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Life Science Journal 2014;11(1s) http://www.lifesciencesite.com
307
Physicochemical Characteristics of Goat’s Milk
Hayam M. Abbas, Fatma A.M. Hassan, Mona A.M. Abd El-Gawad and A. K. Enab
Dairy Department – National Research Center, Dokki, Giza, Egypt
Prof.hayamabbas@yahoo.com
Abstract: As goat’s milk has many therapeutic properties and nutritive value, various investigators studied its
chemical composition and physical characteristics; where these compositional changes, may alter the processing
quality of goat’s milk. So, this study aware with some physiochemical properties of goats milk as a functional diet
for human health.
[Hayam M. Abbas, Fatma A.M. Hassan, Mona A.M. Abd El-Gawad and A. K. Enab. Physicochemical
Characteristics of Goat’s Milk. Life Sci J 2014; 11(1s):307-317]. (ISSN: 1097-8135).
http://www.lifesciencesite.com. 56
Keyword: Goat’s milk, Milk lipids, Milk proteins, Physicochemical Characteristics.
Introduction
Since ancient times, goat animal has been
exploited for its milk. The production of goats milk
(caprine) is major importance in several countries
where climatic conditions are not favorable for cattle
keeping (Juarez and Ramos, 1984). In 1981, world
goat’s milk production was 7236 tons contributed
only 1.6% to all world milk production and ranked
the fourth after cows (91.2%), buffaloes (5.6%) and
ewes (1.9%) milk (Le-Jaouen 1981). However, world
production of goat’s milk reached in 1994 approx. 8
million tons/year (Dostalova, 1994). In 1997, Le-
Pape et al., stated that consumption of goats milk and
goats cheese was increasing most rapidly in Northern
European countries, thus was attributed to consumer
mistrust of cow like products after the BSE scare. In
Egypt, the total population of goat animals is approx.
3198000 produced about 13000 tons of milk,
(Egyptian Central Organization 1996),however a
growing interest with respect to production and
utilization of goats milk is recently observed.
Dairy product goat and sheep farming are a vital
part of the national economy in many countries,
especially in the Mediterranean and Middle East
region and are particularly well organized in France,
Italy, Spain and Greece (Chiafalo et al., 2004)
presently, India possesses 126 million goats which
contribute 14.5% of the world (FAO, 2009).
Goats milk, as all other milks, contains various
nutrients either as major components or as macro and
micro components. It’s considered as an ancient
product for the diet of today. Jenness (1980) recorded
that goats milk is approx. isocaloric as cows and
buffalo’s milk each furnishes about 750 Kcal/l.
In 1981, Le-Jaouen reported that goat’s milk has
similar vitamins contents of human milk except lower
content of folic acid, Vit. C and Inositol. He added
that goats butter is reputed to been effective remedy
against disease such as rheumatism and arthritis.
Goat’s milk contains vitamins, minerals, trace
elements, electrolytes, enzymes, proteins, and fatty
acids that are easily assimilated by the body. Goat’s
milk has a similarity to human milk that is unmatched
in cow milk and also has several medicinal values.
Therefore awareness about advantage of consumption
of goats milk should be popularized so that
production and utilization of goat’s milk could be
enhanced (Kumar et al., 2012).
Goats milk shows therapeutic virtues for
individuals with certain dietetic problems, thus
physicians have traditionally recommended goats
milk for infant and others allergic to cow milk.
Similarly it has been used in treatment of ulcers
(Mereado, 1982, Kumar et al., 2012).
Superiority of goats milk is due to better fat and
protein digestibility and assimilation; to its
significantly higher minerals & vitamins composition
and to incidence of allergy is lower (Bielak 1993; and
Dostalova, 1994, Belewu et al., 2002).
As goat’s milk has these therapeutic properties
and nutritive value, many investigators studied its
chemical composition and physical characteristics
where these compositional changes, may alter the
processing quality of goats milk.
Some Factors affecting the composition of goat’s
milk Composition of goat’s milk widely differs
according to many various factors. The three main
effective factors are breeds (indigenous or selected
breeds), stage of lactation, feeding or rations
components.
a) Breed influence
Origin and type of bread markedly affected milk
yield and composition. It is necessary to
distinguished between two types of goats milk, the
first (which is the more common) is produced from
indigenous breeds which have a low average milk
yield but have a high total solid. The second type is
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308
produced by highly selected breeds with high yield
but with a lower total solid (Atinsoyinu et al., 1977,
El Zayat et al.,1984, Kalantzopoulos 1993). The
mean gross composition of goats milk produced from
different breeds in different countries was
summarized in Table (1).
Helmut and Fiechter (2012) studied the
chemical composition and physical properties of
goat's milk species in Austria. Thus, milk samples of
six dairy goat breeds in Austria (Bunte Deutsche
Edelziege, Pinzganer Ziege, Saanenziege,
Strahlenziege, Toggenburger Ziege, WeiBe Deutsche
Edelziege) were analysed for physicochemical
characteristics for 8 months from March to October.
Considerable seasonal variations, but nearly no
statistically significant differences between milk
samples from these six goat breeds were observed
regarding most parameters.
b) Stage of lactation
Stage of goat lactation is markedly affected the
resultant milk either yield or composition. Csapo-
Janos et al. (1984) reported that TS, casein and NPN
contents are gradually increased throughout lactation
period while TP and WP fluctuated and then
increased sharply at the end of lactation period.
However, in (1985), Garefa et al. showed that fat
content decreased during milking period from 5.96 to
4.76% and protein increased from 3.30 to 3.75%.
Brown et al., (1995) stated that relative amount of
αs2-CN decreased with stage of lactation, also relative
amount of K-CN increased by 50% after peak
lactation and its concentration. Almost doubled near
the end of lactation. Kracmar et al. (1998) studied
the change in amino acids composition of goat’s milk
during lactation period from 5th to 33rd days in White
Short Wooled goats. They concluded that: (a)
decrease in non-essential amino acids was ranged
from 0.39 to 10.05; (b) decrease in essential amino
acids was ranged from 0.79 to 41.6%; (c) Threonine
and Iso-leucine was decreased sharply (d) All other
amino acids widely decreased.
Bhosale et al. (2009) indicated that lactation had
significant increasing effect on fat, protein, ash, TS,
SNF, titratable acidity and viscosity. All milk
components are gradually increased from I to IV
lactation with exception of lactose and pH.
Hejtmankova et al. (2012) studied the changes
in composition of whey protein of Czech white short-
haired goat throughout the lactation period and found
that at the end of the lactation period the content of β-
lg increased steeply, and the β-Lg/-La ratio reached
a maximum value of 1.94% in goat milk. In addition,
goat milk contains a similar amino acids profile to
ewe milk but the amino acid pattern in whey protein
differs from that in milk.
Table (1) : Mean composition of goat’s milk produced form different breeds in various countries.
Country
Breed
%
References
Total
solids
Fat
Protein
Lactose
Ash
Germany
Improve fawn
12.43
3.92
2.9
4.01
-
Graf et al. (1970)
Nigeria
Saanen
12.15
3.41
3.07
4.54
-
Mba et al. (1975)
Nigeria
African Dwarf
18.68
6.90
3.91
6.30
0.82
Akinsoyinu et al. (1977)
Australia
Saanen
13.47
4.61
3.39
4.93
-
Ranawana & Kellaway (1977)
USA
Pygmy
21.55
7.76
4.71
5.58
-
Jenness (1980)
Egypt
Breed in Sinai
peninsula
12.91
4.04
3.35
4.48
0.84
El-Zayat et al. (1984)
Iraq
Native
13.39
3.42
3.76
5.3
0.83
Ali and Hassan (1988)
Egypt
Baladi
12.33
4.06
2.92
3.88
0.80
El-Alamy et al. (1990)
Greece
____
11.76
3.44
3.35
4.30
0.79
Voutsinas et al. (1992)
Saudi
Arabia
Masri
--
3.06
3.41
4.51
0.77+0.7
Sawaya et al. (1994)
Poland
Improved white breed
--
4.1
2.9
--
0.80
Szymanowska & Lipecka
(1997)
c) Feeding.
Ration is the main factor affects milk
composition as it is the source of milk constituents,
and controls the fermentation process in rumen. For
example, El-Alamy et al. (1987) reported that goats
fed on concentrate and roughage ration of 70: 30 gave
significantly higher fat and TS contents. However,
Kholif and Abou-El-Nor (1998) studied the effect of
replacing corn with powder Date seeds in diets of
Baladi lactating goat’s on their productive
performance during the 1st week of lactation. They
reported that Fat, TS, TP as well as total saturated,
short and medium chain fatty acids contents tended to
be higher, while lactose content and C15, C16 total
unsaturated fatty acids were decreased. Morsy, et al.
(2012) concluded that supplementing Anise oil,
Clove oil or Juniper oil for lactating goats improve
rumen fermentation as propionate production and
Life Science Journal 2014;11(1s) http://www.lifesciencesite.com
309
reduce acetate proportion and improved milk protein
of lactating goats. Juniper oil supplementation
improved conjugated linoleic and omega 3 fatty acids
in milk fat. Juniper oil supplementation to dairy
animals can contribute to improve the health
properties of milk.
Main chemical composition of goat’s milk
1- Milk proteins
Generally, two main groups of milk protein are
distinguished; namely casein micelles and whey
protein. Five principal proteins of goats milk closely
resemble their homolog's in cow's milk are s2-CN,
β-CN, K-CN, β-lg and -La (Jenn ess 1980). He
showed that goat’s milk lacks homolog of bovine s1-
CN, the most abundant protein in cows milk.
Distribution of amino acids composition of isolated
goat milk proteins is showed in Table (2) as reported
by Christrian (1996).
Jooyandeh and Aberoumand (2010) showed that
non protein nitrogen (NPN) content of goat and human
milk are higher than in cow milk while Hejtmankova et
al. (2012) concluded that total essential amino acids
were approximately 40% of the total amino acids in
goat and ewe milk as well as in goat and ewe whey.
2- Casein micelles
Casein is the main protein fraction in all milks
which represents approx. 80% of the total protein. The
most significant aspect of the structure of milk casein is
the fact that -CN, β-CN and calcium phosphate are
located in the interior of the micelles, whereas K-CN is
predominantly located on the surface of the spherical
casein micelle to form protective layer at the surface of
each spherical micelle (Christrian 1996). The size of
casein micelles varies considerably within and
between species. They seem to be smaller in goats
milk than in cow's milk. Peak frequency of micelle
diameters of cows and goats milk was 75 and 50nm
resp. (Le-Jaouen 1981).
Casein of goat milk was separated mainly into
two groups. The faster group resembles S-CN from
cows. The second with lower mobility resemble
bovine β-CN plus K-casein; S-CN group included 2-
3 zone and represented 37.25% of whole casein while
β-CN included two components which represented
62.75% (El-Shibiny 1979). These data were
confirmed lately by Hefinawy and Mehanna (1988);
Mahran et al. (1988) and Abd-El-Salam (1992).
Goat casein fraction can be also subdivided into
S1-CN, S2-CN, β-CN and K-CN, which occur as
micelles complex in approx, proportion of 1.2.5.2
respectively being considered a β-CN rich and S1-
CN poor (Remeuf and Lenior, 1985). However,
Jaubert et al. (1997) recorded that this proportions are
S1, S2 β+-CN and K-CN were 10.4, 14.5, 62 and
13.2% in total casein.
Goat K-CN differs from its bovine counterpart
in having a chain of 171 instead of 169 amino acid
residue; Val and His being insert at position of 132
and 133. However, it likes bovine K-CN in having
the same Phe. in position of 105 and Met. in position
106 (rennin action).
Another special characteristic of goats milk is
higher level of polymorphism of S1-CN where clear
differences in the levels of protein synthesized
between alleles exist which correlates to composition
of milk and with some milk processing parameters. It
has been clearly demonstrated that genetic
polymorphism in caprine S1-CN is strongly related
to the casein content. Grosclaude et al. (1994)
showed the existence of at least 14 alleles at S1-CN
locus, distribution in 7 different classes of protein
variants (A-G) associated with 4 levels of expression
ranging between O (S1-CN null) and 3.6 gL-1 per
allele (S1-CN A, B and C), with E as an intermediate
variant (1.6 gL-1). Variants A, B, C and E differ only
by amino acid substitutions whereas variant D, F and
G appear to be associated with a reduced S1-CN (0.6
gL-1).
In (1998), Trujillo et al., reported that 3 variants
are associated with high S1-content in goat milk (A,
B, C); 1 to an intermediate content (E); 3 to a low
content (D, F, G) and 1 to a null content.
The most recent genomic data was recorded by
Trujillo et al. (1997). They demonstrated that caprine
casein present 8 different S1-CN genotypes (BB, BE,
BF, BO, EE, EF, EO and FF) ordered from highest to
lowest according to their theoretical protein content;
and they differ in their mobility in alkaline urea
PAGE.
Chianese et al. (1997) detected three noval S1-
CN variants H, I, L in caprine milk from Italian
breeds. Iametti et al. (1997) recorded that genetic
variants of S1-CN have different isoelectric points
pH. (A) 3.87-3.76; B) 3.72-3.60; (F) 4.01-3.95.
A relationship between the occurrence of
polymorphic forms of S1-CN and physico-chemical
properties of milk is emphasized, this relation
affected caprine milk processing quality (Mahaut and
Korolezuk 1994; Tziboula 1997 and Mahmoud&
Usman 2010).
Goat's milk that lacked S1-CN had lower
percentages of milk components and poorer
coagulation properties than milk that contained S1-
CN, suggesting that the presence of S1-CN in milk
should improve coagulation properties (Clark and
Sherbon, 2000).
3- Whey proteins (WP)
Goat whey proteins were separated to 5
fractions. They are β-lg (presented 60% to total WP),
-la, serum albumin, immunoglobin and protease
Life Science Journal 2014;11(1s) http://www.lifesciencesite.com
310
peptones (El-Shibiny 1979 and Mahran et al., 1988).
Kalantzopoulos (1993) stated that goats’ milk
contains four times less -la, three times less serum
albumin but more β-lg than cows homologs.
Goat β-lg like its bovine homolog consists of a
polypeptide chain of 162 amino acid residues but
differs from bovine β-lg at six positions.
On the other side, -la of bovine and goats milk
is differed in their amino acid sequence. There are 12
differences between goat la-B (the common variant
in cattle of European origin) in the chain of 123
residues (Jenness, 1980).
Goats milk content 2.75% total protein, 0.433
(g/100 g) whey proteins and 0.119 (g/100g) β Lg/ the
continents of total protein as well as acid whey
protein nearly constant throughout the lactation
period; the average ratio of whey total protein was
15.8±2.61% in goat milk Hejtmankova et al. (2012).
Table(2): Amino acid composition of isolated goat’s milk proteins (mg/100g).
Amino acid
S2-Casein
-Casein
K-Casein
-Lacto-globulin
-lactal-bumin
Alanine
10
5
16
16
5
Arginine
6
3
5
3
1
Aspartic acid
17
9
16
14
22
Cysteine
2
0
3
5
8
Glutamic acid
45
43
26
24
13
Glycine
4
6
1
5
5
Histidine
5
5
4
2
3
Isoleucine
11
9
11
10
8
Leucine
12
20
8
21
13
Lysine
22
12
8
16
13
Methionine
4
6
1
4
0
Phenylalanine
8
9
4
4
4
Proline
18
33
19
8
2
Serine
14
15
13
6
6
Threonine
14
12
15
8
6
Tryptophan
2
1
1
2
4
Tyrosine
11
4
9
4
4
Valine
12
21
11
10
6
Total
217
213
171
162
123
Kalantzopoulos (1993) showed an Electrophoretic pattern of cows, sheep's and goats casein (Fig. 1).
Fig. (1). Electrophoretic pattern of bovine, ovine and caprine casein on polyacrylamide gel
Life Science Journal 2014;11(1s) http://www.lifesciencesite.com
311
4- Minor proteins
Goats milk, like cows milk, contain 20 to 200
ug/ml each of lactoferrin and transferring, while
contains a mean prolactin conc. Of 44+5 ug/ml (cow
milk contained 60 + 2ug/ml). Goats milk contains
approx. 12 ug/ml of folate-binding protein, it contains
also greatest level of immunoglobulin's which
resemble 30-50 ug of IgA; 10-40 ug of IgB and 100-
400 ug of IgG ml in mature milk (Jenness 1980 and
Shimzaki et al., 1991 and Helemet and Fiechler,
2012).
5- Milk lipids
Fat is composed essentially of glycerides and
steroids (99%). The fat forms globules which are
suspended in milk as an emulsion.
Fat globules of goats milk resemble those of
cows milk in lipids composition and properties of the
globule membrane but goats milk lacks agglutinin
(Jenness 1980). Average total lipids content was
about 5+1.2% for goats’ milk; whole milk contains
97% free lipids and 1% bound lipids. Free lipids were
96.8% triglycerides. In this respect, goat milk
resembles cows milk, however contained
significantly more free lipids than did for cows milk
(Cerbulis et al., 1982).
Triglyceride (TG) composition is also differed
in goats and cows milk (Fig. 2) where these were 16
peaks corresponding to TG of 24 to 54 carbon atoms.
In cow milk there were clear maxima, located at C38
and C50-52 (12.8 and 12.0% respect. average
values).Whereas in goats milk, the TG content
increased with the number of carbon atoms reaching
maximum (13%) at C40 and C42. The largest relative
differences between goat and cow milk fat were
found in TG C42, C44, C50, C52 and C54 (Forntecha et
al., 1998).
The average diameter of globules in goats milk
is about 1.5-2 um compared to 2.5-3.5 um for cows
milk and the percentage of globules of less than 1.5
um is 28% for goats milk vs 10% for cows milk (Le-
Jaouen, 1981 and Kalantzopoulos, 1993). Fat globule
membrane protein of goats milk has 1.64% sialic
acid, 3.28% hexos, 2.83% hexoamin and 0.17%
phosphorus which were similar for cows and
buffaloes milk (Singh et al., 1977).
Minutes Minutes
Fig. (2). Gas chromatographic profiles of triglycerides of a goat milk fat sample (a) and of the reference cow
milk fat (b), using short capillary column.
Fat has largely the same composition of fatty
acid as in cow’s milk, however the proportions are
different. It is rich in short chain fatty acids (C4 to
C10) which represent 15% of all fatty acids (Le
Jaouen, 1981). There are three fatty acids higher (two
fold) in goats milk than cows milk; C8, C10, C12
(Juarez and Ramos, 1984).
Fatty acids composition of goats milk reported
by various authors and compared with those of cows
milk is summarized in Table (3).
Chilliard and Freund (1997) summarized the
characteristics of goats milk lipids compared with
cows and human milks as follows.
1) Goat’s milk has higher fat contents than cows
and human milk.
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312
2) It has a higher content of small fat globules and
does not contain agglutinin.
3) It has low tochopherol and carotene contents.
4) It has a higher content of C8, C10, C12 fatty acids.
5) Lipoprotein lipase activity is lower in goat’s
milk than cow’s milk but in goat milk this
activity is more closely bound to the fat globules
and highly correlated with lipolysis.
Indratiningsih, et al. (2012) showed that
fermentation process increased conjugated linoleic
acid (CLA) content of goat milk from 3.09mg/g fat in
fresh milk to 3.26 mg/g fat in fermented.
6- Lactose
Lactose is the main constituent of the dry matter
of milk. It is reducing carbohydrate and it is present
in its liquid phase. Lactose of goat’s milk does not
differ from that of cows milk but its content varies
very little during lactation period (Le-Jaouen, 1981).
Bhosale et al. (2009) indicated that the lactation had
significant increasing effect on lactose.
Helmut and Fiechter (2012) showed that goats
milk contain about 4.23% lactose. This data obtained
from six dairy goats breeds in Austria. No recent
further data are available for the lactose content of
goat’s milk.
7- Minerals and trace elements
Mineral composition can be used recently to
distinguish or identify of animal origin of raw milk;
cows milk on one hand and goats & ewes milk on the
other (Rincon et al., 1994).
Levels of some minerals and trace elements
in goats and cows milk were determined by various
authors as mentioned by Jenness (1980) Tables (4) &
(5).
Table (3): Fatty acids composition percent of goat’s milk reported by different authors and compared with
those of cows milk.
Acid
Goats milk
Cows milk
Garcia et
al., 1979
Boccignone et
al., 1981
Sawaya et
al., 1994
Martin Hernandez
et al., 1986
Hellin et
al., 1998
Martinez-Castro
et al., 1979
C4.0
2.3
1.81
3.0
1.8-2.8
3
2.5-6.2
C6.0
2.7
2.03
2.0
2.2-3.4
6.3
1.5-3.8
C8.0
3.2
2.68
2.0
2.4-3.9
2.9
1.0-1.9
C10.0
11.5
8.45
6.1
8.8-13.4
10.4
2.1-4.0
C12.0
5.3
5.21
2.9
3.8-5.5
5.6
2.3-4.7
C14.0
10.4
10.52
9.5
8.5-11.6
12.8
8.5-12.8
C14.1
-
00.96
0.4
0.5-0.8
-
0.6-1.5
C16.0
24.9
24.33
28.6
23.3-32.1
34.8
24.0-33.3
C16.1
-
2.58
2.5
1.0-2.0
-
1.3-2.8
C18.0
9.7
9.49
10.3
4.3-11.2
6.8
6.2-13.6
C18.1
21.6
23.96
26.3
16.2-26.6
13.3
19.7-31.2
C18.2
1.6
1.68
2.6
1.2-2.5
3.9
1.3-5.2
C18.3
1.2
-
-
0
0.9
-
Table (4): Trace mineral content of goat’s milk.
Country
Breed
Time postpartum
Animals
Samples
Fe
Cu
Mn
Zn
1
-------
(mg per liter)
-----
(g/liter)
Nigeria
Dwarf
1-5 days
10
5
2.46
3.14
.20
14.11
319.7
2-18 weeks
10
17
.43
.28
.05
4.01
108.5
Egypt
?
?
26
26
.56
.13
.19
1.92
Greece
?
?
56
2.2
Japan
?
4-5 mo
2
2
.65
.29
Life Science Journal 2014;11(1s) http://www.lifesciencesite.com
313
Table (5): Principal minerals and citrate in goat’s milk.
Country
Animals
Sample no.
Na
K
Ca
Mg
P
Cl
Citrate
Breed
No.
______________
(mg/100ml)
__________
Eire
?
9
9
151
86a
Egypt
?
?
50
136
61b
172
England
Saanen-Welsh
14
11-23
44
180
153
98
Saanen
4
4
ca 150
Saanen
1
4
ca 180
Sanen-Toggenburg
6
31
40
241
136
70c
Iran
?
4
?
11.5
Japan
?
2
2
51
212
137
14.5
106
161
Toggenburg
2
31
41
190
133
36d
116
121
Philippines
Saanen
11
?
139
121
Trinidad
British-Alpine
16
53
164
85c
13
75d
Anglo-Nubian
16
56
153
90c
10
82d
USA
?
1
39
242
202
Pygmy
6
6
198
153
139
Four breedse
24
170
137
17
112
?
4
38
193
138
21
95
204
151
Yugoslavia
Composite
3
123
98
Scotland
Ayshire (Cow) Bulk
12
58
140
118
12
95
104
176
a Inorganice P (Pi). bProbably inorganic P (Pi) only. cSeems very low.
dseems very high. eFrench Alphine, Nubian, Saanen and Toggenburg.
Distribution of Ca, Mn and P in goats’ milk
between colloidal and dissolved state were very
similar to those of cow and buffaloes milks in Egypt.
breed (Ahmed 1979). The distributions were total Ca
(131.68 mg/100 ml), soluble Ca (36.70 mg/100 ml);
total Mn (8.4 mg/100 ml); soluble Mn (2.2
mg/100ml); total P (44.83 mg/100ml) and soluble P
(30.11 mg/100ml).
Level of other trace elements was also
determined by Middleton and Fitz-Gerald (1981) as
listed in table (6). They concluded that goats’ milk is
higher in Cu but lower in Fe and Cd.
Table (6): Some trace elements in goat’s milk
compared with cows milk
Trace elements
mg/L
Goats milk
Cows milk
Cd
0.002
0.006
Cr
0.013
0.016
Cu
0.287
0.194
Fe
0.427
0.730
Pb
0.035
0.039
Ni
0.01
0.01
Zn
4.756
4.275
El-Alamy et al. (1990) determined also trace
elements and minerals of Egyptian Baladi goat’s
milk. They mentioned that, K (142 mg/100 ml), Cl
(148 mg/100ml) and Mg (22.3 mg/ml) contents were
also higher than cow’s milk.
Gueguen and Freund (1997) reviewed the
mineral composition of goats’ milk in France. They
concluded that it is similar to that of cows milk but it has
higher contents of K, Cl and Mg (1900, 1600 and 130
mg/kg) for goats milk vs. (1500, 110, 110 mg/kg) for
cows milk. They added that goats milk has content of P is
2-3 x higher than that of human milk and its Ca. P ratio is
great deal lower than that of human milk.
Urbriene et al. (1997) recorded that human and
goats milk have similar content of some microelements
except Fe which is 1.8-2 x higher in human milk, while
the concentration of macro elements is similar in goats
and cows while concentration of K, Ca and Mg were
widely varied. In (1998), Gue et al., reported also that
ration of Na: K (which represented 1: 3) is the main
reason for lower alcoholic stability of goats milk.
Belewu, and Aiyegbusi (2002) reported that,
the milk of goat (West African dwarf) which
contained more mineral contents similar to that of
human milk, is pointer to the nutritional contribution
of goat milk in a country like Nigeria prevailing
undernourishment and malnutrition are accompanied
by low intake of some minerals and vitamins among
the populace and most especially Vulnerable
(Pregnant, Lactating mothers, infants and weanlings
and the sick) groups.
Guzeler et al. (2010) showed that, results of
the statistical analyses indicated significant
lactational effects on total solids, fat, non-dry matter,
protein, lactose, energy value, titratable acidity, pH,
specific gravity (P<0.01) and sodium (P<0.05), but
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314
there was no similar effect on the contents of
calcium, phosphorus, magnesium and potassium
values of goat's milk (P < 0.05).
8- Miscellaneous.
Vitamins
Vitamins content of goats milk varies with
season, feeding and other factors. Le-Jaouen (1981)
listed vitamin content of goats, cows and human
milks (Table 7). He demonstrated that goats’ milk has
similar content of vitamins as human milk with
exception of a lower content of folic acid, vit. C and
Inositol. He added that goats’ milk contains less vit.
B6 and B12 than cows milk but this does not present
nutritional problems. This data were confirmed also
by Kalantzopoulos (1993).
Table (7): Vitamins content of milk in different
species.
Goat
Cow
Human
Vitamin A (IU/100 ml)
191
159
190
Vitamin B-1 (Thiamin)
0.04
0.04
0.02
Vitamin B-2 (Riboflavin)
0.18
0.17
0.04
Niacin
0.19
0.09
0.15
Vitamin B-6
0.01
0.06
0.01
Pantothenic acid
0.34
0.34
0.18
Biotin
0.004
0.003
0.001
Folacin
0.0008
0.0059
0.0038
Vitamin B-12
0.00007
0.00042
0.00003
Vitamin C
1.5
2.1
4.3
Vitamin D (IU/100 ml)
2.4
2.2
2.2
Vitamin E
?
0.10
0.65
Other factors
Choline
15.0
13.7
9.0
Inositol
21.0
11.0
33.0
(mg/100 ml unless otherwise indicated)
In (1997) Jaubert and Freund summarized the
differences in vitamins content between goats, cows
and human milks as follows.
1) Goats and cows milks have similar content of
Vit A and C < human milk.
2) Goats milk has lower content of Vit. E than
human milk.
3) Goats and human milk have similar content of
Vit. B12.
4) Goats milk has higher content of Vit B-group
(B1, B2, B3, B5, B6 and B8) than human milk.
5) Vit. D contents are similar in the three milks.
Enzymes.
Goats milk has lower activities of certain
enzyme, e.g. ribonuclase, alkaline phosphatase, lipase
and xanthin oxidase than bovine milk. In contrast to
bovine milk, lipase activity in goats milk significantly
correlated with spontaneous lipolysis probably due to
the particularities of the lipolysis system and plays a
major in off-flavour development in milk (Jenness,
1980 and Kalantzopoulos, 1993).
Some physical properties of goat’s milk.
Little studies were done for estimating the
physical properties of goat’s milk. So some
miscellaneous physical properties were focused here.
Viscosity of Egyptian goats milk was 2.385 CP
recorded by( El-Zayat et al. ,1984) and 1.520 for
Indian goats milk recorded by( Majee et al.,1994)
against 1.230 for cow's milk (O'Connar and Fox,
1979).Natural acidity of goats milk is slightly
lower(0.16%, El-Alamy et al.,1990) vs. 0.17-0.18%
for cows' milk (Le-Jaouen, 1981).
Goats’ milk has less alcoholic stability when
compared with cows milk where it precipitates on
addition of 44% ethanol vs. 70% for cows milk (El-
Zayat et al., 1984 and Gue et al.,1998). It has
freezing point slightly higher than cows milk equal -
0.543°C (Alkanhal 1993) vs.-0.564°C for cows one
(Linzell, 1967). However, its specific gravity ranged
between 1.0263 to 1.0335 vs. 0.1320 for cows milk
(Ali and Hassan 1988, Voutsinas et al.1992, Hamed
et al.1993 and Majee et al.1994, Mahmood and
Usman (, 2010).
Helmut and Fiechter (2012) showed that the
mean values obtained for all breeds of goats in
Austria during the whole season were as follows: pH
6.55, freezing point depression -0.549°C. Jooyandeh
and Aberoumand (2010) showed that lipids in sheep
and goats milk have different physical characteristics
than cow milk.
Conclusion
Goat’s milk, as all other milks, contains various
nutrients either as major components or as macro and
micro components. It considered as an ancient
product for the diet of today. Several tries were made
to utilize goat's milk in manufacture of various dairy
products.
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