A study on the effect of thermal treatment on composition and some properties of camel milk

Abstract

The present study was carried out to investigate the effect of different thermal treatments on the composition and chemical properties of camel‘s milk .The rennet clotting time of camel‘s milk was also investigated. Camel milk samples were thermally treated at 63, 80, 90°C for 30 min. and 72 °C for 15 sec., 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 values (expressed as average ± SD) 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 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 also affected the total solids in the samples, the values being 10.0±1.168, 10.10±1.057, 10.16±1.089, and 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 with increase in thermal treatments but casein number and the percentage of denaturation were increased. Rennet clotting time in the presence of different concentrations of CaCl2 (0 - 20 mg /100 ml) was found to increase with rise in temperature. However, increase in the amount of calcium chloride was found to decrease the rennet clotting time at all thermal treatments. Incubation of milk with yoghurt culture at 40°C for 12 hours revealed a significant increase in the acidity level and a substantial decrease in the pH level at all the applied thermal treatments.