Compositional, Rheological and Organoleptic Qualities of Camel Milk Labneh as Affected by Some Milk Heat Treatments

The present study was carried out to investigate the chemical, rheological and microstructure properties of camel milk Labneh. Labneh samples were manufactured from camel milk thermally treated at 63° (T1), 85° (T2) and 95°C (T3) for 30 min, whereas the control sample was manufactured from camel milk pasteurized on 72°C for 15 sec. Chemical composition of resultant Labneh samples showed that total solids, protein and fat contents were only significantly increased in Labneh samples which manufactured from camel milks thermally treated at 85° and 95°C for 30 min., while the lactose content was decreased by increasing the thermal treatment of camel milk. The pH ranged from 4.90 to 4.78 during 1 to 9 days of the study and titratable acidity ranged from 0.82 to 1.02% as percentage of lactic acid. The differences in acidity and pH values in response to the applied thermal treatments were only significant in highest treatment (95°C/30 min). The changes in the apparent viscosity were increased linear with the increase in the thermal treatment of camel milk and also increased with storage time. The control sample has presented a higher index of syneresis than the other treatments and this index was decreased as storage time progressed (9 days) in all samples. Scanning electron microscopy (SEM) revealed that the protein matrices of the high thermally treated Labneh samples (T2 and T3) appeared to be relatively more intensive than the control. In these treatments, the casein micelles were predominantly linked by particle to particle attachment in chains with comparatively small interspaced voids (T2), rather than by particle fusion into big aggregates (T3). However, the control exhibited a more open, loose and less dense protein network than experimental treatments. The overall acceptability scores of the sensory evaluation revealed that T3, fresh as well as, stored was the significantly most accepted, while the control sample was the least. As storage progressed the organoleptic scores insignificantly decreased in all treatments. The obtained results showed that the thermal treatment of camel milk at 95°C for 30 min had good significant impact on the physiochemical, texture and sensory properties of resultant Labneh.