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United Arab Emirates University (2021)

VARIABILITY OF THE PROXIMATE AND PROTEIN COMPOSITION OF CAMEL MILK (Camelus dromedarius)

Mohamed, Huda Musa Elsayed

Titre : VARIABILITY OF THE PROXIMATE AND PROTEIN COMPOSITION OF CAMEL MILK (Camelus dromedarius)

Auteur : Mohamed, Huda Musa Elsayed

Université de soutenance : United Arab Emirates University

Grade : Doctor of Philosophy (PhD) 2021

Résumé partiel
Dromedary camel milk (Camelus dromedarius) has unique physical, nutritional, and technological properties when compared with other milk. Unlike bovine milk, the processing of camel milk into fermented products and its treatment using ultra-high temperatures is technically challenging. Therefore, this research aimed to determine the variability in the proximate composition and the protein composition of camel milk collected from individual animals that are reared under intensive management in the UAE. To determine the proximate composition of samples (n = 217) were analyzed by NIR and MIR spectroscopy methods. The results obtained by the two methods were also compared. The results of proximate composition showed a wide variation in the concentration of proteins (2.4 - 4.0%), fats (1.2 - 7.3%), lactose (3.0 - 5.7%) and total solids (9.1 - 15.2%). Excellent positive correlations between the two methods were obtained (p < 0.001) ; for protein (r ≥ 0.96), fat (r ≥ 0.99), lactose (r = 0.82) and total solids (r = 0.90). The mean of the relative difference ((MIR values - NIR values)/0.5 (MIR values + NIR values) × 100%) were : for protein (+13.4%), fat (+0.9%), lactose (-0.7%) and total solids (-3.4%). The difference between the two methods may be because of differences in milk homogeneity, especially with respect to casein micelles and fat globules.

Because proteins confer many of the properties of milk and its products, this research aimed to determine the concentrations of camel milk proteins, their correlations, and the relative concentration of the caseins. Raw milk samples were collected from individual dromedary camels (n = 206) in the morning and evening. Capillary electrophoresis results showed wide variation in the concentrations (g/L) of proteins between samples as follows : α-lactalbumin, 0.3 to 2.9 ; αS1-casein, 2.4 to 10.3 ; αS2-casein, 0.3 to 3.9 ; β-casein, 5.5 to 29.0 ; κ-casein, 0.1 to 2.4 ; unknown casein protein 1, 0.0 to 3.4 ; and unknown casein protein 2, 0.0 to 4.6. The range of percent composition of the 4 caseins was as follows : αS1-, 12.7 to 35.3 ; αS2-, 1.8 to 20.8 ; β-, 42.3 to 77.4 ; and κ-, 0.6 to 17.4. The relative proportion of αS1-, αS2-, β-, and κ-caseins in camel milk averaged (26:4:67:3, wt/wt) which is different from that of bovine milk (38:10:36:12, wt/wt). This difference might explain the dissimilarity between the two milks with respect to technical and nutritional properties.

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Page publiée le 24 juin 2022