Effect of storage period on the physicochemical properties of Sudanese camel (Camelus dromedarius), milk set type yoghurt

The present study was carried out in the laboratory of Dal Group for Food, Department of Quality & New product development (NPD), Khartoum, Sudan, to assess the effect of storage period on physicochemical properties of camel milk set type yoghurt (CMY). CMY was produced by adding skim milk powder and modified starch either individually or combined to fortified camel milk with 4% milk protein, 1% gum Arabic with or without stabilizer and stored for 30 days at refrigeration temperature. The physicochemical parameters included: (pH value, titratable acidity, viscosity, water holding capacity, total solids content, protein content, fat content, lactose content, glucose content and sucrose content ) were measured at storage intervals of 0, 7, 14, 21, and 30 days. In order to assess the effect of addition of skim milk powder and modified starch on physicochemical properties of camel milk set type yoghurt during those storage periods. The results found  that the total solid, protein content, titratable acidity, viscosity, water holding capacity of camel milk set-yoghurt samples with or without stabilizer as well as the control yoghurt were significantly (P>0.05) increased during storage period, while the pH values, fat content, lactose content, sucrose and glucose were significantly (P>0.05) decreased during  those storage periods.  The results indicated that, the highest (P<0.05)   total solid, lactose, fat,  glucose and titratable acidity was found in camel milk set yoghurt supplemented with 3% skim milk (SMP), while the yoghurt supplemented with 3% SMP+3% stabilizer had the highest (P<0.05) protein and sucrose content. The results showed that the control yoghurt had the highest pH value at the end of the storage period compared with other treatments. On the others hand, the camel milk set-yoghurts fortified  with 2% starch +1% skim milk +3% stabilizer had the highest (P<0.05) viscosity and  water holding capacity values in comparison with other treatments. The result also revealed that the combined used of skim milk with modified starch improved the physicochemical properties more than the used of starch only. Statistical analysis pointed out that there were no significant differences in physicochemical properties found between camel milk yoghurt with or without stabilizer addition during the storage period of the present study.