Agricultural and Marine Sciences, 18:7-24 (2013) Sultan Qaboos University 7 __________________________________________ *Corresponding author/E-mail: kadim@squ.edu.om Composition, Quality and Health Aspects of the Dromedary (Camelus dromedarius) and Bactrian (Camelus bacterianus) Camel Meats: A Review Isam T. Kadim1*, Osman Mahgoub1, Waleed Al-Marzooqi1, Samera K. Khalaf1, and Gulzhan Raiymbek2 1Department of Animal and Veterinary Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, PO Box 34, Muscat, Sultanate of Oman 2Al-Farabi Kazkh National University, Almaty, Kazakhstan السنام ذات اإلبل والصفات النوعية والصحية للحوم القيمة الغذائية عام استعراض والسنامني: الواحد خلف1 قاسم وسميرة املقبالي1 وربيع املرزوقي1 وليد و محجوب1 عثمان و كاظم1 عصام توفيق قوجلان رامبوك2 و ذات املناطق في وخاصة العالية الغذائية القيمة ذو للبروتني اجليدة املصادر من السنامني أو الواحد السنام ذات اإلبل تعتبر اخلالصة: حتملها تتضمن والتي فريدة وظيفية بصفات اإلبل تتميز األخرى. املزرعة حيوانات بقاء على تؤثر سلبياً والتي البيئية القاسية الطبيعة وقلة فيها تعيش التي للمناطق القاسية والطبوغرافيا املياه توفر وقلة املباشرة الشمس واشعة املنخفضة أو العالية احلرارة لدرجات من للحيوان انتهاء العمر االنتاجي بعد كبيرة أعمار عند وتذبح الغذائية متطلباتها توفر عدم مع تقليدية اإلبل بطرق تربى النباتي. الغطاء الدهون من %17 و من العظام %26 و العضالت من %57 على عامة بصورة اإلبل ذبائح حتتوي للسباق. صاحلة تعد لم التي انتاج احلليب أو من %1.2 و الدهن من %3 و البروتني من %19 املاء و من %78 من اإلبل حلوم للذبيحة. تتكون اخللفي بالربع مقارنة االمامي الربع مع ثقل اإلبل حلوم محتوى يعتبر البشر. من تغذية العدد املتزايد في الصحية الغذائية املواد من اإلبل للحوم قلة الدهون العضلية وتعتبر األمالح صنع ميكن عضالتها. الدهون في نسبة انخفاض بسبب احليوانات حلوم بقية من مثيالتها من أعلى املعدنية واألمالح األمينية األحماض من التربية طرق حتسني على املستقبلية البحوث تتركز أن يجب لذلك الغذائية. قيمتها لزيادة حلوم اإلبل والشاورما من والنقانق الهمبيرجر ولتسويق اللحوم ومنتجاتها. اإلبل حلوم تصنيع تقنية بتحسني االهتمام مع اللحوم إنتاج لزيادة اللحوم. تصنيع ، الكيميائي التركيب القيمة الغذائية ، النوعية ، الصفات ، مفتاحية: ابل كلمات ABSTRACT: The dromedary and bactrian camels are good sources of high quality protein especially in areas where the climate adversely affects the survival of other livestock. The camel has unique physiological characteristics, including a great tolerance to high and low tem- peratures, solar radiation, water scarcity, rough topography and poor vegetation. Camels are mostly produced under traditional systems on poor levels of nutrition and are mostly slaughtered at old ages after completing a career in work, racing or milk production. In general, camel carcasses contain about 57% muscle, 26% bone and 17% fat with fore-quarters (cranial to rib 13) significantly heavier than the hind halves. Camel lean meat contains about 78% water, 19% protein, 3% fat, and 1.2% ash with a small amount of intramuscular fat, which renders it a healthy food for growing human populations. The amino acid and mineral contents of camel meat are often higher than other meat animals, probably due to lower intramuscular fat levels. Camel meat has been processed into burgers, patties, sausages and shawarma to add value. Future research efforts need to focus on exploiting the potential of the camel as a source of meat through multidisciplinary research into efficient production systems and improved meat technology and marketing. Keywords: Camel, meat quality, nutritive value, meat composition, meat processing. Introduction The family Camelidae include two subfamilies: Camelinae (Old World Camelids) and Laminae (New World Camelids). The subfamily Camelidae includes two species: Camelus dromedarius and Camelus bacterianus. The dromedary or the one-humped camel (Camelus dromedarius) is mostly distributed in the hot arid areas of the Middle East, Asia and Africa, whereas the bactrian two-humped camel (Camelus 8 Kadim et al. 9 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review bacterianus) is found in central Asia, Kazakhstan, Russia and China (Dorman, 1986). The New World camelids consist of the following species: the guanaco (Lama guanacoe) and the vicuna (Vicugna vicugna), which are wild and the llama (Lama glama) and the alpaca (Lama pacos),which are domesticated and mainly found in South America (Murray, 1989). The camel was domesticated by secondary nomads around 5000 years ago in South Arabia primarily for transport and labour (Wilson, 1998). The dromedary is more abundant than the bactrian camel representing almost 90% of the genus Camelus. Phylogenetic analysis (micro-satellite loci) showed that camel breeds can be classified according to countries of origin (Mburu et al., 2003). The camel is an important domestic animal in various countries for producing valuable food and for its adaptation to extremely harsh environments (Kadim et al., 2008). It can survive on sandy terrain with poor vegetation and may chiefly consume feeds unutilized by other domestic species (Tandon et al., 1988). Therefore, the role of the camel as a meat producer is becoming more important due to the versatile role it plays rather than as a symbol of social prestige, which was the major role it used to play, and which has since greatly diminished (Dawood and Alkanhal, 1995). Camel meat is described as tough, coarse, watery and sweetish in taste compared to meats from other animals. This may be partly attributed to the fact that camel meat is usually a by-product of primitive traditional systems of production where it is mainly obtained from old males and females that have become less effective in their primary roles of providing transportation, milk, or as breeding females (Kadim et al., 2008). However, evidence suggests that the quality characteristics of camel meat are not much different from beef if animals are slaughtered at comparable ages (Khatami, 1970; Knoess, 1977; Elgasim et al., 1987; Tandon et al., 1988; Kadim et al., 2011). Although the marketing systems for camel meat are not well organised, there is evidence of a high demand for camel meat (Kadim et al., 2008). Camel meat could be a good source to meet the growing needs for meat in developing countries, especially for low income population groups (Kadim et al., 2008). Generally, camel meat is a significant source of animal protein and preferred over other meat animal species due both to the belief in it medicinal benefits and to its availability at affordable prices. This review outlines the nutritional and health value, quality characteristics and the availability of muscle bioactive compounds in dromedary and bactrian camel meats. A comparison of the nutritional properties of dromedary and bactrian camel meats with other species is also highlighted. Chemical Composition of Camel Meat Camel meat composition varies according to breed, age, sex, condition and location on the carcass. However, the composition of camel meat is generally similar to meat from other species where an inverse relationship existed between the moisture and protein and fat content of the meat (Table 1). Composition is an important indicator of meat functionality. For instance, moisture content plays an important role in keeping and eating qualities of camel meat (Kadim et al., 2008) whereas protein and fat contents dictate the manufacturing quality of meat. Table 1 shows that moisture content varies widely in camel meat (67.8 to 78.9%). Different muscles within the same camel carcass appear to have similar moisture contents (Babiker and Yousif, 1990; Gheisari et al., 2009; Kadim et al., 2013) as well as for the bactrian (Raiymbek et al., 2012a). However, the range of moisture content of Biceps femoris (74.3-78.5%) and Triceps brachii (77.7- 78.4%) muscles was higher than those from Longissimus dorsi muscle (72.1-73.8%) due to the higher fat content in the Longissimus thoracis muscle (Kadim et al., 2013; Raiymbek et al., 2012a). According to Kadim et al. (2006), the moisture content of dromedary camel meat decreases with the increases in the animal age. The differences between the maximum and minimum moisture contentsof camel Longissimus thoracis were 3.2, 6.4 and 12.3% for 1-3, 3-5 and 6-8 years age groups, respectively (Kadim et al., 2006). This indicates that the variation in moisture content within the samples is greater in older animals. Gheisari et al. (2009) found no differences in moisture content between camel meat and meat from other species at a similar age and sex. The protein content of camel meat is in the range of 17.0 to 23.7% (Table 1). There are slight differences between various muscles and different age groups (El- Faer et al. 1991; Kadim et al., 2006, 2012; Raiymbek et al., 2012a). Meat from young camels has similar protein content to those found in young cattle, lamb and goat meats (Elgasim and Alkanhal, 1992; Kadim et al., 2009b). The protein contents of six skeletal muscles (Semitendinosus, Infraspinatus, Semimembranosus, Biceps femoris, Triceps brachii and Longissimus thoracis) in dromedary and bactrian camels were studied by Kadim et al. (2013) and Raiymbek et al. (2012a). The highest protein content was found in the Semitendinosus muscle in bactrian, while the Semimembranosus contained the highest protein content in dromedary camel (Kadim et al., 2013; Raiymek et al., 2012a). Total collagen content is higher in camel Longissimus thoracis muscle than in Semitendinosus or Triceps brachii muscles, possibly due to morphological requirement for stabilizing the hump attached to the Longissimus thoracis (Babiker and Yousif, 1990). The fat content of camel meat ranged from 1.1 to 10.6 % (Table 1). Differences in the fat content in various camel muscles were reported (El-Faer et al., 1991; Elgasim and Alkanhal, 1992; Kadim et al., 2006, 2008, 2009a,b; Gheisari et al., 2009). An animal’s age has a great effect on the fat content, with camel meat from older animals’ containing higher fat compared with meat from younger animals (Kadim et al., 2006). The ash content in the dromedary and bactrian camel meats has been reported in the range of 0.75 to 8 Kadim et al. 9 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review 1.38% (Table 1). Ash content varies with muscles and between muscles (Babiker and Yousif, 1990; Dawood and Alkanhal, 1995; Gheisari et al., 2009; Kadim et al., 2013; Raiymbek et al., 2012a). Gheisari et al. (2009) found that age had a significant effect on ash content of camel meat, whereas others found no effect of age on ash content (El- Faer et al., 1991; Al-Shabib and Abu-Tarboush, 2004; Shehata, 2005; Kadim et al., 2006, 2008). Camel meat has relatively lower ash content than beef, lamb and goat meat (Elgasim and Alkanhal, 1992; Gheisari et al., 2009; Kadim et al., 2008). Amino Acid Composition According to Dawood and Alkanhal (1995), the essential amino acid content of camel meat is not affected by an animal’s age. Camel meat has a comparable essential amino acid contents to beef, lamb and goat meat (Table 2). The amount of camel meat required to supply the daily requirements of essential amino acids for adult consumer is similar to that from lamb (based on methionine which has the lowest content in meat) but is less than the amount required from beef. Table 2 shows that leucine (7.08 to 9.51% of protein) and lysine (8.33 to 9.85% of protein) are among the highest essential amino acids in camel meat. Essential amino acids contents of camel meat varied slightly among different muscle locations in the carcass. The essential amino acid contents in Longissimus dorsi and Semitendinosus muscles differed by >2.1% with the exception of leucine, methionine and tryptophan, which differed by 18.5, 25.4 and 14.6 %, respectively (Al- Shabib and Abu-Tarboush, 2004). Similarly, essential amino acid contents in the Infraspinatus, Longissimus dorsi and Semitendinosus muscles differed by > 4.2% with the exception of isoleucine, methionine, threnonine, tryptophane and valine which differed between 8 to 42% (Dawood and Alkanhal, 1995). On the other hand, differences in essential amino acids reported across Table 1. Chemical composition (%) of dromedary and bactrian camel muscles. Muscle Type Moisture Protein Fat Ash Dromedary camel Longissimus thoracis 73.8 19.0 6.2 0.85 Kadim et al. (2013) Infraspintus 73.2 18.2 5.3 0.96 Triceps brachii 77.7 17.1 1.9 1.00 Semitendinosus 75.4 18.5 3.1 0.91 Semimembranosus 63.0 22.1 2.5 0.93 Biceps femoris 74.3 20.8 2.5 1.00 Longissimus thoracis 65.7 19.5 2.1 1.20 Kadim et al. (2011) Longissimus thoracis 73.8 23.7 3.6 - Al-Bachir & Zeinou (2009) Biceps femoris 73.0 22.8 1.1 0.75 Gheisari et al., (2009) Triceps brachii 72.0 21.2 1.4 0.81 Longissimus dorsi 68.3 21.5 1.6 0.69 Biceps femoris 71.4 22.2 1.6 0.98 Triceps brachii 70.5 20.3 2.4 1.06 Longissimus dorsi 67.8 20.5 2.5 0.95 Longissimus thoracis 74.8 21.1 2.8 1.34 Kadim et al. (2009a) Longissimus thoracis 71.7 22.7 4.4 1.10 Kadim et al. (2006) Longissimus dorsi 75.9 21.6 1.4 1.05 Babiker and &Yousif (1990)Semitendinosus 75.8 21.4 1.4 1.38 Triceps brachii 75.2 22.1 1.4 1.22 Bactrian camel Longissimus thoracis 72,1 17.0 10.0 0.9 Raiymbek et al. (2012a) Infraspintus 78.5 18.0 2.5 1.0 Triceps brachii 78.4 17.5 3.0 1.0 Semitendinosus 78.0 18.8 2.2 1.0 Semimembranosus 79.0 18.2 2.0 1.0 Biceps femoris 78.5 18.3 2.1 1.1 10 Kadim et al. 11 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review different camel muscles ranged between 0.5 to 9.5% (Elgasim and Alkanhal, 1992; Dawood and Alkanhal, 1995; Al-Shabib and Abu-Tarboush, 2004). Tryptophan concentration in camel meat was lower than in other meats (Dawood and Alkanhal, 1995). Al-Shabib and Abu- Tarboush (2004) reported that tryptophan concentration was 1.76% of the total amino acids, which was higher than the 1.28% reported for beef (Kadim et al., 2008). The glutamic and aspartic acids, the major non- essential amino acids in camel meat ranged from 15.95 to 18.60% and from 9.30 to 10.80% of protein, respectively (Table 3). Similar to the essential amino acids, non- essential amino acid content also varied slightly between muscles, and larger variations are found between studies. In general, camel meat maybe a better source of non- essential amino acids than beef, lamb, and goat meats (Table 3). Although, Elgasim and Alkanhal (1992) found low alanine levels in camel meat compared to other red meats, Dawood and Alkanhal (1995), Al-Shabib and Abu- Tarboush (2004) and Kadim et al. (2011) found similar concentration of alanine in camel meats and other red meats. Fatty Acid Composition The fatty acid composition of meat is of great concern to consumers due to its important effects on human health. Reduction of saturated fatty acid intake is very important to prevent obesity, hypercholesterolemia and to decrease the risk of cancer (Chizzolini et al., 1999). On the other hand, diets containing lipids with a high level of monounsaturated fatty acids and polyunsaturated fatty acids have been shown to be effective in lowering serum cholesterol levels (Mensink and Katan, 1989). Rawdah et al. (1994) identified 22 fatty acids in camel meat (Table 5). Major fatty acids in camel meat were also reported by Al-Bachir and Zeinou (2009) and Kadim et al. (2011). Rawdah et al. (1994) reported levels of 18.93% oleic (C18:1) and 12.07% linoleic acid (C18:2) in the camel meat. However, about twice the percentage of oleic (C18: 1) and less than half the percentage of linoleic acid (C18: 2) were reported by Al-Bachir and Zeinou (2009) and Kadim et al. (2011). Linoleic acid is derived entirely from the diet (Wood et al., 2008) and such differences are not unexpected from studies from different regions. The major saturated, monounsaturated and polyunsaturated fatty acids in camel meat are (C16:0), (C18:1) and (C18: 2), respectively (Table 4). The variation of total saturated fatty acids (51.5-53%) was small in comparison to monounsaturated (29.9 and 41.4%) and polyunsaturated (5.6% and 18.6%) fatty acids, which is in agreement with Rawdah et al. (1994) and Kadim et al. (2011). The fatty acid composition, total saturated, unsaturated, monounsaturated and polyunsaturated fatty acids of Infraspintus, Triceps brachii, Longissimus Table 2. Essential amino acid composition in camel meat (mg/100g). Amino acid1 His Ileu Leu Lys Met Phe Thr Trp Val Longissimus thoracis 4.4 4.7 8.3 9.4 2.9 4.3 4.5 - 5.6 Kadim et al. (2011) Longissimus Dorsi 3.4 4.2 7.1 9.1 1.6 5.6 4.8 1.6 4.7 Al-Shabib &Abu-Tarboush (2004)Semitendinosus 3.4 4.3 8.4 9.1 1.3 5.5 4.8 1.9 4.6 Infraspinatus 4.7 5.3 8.6 8.4 2.6 4.1 4.2 0.5 4.9 Longissimus Thoracis 4.3 5.4 8.3 8.6 2.2 4.4 4.7 0.7 5.3 Dawood & Alkanhal (1995) Semitendinosus 4.5 4.9 8.3 8.3 2.5 4.2 4.2 0.6 5.4 Longissimus dorsi & Semitendinosus 5.6 5.9 9.5 8.9 3.6 4.7 4.8 - 6.3 Elgasim & Alkanhal (1992) Camel 5.6 5.9 9.5 8.9 3.5 4.7 4.8 - 6.3 Beef 6.2 6.5 10.7 9.1 2.7 5.7 5.5 - 6.6 Lamb 5.9 5.8 9.6 8.5 3.3 4.9 4.2 - 5.9 Goat 4.7 6.0 7.9 10.9 3.9 6.5 4.4 - 6.8 Camel 3.4 4.3 7.7 9.1 1.4 5.5 4.8 1.8 4.7 Al-Shabib &Abu-Tarboush (2004) 1Amino acids: His - Histidine, Ileu - Isoleucine, Leu - Leucine, Lys - Lysine, Met - Methionine, Phe - Phenylalanine, Thr - Threonine, Trp - Tryptophane, Val - Valine 10 Kadim et al. 11 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review Table 3.Non-essential amino acid composition in camel meat (mg/100g). Amino acid1 Ala Arg Asp Glu Gly Pro Ser Tyr Longissimus thoracis 6.5 6.6 9.3 15.9 4.3 3.9 3.6 3.5 Kadim et al. (2011) Infraspinatus 6.3 7.5 9.3 17.1 6.0 5.4 3.5 3.0 Dawood & Alkanhal (1995)Longissimus dorsi 6.2 7.1 9.3 17.3 5.9 4.9 3.8 3.4 Semitendinosus 6.3 7.5 8.6 16.4 5.9 5.9 3.6 3.3 Longissimus dorsi and Semitendinosus 3.9 7.1 10.8 18.6 6.1 3.9 3.2 3.8 Elgasim &Alkanhal (1992) Camel 3.9 7.1 10.8 18.6 6.1 3.9 3.2 3.8 Beef 7.7 7.1 10.8 16.5 6.2 4.5 4.2 4.1 Lamb 6.7 6.9 10.3 17.9 5.5 3.8 2.9 3.5 Goat 4.7 7.1 10.8 15.6 5.2 3.8 3.6 5.9 Camel 6.5 6.9 9.7 17.0 6.2 - 4.3 3.3 Al-Shabib & Abu Tarboush (2004) 1Amino acid: Ala - Alanine, Arg- Arginine, Asp - Aspartic acid, Glu - Glutamic acid, Gly - Glycine, Pro - Prolene, Ser - Serine, Tyr - Ttyrosine Table 4. Fatty acids composition (%) of the Infraspinatus (IS), Triceps brachii (TB), Longissimus thoraces (LT), Semitendinosus (ST), Semimembranosus (SM), and Biceps femoris (BF) muscles of the dromedary camel (Kadim et al., 2013). Muscle IS TB LT ST SM BF SEM1 Saturated fatty acid 12:0 1.71c 1.42 1.13a 1.66 1.53 1.44 0.186 13:0 1.22 1.13 1.24 1.24 1.24 1.21 0.066 14:0 7.62 7.78 7.16 7.24 7.48 7.83 0.544 15:0 2.32 2.14 2.39 2.40 2.35 2.12 0.095 16:0 27.64 27.26 26.92 25.09 26.45 26.16 2.378 17:0 2.38 2.17 2.46 2.21 2.38 2.15 2.088 18:0 8.79 8.90 9.82 8.71 8.37 8.02 2.277 20:0 0.08 0.03 0.09 0.02 0.04 0.03 0.022 21:0 0.03 0.00 0.03 0.01 0.01 0.00 0.007 22:0 0.02 0.01 0.02 0.01 0.00 0.02 0.004 Mono-unsaturated fatty acids 14:1 1.63 1.62 1.35 1.73 1.63 1.62 0.112 15:1 1.04 1.03 1.01 1.01 1.03 1.02 0.051 16:1 8.88 8.56 8.25 8.79 8.66 8.57 2.233 17:1 0.16 0.14 0.14 0.15 0.11 0.11 0.039 C18:1n9 25.04 26.26 26.21 26.42 26.80 26.88 2.182 Poly-unsaturated fatty acids C18:2n6 7.14 7.83 7.11 7.79 7.98 7.94 0.207 C18:3n3 0.64 0.43 0.59 0.62 0.54 0.54 0.122 C20:2 0.52 0.34 0.62 0.64 0.43 0.42 0.016 C20:3n6 0.33 0.23 0.34 0.43 0.42 0.41 0.009 C20:4n6 2.81 2.72 2.84 2.83 2.55 3.51 0.033 Total saturated FA (SFA) 51.81 50.84 51.26 48.59 49.85 48.98 8.942 Total unsaturated FA (USFA) 48.19 49.16 48.74 50.41 50.15 51.02 2.311 Total Mono- unsaturated FA (MUSFA) 36.75 37.61 37.24 38.10 38.23 38.20 2.174 Total Poly - unsaturated FA (PUSFA) 11.44 11.55 11.50 12.31 11.92 12.8 0.217 SFA: USFA 1.08 1.03 1.05 0.96 0.99 0.98 3.869 SFA: MUSFA 1.41 1.35 1.38 1.28 1.30 1.28 4.113 SFA: PUSFA 4.54 4.40 4.46 3.95 4.18 3.82 4.120 1SEM: standard error for the mean. Means on the same row with different superscripts are significantly different (P<0.05). 12 Kadim et al. 13 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review thoraces, Semitendinosus, Semimembranosus, and Biceps femoris muscles of the dromedary was studied by Kadim et al. (2013) (Table 5). The fatty acid composition of the six muscles was generally similar with the exception of palmitic and oleic fatty acids. The Semitendinosus muscle had lower palmitic acid than Infraspintus, Triceps brachii, Longissimus thoraces and Semimembranosus muscles. The Infraspintus muscle contained lower oleic acids than other muscles. Of the six muscles studied, palmitic acid is the most abundant saturated fatty acid in camel intramuscular fat, followed by stearic acid, and myristic acid. The main monounsaturated fatty acids in the six muscles were oleic acid followed by palmitoleic acid. The main polyunsaturated fatty acids in the muscles were linoleic acid and archidonic acid. The percentage of polyunsaturated fatty acids in camel meat (18.6%) was within the range reported for beef (8.8%) and buffalo (28.6%) and deer (31.4%) (Sinclair et al., 1982). The ratio of linoleic and linolenic acids in camel meat is about 10.9 which is much higher than that of the meat of cattle, sheep or goat (2.0, 2.4 and 2.8, respectively) (Sinclairb et al., 1982). The camel hump is commonly used as cooking oil in camel producing countries. On a fresh weight basis, the camel hump is composed of about 64.2-84.8% fat, with a very high content of saturated fatty acids of about 63.0% (Rawdah, et al., 1994; Kadim et al., 2002). Researchers, therefore, focused on the composition of the hump (Mirgani, 1977; Emmanuel and Nahapetian, 1980; Abu-Tarboush and Dawood, 1993; Kadim et al., 2002). Palmitic acid, stearic acid and oleic acid are the most abundant fatty acids in the hump. The composition of the hump fatty acids is affected by the animal age. The highest percentage of unsaturated fatty acids and lowest percentage of saturated fatty acids were in animals of less than one year whereas an opposite trend was in animals in the 1-3 years old age group (Kadim et al., 2002). Mineral Composition Minerals are generally classified as essential elements that are required for growth and health or toxic elements, which pose health risk to animals and humans. Both the deficiency and excess intake of essential elements as well as exceeding the safe limits of toxic elements can be detrimental to human health. Table 6 gives essential mineral contents of various cuts of camel meat by various authors. Calcium content (mg/100g fresh weight) was reported to be in the range of 4.9- 11.48 (Table 6). The level of variation reported by Kadim et al. (2006; 2011), indicates that physiological factors play a major role in determining the calcium contents in camel meat. Small variations in calcium content are found among different meat cuts (Table 6). The calcium content between different meat cuts range from 10 to 27% (Dawood and Alkanhal, 1995; Rashed, 2002) Cobalt and chromium contents were in the range of 0.003-0.004 and 0.008- 0.03 (mg/100g fresh weight) (Kadim et al., 2006). Copper contents in camel meat ranged between 0.04 to 0.12 mg/100g fresh weight (Table 6). The foreleg contains a higher copper content compared with other meat cuts (Rashed, 2002). The iron content in camel meat (1.16-3.39 mg/100 g fresh meat) varied among different meat cuts (Table 6) which is most probably due to the different physiological requirements of myoglobin of different muscles. As with other red meat species, meat cuts containing oxidative muscles (e.g. leg and neck) have a higher iron content than glycolytic muscles. Potassium is the major element in camel meat (193.4-379.1 mg/100g fresh weight) and magnesium content in camel meat ranges between 10.41- 21.03 mg/100g fresh weight (Kadim et al., 2009). Meat cuts from the limbs have higher potassium and magnesium content compared with the loins and ribs (Table 6). Meat from Saudi Arabian camels contained similar manganese content (0.01 mg/100g fresh weight) across four different meat cuts (El-Faer et al., 1991; Elgasim and Alkanhal, 1992). However, meat from camels in Egypt appears to have higher manganese content (mg/ 100g dry matter) and the concentration varied among different meat cuts (Rashed, 2002). The sodium content in Table 5. Fatty acid composition of the fat in camel meat. Fatty acids (%) Rawdah et al. (1994) Al-Bachir and Zeinou (2009) Kadim et al. (2011) Saturated (S) 14:0 7.68 4.53 3.10 15:0 1.66 - 2.10 16:0 25.98 30.29 28.50 17:0 1.48 2.54 - 18:0 8.63 25.51 19.30 Monounsaturated (MUS) 14:1 1.0 - 1.60 16:1 8.06 - 6.30 17:1 0.94 - - 18:1 18.93 32.01 33.50 20:1 trace - - Polyunsaturated (PS) 18:2 6 12.07 5.13 3.20 20:2 6 0.11 - - 18:3 3 0.52 - 1.20 20:3 9 0.37 - - 20:3 6 0.30 - - 20:4 6 2.84 - 1.20 22:4 6 0.10 - - 20:5 3 0.32 - - 22:5 3 0.48 - - 22:6 3 0.10 - - P/S 0.36 - 0.11 Total saturated 51.54 - 53.00 Total MUSFA 29.90 41.40 Total PUSFA 18.55 - 5.60 3/ 6 0.092 - - w w w w w w w w w w w w 12 Kadim et al. 13 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review camel meat was in the range of 40.2-87.3 mg/100g (Table 7). The loin cuts had the lowest sodium content among the different meat cuts (Elgasim and Alkanhal, 1992; Rashed, 2002; Kadim et al., 2006). Phosphorus is the second most abundant element in camel meat (105.6-199.0 mg/100g fresh weight) and the leg and shoulder cuts have a slightly higher phosphorus content than ribs and neck cuts (El- Faer et al., 1991). The sulfur content was in the range of 54.99-136.57 mg/100g fresh weight. The sulfur content in four meat cuts varied by 17% only (El-Faer et al., 1991). Red meat is an important source of zinc. Camel meat contains about 3.07 to 4.80 mg/100g fresh weight (Table 6). The variation between different cuts was 7.6% (Dawood and Alkanhal, 1995) but a higher percentage of variation (47-56%) has been reported in other studies (El- Faer et al., 1991; Rashed, 2002). The mineral concentrations of Infraspinatus, Triceps brachii, Longissimus thoraces, Semitendinosus, Semimembranosus, and Biceps femoris muscles of the dromedary (Kadim et al., 2013) and bactrian camels (Raiymbek et al., 2012) are presented in Table 7. The phosphorus magnesium, sodium, potassium and iron contents of camel muscle samples varied between muscles. The Triceps brachii muscles and had the highest mean value of phosphorus, calcium, magnesium and potassium (Table 7). The Semitendinosus muscle in the dromedary and bactrian camels had more magnesium than Infraspinatus, Triceps brachii, Longissimus thoracis, and Biceps femoris muscles. The Semitendinosus and Semimembranosus muscles had more iron than other muscles in the dromedary. The Longissimus thoracis muscle had a lower and the Triceps brachii higher (P<0.05) potassium than other muscles (Table 7). For trace elements (zinc, iron, lead, selenium, copper), there was small variation between the muscles of dromedary and bactrian camels (Table 7). Table 6. Mineral concentrations in camel meat (mg/100g fresh weight. Mineral1 Factor Ca Co Cr Cu Fe K Mg Mn Mo Na P S Zn Rump - 0.004 - 0.12 2.5 - - - 0.04 - - - - Badiei et al. (2006) Intercostal 8.5 0.29 0.42 0.13 51.0 515 29.5 0.19 - 300.5 - - 74.0 Rashed (2002) Scapula 10.0 0.35 0.32 0.21 54.5 670 51.0 0.22 - 225.0 - - 58.0 Sirloin 10.2 0.27 0.41 0.16 44.0 446 28.0 0.16 - 188.5 - - 66.0 Flank 8.4 0.32 0.33 0.12 49.0 811 49.5 0.19 - 223.0 - - 69.5 Front knuckle 8.4 0.26 0.42 0.25 44.5 630 37.0 0.17 - 299.5 - - 73.5 Front limb 9.8 0.19 0.37 0.26 50.5 548 42.5 0.19 - 312.5 - - 85.5 Chuck 11.5 - - - 3.2 249 17.4 - - 73.5 - - 3.7 Dawood &Alkanhal (1995) Ribeye 8.1 - - - 2.9 231 16.3 - - 67.1 - - 3.7 leg 10.3 - - - 3.4 251 17.1 - - 69.7 - - 3.9 Leg+loin 4.9 - - 0.04 1.9 228 17.7 0.01 - 47.9 - - 3.2 Elgasim &Alkanhal (1992)2 Shoulder 5.1 - 0.01 0.07 1.2 357 20.6 0.01 - 69.1 196 56.1 3.5 El-Faer et al. (1991) Thigh 5.4 - 0.01 0.09 1.4 361 21.0 0.01 - 70.4 199 55.0 3.1 Ribs 4.7 - 0.01 0.07 1.2 324 18.5 0.01 - 84.1 181 58.0 3.9 Neck 5.6 - 0.03 0.09 1.4 338 18.5 0.01 - 87.3 181 64.4 4.8 Effect of specie Camel 5.9 0.003 0.008 - - 193 12.9 - 0.08 45.3 105 - - Kadim et al. (2009a)Beef 6.2 0.003 0.009 - - 416 20.5 - 0.006 51.0 162 - - Camel 4.9 - - 0.04 1.94 228 17.7 0.01 - 47.9 - - 3.2 Elgasim & Alkanhal (1992)Beef 6.97 - - 0.06 2.66 277 24.8 0.02 - 31.2 - - 4.1 1Mineral: Ca - Calcium, Co - cobalt, Cr - Chromium, Cu - Copper, Fe - Iron, K- Potassium, Mg - magnesium, Mn - Manganese, Mo - Molybdenum, Na - Sodium, P - Phosphorus, S - Sulfate, Zn -Zinc 14 Kadim et al. 15 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review camel blood concluded that camels could be less efficient than other ruminants in detoxifying these elements in its body (Al-Qarawi and Ali, 2003).The monitoring of toxic material levels in camel products should pay particular attention to toxic compounds in the offal because this is consumed by low income people as a source of animal protein (Faye et al., 2008). Nutrition, management, breed, sex and age of animals play an important role in determining the level of various elements in the meat and the camel blood (Faye et al., 2008). For instance, the calcium content in the camel The concentrations of silver, gold and nickel in five camel meats have been reported at 0.06-0.12, 0.10-0.21 and 0.05-0.38 mg/100g dry matter, respectively (Rashed, 2002). The concentration of the three minerals varied among different muscles by 100, 110 and 750% (Table 8). The concentrations of nickel, beryllium and vanadium increased in the dromedary camel Longissimus thoracis with increasing animal age (Kadim et al., 2006). The level of lead in camel Longissimus thoracis was 2.5 times the concentration in beef Longissimus thoracis (Kadim et al., 2009). Studies on the levels of trace and heavy elements in Table 7. Macro and micro-element levels (mg/100g) in Infraspinatus (IS), Triceps brachii (TB), Longissimus thoraces (LT), Semitendinosus (ST), Semimembranosus (SM), and Biceps femoris (BF) muscles of the dromedary (Kadim et al., 2013) and bactrian camels (Raiymbek et al., 2012b). Dromedary Bactrian Muscle Muscle IS TB LT ST SM BF IS TB LT ST SM BF Phosphorus 6.49 7.76 5.23 6.39 7.96 6.79 3.32 3.72 2.29 3.97 3.66 3.74 Calcium 0.07 0.08 0.05 0.07 0.08 0.07 0.05 0.05 0.05 0.05 0.05 0.05 Magnesium 1.73 2.21 1.37 3.39 2.17 1.84 2.48 3.03 2.51 3.5 3.27 3.45 Sodium 6.33 5.98 5.18 7.38 5.78 6.93 5.01 4.57 3.59 5.78 4.93 5.16 Potassium 81.7 103 25.2 71.3 80.9 85.6 74.4 80.5 36.9 80.0 77.7 73.5 Zinc 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.01 0.02 0.02 0.02 Iron 0.02 0.06 0.03 2.42 2.52 0.05 0.06 0.08 0.05 0.08 0.12 0.08 Lead 0.001 0.01 0.01 0.01 0.03 0.002 0.03 0.03 0.03 0.03 0.03 0.02 Selenium 0.003 0.003 0.004 0.004 0.003 0.003 - - - - - - Copper 0.002 0.001 0.001 0.05 0.07 0.004 0.002 0.002 0.004 0.002 0.002 0.001 1SEM: standard error for the mean. Means on the same row with different superscripts are significantly different (P<0.05). Table 8. Toxic/non-essential elements concentrations (mg/100g) of fresh weight. Mineral1 Factor Ag Al Au Cd Ni Pb Sr Effect of meat cut Intercostal 0.07 - 0.11 - 0.24 - - Rashed (2002) Scapula 0.06 - 0.10 - 0.38 - - Sirloin 0.11 - 0.19 - 0.05 - - Flank 0.09 - 0.12 - 0.13 - - Front knuckle 0.12 - 0.17 - 0.19 - - Front limb 0.11 - 0.21 - 0.21 - - Shoulder - 0.51 - - - - 0.02 El-Faer et al. (1991) Thigh - 0.15 - - - - 0.03 Ribs - 0.12 - - - - 0.02 Neck - 0.58 - - - - 0.03 Effect of specie Camel - - - 0.003 0.025 0.015 - Kadim et al. (2009b) Beef - - - 0.003 0.044 0.006 - 1Mineral: Ag - Silver, Al - Aluminum, Au - gold, CD - cadmium - Ni - nickel, Pb - Lead, Sr - Strontium 14 Kadim et al. 15 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review meat reported from the same laboratory (Kadim et al., 2006; 2011) or across different laboratories (Dawood and Alkanhal, 1995; Kadim et al., 2006) supports this contention. It is worth mentioning that the biological variation of elements even within the same herd that has a similar farming background is very high (Kadim et al., 2006). Meat Quality Characteristics Camel meat is often regarded as inferior to other meats. This might be attributed to the strong reluctance of camel owners to sell their young stock, and they usually slaughter older camels at the end of their productive life. Most camel meat trade is of meat from old camels with a low quality, which has a direct bearing on the extent of demand for meat outside the camel herding societies. However, numerous studies have reported that meat quality characteristics from young dromedary camels are comparable to those of beef (Leupold, 1968; Fischer, 1975; Knoess, 1977; Mukasa-Mugerwa, 1981; Kadim et al., 2006, 2009; Shariatmadari and Kadivar, 2006). Nevertheless, camel meat had a significantly lower level of sarcoplasmic proteins as a proportion of total proteins than beef (Babiker and Tibin, 1986). Camels 2-4 years-old and beef 2-3 years-old had similar meat quality characteristics of the Longissimus thoracis muscle (Kadim and Mahgoub, 2008). The camel Longissimus thoracis, Semitendinosus and Triceps brachii muscles lose more water during cooking than beef (48% vs. 37%) while no tenderness differences were observed between the two species (Kamoun, 1995a,b). In contrast, Babiker and Tibin (1986) reported that camel meat has less cooking losses and higher water holding capacity than beef meat. The effect of age on meat quality is discussed in order to optimize the best age for slaughtering camel for high quality meat. Table 9 depicts the effect of camel age on meat quality parameters and shows that meat becomes less tender and of inferior quality with increasing animal age (Kadim et al., 2006). However, Kamoun (1995a,b) noted that age is not a predominant factor in meat quality, in the case of dromedarius fed the same diet and slaughtered between one and four years of age. Kadim et al. (2006) suggested that the male camels should be slaughtered between one to three years of age. This is in agreement with the conclusion of Dina and Klintegerg (1977). At this age the animals were not yet fully grown, averaging about 60-70% of full live weight, and therefore, their meat is tender. Meat quality parameters of Longissimus thoracis and Biceps femoris muscles inf our Indian camel breeds was compared by Suliman et al. (2011), and the results indicated little variation between the four breeds (Table 10). The shear force values in Longissimus thoracis muscles ranged from 6.45 kg in Magahem to 14.32 kg in Shoal, while in Biceps fermoris muscles the ranges were between 19.44 kg for Wodoh to 23.3 for Shoal. On the other hand, various breeds exhibited a similar myofibrillar fragmentation index, ultimate pH and sarcomere length for both Longissimus thoracis and Biceps femoris (Table 10). Muscles of the loin region were tenderer than those from the leg. The eating quality of six muscles of the dromedary camel was studied by Kamoun (1995b) who concluded that the Vastuslateralis muscles had the highest weight and volume losses (51.1 and 47.8%, respectively) whereas Psoas major muscles had the lowest (44.6 and 41.1%, respectively) (Table 11). The Triceps brachii and Vastuslateralis muscles contained more soluble collagen than Semitendinosus, Psoas major, Longissimus thoracis and Semimembranosus muscles, possibly indicating a less thermal stable bond between collagen molecules and weaker connective tissue structures of those muscles (Kamoun, 1995b). Although all six muscles studied by Kamoun (1995b) were ranked acceptable for tenderness, the Longissimus thoracis muscle was tenderer and had less detectable connective tissue than the other muscles. The Longissimus thoracis muscle had the highest juiciness score and the Semitendinosus and Vastuslateralis muscles were less juicy than Psoas major, Semimembranosus and Triceps brachii muscles. Ultimate Muscle pH The ultimate pH of muscles is a consequence of lactic acid accumulation via glycolysis that affects meat quality characteristics (Simek et al., 2003). According to Laack et al. (2001), 40-50% of variation in ultimate pH is determined by glycogen concentration. It needs 0.81g/100g of glycogen to lower the pH of one kg of muscle from 7.2 Table 9. Effect of age on some meat quality characteristics of the dromedary camel Longissimus thoracis muscle. Kadim et al. (2006) Kadim et al. (2009b) Age group (yr) Age group (yr) 1-3 3-5 5-8 1-2 8-10 Ultimate pH 5.91 5.84 5.71 5.68 5.65 WB- Shear force value (Newton) 68.4 79.5 131.9 66.1 87.3 Sarcomere length (µm) 1.85 1.24 1.06 1.66 1.60 Myofibrillar fragmentation Index (%) 80.99 73.3 60.4 72.2 67.3 Expressed juice (cm2/g) 29.6 27.36 21.26 38.1 37.4 Cooking loss (%) 26.06 23.72 22.42 23.4 22.0 Colour parameters L* (lightness 37.74 34.03 31.69 39.1 38.1 a* (redness 13.37 13.82 16.18 16.5 15.6 b* (yellowness) 6.09 6.78 7.26 5.58 6.29 16 Kadim et al. 17 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review pH in camel muscles is a consequence of low muscle glycogen as a result of pre-slaughter stress, including, poor nutrition, rough handling and long transportation. The ultimate pH has an effect on several meat properties like colour, tenderness, water-holding capacity, flavor, and drip loss all of which influences consumer acceptance of camel meat. Glycogen degradation speed differs between “red” and “white” muscles. Red muscles have many red fibres, which contract slowly, have an oxidative metabolism and a low concentration of glycogen. White muscles contract rapidly and have a high concentration of glycogen, normally with a glucolytic metabolism and an active degradation to lactic acid (Lawrie, 2006). The ultimate pH of dromedary camel meat ranges between 5.5 and 6.6 (Babiker and Yousif, 1990; Kadim et al., 2006, 2009a,b, 2010, 2013). Generally, young camels tend to produce meat with a higher pH than older camels due to lower levels of glycogen. In this respect, Kadim et al. (2006) found that camels younger than three years had a pH value (5.91) which was higher than camels older than six years (5.71). The ultimate pH of Longissimus thoracis muscles varied between 5.53 and 5.75 and between 5.68 and 5.80 for electrically stimulated and non-stimulated camel carcasses, respectively (Kadim et al., 2009a). The breed of camels did not differ in terms of ultimate pH in Longissimus thoracis and Biceps femoris muscles (Suliman et al., 2011). Tenderness (Shear Force Value) Tenderness is the most important organoleptic characteristic and is the predominant quality determinant of meat compared to flavor and colour (Koohmaraie, to 5.5 (Warris, 1990). The ultimate pH of camel muscles is the result of a combination of many factors including pre-slaughter handling, postmortem treatment, glycogen storage and muscle physiology. Low muscle glycogen stores at slaughter prevents the development of a desirable pH postmortem (Ashmore et al., 1973). A high ultimate Table 10. Effect of Camel breed on some meat quality characteristics of the dromedary camel Longissimus thoracis and Biceps femoris muscles (Suliman, et al., 2011). Breed Magahem Wodoh Shoal Sofor Muscle1 Muscle1 Muscle1 Muscle1 LT BF LT BF LT BF LT BF Ultimate pH 5.76 5.90 5.87 5.90 5.91 5.82 6.07 6.03 WB- Shear force value (kg) 6.45 23.32 13.73 19.44 14.32 23.25 10.40 22.77 Sarcomere length (µm) 1.69 1.68 1.68 1.66 1.64 1.69 1.65 1.67 Myofibrillar fragmentation index (%) 71.6 62.4 66.2 60.9 65.4 63.0 67.0 61.2 Cooking loss (%) 23.7 28.3 21.9 26.0 22.9 31.2 22.4 28.7 Colour parameters L* (lightness) 31.6 30.0 33.4 28.1 31.6 31.2 31.2 29.7 a* (redness) 11.8 13.3 13.0 13.6 12.8 13.4 15.0 13.1 b* (yellowness) 4.03 4.07 4.74 3.91 4.43 4.26 4.85 3.91 1Muscle: LT - Longissimus thoraces, BF - Biceps femoris. Table 11. Eating quality attributes of the six major muscles (Kamoun, 1995b). Parameter Muscle1 PM LT SM ST VL TB Myoglobin (mg/g) 3.9 4.1 5.8 3.4 4.1 5.1 Collagen (mg/g) 3.3 4.1 5.0 7.5 6.6 5.6 Sensory tenderness 7.2 6.6 3.7 3.6 1.9 3.9 Collagen soluble (%) 29 29 30 34 42 41 Sensory juiciness 6.2 6.8 5.2 3.8 4.1 5.8 Cooking weight loss (%) 45 45 49 48 51 51 Cooking volume loss (%) 41 42 46 44 48 45 1Muscle: PM - Psoas major, LT - Longissimus thoracis, SM - Semimembranosus, ST - Semitendinosus, VL - Vastus lateralis, TB - Triceps brachii. 16 Kadim et al. 17 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review 1988). Muscle characteristics, glycogen content, collagen content, solubility, and the activities of proteases and their inhibitors are the most important physiological parameters that determine meat tenderness (Hocquette et al., 2005). Major variation in meat tenderness is related to the variability of muscle characteristics (Renand et al., 2001). The Longissimus thoracis muscle had more soluble collagen than the Semitendinosus and Triceps brachii muscles (Kamoun et al., 1995b). The Triceps brachii muscle had the highest shear force values, maximum connective tissue strength and lowest collagen solubility compared to Longissimus thoracis, Semitendinosus, Semimembranosus, Psoas major and Vastuslateralis in camels, indicating that it is the toughest muscle in this group (Babiker and Youssif, 1990) The Psoas major and Longissimus thoracis muscles were the most tender and had less detectable connective tissue than other muscles. In another study, Kadim et al. (2013) found that Infraspinatus, Triceps brachii and Longissimus thoracis camel muscles had lower shear force values than semitendinosus, semimembranosus and biceps femoris muscles, which might be due to less connective tissue (Table 12). Raiymbek et al. (2012) reported a similar observation for bactrian camel muscles (Table 12). The tenderization process starts after slaughter and it varies among individual carcasses and depends on the postmortem activity of the calpainproteolytic enzymes that include calpastatin (Parr et al., 1999). The most marked difference in meat quality characteristics between camel meat and other livestock is largely believed to be tenderness (Mukasa-Mugerwa, 1981). Camels are usually slaughtered at the end of their productive life (more than10 years) which is classified as of low quality compared with meant from other animals. Average shear force value of camel meat at 5-8 years was 48% and 40% higher than those of 1-3 and 3-5 year olds, respectively (Kadim et al., 2006). A number of studies have also shown that shear values of meat increase with increasing camel age (Dawood, 1995; Kadim et al., 2006). Differences due to age may be related to changes in muscle structure and composition as an animal matures, particularly in the nature and quantity of connective tissue (Asghar and Pearson, 1980), Significant differences (P<0.05) were found between the different ages (8, 16 and 26 months of age) and cuts (chuck, ribeye and leg) for shear force values of male Nahdi camels (Dawood, 1995). Aging Historically, meat has been aged to improve its quality characteristics because meat is often unacceptably tough immediately following rigor onset. Ageing is the process that causes an improvement in tenderness, flavour, colour and texture over time and involves specific degradation of structural proteins (Hwang et al., 2003; Jaturasitha et al., 2004). The time required for ageing varies with the type, size, species, and age of the animal. Moderate temperature Table 12. Meat quality characteristics of six muscles of the dromedary and bactrian camel carcasses. References Kadim et al. (2013) Raiymbek et al. (2012) Muscle1 Muscle1 IS TB LT ST SM BF IS TB LT ST SM BF Age (yr) 1.5-2 2-3 Ultimate pH 5.64 5.73 5.61 5.67 5.83 5.74 5.73 5.69 5.63 5.68 5.60 5.68 WB-Shear Force 34.8 42.1 41.8 36.8 42.4 40.2 10.8 8.9 6.0 10.0 9.8 8.6 Sarcomere length (µm) 31.6 29.2 33.5 28.5 30.6 29.5 1.45 1.54 1.70 1.47 1.53 1.52 Myofibrillar fragmentation index (%) 6.3 6.7 6.5 9.0 12.9 10.3 76.8 76.9 73.9 77.7 76.7 78.4 Water-holding capacity 1.7 1.7 1.7 1.5 1.4 1.5 38.2 37.9 37.1 40.4 41.3 38.8 Cooking loss (%) 31.6 29.2 33.5 28.5 30.6 29.5 32.7 32.6 25.1 34.3 33.9 32.1 Colour L* 41.7 40.2 43.5 40.5 40.6 40.6 32.4 30.8 33.4 30.2 30.8 30.1 a* 12.7 12.6 14.0 10.5 13.6 13.3 13.2 13.1 13.8 12.8 13.8 13.5 b* 2.6 3.7 4.1 2.2 2.9 3.8 3.8 3.4 3.9 3.2 3.5 3.6 1Muscle: IS - Infraspintus, TB - Triceps brachii, LT - Longissimus thoracis, ST - Semitendinosus, SM - Semimembranosus, BF - Biceps femoris. 18 Kadim et al. 19 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review storage may accelerate the ageing process by keeping carcasses at temperatures of 15oC or greater (Petrovic et al., 1993). The ageing processes originate within the myofibers and are responsible for degradation of cellular constituents. This resembles the method adopted by Kadim et al. (2009a), where camel Longissimus thoracis muscles were stored at a temperature of 2-3oC for seven days. Ageing at 2-3oC for 7-days improved camel meat quality characteristics (Table 13). This implies that ageing may be one of the postmortem treatments which increase camel meat tenderness that might be adopted in the camel meat industry. According to Lagerstedt et al., 2008), increasing ageing time from four to seven days may cause more cooking losses in beef meat. However, Kadim et al. (2009a) found no differences in cooking loss with ageing of camel Longissimus thoracis muscles from two to seven days. The level of improvement in tenderness within a certain ageing time varies among different meat cuts, ages of the animal and species due to differences in the level of endogenous enzymes, contraction status and connective tissue content (George-Evins et al., 2004). In general, ageing can improve quality characteristics of meats that have relatively small amounts of connective tissue and that have not cold-shortened (Wheeler et al., 1999). Myofibrillarfragmentation Index The myofibrillar fragmentation index is a useful indicator of the extent of myofibrillar protein degradation of post- slaughter camel meat (Kadim et al., 2006, 2009a,b, 2011, 2013; Raiymbek et al., 2012). The differences in rates of fragmentation of myofibrillar proteins may account for differences in the rate of postmortem tenderization of meat (Nagaraj et al., 2005). The structural changes occurring in muscle tissue after slaughter are generally believed to be caused by alterations in and interactions of myofibrillar proteins in the tissue (Nagaraj et al., 2006). Claeys et al. (1994) reported that at a higher pH, proteins preferentially solublized were titin, filamin, nebulinand myosin heavy chain. Except for myosin, all are preferentially degraded by calpains, which has an optimum effect atpH values near neutrality. Similarly, Silva et al. (1999) verified that the myofibrillar fragmentation index in meat was significantly higher at ultimate pH 6.5 than at 5.7. There is a correlation between the myofibrillar fragmentation index and the tenderness of meat (Veisethet al., 2001). The myofibrillar fragmentation index of camels above 6 years was lower than those of 1-3 years of age (Kadim et al., 2008, 2009a). The same authors established a strong relationship between physical disruptions of the myofibrils and the tenderness of camel meat. Water Holding Capacity (Expressed Juice) Water retention in meat is primarily caused by immobilization of water within the myofibrillar system. Applying pressure can cause a shift of water from the intercellar to the extracellular space and then onto the meat surface as a result of structural alterations at the level of the sarcomeres or of the myofilaments structure. Water retention affects the retention of minerals, vitamins and volume of water (Beriain et al., 2000) and is influenced by muscle pH because of the electrostatic effects of meat proteins (Hamm, 1975). The dromedary and bactrian camel meats contain higher expressed juice than other camelidae such as llama and alpaca, possibly because of the lower fat content (Cristofaneli et al., 2004). The amount of water loss was likely due to the ultimate pH of the muscle, composition of muscle and denaturation of proteins by the ionic strength of the extracellular fluid and oxidation of lipids which decreases the solubility of proteins (Dyer and Dingle, 1967). Kadim et al. (2006) reported that meat Table 13. Effects of age and ageing on meat quality attributes of Longissimus thoracis of dromedary camel (Kadim et al., 2009a). Age (year) 1-3 4-6 7-9 10-12 Ageing 7-day Ageing 2-day Ageing 7-day Ageing 2-day Ageing 7-day Ageing 2-day Ageing 7-day Ageing 2-day Ultimate pH 5.86 5.85 5.79 5.78 5.71 5.71 5.60 5.61 Expressed juice (cm2/g) 38.6 37.2 37.2 36.6 30.8 30.3 21.3 21.1 Cooking loss (%) 25.7 25.0 23.9 22.7 21.3 19.8 18.9 17.8 WB-shear force (kg) 7.28 8.10 8.41 8.97 9.14 9.76 11.29 12.79 Sarcomere length (µm) 1.73 1.47 1.65 1.67 1.48 1.47 1.39 1.37 Myofibrillar fragmentation index 77.9 73.5 71.6 69.8 66.9 64.5 62.7 60.2 Lightness (L*) 40.5 39.80 38.71 36.86 35.31 33.72 30.15 28.47 Redness (a*) 15.6 15.7 16.9 16.1 18.2 19.0 19.9 19.5 Yellowness (b*) 5.40 5.51 6.04 6.03 7.03 7.05 7.93 7.98 18 Kadim et al. 19 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review from camels slaughtered at one to three years had higher water-holding capacity values than those slaughtered at five to eight years of age, probably due to variations in fat content and the binding ability of meat proteins (Table 9). The water-holding capacity decreases as fat levels increase due to an increase in the ratio of moisture to fat (Miller et al., 1968). Dawood (1995) reported that young camel meat (eight months of age) had significantly higher water- holding capacities than meat from 26 month-old camels. The volume of the dromedary camel meat was reduced by 44.3% and weight by 48.2% after being boiled in water for 40 min (Kamoun, 1995b). The Longissimus thoracis and Biceps femoris muscles from mature camels had 37.9 and 37.1% cooking loss which was higher than the 33.2 % cooking loss in Semitendinosus muscle, which coincided with its high water-holding capacity (Babiker and Yousif, 1990). A higher cooking loss was observed in the Longissimus thoraces muscle (33.5%) when compared to the Infraspinatus (31.6%), Triceps brachii (29.2%), Semitendinosus (28.5%), Semimembranosus (30.6%) Biceps femoris (29.5%) with no significant differences between the last five muscles (Kadim et al., 2013). In the bactrian camel (Table 12), variation in expressed juice between Infraspinatus, Triceps brachii, Longissimus thoracis, Semitendinosus, Semimembranosus, and Biceps femoris muscles ranged from 37.10cm2/g (Longissimus thoraces) to 41.27cm2/g (Semimembranosus) cm2/g (Raiymbek et al., 2012a). The variation between muscles might be due to location, activity, proportion of muscle fiber types, pH, intramuscular fat and the ratio of water to protein of individual muscles. However, Suliman et al. (2011) found that Biceps femoris muscles had a higher cooking loss than Longissimus thoraces muscles in four different camel breeds. According to Shehata (2005), young camels (10-12 months old) had a higher cooking loss than old animals. Longissimus thoracis from two to three year old camels had significantly lower cooking loss (24.3%) than the values mentioned above (Kadim et al., 2009a,b). The cooking loss of camel longissimus thoracis was not different from that in cattle Longissimus thoracis of the same age. Cooking loss is important because of its potential to change the level of nutrients in the meat once it is cooked. For example, while it generally regarded that the protein content of camel meat is similar to other red meats (Elgasim and Alkanhal, 1992; Gheisari et al., 2009), the higher cooking loss in camel meat (33-38%), compared to beef (24.6%), will generate a more nutritionally dense cooked meat (Kadim et al., 2009). Colour (L*, a*, b*) Meat colour is one of the most important sensory characteristics according to which consumers make judgments on meat quality. The degree of meat pigmentation is directly related to the chemical structure of myoglobin content. Myoglobin concentration within a given muscle will differ according to the species or age and is dependent on muscle fibre type proportions, muscle pH, age, intramuscular fat, and muscle texture (Gardner et al., 1999; Lawrie, 2006). There was a negative linear relationship between colour values and pH in Longissimus thoracis muscles (Menzies and Hopkines, 1996). Postmortem protein degradation is directly related to the ultimate pH, which increases light scattering properties of meat and thereby increases L* value (Offer, 1991). Low ultimate pH meat samples might lead to more protein degradation resulting in higher colour values than the high ultimate pH meat samples. Abril et al. (2001) reported that reflectance spectrum value for meat samples was higher for an ultimate pH above 6. Postmortem glycolysis decreases muscle pH making muscle surfaces brighter and superficially wet. If the ultimate meat pH is high, the physical state of the proteins will be above their iso- electric point, and the proteins will associate with more water in the muscle and therefore, fibers will be more tightly packed (Abril et al., 2001). Babiker and Yousif (1990) reported that dromedary camel Longissimus dorsi muscles had higher lightness (L*), redness (a*) and yellowness (b*) values than Semitendinosus and Triceps brachii muscles. Suliman et al. (2011) found that the colour of the Biceps femoris muscle was not affected by breed of camels. A high redness (a*) colour component in the camel Longissimus thoracis muscle was associated with a lower lightness (L*), which might be due to an increase in myoglobin content. Camel muscle lightness L* values indicated that the Longissimus thoraces muscle (43.5) had the lightest (P<0.05) lean colour, which was possibly due to high fat content (Kadim et al., 2013). The Semitendinosus muscle had the darkest coloured lean compared to Infraspinatus, Longissimus thoraces, Triceps brachii, Semimembranosus, and Biceps femoris camel muscles. The Longissimus thoraces, semimembranosus and biceps femoris dromedary camel muscles had higher redness (a*) values than the Semitendinosus muscle, while a* value for Infraspinatus and Triceps brachii muscles were in between. CIE a* values were similar among Longissimus thoraces, Semimembranosus and Biceps femoris muscles (Kadim et al., 2013). In camels, the highest average yellowness (b*) value was recorded in the Longissimus thoraces muscle with comparable values to the Triceps brachii and Biceps femoris muscles. In bactrian camel, the Longissimus thoraces muscle had higher lightness (L*) values and Infraspinatus han Triceps brachii, Semitendinosus, Semimembranosus and Biceps femoris muscles (Raiymbek et al., 2012a). The age of the camels has a significant effect on their meat colour (Kadim et al., 2006). Meat colour from 6-8 and 10-12 year old dromedary camels was darker (lower L*), redder (higher a*) and yellower (high b*) than 1-3 year old camels because of higher concentrations of myoglobin (Kadim et al., 2006). Health Aspects of Camel Meat Meat is a valuable source of food rich in many essential amino acids, minerals, vitamins and bioactive compounds 20 Kadim et al. 21 Composition, quality and health aspects of the Dromedary and Bactrian camel meats: a review such as carnosine, anserine, glutathione and essential fatty acids such as Omega 3 fatty acids (Williams, 2007; Schonfeldt and Gibson, 2008). Apart from the nutritional value of meat, it provides several eating attributes and fulfilling experiences that normally are not achieved by other protein sources. Beef, lamb, pork, poultry and fish are considered the major sources of animal protein worldwide. However, in Africa, the Middle East and some Asian countries, especially in arid and semi-arid regions, camel meat is regarded as a main source of animal protein that equals and in some cases surpasses other meats in commercial importance. Several epidemiological studies linked health problems such as obesity and high saturated fat and cholesterol intake to increased consumption of animal products (Biesalski, 2005; Chao et al., 2005). This has led to a concern that total dietary fat intake should be restricted by consuming smaller portions less frequently (Schonfeldt and Gibson, 2008) or replacing red meat consumption with white meat. The low cholesterol and fat contents in camel meat could potentially be considered as a better alternative to the higher fat and cholesterol contents of mutton and beef. Camel Meat as Medicine Meat in general is considered a functional food for cures of many ailments and for improved performance in many cultures around the world (Migdal and Živkovic, 2007). Camel meat and offals such as liver are believed to have medicinal properties and are eaten raw (Bin Saeed et al., 2005). Kadim et al. (2008) stated that Somalis and Indians particularly believe in the health benefits of consuming camel meat. Among many African and Asian countries, camel meat has traditionally been used to cure the following ailments: (1) seasonal fever, sciatica and shoulder pain, as well as for removing freckles (by placing hot camel meat slices on the freckled area); (2) camel meat soup was used to cure corneal opacity and to strengthen eyesight; (3) camel fat was used to ease hemorrhoidal pains and the hump fat was used to remove tapeworm; and (4) dried camel lungs used to be prescribed as a cure for asthma, especially if taken with honey. Kurtu (2004) reported that the majority of camel meat consumers believe it is a healthier option during the dry season in which cattle are infected with various zoonotic diseases. This belief probably originated from the historical use of animals’ organs, including meat, in folklore and traditional medicine. Lev (2006) cited the use of camel meat in remedial formulation by Al-Tabari, Al- Kindi and Al-Qazwini which indicate the roots of some of the current beliefs. The camel is distinguished from other animals by the fact that the percentage of its intramuscular fat declines as the animal gets older. This quality, only found in camels, makes their meat less fatty, so its consumption is healthy and recommended for weight loss. And this quality also reduces the risk of cardiovascular disease and atherosclerosis since it lowers the percentage of cholesterol in the blood. Camel meat has other medical qualities, too, such as protecting against cancerous tumors, as claimed by some researchers, because it contains unsaturated fatty acids like linoleic acid which interact with other unsaturated fatty acids taken from vegetable oils to protect against cancer. Camel meat can also be used as a cure for exhaustion and fatigue because it contains energy needed by body cells. Such energy comprises sugar not fat, since, a camel’s fat is concentrated in its hump whereas other animals store it in their muscles. In addition, camel meat contains glycogen, a carbohydrate which is easily absorbed and metabolized in the body, and which is converted to glucose which in turn activates nerve as well as other cells. Conclusion The nutritional value of dromedary and bactrian camel meat is similar to other red meats. However, meat from young camels can be considered as a healthy option due to its low fat and cholesterol contents. 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