Camel milk and camel milk products have always been highly esteemed playing even today an important role in the diet of the population in the rural areas of Africa, Asia and the Middle East, with scarce agricultural areas, high temperatures and small amount of precipitation. In aggravated environmental circumstances, camels may produce more milk than any other species, while their demand for food is very modest. A camel produces between 1000 and 2000 L of milk in the period from 8th until 18th month of lactation, while the daily production of milk is between 3 and 10 L.
The goal of the research is to present the chemical composition of camel milk, dairy products and other products made from camel milk. On average camel milk contains 81.4 – 87 % of water, 10.4 % of dry matter, 1.2 – 6.4 % of milk fat, 2.15 – 4.90 % of protein, 1.63 – 2.76 % of casein, 0.65 – 0.80 % of whey protein, 2.90 – 5.80 % of lactose and 0.60 – 0.90 % of milk ash. Variations in the contents of camel milk may be attributed to several factors such as analytical measurement procedures, geographical area, nutritive conditions, breed, lactation stage, age and number of calvings. Camel milk is becoming an increasingly interesting product in the world, not only for its good chemical properties, but also for its interesting and tasteful products.
In just a few centuries. camels have inhabited several areas, where they play an important role in the production of milk, dairy products, production of meat and other products such as chocolate, soaps, etc. Camels are raised in areas with small amount of precipitation and long dry periods. Bactrian camels are mostly raised in areas where annual temperatures do not exceed 21°C. It is assumed that camel taming began 2000 – 4000 years before Christ.
Most camel breeds are classified on the basis of their clan (family) name and according to geographical areas where camels have been raised. One exception is Somalia, where there are three camel breeds classified according to phenotype (Hour, Siifdaar and Eyddimo). Camels belong to the family Camelidae and suborder Tylopoda. The family Camelidae contains the Genera camelus (Old World Camelids) and Lama (New World Camelids).
Different kinds of camel milk
There are two distinct camel genera. one-humped camels and two-humped camels. One-humped and two-humped Bactrian camel belong to the one-humped camel genus. The title “Bactrian” for two-humped camels refers to the area of “Bactria” in Northern Afghanistan, where this camel is believed to have originated from. One-humped camel is thinner and taller, with a thinner coat, and it dwells in warmer semi-dry areas. The two-humped camel is smaller and has a thicker and longer coat; it dwells in cold mountainous areas.
According to the FAO data (2008), the number of camels in the world amounts to about 20 million, 14 million of which are located in Africa and 4 million are in Asia. In the total number of camels, one-humped camels are dominant (16 million). In global perspective, the economic significance of camel breeding is minimal in comparison with breeding other domestic animals. The reason lies in larger costs of camel milk production as opposed to e.g. cow milk.
Physiological Adaptation to Desert Environment
Camels live in habitats with high temperature differences and scarce precipitation. In the course of evolution, camels have adapted to the conditions of such environment.
They can store in their humps up to 36 kg of fat which serves as a source of water and energy when nutrients are not available. These humps enable the camel to travel up to 161 km without consuming water. Camels rarely sweat, even at a temperature up to 49°C. During winter, desert plants may hold enough water to enable camels to survive without water for a few weeks. A camel may endure considerable dehydration.
In warm surroundings it may tolerate a loss of water of at least 27 % of its body weight, which is twice as much as in other mammals. In warm periods, the animal’s coat has an important role (a camel with a thicker coat consumes less water). Camels do not breathe hard, but they sweat. Sweat is excreted in moderate quantities; however, the coat is not moist but dry. Camels may produce concentrated urine in their kidneys. Under certain circumstances urea is not excreted by urine but it is integrated into the microbe protein.
Desert sand may present a problem to humans, but camels have developed special adaptations such as a thin membrane on the eye and an internal eyelid, which protects the eyes from sand storms, but still lets enough light through so camels are able to see. Double rows of long eyelashes also keep sand away from the eyes. Camels may close their nostrils and thus prevent sand from entering the nasal cavity.
Lactation According to statistical data (FAO, 2008), camel milk production in the world amounts to about 5.3 million tons annually, with a mere 1.3 million tons consumed by people, while the remaining quantity represents food for calves. In aggravated environmental conditions, camels may produce more milk than any other species (Farah et al., 2007), while their demand for food is modest. A camel produces between 1000 and 2000 L of milk from 8th – 18th month of lactation (FAO, 2006). Their average daily production of milk ranges from 3 – 10 L during 12th – 18th month of lactation (Farah et al., 2007). The daily production of milk may be increased to 20 L provided a better animal feed, availability of water and veterinary care (FAO, 2006).
Camels become sexually mature when they reach 4 to 5 years of age. On average camels have their first calving when they are 6 or 7 years old. In normal conditions (partus every second year), camels should have 8 – 10 calves during their life, with their average life expectancy being from 25 to 30 years. Pregnancy period lasts 13 months on average. After delivery, the young are not separated from the mother; if that happens,
the mother will stop secreting (producing) milk. As opposed to dairy cows which are separated from their calves after delivery, but still produce milk for six to nine months, a camel remains in lactation for twelve to eighteen months on average.
Chemical Composition of Camel Milk
Variations in the composition of camel milk may be attributed to several factors such as analytical measurement procedures, geographical area, nutritive conditions, breed, stage of lactation, age and number of calvings (Khaskheli et al., 2005). Geographical origin and seasonal variations are factors which influence the most the change in the camel milk composition. Konuspayeva et al., (2009) studied the effect of geographical origin on the composition of camel milk and the study showed that camel milk from camels located in east Africa has a larger amount of fat than the milk from camels in Africa and western Asia. Seasonal variations also play a significant role in the composition of camel milk, even with camels of the same breed and from the same region (Bakheit et al., 2008).
Water in camel milk
The amount of water in camel milk varies from 81.4 – 87 % (Bhakat and Sahani, 2006). Animal feed and consumption of water have the greatest influence on the amount of water in camel milk. In the dry period the production of camel milk is reduced and it increases in the rainy period. The milk of one-humped camels which dwell in warmer climate zones has a smaller amount of fat and greater amount of water (Wernery, 2006). The water in the milk is in its greater part found as free water, while the other part is found in the form of bound water. Milk ingredients soluble in water are lactose, α-lactalbumin and a part of salt, while the insoluble ingredients are milk fat, casein and β-lactoglobuline.
Dry Matter in Milk
The dry matter in camel milk consists of milk fat, lactose, proteins and milk ash. The average share of dry matter in camel milk amounts to 10.4 % (Kouniba et al., 2005). Stage of lactation and season of the year have a significant influence on the daily amount of milk, composition of fat, protein and dry matter (Zeleke, 2007).
The Bactiran camel milk has greatest share of milk fat and dry matter, while the milk of hybrids has the greatest amount of proteins; the one-humped camel milk has the greatest share of lactose (Table 3).
Milk fat is emulgated in camel milk, which means that it is found in the form of fat globules dispersed in milk serum. The diameter of fat globules in camel milk varies between 1.2 – 4.2 micron. The amount of milk fat in camel milk ranges between 1.8 and 5.0 per 100 g (Khaskheli et al., 2005), with average being 2.63 ± 0.40 g per 100 g. Milk fat from camel milk is composed of triacylglycerole, which represents about 96 % of the total amount of lipides of various fat acid composition (Gorban and Izzeldin. 2001).
The composition of fat acids is subject to influences from the environment and physiological factors such as nutrition, stage of lactation and genetic differences within a species (Farah et al., 1989). Dominant fat acids in camel milk are palmitic and oleic acid (Attila et al., 2000). In comparison with cow milk, camel milk fat contains a lower concentration of short-chain fatty acids (Abu-Lehia, 1989) and a lower concentration of carotene (Stahl et al., 2006).
Due to a lower concentration of carotene, camel milk is prominently white. Camel milk also contains a higher concentration of long-chain fatty acids in comparison with cow milk (Konuspayeva et al., 2008). Similarly, average values of unsaturated fatty acids (43 %) are higher in camel milk, especially essential fatty acids (Haddadin et al., 2008). The amount of saturated fatty acids (Konuspayeva et al., 2008) is higher in cow milk (69.9 %) than in camel milk (67.7 %). Cholesterole concentration (Konuspayeva et al., 2008) in camel milk (37.15 mg/100 g) is higher than
in cow milk (25.63 mg/100 g). Rüegg and Farah (1991) studies physical constants of milk fat, solubility temperature and temperature of thickening. These two constant values are established to be higher than camel milk (41.9°C and 30.5°C), in comparison with cow milk (32.6°C and 22.8°C). This is because camel milk fat contains a smaller amount of short-chain fatty acids (C4-C12) and a greater amount of long-chain fatty acids (C14-C22) in comparison with cow milk (Haddadin et al., 2008).
Camel milk has a higher concentration of caprylic, palmitoleic, oleic and α-linoleic acid in comparison with cow milk acids. The concentration of myristic, palmitic and stearic acid is also higher in camel milk in comparison with mare milk.
Camel milk contains two fractions of proteins: casein and protein whey. The total amount of camel milk varies from 2.15 to 4.90 % (Konuspayeva et al., 2009), which is 3.1 % on average. The content of proteins in camel milk is influenced by the breed and season. The breed Majaheim produces milk with higher protein content in comparison with other breeds (Wadah and Hamra). Protein content varies depending on the season, and it is lowest (2.48 %) in August and the highest (2.9 %) in December and January (Haddadin et al., 2008).
Casein in camel milk
Casein (CN) is the basic milk protein. The share of casein in the milk of one-humped camels is 1.63 – 2.76 %, which represents about 52 – 87 % of all proteins (Khaskheli et al., 2005). The share of casein differs with certain camel breeds, so the breed Safrah contains the highest share of casein in comparison with the breeds Majaheim and Wadah. Casein fractions in camel milk are αs1-casein (22 %), αs2-casein (9.5 %), β-casein (65 %) and κ-casein (3.5 %). αs2-casein contains 11 phosphoserine residue which provides casein with a powerful affinity towards calcium, magnesium and oligo elements, -casein differs from other caseins with its sensitivity to chymosin, low affinity to calcium and the presence of carbohydrates within the structure.
The average diameter of casein micelles in milk is 260 – 300 nm, which is twice as much in comparison with 130 nm in cow milk (Farah et al., 2004). Camel milk
is similar to human milk because it contains a high concentration of β-CN and such high concentration might have an effect upon its better digestibility and decreased frequency of allergies in infants.
Camel milk has a higher concentration of -casein in comparison with cow milk, while the concentrations of - and α-casein are lower in camel milk. Caseins are easily digestible in the host’s bowels and are an excellent source of amino acids whose composition is suitable for the growth and development of the young. Amino acid composition of camel milk is very similar to cow milk.
Concentrations of essential and non-essential amino acids are higher in the cow milk casein in comparison with dairy camel breeds, except the concentration of arginine which is higher in the milk of Safrah breeds. Concentration of essential amino acids is higher in cow β-casein in comparison with β-casein in dairy camel breeds, with exceptions like lysine, threonine, methionine and isoleucine, the concentrations of which are higher in camel milk. The concentration of glycine and serine are higher in the cow β-casein, while the concentration of arginin is higher in the milk by Majaheim breed.
Concentration of nonessential amino acids in κ-casein in cow milk is higher in comparison with camel milk, except arginin the concentration of which is higher in camel milk κ-casein. Cow milk κ-casein contains a higher concentration of essential amino acids in comparison of camel milk, except for lysine whose concentration is higher in the camel κ-casein. Camel milk hydrolysis -CN takes place on peptide connection Phe97-Ile98 by cymosine action, while in the cow milk it takes place on Phe105-Met106 (Kappeler et al., 1998). Camel milk -CN contains an additional proline residue in its sequence (Pro 95). An additional proline residue has an important role in the stability of camel milk -CN.
Whey proteins found in camel milk are α-lactalbumin, serum albumin, lysozyme, lactoforrin, lactoferrin, peptidoglycan recognition proteins, lactoperoxidase and immunoglobulins. Camel milk whey proteins constitute 20 – 25 % of all proteins. The amount of whey proteins in the milk of one-humped camels varies between 0.63 and 0.80 % (Khaskheli et al., 2005). Camel milk contains a smaller amount of β-
lactoglobuline in comparison with cow milk. The basic whey protein in cow milk is β-lactoglobuline (50 %), while in the camel milk it is α-lactalbumin.
Laktoferrin in camel milk at pH 3 – 4 loses iron at its N-terminal end, and at pH 6 – 7 on its C-terminal end, while lactoferrin in the milk of other animal species retains iron at pH 3 – 4 (Khan et al., 2001). Whey obtained after camel milk coagulation is white (El-Zubeir and Jabreel, 2008) in comparison with the greenish whey obtained from cow milk. This is because the whey obtained from camel milk contains a greater concentration of smaller casein micelles and fat globules, as well as a low concentration of riboflavin. milk proteins are less stable at high temperatures (140°C) in comparison with cow milk owing to the absence or lack of β-lactoglobulin and -CN in camel milk. The addition of urea or formaldehyde does not influence on thermal stability of camel milk. However, camel milk whey is thermally more stable in comparison with cow milk whey (Wernery, 2006). The denaturation of camel milk whey proteins is lower (32-35 %) in comparison with cow milk whey (70-75 %) at 80°C/30 minutes. During thermal processing of camel milk whey
. when pH is less than 5, the result is the aggregation of whey proteins because of the high content of α-lactalbumin, which means that whey proteins in cow milk are more sensitive to acidity than whey proteins in cow milk (Laleye et al., 2008).
The amount of lactose in camel milk varies from 2.91 g per 100 g to 4.12 g per 100 g, which is less when compared to cow milk (4.4 – 5.8 %) (Khaskheli et al., 2005). Large differences in content of lactose may be conditioned by animal nutrition. i.e. dependent on the kinds of plants with which animals are fed (Khaskheli et al., 2005). Camels usually like halophile plants such as Atriplex, Salosa and locust tree in order to satisfy their physiological needs for salt (Yagil, 1982).
Camel milk contains vitamins C, A, E, D and B group (Haddadin et al., 2008). It is well known that milk is a rich source of vitamin C (34.16 mg/L) which is 3 – 5 times greater in milk in comparison with cow milk (Stahl et al., 2006). Moreover. milk contains more niacin (B3), folic acid, pantothenic acid, vitamin B12, but contains less vitamin A and riboflavin (Stahl et al., 2006).
Camel Milk Products
this milk products have an important role in the diet of the population in rural areas of Africa, Asia and the Middle East. This specially refers to those who live in dry areas so raw milk and fermented products ensure a source of energy and nutrients.
This is a traditional product in Turkey, Kazakhstan and Turkmenistan. It is a sparkling white beverage made of fermented milk with extremely sour taste. It is made from raw milk or milk diluted with warm water in the ratio 1:1. Milk is then stored in goatskin or ceramic vessels. It is inoculated with 1/3 or 1/5 of previously fermented milk. Incubation lasts 3 to 4 hours at 25-30˚C, but it is left for 8 hours on the same temperature to obtain its typical taste. It is also possible to add some milk cultures such as Lactobacillus casei and Streptoccoccus thermophilus as well as some yeasts, and in that case incubation would last 8 hours at 25˚C and another 16 hours at 20˚C.
This is traditional fermented milk in Eastern Africa, Kenya and Somalia. The product has a low viscosity, smoky aroma and an astringent taste. Fresh milk is placed into previously smoked pumpkin vessels and is left for 2 days at a temperature of 25 to 30˚C in order to ferment (Lore et al., 2005). Thus we obtain a product of variable taste and aroma, which is often hygienically improper. The ember of specific wood such as Olea Africana or Acacia busia is used for smoking. It was established that the smoke improves the colour and taste, and prolongues the expiry date up to 20 days.
Farah et al., (1990) have studied the possibility of improving the traditional Suusac by adding mesophile dairy culture. In that case, milk is warmed up to 85˚C/30 min and cools to 22 – 25˚C. Then it is inoculated with 2 – 3 % dairy cultures and it incubates at 27-30˚C for 24 hours.
It is traditionally produced and consumed in Sudan and Somalia. Raw milk is placed into goatskin which is hung on camel’s saddle. The bags are usually covered with green grass or dry grass moistened by water, and then they are wrapped in firm net made of palm leaves. Owing to a specifically rough camel’s walk, during the journey the milk is shaken and stirred and the oxygen penetrates into the milk which has a significant role in fermentation. Fermentation is stimulated by adding several seeds of black cumin (Nigellica sativa) and an onion into the milk. Incubation lasts one day at a temperature of 25 to 30˚C.
Chemical Composition of Fermented Milk
The differences in chemical composition of these fermented milks depend on the influence of many internal and external factors such as breed, age, the health of the animal, genotype, stage of lactation, season, as well as availability of water and green animal feed. Fermented milk used as dairy culture and the process of preparing and conservation of the culture may also influence the chemical composition of the product .
Isolated Dairy Cultures
There are 48 kinds of lactic acid bacteria isolated and identified in Shubat. The dominant kinds were Lactobacillus (44 %), then Enterococcus (19 %), Kluyveromyces (14 %) and Leuconostoc (10 %). Lore et al., (2005) isolated 45 kinds of lactic acid bacteria from traditional samples of Suusac. Those were mostly Leuconostoc mesenteroides subsp. mesenteroides (24 %) and Lactobacillus plantarum (16 %). Owing to smoking and acacia wood burning. the pumpkin vessel presents a favourable environment for the development of such bacteria which can usually be found in plant fermentations. Lactobacillus fermentum, Lactobacillus plantarum, Lactococcus lactis, Enterococcus spp. and Leuconostoc spp. together with the dominant kind Lactobacillus paracasei subsp. paracasei were isolated and characterised in the microbe flora of
Gariss. By adding onion and black cumin seeds we create a favourable environment for the development of L. plantarum and probably inhibit the growth of other kinds of bacteria.