Abstract
Rheological properties of date extract concentrate (dibbs), milk, and milk-dibbs drink of different dibbs concentration were experimentally determined. The dibbs was extracted from three date cultivars (Khlass, Sukkari, and Nubot Seif), and then added to milk in a specified amounts ranging from (2.5 to 15 mL dibbs/100 mL milk) to form the sweetened and nutritious milk-dibbs drinks. It was found that milk, dibbs, and milk-dibbs drinks exhibited pseudoplastic behavior following a power law model at the temperature range 5 to 65°C. The flow behavior indices ranged between 0.705 to 0.888 for dibbs and milk-dibbs drinks based on date cultivar, temperature, and concentration. For the dibbs and milk-dibbs drinks, the consistency index was found to decrease with the increase of temperature, and increase with the amount of dibbs added. Results showed a significant influence of date cultivars on the rheological properties of dibbs and milk-dibbs drink. Utilizing the Arrhenius model, the activation energies ranged from 5×10
3
kJ kg
−1
mol
−1
to 21× 10
3
kJ kg
−1
mol
−1
at shear rate 100 s
−1
.