Evaluation of Chemical Quality of Camel ’ s and Cow ’ s Milk with Special Reference to Some Heavy Metal Residues

In Egypt, several detailed studies have been carried out on chemical quality and composition of buffalo, cow, and goat milk but it is rare for camel milk. Consequently, the present study was carried out to evaluate the chemical quality and composition of protein, fat, and minerals of camel’s milk compared to cow’s milk to fill the gap in this respect, monitoring the level of heavy metals residues to ensure the availability of these milk for consumption. Random fifty milk samples collected from healthy camel and cow at Marsa Matrouh and Alexandria Governorates. The samples were analysed for titratable acidity, pH and acid values as a chemical quality index. Also, for total protein, fat, Ash, Cholesterol content, amino acids and fatty acid pattern, minerals, and some heavy metal residues. The obtained results revealed high chemical quality index of camel’s and cow’s milk. Total percentage of fat, protein, ash and cholesterol content were (4.6, 2.72, 0.79% and 9 mg/100 ml) and were (3.7, 3.5, 0.8%, and 5.5 mg/100ml) for camel’s and cow’s milk, respectively Amino acids pattern showed higher significant percentage of threonine, serine, glutamic, proline, cystine, methionine, leucine, histidine, lysine, ammonia, and total essential amino acids in camel’s milk. Tyrosine and isoleucine in cow’s milk showed highly significant percentage. Fatty acids profile showed the presence of 11 various fatty acids, in camel’s milk and 13 in cow’s milk, respectively. Butyric (C4:0) and Caproic acids (C6:0) were not detected in camel’s milk, and pentadeconoic acid (C15:0) was not detected in cow’s milk. Short chain fatty acids showed significantly higher percentage in cow’s milk but medium chain of high nutritive value also, linoleaic and linoleic acids which have potential health benefits and have potent anticarcinogenic effect were significantly higher in camel’s milk. Minerals concentration (Fe, Mg, Ca, P, Na, and K) showed insignificantly higher camel’s than cow’s milk. Heavy metal residues declared that cow’s milk showed significant higher concentration of zinc, cobalt, lead, and chromium than camel’s milk with mean values (100.02, 11.792, 8.038, and 0.98mg/kg), respectively. Generally, 100% of cow’s milk samples exceeded permissible limit of lead, zinc and Cadmium percentage in cow’s and camel’s milk exceeding permissible limit in (80%, 20%) of samples, respectively.


INTRODUCTION
Milk is an almost ideal and easily digestive food with high nutritive value.It supplies body building proteins, bone forming minerals and health giving vitamins and furnishes energy giving lactose and milk fat, supplying certain essential fatty acids, it is important for pregnant mothers, growing children, adolescents, adults, invalids, convalescents, and patients alike. 1,2lk differs widely in its compositions, depending on species, breed, individual variation, season, age, milking interval, completeness of milking, irregularity in milking, yield, lactation effect, exercise, and excitement. 1,3,4though, the word "Milk" fit for human consumption refers only to cow's milk, in certain parts of the world, buffaloes, goat, sheep, and camels are kept for milk for human consumption. 5 Egypt, cow's and buffaloes milk were most commonly used as human food, camel's milk is often the only regular source for its owner, bedouins are used to drink milk and to make white soft cheese.Camel's milk in U.S.S.R. is used for the preparation of various fermented products, butter gurag and cheese.Camel milk is mainly consumed in the raw state by nomads.7][8] Lactation periods of camel vary from 9 to 18 months with annual milk yields of between 2-6 liters under desert condition and up to 12 to 20 liters under more intensive breeding systems. 7mel's milk is generally opaque, white has a sweet and sharp taste, with unpleasant smell but sometimes, it is saltish.It is more viscous than cow's milk. 9,10veral reports showed that camel has pH between 6.5 -6.7, pH higher than 6.7 indicate mastitis milk, but pH below 6.5 indicates the presence of colostrums or bacterial contamination (1,27,28) Table (1) showed insignificant, higher mean value of titratable acidity percent in cow's milk rather than camel's milk.
Also , our results revealed in significant different pH mean values of camel's and cow's milk which were 6.67± 0.182 and 6.61± 0.16 ; respectively.The fresh Camel's milk has lower acidity and pH than those of cow's milk. 6,29,30Nearly similar results were recorded by several previous studies. 1,27,29,31,32,While higher values were reported in some studies. 9,33wever, other studies evaluated lower values of titratable acidity and pH. (10,34,35)

2-Acid value :-
The extent of lipolysis of milk fat is usually expressed as acid degree value which expressed as g of free fatty acid oleic / l00 g fat. 1 Table : 1 showed that acid values of camel's and cow's milk ranged between (0.09-0.15) and (0.1-0.35),respectively.Nearly similar results were recorded. 1The flavor caused by free fatty acids is not always undesirable, free fatty acids contribute to the desirable flavour of several cheese varieties' e.g., Cheddar and Roguefrt. 1

Main constituents of camel's and cow's milk :-
Publication dealing with the composition of camel milk are relatively scarce. 10The Data summarized in table (2)   verified insignificant and higher fat % of camel's milk (4.6%) and insignificant lower protein % (3.5%) than cow's milk.Also, it showed nearly the same level of ash % 0.79 .and0.8, and camel's and cow's milk, respectively.The fairly wide range of values of the main constituents of camel's and cow's milk could be mainly related to the different genetic potential of breed, varying physiological, and feeding condition or to stage of lactation.One of the important factors that affects camel milk composition is the water. 36These results nearly to somewhat the same ranges of fat , protein, and ash % it was ported in previous studies. 10,3135,37,38owed that the main percent of protein, fat, and ash of camel's milk are generally similar to those of cow's milk.were (C6:0, C8:0, C18:0, C10:0, C12:0, C15:0, and C18:3.Pentadeconaic acid (C15:0) was not detected in cow's milk.Individually the % of major fatty acids were within the range of variation of those previous studies. 29,42But very different values were reported by other studies. 43,44,45ese result were in accordance with other investigator who observed that total saturated and unsaturated fatty acids showed the same percent in camel's and cow's milk. 37Oleic acid and palmitic were the most abundant of unsaturated and saturated fatty acids, respectively.

Hydrogen ion concentration (pH):
attention.So, the present study attempts to evaluate the chemical quality and composition of proteins, fat, and minerals of camel's milk in compared to cow's milk to fill the gap in this respect, also at monitoring the level of heavy metals residue and trace elements to ensure the availability of these milk for consumption.

Results and Discussion Chemical quality index: 1-Titratable acidity % and pH :
acidity represented by titratable acidity, which expressed % of lactic acid.Milk behaves as a buffer solution, fresh milk