Chemical
Composition
W. N. SAWAYA,
and Nutritional
J. K. KHALIL,
A. AL-SHALHAT,
ABSTRACT
The chemical composition and nutritional quality of camel milk
was studied. Results showed 11.7% total solids, 3.0% protein,
3.6% fat, 0.8% ash, 4.4% lactose, 0.13% acidity and a pH of 6.5.
The levels of Na, K, Zn, Fe, Cu, Mn, niacin and vitamin C were
higher and thiamin, riboflavin, folacin, vitamin Bt,, pantothenic
acid, vitamin A, lysine and tryptophan were relatively lower than
those of cow milk. Gas liquid chromatography analysis of milk
fat showed a molar percent of 26.7 for palmitic, 25.5 oleic, 11.4
myristic, and 11.0 palmitoleic. In vitro protein digestibility and
calculated protein efficiency ratio values were 81.4% and 2.69,
respectively, based on 90.0% and 2.50 for ANRC-Casein.
INTRODUCTION
THE
TOTAL
POPULATION
of camels in the world
is
about 14.1 million, of which 9.6 million are in Africa
and the Near East and 4.2 million in Asia (FAO, 1976).
There are two different species of camels belonging to the
genus camelus, namely, the Dromedary Camel (Camelus
dromedarius;
one-humped) and Bactrian Camel (Camelus
bactrianus, two-humped). Camels in Africa and the Near
East are dromedaries
while those in Asia are Bactrians.
Camels in Saudi Arabia (i4 600,000) are all dromedaries of
the Najdi breed. They play a major role in the economic
life and survival of the desert dwellers and are a major
source of protein and energy for them. Unlike other milk
producing animals, the camel can thrive under extreme
hostile conditions of temperature, drought and lack of
pastures and can still produce milk of high nutritional
quality (Yagil and Etzion, 1980).
Knoess (1977) reported that daily yields of milk vary
considerably ranging from 3.5-35.0 kg per animal per day
with an average lactation yield of 1068-1373 kg in Egypt
to 4575-20675 kg in Pakistan.
Although data on the chemical composition of camel
milk is reported by some workers (Ohri and Joshi, 1961;
El-Bahay, 1962; Knoess, 1977; El-Amin, 1979; Yagil and
Etzion, 1980), there is limited information on the nutritional quality of camel milk except for the report of
Pant and Chandra (1981) on the nutritional value of camel
milk casein. Moreover, not much information is available
on the fatty acid composition, amino acid contents and
minor constituents such as mineral elements and vitamin
contents of camel milk especially that of Najdi breed of
Saudi Arabia.
The present investigation was undertaken to study the
gross composition, and nutritional quality of Najdi camel
milk of Saudi Arabia.
-MATERIALS
& METHODS
Collection of samples
Eleven milk samples were collected from eleven different healthy
flocks &J 500 camels) from three different areas of the Central and
The authors are affiliated
with the Food Science & Nutrition
Section, Regional
Agriculture
& Water Research Center, Ministry
of
Agriculture
and Water, P.O. Box
17285,
Riyadh
11484, Saudi
Arabia.
744-JOURNAL
OF FOOD
SCIENCE-Volume
49 (1984)
Quality of Camel Milk
and H. AL-MOHAMMAD
Easternregionsof Saudi Arabia. Each samplerepresenteda pooled
sample collected at random from 5-10 different individual camels
in each flock. Samples collected were immediately refrigerated.
Analyses for pH, acidity, lactose and ascorbic acid were done within 24 hr of collection. The rest of the samples were freeze-dried
(Stokes, Model 902-l-8) and stored under refrigeration for further
analyses. Mineral analyses were done on 11 milk samples. Vitamin
analyses were done on two pooled milk samples representing the 11
milk samples collected from the two regions of Saudi Arabia.
Chemical composition
Proximate analysis, lactose content and acidity were determined
according to procedures outlined in AOAC (1980).
Mineral analyses
For the determination of mineral elements (Na, K, Ca, Mg, P,
Fe, Cu, Zn and Mn), the ash was dissolved in 20% HCl. The final
diluted solution for Ca and Mg contained 1% lanthanum to overcome interference, especially by phosphates. All minerals except
Na, K and P were determined with an atomic absorption spectro-
photometer (Perkin Elmer, Model 603). Na and K were determined
with a flame photometer (Beckman, Klina flame). Phosphorus was
determinedspectrophotometricallyusingthe procedureof Watanabe
and Olsen(1965).
Vitamin analysis
Standard methods in the AOAC (1980) were used to determine
the contents of vitamin A (Method 43.008), ascorbic acid (Method
43.036), riboflavin (Method 43.168), thiamin (Method 43.024) and
niacin (Method 43.150). Pyridoxine-HCl (Be) was determined
according to Atkin et al. (1943). Pantothenic acid was determined
by the procedureof Neilandsand Strong (1948). Vitamin Br 2 was
determined according to AOAC (1980) and U. S. pharmacopeia
(Anonymous, 1980a).Folacin wasassayedaccordingto Hurdle et al.
(1968).
Fatty acid analysis
Fatty acid composition was determined by gas-liquid chroma-
tography using an HP-5370A gas-liquid chromtaograph equipped
with a flame ionization detector. Fatty acid methylesters were
prepared by refluxing the milk fat with 15 ml of a 14% solution
of BFS-MeOH and 5 mi benzene according to procedures outlined
in AOCS (1974). Fatty acid methylesters of chain length Ctz:oC24: 1 were analyzed using a 2 mm i.d. x 10 ft glass column packed
with 10% DEGS on 100/120 meshSupelcoport. Column temperature was programmedfrom 120-200°C at 4”C/min and a 48 min
hold. Flow rate of carrier gas, nitrogen, was 40 ml/min with flow
rates of 40 and 200 ml/min for hydrogen and air, respectively.
Fatty acid methylesters of chain length Ce :o-Cro:o were analyzed
using a 2 mm i.d. x 8 ft glass column packed with a 10% SP 2300
on SO/l00 mesh Supelcoport. Column temperature was programmed
from 85-220°C at 4”C/min. and 16 min final hold. All other conditions were the same as above. For the analysis of butyric acid, the
crude fat exctraction was done according to AOAC (1980). The
butyric ethylester was prepared using the procedure of Withington
(1967) and was analyzed using a 4 mm i.d. x 6 ft glass column
packed with 10% SP 1200 with 1% phosphoric acid on 80/100
chromosorb WAW. Column temperature was programmed from
80-190°C at 4”C/min with 8 min initial hold and 8 min final hold.
All other conditions were constant as above. Peaks were identified
by comparing their retention times with those of authentic standards and peak areas were integrated by a computing integrator.
Fatty acid protile was quantitated according to procedures outlined in AOCS (1977).
value of 3.54% for Egyptian camel milk while Knoess
(1977) and El-Amin (1979) both reported higher values for
Ada1 and Sudanese camel milks (4.5% and 3.6-4.7%, respectively).
The fat content of the local dromedary camel milk
(3.60%) agreed well with the data reported by El-Bahay
(1962) and Yasin and Wahid (1957) on the fat content
of Egyptian camel milk but was substantially lower than
those reported by Knoess (1977) and El-Amin (1979) on
Ada1 and Sudanese camel milks, respectively. Although
camel milk was comparable in its fat content to COW milk,
it has been reported that it is difficult to extract the fat
by the traditional method of churning sour milk due to
firm bonds between the fat and protein of milk (Khan
and Appanna, 1967).
The ash content of the milk (0.79%) was relatively
higher than mean values reported for cow milk. The ash
content of dromedary camel milk of Saudi Arabia was
comparable to that of Egyptian camel milk (El-Bahay,
1962) but less than those of Ethiopian (Knoess, 1977) and
Sudanese (El-Amin, 1979) and higher than that of Pakistani
camel milk (Yasin and Wahid, 1957). The ash content of
camel milk could be greatly affected by drought conditions
(Yagil and Etzion, 1980) hence it is very likely that great
variations in the ash content of the dromedary milk could
occur.
Amino acid analysis
Freeze-driedsamplesin duplicate(5 mgprotein) werehydrolyzed
with 6N HCl for 24 hr at 110°C (Moore and Stein. 1963). For
tryptophan analysis, sampleswere‘ hydrolyzed with 5N NaOH
(Hugli and Moore, 1972). Cystine was determinedas cysteic acid
(Moore, 1963). AU the hydrolysateswere analyzedon a Beckman
Model 120Caminoacid analyzer.
In vitro protein digestibility (IVPD) and calculated
protein efficiency ratio (C-PER)
IVPD was measuredaccordingto the method outlined by Satterlee et al. (1979), usinga modification of the multienzymeautomatic recordingtechniqueof Hsuet al. (1977). C-PERwasobtained
by using data from IVPD and essentialamino acid composition
of the protein accordingto proceduresoutlined by Satterleeet al.
(1979). Animal Nutrition ResearchCouncil (ANRC) caseinwas
includedfor comparison.
RESULTS 8~ DISCUSSIONS
Chemical composition
Table 1 represents results of the physicochemical analyses
of dromedary camel milk with corresponding values for
cow milk as reported by Johnson (1978). Average value for
pH of the milk at 25’C was 6.49. This was close to that of
cow milk but slightly lower than that of Egyptian camel
milk which was reported by El-Bahay (1962) to be 6.56
for 150 samples of milk. Moreover, the titratable acidity
was on the low side in comparison to that of cow milk.
Ohri and Joshi (1961) found that the acidity of camel
milk 2 hr after milking was low (0.03%) and increased to
0.14% in 6 hr. Moreover, Kerashkov in 1962 as cited by
Bhimasena Rao et al. (1970) observed that the development
of acidity in the bactrian camel milk at lo-40°C was much
slower than in cow milk.
The mean lactose content of Najdi camel milk (4.40%)
was slightly lower than that of cow milk, 4.9%, but higher
than that reported by Shalash (1979) for Egyptian and
Knoess (1976) for Ethiopian camel milk. It is worth
mentioning here that Cook and Al-Turki (1975), in determining the intestinal lactase concentrations in adult Arabs
in Saudi Arabia, found high levels of the enzyme and
related this to the traditional consumption of camel milk
which is the main source of milk intake for desert dwellers.
The water content in camel milk was close to that of
cow milk and compared well with values reported on other
camel milks, including those of Ethiopia (Knoess, 1977),
Egypt (El-Bahay, 1962) and Sudan (El-Amin, 1979).
The protein content of camel milk (2.95%) was slightly
lower than that of cow milk and substantially lower than
other camels milks. El-Bahay (1962), reported a protein
Table
l-Physical
and chemical
Component
characteristics
Min
Moisture %
86.6
Protein (Nx6.37) 96
2.35
Fat %
2.40
Ash %
0.75
Lactose %
3.91
Acidity %
0.11
PH
6.38
Max
88.1
2.95
3.60
0.79
4.40
0.13
6.49
Table 2 represents the contents of nine nutritionally
essential elements of the Najdi camel milk. In comparison
to Egyptian camel milk (Ahmed et al, 1977), the P content
of the Najdi camel milk was similar to the mean value of
Egyptian camel milk but the contents of Ca and Mg were
relatively lower (Egyptian camel milk, mg/lOOg: Ca = 196.5,
P = 62.6, Mg = 21 .O). On the other hand, the Ca content of
Najdi camel milk was substantially higher and its P content
was relatively lower than those of Ada1 camel milk of
Ethiopia (mg/lOOg: Ca = 40, P = 138) reported by Knoess
(1977). The contents of Ca, P and Mg in the Najdi camel
milk were close to those of cow milk.
The levels of Na and K were slightly higher than those of
cow milk (Johnson, 1978). Yagil and Etzion (1980) found
that the levels of Na and K in dromedary camel milk were
directly affected by seasonal heat and by the level of water
intake. Therefore, the contents of these elements in camel
milk are always subjected to variations depending on the
conditions prevailing at the time the animal is milked.
With respect to the micronutrients, the iron content of
camel milk was relatively lower than the iron content of
both Egyptian camel milk (0.369 mg/lOOg) and Ada1
camel milk (0.5 mg/lOOg) as reported by Ahmed et al
(1977) and Knoess (1976), respectively. On the other
hand, the Fe content of Najdi camel milk was almost six
fold that of cow milk (0.045 mg/lOOg). In general, iron
content in milk is not usually affected, to a great extent,
by its levels in the diet. Hence, the variation observed in
the iron content here might be due to breed differences
and/or analytical procedures.
Cu level of the milk was substantially lower than the
values obtained by Ahmed et al. (1977) for the Egyptian
camel milk (0.49 mg/lOOg), but was about 12 fold that of
COW milk (0.013 mg/lOOg) as reported by Johnson (1978).
Variations in the levels of Cu in different camel milk could
be due to various reasons such as the variations in the Cu
of fresh camel milk
Mean f S.E.
(n=22)
90.4
3.40
5.65
0.82
4.79
0.14
6.65
Minerals
- Cow milka
f. 0.35
f 0.09
2 0.50
t 0.008
i 0.087
f 0.004
?: 0.024
87.0
3.5
3.5-3.7
0.7
4.9
0.15-0.18
6.5-6.7
a Adapted from Johnson i1978)
Table P-Mineral
Ca
Mg
P
106 f 2.0
12 f 0.2
63 f 1.6
Na
69*
content
(mg/lOOg)
K
1.4
156 f 4.2
of camel milka
Fe
0.26 f 0.02
cu
Zn
Mn
0.16 f 0.02
0.44 t 0.04
0.02 f 0
a Means f standard error of means (n = 22)
Volume 49 (1984)-JOURNAL
OF FOOD SCIENCE-745
COMPOSITION/QUALITY
OF CAMEL MILK..
Table 3- Vitamin
.
con tents (mg/kg)
of camel milka
Vit. A
(I.U.)
Thiamin
Riboflavin
B6
812
Niacin
Folacin
Pantothenic
acid
Vit. C
500 t 6.20
0.330 r 0.0
0.416 * 0.016
0.523 f 0.115
0.0015 k 0.0004
4.61 + 0.24
0.0041 c 0.0006
0.88 f 0.22
23.7 f 2.65
a Means i standard error of means (n = 4)
I
Table 4-Fatty
Fatty acid
of camel
Fatty acid
< 0.1
c4:o
c6:0
%:o
ClO:O
0.2
0.2
0.2
0.9
0.2
11.4
1.6
1.7
26.7
11 .o
1.2
C12:o
c13:o
c14:o
C14:l
c15:o
c16:0
c16:1
c17:o
a Represents
acid composition
Molar % of
total fatty acid
average
c18:0
c18:1
c18:2
c18:3
c2o:o
c20:2
c20:4
c20:5
c22:o
c22:6
c23:0
c24:0
c24:1
milka
Molar % of
total fatty acid
11.1
25.5
3.6
3.5
0.6
0.2
0.4
0.1
0.2
< 0.1
0.1
0.1
0.1
of two determinations.’
levels of the feed, breed differences and/or use of different
analytical procedures.
As for Zn and Mn contents, the Zn content was comparable to that of cow milk (0.39 mg/lOOg) but the Mn
content was substantially higher. Johnson (1978) reported
Mn levels of various cow milk samples analyzed by different workers. These samples showed little variation in
the concentration of Mn. Hence, the difference in Mn
values reported here could probably be due to species differences. In terms of the RDAs of the NRC/NAS (Anonymous, 1980b), 1 kg of camel milk can supply 132% of Ca,
79% of P, 26-34% of Fe, Zn and Mg with 80 and 84% of
the minimum suggested daily intake for Cu and Mn, respectively.
Vitamins
Table 3 represents the vitamin contents of Najdi camel
milk. The mean value of the vitamin A content of the milk
was lower than the mean value reported by Ahmed et al.
(1977) on Egyptian camel milk (129.62 I.U./lOOg) as
well as that of bactrian camel milk (7.57 pg/ml) reported
by Khan and Appanna (1967). Moreover, vitamin A content of dromedary camel milk was also lower than that
of cow milk (159 I.U./lOOg). Since the content of vitamin
A in milk is known to be directly affected by the levels of
the vitamin and carotenes in the diet, the level of fat in
milk, and breed differences, variations in the content
of vitamin A are expected and are not unusual. Thiamin
and riboflavin contents of Najdi camel milk were almost
half of their values in Ada1 camel milk of Ethiopia (thiamin
= 0.6 mg/kg, riboflavin = 0.8 mg/kg) reported by Knoess
(1977). When compared to those of cow milk (Hartman
and Dryden, 1978), the riboflavin level in camel milk was
substantially lower than that of cow milk (1.74 mg/kg) but
the thiamin content was only slightly lower (0.43 mg/kg).
No published data are available on the content of certain other vitamins in dromedary camel milk including vitamins Be, Brz, niacin, pantothenic acid and folacin nor on
camel milk of the Najdi breed under investigation. However, in comparison to cow milk (Hartman and Dryden,
1978), the contents of vitamin Be and thiamin of Najdi
camel milk were comparable to those of cow milk (0.6
mg/kg) while those of pantothenic acid, folacin and Brz
746-JOURNAL
OF FOOD SCIENCE-Volume
49 (1984)
were lower (cow milk mg/kg: thiamin = 0.43; pantothenic
acid = 3.39; folacin = 0.059; Br2 = 0.0042). On the other
hand, niacin content in camel milk was substantially
higher than that of cow milk (0.93 mg/kg). The level of
vitamin C was close to that of Ada1 camel milk (Knoess,
1977) but relatively higher than that of cow milk. The
availability of a relatively fair amount of vitamin C (23.7
mg/kg) in camel milk is of significant relevance to the
human diet in areas where green vegetables and fruits are
hard to find. According to the Recommended Dietary
Allowances (RDAs) of the National Research Council
(NRC)/National Academy of Science (Anonymous, 1980b)
1 kg of camel milk furnishes approximately 50% of vitamin
Brz, 40% ascorbid acid, 30% vitamin A, 24% of the vitamins niacin, thiamin, riboflavin and Be and only 1% folatin. The low levels of folacin in camel milk might be of
nutritional significance, especially if camel milk is to be
utilized as the major source of this nutrient in infant
feeding.
Fatty acid composition
GLC analysis of the indigenous fatty acids of camel
milk fat expressed as molar % (Table 4) showed that
palmitic (26.7%) and oleic (25.5%) acids were the major
fatty acids present followed by myristic (11.4%) and
stearic (11.1%) acids. Palmitoleic acid was present in substantial quantities (11.0%) with lower but significant
amounts of linoleic (3.6%), linolenic (3.5%) and arachidonic
(0.4%) acids. Butyric acid as well as short chain fatty acids
C6:o-C1e:o were present in very small amounts. Not much
information is available in the literature on the fatty acid
composition of camel milk. However, Dhingra in 1934 as
cited by Bhimasena Rao et al. (1970), reported on the
distribution of ten fatty acids as their molar percent in
camel milk fat and indicated the presence of higher values
of the short chain fatty acids C4:e (5.9%), Ce:e (1.9%),
C&e (1 .l%) and Cl0 (2.1%) while the percent of palmitic,
oleic and linoleic fatty acids were 28.3%, 34.1% and 3.3%,
respectively.
In comparison to cow milk (Kurtz, 1978), the Najdi
camel milk fat showed higher degree of unsaturation with
higher quantities of the essential fatty acids and specifically higher quantities of palmitoleic acid. Moreover, the
levels of short chain fatty acids C4:o-Cre:o in camel milk
were lower than those of cow milk. However, both cow
and camel milks contained comparable values of palmitic
and oleic acids, both of which accounts for approximately
50% of the total fatty acids in the two milks.
Amino
acid composition
Table 5 represents the amino acid composition of the
dromedary camel milk of Saudi Arabia. The amino acid
profile of camel milk was essentially comparable to that of
cow milk except that camel milk had slightly higher values
for cystine plus methionine, 3.5 g/lOOg (cow milk, 3.32
g/lOOg protein, Posati and Orr, 1976; 3.01 g/lOOg protein,
Pellett and Shadarevian, 1970) and a lower value for lysine,
7.0 g/lOOgprotein(cow milk, 7.93 and 8.05 g/lOOg protein,
respectively). Data are lacking in the literature on the
amino acid composition of the dromedary camel milk
except for the report of Holler and Hassan (1965) on 16
amino acids in the dromedary camel milk casein of Sudan.
Table Z-Amino
acid composition
digestibility
iI VPD) and calculated
of camel milk
(g/lOOg
protein
protein),
in vitro protein
efficiency
ratio (C-PER)
FAOIWHO
reference pattern
(1973)
CC%llel
milka
Amino acid
Aspartic acid
Threonine
Serine
Glutamic acid
Proline
Glycine
Alanine
Valine
Methionine (M)
Cystine (C)
M+C
lsoleucine
Leucine
Tyrosine (T)
Phenylalanine (P)
T+P
Lysine
Histidine
Arginine
Tryptophan
7.6
5.2
5.8
23.9
11.1
1.7
2.8
6.1
2.5
1 .o
3.5
5.4
10.4
4.5
4.6
9.1
7.0
2.5
3.9
1.2
lVPDb
C-PERb
81 .4
2.69
4.0
5.0
3.5
4.0
7.0
6.0
5.5
1.0
,a Represents average of two determinations (variation < 5%).
b IVPD and C-PER of ANRC-casein under similar conditions were
90.0% and 2.50, respectively, as determined by the procedure of
Satterlee et al (1979).
In general, the amino acid composition of the Sudanese
camel milk casein was close to that of the camel milk of
Saudi Arabia with levels of lysine (7.58 g/15.6g N) and
methionine (3.47 g/l 5.6g N), respectively. No value for
tryptophan was reported. Dromedary camel milk of Saudi
Arabia compared favorably with the essential amino acid
requirements of the FAO/WHO (1973). As ‘%of FAO/WHO
requirements, lysine represented-l 28, sulphur amino acids100, threonine-129, isoleucine-135,leucine-148, valine-12 1,
phenylalanine + tyrosine-15 1 and tryptophan-125.
IVPD and C-PER
The IVPD of camel milk (81.4%) was lower than that of
ANRC-casein, 90.0%, but the C-PER (2.69) was slightly
higher (2.50 for ANRC-casein). Pant and Chandra (1981),
reported similar findings on the nutritive value of casein
obtained from different sources. The digestibility coefficient of cow milk casein was found to be 95.7 while that
of industrial casein and camel milk casein were 88.0 and
77.9, respectively. On the other hand, the PER values for
cow milk, industrial casein and camel milk casein were
1.85, 1.6 1 and 2.05, respectively. The lower IVPD value
reported for camel milk could be due to certain configurational differences in the camel milk protein as compared
to that of cow milk and further work would be needed
for more elaboration on this subject. The higher C-PER
values observed here as compared to that of casein and
rat PER values reported by Pant and Chandra (1981) for
camel milk could be due to the relatively higher values of
sulphur amino acids in camel milk which are usually considered as limiting in milk.
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Ms received g/2/83; revised 11/12/83;
accepted 11/25/83.
We thank Dr. Salah Abu-Shakm
for his critical review of the manuscript. Skillful
technical
assistance by Messrs. J. Devi Prasad and M.
Al-Mohammad
is highly appreciated.
Volume 49 (1984)-JOURNAL
OF FOOD SCIENCE-747
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