Namariq Dhahir¹, Jean Feugang², Katherine Witrick³, Hasan Shamimul², Amer AbuGhazaleh^1,

The objective of this study was to investigate the efficacy of different thermal pasteurization methods on (1) the survival of the total aerobic bacteria, E. coli O157: H7, in camel milk, and (2) the camel milk components such as the fatty acid profile, lipid peroxidation, protein fractions, and the composition of volatile compounds. Samples of camel milk (N=9) were pasteurized at 65°C/30 min (PAST-1), 72°C/5 min (PAST-2), and 80°C/15 min (PAST-3). The survival of E. coli O157: H7 was evaluated using the traditional plate count agar (PCA) method while the total aerobic bacteria were enumerated using the petrifilm aerobic count plates (ACP). Complete elimination (P<0.05) of the total aerobic bacteria were achieved using PAST-1 and PAST-3 methods but not PAST-2 (3.4 log₁₀ CFU/ml reduction). All pasteurization methods had a significant (P<0.05) bactericidal effect on E. coli O157: H7 resulting in a 6 log₁₀ CFU/ml reduction. There were no significant (P>0.05) differences in the fatty acid profile including the cis-9, trans-11 conjugated linoleic acid (CLA), and trans-10, cis-12 CLA, and the lipid peroxidation products between raw and pasteurized milk samples. The milk protein profile was marginally altered by PAST-2 and PAST-3 treatments but not PAST-1. Thirty-four volatile compounds (VCs) were detected in the raw milk samples compared to 29 VCs in the pasteurized milk samples. Pasteurization treatments altered the concentrations of some milk VCs, increasing the Heptanal, Tridecanal, and Undecanal while decreasing the 2-Decanal and 2-Undecanal. This study shows that PAST-1 and PAST-3 treatments are more effective than PAST-2 at inactivating total aerobic bacteria. Additionally, the absence of significant changes in milk compositions indicates that PAST-1 and PAST-3 could be applied without affecting the nutritional value of camel milk.

camel milk, pasteurization, bacteria, milk composition