.8% fat, 3.5% protein, 4.1% lactose,
and 0.8% minerals (Table 14.3). Goat milk contains
slightly less total casein, but more nonprotein nitrogen than
cow milk. Goat and cow milk have 3-4 times greater levels
of protein, and minerals, but much less lactose than human
milk. Total solids and caloric values of goat, cow, and
human milks are similar (Park, 2005). The lower casein
content of goat milk compared to cow milk is closely
related to slower coagulation properties and lower yield of
curds during cheese manufacturing. Compositional differ-
ences in milk are highly correlated with growth rates of
the young of the different species, where the newborn of
goats and cows grow much faster than human infants.
Constituents
Goat
Cow
Human
Basic nutrients
Fat (g)
3.8
3.6
4.0
Protein (g)
3.5
3.3
1.2
Lactose (g)
4.1
4.6
6.9
Minerals (ash) (g)
0.8
0.7
0.2
Total solids (g)
12.2
12.3
123
Calories (cal)
70
69
68
Minerals
Ca (mg)
134
122
33
P (mg)
141
119
43
Mg (mg)
16
12
4
K (mg)
181
152
55
Na (mg)
41
58
15
Cl (mg)
150
100
60
Lipids
The range of milk fat content in goat milk of different
breeds and within different seasons is 2.4-7.8%. Diameters
of fat globules in goat, cow, buffalo, and sheep milk
average 3.5, 4.6, 5.9, and 3.3
S (mg)
2.89
Fe (mg)
0.07
0.08
0.20
Cu (mg)
0.05
0.06
0.06
Mn (mg)
0.032
0.02
0.07
m, respectively (Park,
1990). The smaller fat globules of goat milk provide a
better dispersed and naturally homogenized milk fat and
better digestibility compared to milk with larger fat glob-
ules, because a greater relative surface area of fat globules
is exposed for digestive action by lipases (Jenness, 1980).
Goat milk fat has signifi cantly higher levels (+42% dif-
ference) of short- and medium-chain length fatty acids
(MCT; C4:0—C14:0) than cow and human milk (Table
14.4). This unique difference in MCT contents in goat milk
has been used for treatment of a variety of fat malabsorp-
tion syndromes in patients (Babayan, 1981). There is a
great potential to provide goat milk products with benefi -
cial properties for human nutrition and health. Goat milk
has a higher content of MCT and conjugated linoleic acid
(CLA) and lower levels of cholesterol than cow milk. Goat
milk fat contains about 98% of free lipids (about 97% are
triglycerides), and 1-3% bound lipids that are mainly in
the form of membrane lipids (phospholipids) associated
with fat globules (a remainder of the secretory cell mem-
branes), of which about 47% are neutral and 53% are polar
lipids (Cerbulis et al., 1985 ).
μ
Zn (mg)
0.56
0.53
0.38
I (mg)
0.022
0.021
0.007
Se (
μ
g)
1.33
0.96
1.52
Vitamins
Vitamin A (I.U.)
185
126
190
Vitamin D (I.U.)
2.3
2.0
1.4
Thiamine (mg)
0.068
0.045
0.017
Ribofl avin (mg)
0.21
0.16
0.02
Niacin (mg)
0.27
0.08
0.17
Pantothenic acid (mg)
0.31
0.32
0.20
Vitamin B 6 (mg)
0.046
0.042
0.011
Folic acid (
μ
g)
1.0
5.0
5.5
Biotin (
μ
g)
1.5
2.0
0.4
Vitamin B 12 (
μ
g)
0.065
0.357
0.03
Vitamin C (mg)
1.29
0.94
5.00
Data compiled from Posati and Orr (1976), Jenness
(1980), Haenlein and Caccese (1984), and Park and
Chukwu (1988) .
detailed chemical compositions of goat milk. As known
for cow milk, composition of goat milk also varies with
diet, breed, animals within breed, parity, environmental
conditions, udder health, feeding and management condi-
tions, season of year or kidding, locality, and stage of lacta-
Protein
Goat milk contains fi ve principle proteins:
α
s2 - casein (
α
s2 -
CN),
β
- casein (
β
- CN), K - casein ( K - CN),
β
- lactoglobulin
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