Abstract

The present study was carried out to investigate the effect of different thermal treatments on the composition and chemical properties of camel milk. The rennet clotting time of camel milk was also investigated. Camel milk samples were thermal treated at 63, 80 and 90°C for 30 min and 72°C for 15 s, whereas raw milk sample was served as a control. We found that the fat content was not affected by the applied treatments (3.2±0.189%), but the protein contents average ± SD values were found to be 3.2±0.148, 3.4±0.136, 3.4±0.149, 3.3±0.049 and 3.1±0.157%, respectively. The ash contents were also affected by the thermal treatments and their average ± SD values were 0.70±0.065, 0.71±0.056, 0.73±0.052, 0.71±0.088 and 0.68±0.096%, respectively. The thermal treatments affected also the total solids in the samples; 10.0±1.168, 10.10±1.057, 10.16±1.089, 10.05±1.055 and 9.9±1.189%, respectively. The non protein nitrogen (NPN), non casein nitrogen (NCN) and whey protein nitrogen (WPN) gradually decreased as thermal treatments were increased but casein number and the percentage of denaturation were increased. Rennet clotting time in the presence of different concentrations of CaCl₂ (0 to 20 mg /100 ml) was found to be increasing by raising the temperature. However, increasing the amount of calcium chloride was found to be decreasing the rennet clotting time at all thermal treatment. Incubation of milk with yoghurt culture at 40°C for 12 h revealed a significant increase to the acidity level and a substantial decrease in the pH level at all the applied thermal treatments.

Key words: Camel milk, heat treatments, chemical composition, some properties.