Effects of age on fatty acid composition of the hump and abdomen depot fats of the Arabian camel (Camelus dromedarius)

Abstract

This study aimed to quantify concentrations of fatty acids in the hump and abdomen fats of three different age groups of camel. Hump and abdomen fats were extracted from eight each of one-humped camels (Camelus dromedarius) of three age groups: group 1 (<1 year old), group 2 (1–3 years old) and group 3 (>3 years old). The fatty acid methyl ester concentrations of these fats were determined by gas–liquid chromatography (GLC). The percentage of fat in the hump (H) and abdomen (A) fats was significantly (P<0.05) lower for group 1 (H 92.0% and A 94.3%) than for group 2 (H 97.4% and A 97.2%) and group 3 (H 97.6% and A 97.5%), on a dry matter basis. Hump and abdomen fats from the three different groups had similar fatty acid patterns with more saturated than unsaturated fatty acids. The saturated fatty acids in the hump fats accounted for 58.3, 67.6, and 63.0% of the total fatty acids for groups 1, 2 and 3, respectively; group 1 had significantly (P<0.05) lower saturated and higher unsaturated fatty acid concentrations than group 2. The iodine numbers were significantly (P<0.05) higher in group 1 than either group 2 or 3. Palmitic acid (C16:0) was the major fatty acid in hump fat with 32.06, 32.90 and 34.37%, followed by oleic acid (C18:1) 33.65, 21.66 and 28.91.0% and stearic acid (C18:0) 18.85, 24.13 and 20.74% for groups 1, 2 and 3, respectively. Group 1 had significantly higher (P<0.05) oleic acid and lower stearic acid concentrations than group 2. The melting point of both hump and abdomen fats varied between the age groups. This study indicated that age has an effect on the fatty acid composition and the melting point of hump and abdomen fats in one-humped Arabian camels.

Introduction

The camel stores its energy reserves in the form of fat in different depots in their body of which the hump and abdomen depots comprise a considerable amount of the adult body weight, therefore camels can survive long periods without feed. Hump and abdomen fats contain mixtures of fatty acids (Emmanuel & Nahapetian, 1980) and most of these are esterified as triglycerides or phospholipids and vary according to their anatomical location in the body (Duncan & Garton, 1967). In camels, no information is available regarding the relationship between the fatty acid composition and age. It is of interest to determine the types and the composition of fatty acids in the hump and abdomen fats at different age groups in relationship to fat metabolism. Such information will form the basis for further studies on fat composition of the hump or abdomen and its value for human consumption.

Few studies have examined the fatty acid composition of camel hump and abdomen depot fats (Emmanuel, 1981, Emmanuel and Nahapetian, 1980, Mirgani, 1977, Orlov et al., 1985, Rawdah et al., 1994), and most of these have been conducted in a single group. However, the fatty acid compositions of total fats may vary with age. Mirgani (1977) used thin-layer chromatography to determine the fatty acid composition of hump triglycerides from a single-humped camel (Camelus dromedarius) and found that saturated fatty acids accounted for 74% of the total fatty acids, and Emmanuel, 1981, Orlov et al., 1985, Rawdah et al., 1994 showed that the saturated fatty acid contents in hump fats was 64.9, 60.2 and 60.5%, respectively. In the abdomen fat of single humped camels, saturated fatty acids accounted for 63.6% of the total fatty acids (Emmanuel & Nahapetian, 1980).

Most information describing the composition of such fats gives only the overall fatty acid composition. This information is important, but other properties such as melting point, saponification and iodine numbers provide further information. The melting point of a fat depends on its fatty acid composition and the concentration of saturated fatty acids gives the best prediction of melting point (Enser, 1984b, Wood et al., 1978). Saponification number gives a measure of the average chain length of the fatty acids in the fat and the degree of unsaturation of the fatty acids can be measured by the iodine number.

This study compares the fatty acid compositions in the hump and abdomen fat depots of three age groups (less than 1 year old, 1–3 year old and more than 3 year old) of one-humped Arabian camels.