Introduction: semi-arid parts of the world. They

Introduction:

Camels are often viewed as ideal domestic
animals that aid in the survival of populations in arid and semi-arid parts of
the world. They are perfectly suited to life in hot climates under harsh
environmental conditions, and are adapted to having extremely limited
resources, such as water. Camels provide milk almost all year round, in
quantities often larger than other animals living in similar conditions. Camels
are valued as a riding animal and are frequently used to carry heavy loads.
Local communities in arid regions use camel milk and meat as main nutritional
sources in their diet, and make use of their fine hair and hide.

According to the most recent FAO statistics,
there are approximately 19 million camels in the world, however camel milk
processing has not yet been widely investigated or adopted in Europe. The genus
Camelus consists of two species- both
of which live in pastoral areas. Camelus
dromedarius, the one-humped camel, lives in desert environments in Africa
and the Middle East and Camelus
bactrianus, the two-humped camel, mainly lives in the dry cooler areas of
Asia. The production and consumption of camel milk and milk products are
increasing in certain parts of the world, and there is a growing interest in
its potential therapeutic properties and uses as an alternative to cows milk.

 

Composition of Camel Milk:

Camel
milk generally is an opaque white colour and is known to have a faint sweet
odour with a sharp taste (Abbas et al., 2013), cited in (Abrhaley & Leta,
2018). The colour is caused by the fats present, which are finely homogenised
throughout the milk, and the taste is due to the type of fodder and the amount
of drinking water available to the camel (Kumar et al., 2015), cited by
(Abrhaley & Leta, 2018). The proportions of lactose, fat and protein in
camel milk are roughly the same as those in bovine milk, although they differ
in their relative composition, distribution, and molecular structure of the
milk components. The gross proximate chemical composition of camel milk
relative to other species is displayed on the table below. However, composition
values can vary slightly and are influenced by several factors including age,
breed, feeding conditions, stage of lactation, availability of water and
geographical location (Al haj & Al Kanhal, 2010), cited by (Omar et al.,
2016). A camel’s access to water also affects the concentration of each of the
components. The water content in camel milk can sometimes reach up to 91%,
making it more dilute than bovine milk (Zhao, Bai & Niu, 2015), cited in
(Khalesi et al., 2017).

 

Proximate chemical composition of camel milk
and other species’ milk:

Species of the animal

Water (%)

Protein (%)

Fat (%)

Ash (%)

Lactose (%)

Camel

86-88

3.0-3.9

2.9-5.4

0.6-1.0

3.3-5.8

 

 

 

 

 

 

Cow

85-87

3.2-3.8

3.7-4.4

0.7-0.8

4.8-4.9

Buffalo

82-84

3.3-3.6

7.0-11.5

0.8-0.9

4.5-5.0

Sheep

79-82

5.6-6.7

6.9-8.6

0.9-1.0

4.3-4.8

Goat

87-88

2.9-3.7

4.0-4.5

0.8-0.9

3.6-4.2

Human

88-89

1.1-1.3

3.3-4.7

0.2-0.3

6.8-7.0

Source: (Fox, 2003), cited by (Abrhaley & Leta, 2018)

 

The
amounts of fat, protein and carbohydrates in camel milk are lower than the milk
of other ruminants, however, it contains a greater number of vitamins and
minerals (Arab et al., 2014; Konuspayeva et al., 2011), cited by (Khalesi et
al., 2017). According to (Ereifej et al., 2011; Mohamed et al., 2005), vitamins
B1 (thiamine), B2 (riboflavin) and C (ascorbic acid) are some of the main
vitamins present in camel milk, cited by (Khalesi et al., 2017). The
concentration of ascorbic acid in camel milk is approximately two to three
times higher in comparison to cow’s milk (Stahl et al., 2016), cited in
(Abrhaley & Leta, 2018). This high concentration of vitamin C causes camel
milk to have a low pH (6.2 to 6.5), which stabilises the milk and helps it to
last longer without the formation of a cream layer. The mineral content of
camel milk is less than 1%, which include sodium, potassium, calcium,
phosphorous, magnesium, iron, copper and chlorine (Yaqoob & Nawaz, 2007),
cited in (Khalesi et al., 2017). Camel milk contains about ten times more iron
than bovine milk, according to (Ziane et al., 2016), cited in (Khalesi et al.,
2017).

Fat content:

Camel
milk has quite a low fat content; 96% is made up of triglycerides and a low
amount of cholesterol (Ereifej et al., 2011), cited in (Khalesi et al., 2017). (Omar
et al., 2015) found, using capillary electrophoresis, that the average fat
content of whole raw camel milk was 3.39 ± 0.01g mL-1. (Ereifej et
al., 2011) observed that approximately 35 to 50% of fatty acids are
polyunsaturated, which is higher than other milk sources, cited by (Khalesi et
al., 2017). The smallest fat globules amongst different milks that have been
examined have been found to correspond to camel, as shown in the diagram below.
The arrangement of triglycerides results in the existence of several
crystalline forms. Therefore, the melting behaviour of the fat in camel milk is
complicated (Haddad et al., 2011) cited by (Khalesi et al., 2017), and often
causes trouble in processing and technological applications, which I will
discuss in further detail later.

 

Size
distribution of fat particles in the milk from buffalo, cow, goat and camel:

Source: (Meena et al., 2014) cited by (Khalesi
et al., 2017).

 

Proteins:

Camel
milk proteins are classified as caseins and whey proteins. The range of the
casein micelle size is between 260 and 300nm (Hailu et al., 2016; Zhao et al.,
2015), cited by (Khalesi et al., 2016). Camel milk also contains enzymes such
as aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma
glutamyl transferase (?-GT) and lactate dehydrogenase (LDH). Gamma glutamyl
transferase is often used as an indicator for the heat treatment of camel milk
and it contains protective proteins such as lysozyme, lactoferrin,
lactoperoxidase and peptidoglycan recognition protein (PGRP). These protective
proteins take part in antimicrobial activity in the immune system and play an
important role in enhancing the shelf life of camel milk (Wernery, 2009), cited
by (Abrhaley & Leta, 2018).

A
study carried out by (Omar et al., 2016) separated and quantified the major
whey and casein protein fractions using capillary electrophoresis techniques.
Their analysis of the raw whole camel milk samples indicated that the total
solid, lactose and ash content were 11.10 ± 0.02, 4.06 ± 0.05 and 0.65 ±
0.07g  100mL-1 respectively.
The mean protein value content was found to be 2.65 ± 0.05g 100mL-1.
In their electrophoretic pattern, camel whey did not have a band in the
expected position of beta- lactoglobulin, unlike bovine milk, which displayed a
clear band.  It is therefore the dominant
protein in bovine whey, and is absent in camel whey, which corresponds to
similar results found by (El- Agamy., 2009). Camel caseins had a similar
protein composition to bovine milk and (Omar et al., 2016) identified major
peaks as alpha-casein, kappa-casein and beta-casein, as shown on the table
below. The capillary electrophoresis also showed that alpha-lactalbumin was the
main whey protein in the camel milk, containing 2.01 ± 0.02mg mL-1,
followed by lactoferrin (1.74 ± 0.06mg mL-1). The main camel casein
protein was beta-casein which had a concentration of 12.68 ± 0.92 mg mL-1.

 

Major
protein content of camel and bovine milk:

Protein

Camel

Bovine

Whey proteins

 

 

?-Lactoglobulin

ND

5.97 ± 0.14

?-Lactalbumin

2.01 ± 0.02

1.08 ± 0.04

Serum albumin

0.40 ± 0.01

0.36 ± 0.04

Lactoferrin

1.74 ± 0.06

ND

Caseins

 

 

?-Casein

2.89 ± 0.29

12.79 ± 2.31

?-Casein

12.78 ± 0.92

11.66 ± 0.87

?-Casein

1.67 ± 0.01

4.39 ± 0.31

 

Source: (Omar
et al., 2016) Values (mg mL-1) are means (n=6) and standard
deviation of three independent experiments; ND, not detected.

 

 

Technological Applications and
Processing of Camel Milk:

Cheese:

Many
challenges arise when attempting to make cheese from camel milk, when following
the same procedure that is used for bovine milk. The coagulation process is
difficult and long, mainly due to the lower proportion of kappa-casein to
beta-casein species present in camel milk (Kappeler et al., 1998), cited by
(Hailu et al., 2016). The casein micelles in camel milk also have a larger
average diameter in comparison to those found in other milk producing animals-
another factor that contributes to its poor gelation abilities (Bornaz et al.,
2009) cited in (Hailu et al., 2016).

Recent
advances are being carried out to improve the quality and consistency of cheese
produced from camel milk. Usually, bovine milk chymosin is the enzyme of
choice, but in a study carried out by (Hailu et al., 2016), camel milk chymosin
was used. It was reported that the gelation time was reduced from 717 to 526
seconds by increasing the chymosin concentration and using a higher temperature
of 30°C. However, chymosin induced gelation of
the milk only occurred after the hydrolysis of 95% of the kappa caseins. It was
also found that increasing the temperature from 30°C (at 44 Pascals) to 40°C
(at 58 Pascals) and the amount of added chymosin improved the firmness of the
gel formed. The development of curd improved with the addition of calcium
chloride (CaCl2), but this was only observed by (Hailu et al., 2016)
at a pH of 6.3. Therefore, each of these factors could be taken into
consideration for further developments to improve the quality of the curd and
yield of cheese from camel milk.

 

Effect
of (a) chymosin concentration at 40°C (—) and 30°C (???) and (b) pH on the
time of gelation of camel milk:

Vertical
bars show standard errors of least square means (n=3). Source: (Hailu et al.,
2016).

 

Although
cheese from camel milk is not widely produced on an industrial scale, some hard
and soft variations have been successfully made from it. An example of a soft
cheese successfully produced was displayed by (Kamoun and Bergaoui, 1989; Kamoun, 1990), cited
in (El-Agamy), their method was as follows: “The milk was heated to 62°C for two minutes, then a starter culture and calcium chloride
(CaCl2) were added. The milk was kept at 35°C and after 60 minutes,
20 to 30ml (per 100 litres) of rennet was added for coagulation. The curd was
left to settle for four hours, then it was pressed and salted. The yield was
calculated to be 12%, versus 4.5% for the ripened cheese.”

Although camel milk cheese is not yet popular
in westernised countries, it is gaining popularity in the African country of Mauritania.
One product in mass production there is “Camelbert”, a French-style cheese
which is similar to brie. We may see products like this on the market in years
to come if consumers here become familiar with the distinct flavour of camel
milk.

 

 

Yoghurt:

Like
other dairy products, yoghurt has been proven to be difficult to manufacture
from camel milk. The problem is that the texture is found to be weak and
inconsistent, due to the high whey protein to casein ratio in the milk
(Shamsia, 2009), cited by (Berhe et al., 2017). (Ereifej et al., 2011) cited in
(Khalesi et al., 2017), reported that the fermentation stage of camel milk
yogurt is more time consuming than that of yogurt from bovine milk, due to its antibacterial effects and presence of
protective proteins.

Solutions
to these problems are being explored, such as the possibility of growing
commercial starter cultures in the milk to increase the rate of fermentation,
(Berhe et al., 2017). (Hashim et al., 2009) claimed that supplementing the milk
with gelatin, alginate and calcium improved the firmness of the yoghurt, cited
by (Berhe et al., 2017). The texture of the yoghurt was more satisfactory when
the camel milk was mixed with milk from other livestock. (Ibrahem & Zubeir,
2016) found this to be true for ovine (sheep) milk, cited by (Khalesi et al.,
2017). If advances like the above continue, then it is possible that camel milk
yoghurt will be widely available for consumer consumption in years to come. It
could be appealing for people who want to benefit from the probiotic effects of
yoghurt, but want an alternative option to bovine milk products.

 

Butter:

Butter
is a product that is not traditionally made from camel milk. Similarly to
cheese, it is found to be difficult to produce in large quantities using the
same technology as bovine milk. This is due to the smaller size of the fat
globules and their dispersal in the milk, resulting in a significant increase
in churning time and a small yield of butter (El-Agamy). The study of (Farah, 1996), cited in (Berhe et al., 2017) states that, camel
milk is deficient in the protein agglutinin; therefore, making it difficult to
cream.

However, it is possible to produce butter
from camel milk at an optimal churning temperature and with vertical agitation
methods. (Berhe et al., 2013), using the above method, at a churning temperature
between 22 and 23°C, produced butter with 80% fat content. (Farah et al.
1989), reported that the highest fat content of 85% was obtained at a churning
temperature of 25°C, cited in (Berhe et al., 2017). In comparison to bovine
milk butter, camel milk butter is white and more viscous in consistency.

 

 

 

Fermented
Milk Products:

Fresh camel milk is difficult to preserve and
has an unpleasant flavour, thus pasteurised or fermented milk is preferable for
consumption. Fermented milk has a better shelf life than fresh camel milk, and
it is said to taste better (Gorban & Izzeldin, 2001), cited by (Khalesi,
2017). Several different fermented camel milk products are in existence, many
of which have been produced traditionally and consumed for centuries in rural
communities in Africa, Asia and the Middle East.

Gariss is a full cream sour milk, which, in
Somalia and Sudan, translates literally to “sour”. It is made by a fed batch or
semi-continuous fermentation process and a field preparation method. “Field”
processes were a way of life of shepherds, while moving their camel to
different pastures. Part of this method involves leaving the camel milk to
ferment in a goat skin bag at approximately 25 to 30°C for one day.
According to (Dirar, 1993), cited by (Shori 2011), it contains substantial
amounts of alcohol as a result of the fermentation stage.

Suusac (or Suusa) is a second type of
fermented camel milk, and is popular in East Africa. It is also known as “Chal”
in Turkey. (Mwangi et al., 2012) described it as a white product with a watery
consistency and a distinctive taste, cited in (Khalesi et. al., 2017). Like
Gariss, it is also made by a semi-continuous fermentation process and can be
produced with or without a starter culture. Following the homemade method of
producing Suusac, the camel milk is incubated in a pre-smoked gourd for one to
two days at 25 to 30°C.

Shubat is a national drink in Kazakhstan, and
is similar to Suusac. However, they vary slightly in their preparation method. For
Shubat, the milk is fermented at the same temperature, but for eight hours.
This incubation can occur in a ceramic jar or a leather bag, instead of a
pre-smoked gourd.

Process
chart comparing the preparation methods of Gariss, Suusac and Shubat:

 

Source: (Shori, 2011)

 

Orom is another known fermented camel milk
product. It is a soured cream produced in Mongolia from the milk of Bactrian
camels and is usually consumed fresh.

Finally, Oggtt is a dried fermented
camel milk product that is made in Saudi Arabia (Al-Ruqaie et al., 1987) cited in (El-Agamy). It can be
consumed either dry or after rehydration with water.

 

 

The Potential Use of
Camel Milk in Infant Formulae:

The most nutritionally beneficial
option for infants is mother’s milk, as it ensures overall healthy development.
However, some infants are not raised on breast milk alone for their first few
months of life, or some mothers choose to not breast feed at all. Currently,
the most common substitution available for this is bovine milk. According to
(El-Agamy, 2007), 2-6% of children suffer from cow milk protein allergy, or
CMPA, as a result of this substitution, cited by (El-Agamy, 2008). Soy
derivatives are another option to bovine milk, but there is evidence that
10-20% of children with CMPA also have little tolerance to these (Businco et
al., 1992; Maldonado et al., 1998; Zeiger et al., 1999), cited in (El-Agamy,
2008). Thus, finding suitable alternative sources of nutrition, potentially
from camel milk, is an important area of ongoing research.

(El-Agamy et al., 2008) carried out
trials that investigated the suitability of camel milk for infants allergic to
cow milk. Electrophoresis analysis patterns showed that the beta-lactoglobulin
band was dominant in cow milk whey proteins, but not present in camel or human
milk proteins. In camel milk, alpha-Lactalbumin and blood serum albumin (BSA)
bands were reported to be dominant. ELISA (enzyme-linked immunosorbent assay)
tests were also carried out by (El-Agamy et al., 2008) on samples of sera from
cow milk allergic children, for the specificity of their (the antibody) immunoglobulin
E to camel milk proteins. IgE recognition was observed for cow milk proteins,
however no recognition occurred when the sera were incubated with both casein
and whey proteins of camel milk. This proves that the antigens in cow and camel
milk proteins are dissimilar.

 

 

IgE-ELISA
Inhibition of cow and camel milk proteins:

 

Source:
(El- Agamy et al., 2008)

Studies such as (El-Agamy et al.,
2017), show that there is promising potential for camel milk to be used as an
alternative protein source in infant formulae. This is especially due its absence
of the major cow milk allergen; beta-lactoglobulin, which is a similarity
shared with human milk. However, I feel that further research and developments
will be made in the years to come before this is turned into reality.

 

Therapeutic and Medicinal
Properties of Camel Milk:

Anti-diabetic properties:

Camel milk is being considered as a
potential therapy to control diabetes and to relieve the complications that it
causes, such as oxidative stress and slow wound healing. (Shori, 2015) reported
that camel milk contains insulin-like proteins, however they are contained
within micelles, unlike those in humans and other animals. They also show
resistance to proteolysis in the upper gastrointestinal tract, mimic insulin
interactions with its receptor, and are easily absorbed into calcium and then
enclosed into lipid nanocapsules, cited by (Berhe et al., 2017). (Malik et al.,
2012), claim that these nanoparticles aid the absorption of camel insulin and make
its passing into the blood stream easier, cited by (Galil et al., 2015). Furthermore,
results from a trial carried out by (Amjad et al., 2013) showed a decrease in
the mean blood doses of glucose, haemoglobin, and insulin, thus, reducing the
daily insulin requirement of type one diabetic patients, cited by (Abrhaley
& Leta, 2018).

An in vivo study by (Badr, 2013),
also showed that wound healing in diabetics was accelerated by the whey
proteins in camel milk, which improved the immune response of wounded tissue
cells and alleviated other diabetic complications, cited in (Shori, 2015). More
in vivo trials by (Al-Hashem, 2009) and (Al-Ayadhi, 2013), suggested that camel
milk increased the level of antioxidant activity in the body and a positive
therapeutic effect was shown when oxidative stress-associated diseases were
treated, cited in (Shori, 2015).

Therefore, there is sufficient evidence
that the daily consumption of camel milk could potentially prevent diabetes, or
reduce the effects of it. Further in vivo and in vitro research will have to be
carried out to develop already existing information, before we can know this
for certain.

 

Anti-cancer and anti-tumour actions:

Camel milk has shown a positive
effect on certain types of cancer cells through non-genetic mechanisms. A study
by (Korashy et al., 2012) demonstrated that camel milk triggered a controlled
death of cells, known as apoptosis, in human breast (MCF7) and human hepatoma
(HepG2) cancer cells, via apoptotic- and oxidative-stress-mediated mechanisms,
cited in (Abrhaley & Leta, 2018) and (Berhe et al., 2017). Chemotherapy and
other anti-tumour radiation treatments are known to be damaging to cells in
bone marrow, making it difficult for them to reproduce and form different types
of blood cells. Camel milk could help to combat this issue, by reducing
genotoxic and cytotoxic activity through the inhibition of micro-nucleated
polychromatic erythrocytes (red blood cells), which increases the mitotic index
of the bone marrow cells, (Salwa & Lina, 2010), cited by (Abrhaley &
Leta, 2018).

Lactoferrin is the main iron-binding
protein in camel milk and has a potentially beneficial effect on the treatment
of tumours. It has functional properties, for example, it can activate cell
signalling pathways by interacting with polysaccharide ligands on the surface
of cells. This results in the inhibition of tumour growth, again by apoptosis.
Lactoferrin can also penetrate cells and activate the transcription of certain
DNA sequences. A study carried out by (Habib et al., 2013) revealed that high
concentrations (3-5mg per/ ml) of lactoferrin from camel milk reduced the
proliferation of HCT-116 colon cancer cells by 56%, cited by (Abrhaley &
Leta, 2018). Lactoferrin has also been shown to have thrombolytic action,
according to (Garcia-Montoya et al., 2012), as it inhibits blood coagulation
and the formation of the enzyme fibrin, which delays the growth and spread of
metastatic tumour cells (cancer cells that have spread from their primary site
to other parts of the body), cited in (Abrhaley & Leta, 2018; Gader &
Alhaider, 2016). Thus, with the aid of continued research, camel milk may
potentially be used to help slow down the multiplication rate of cancerous
cells and tumours.

 

 

 

Crohn’s disease:

Crohn’s disease and other
inflammatory bowel-related diseases can be very debilitating for the people who
suffer from them, and research to relieve their effects is constantly being
carried out. Crohn’s disease is caused by the primary bacterial infection of Mycobacterium avium – subspecies
paratuberculosis, also known as MAP. This bacterium belongs to the
tuberculosis family and only becomes active when the infected person is in
severe stress; causing a secondary autoimmune response (Urazakov &
Bainazarov, 1991), cited by (Abrhaley & Leta, 2018). It was observed by
(Shabo, 2008), that drinking non-pasteurised camel milk benefitted people
suffering from various symptoms “associated with an infection of the alimentary
canal”. (Shabo, 2008) also claimed that
camel milk has powerful bactericidal
properties, and the immunoglobins present aid in restoring the immune system,
cited by (Abrhaley & Leta, 2018).