Development of a novel yoghurt based on date liquid sugar: physicochemical and sensory characterization

The addition effect of date liquid sugar (DLS, 1-9 % v/v) to yoghurt milk on the physical (colour, firmness and syneresis), chemical (pH, total titratable acidity (TTA), total phenolic content (TPC) and antioxidant activity), rheological (viscosity and flow behaviour), and sensory attributes was scrutinized. Results showed that the pH value decreased by increasing DLS concentration from 1 to 6 %, while the TTA decreased with an increase in DLS from 6 to 9 % (p < 0.05). The whey syneresis, firmness and viscosity values were considerably influenced by the DLS content and acidity of the yoghurts (p < 0.05). A noticeable increase in antioxidant activity and TPC was found by the increasing DLS content (p < 0.05). Yoghurts containing 6 % v/v DLS also had the lowest syneresis and the highest firmness among the different samples. Moreover, a pseudoplastic rheological behaviour was detected for all the produced yoghurts. An increase in DLS concentration of manufactured yoghurts led to an increase in a, b and total colour difference (TCD) values and a decrease in L value (p < 0.05). The sensory evaluation revealed that there was no significant different in the colour scores. However, the used panelists determined the yoghurt supplemented with 6 % DLS had the highest scores for other investigated attributes.