Determination of the effects of jujube pulp addiction (Ziziphus jujuba Mill.) on quality characteristics of set type yogurts

In this study, 3%, 6%, 9%, and 12% of jujube pulp were added to cow's milk and the effects of jujube pulp on the quality properties and antioxidant activities of yogurt were investigated. The yogurt samples were stored for 21 days at 4°C. Titratable acidity, pH value, lactic acid bacteria count, water holding capacity, textural properties, bioactive components, and sensory properties of yogurt samples were analyzed on weekly basis. The compositions and mineral profiles of yogurt samples were determined on the first day of storage. The addition of jujube fruit pulp had a statistically significant effect on the titration acidity, serum separation, water holding capacity, L*, a*, b* values, consistency, color and appearance, texture, flavor, taste, and general acceptability scores of yogurt samples (p<0.05). It was found that the fermentation time was accelerated with the addition of 3% and 6% jujube fruit pulp, and the bacterial viability remained higher in these two samples compared to the control sample during the storage period. Results of the study showed that contents of total phenolic, total carotenoid, and antioxidant activity were increased depending upon increment in the pulp of jujube fruit levels. It was found that yogurt samples containing 3% and 6% jujube fruit pulp have higher properties in terms of bioactive components and sensory analyses. Considering all the results, it was concluded that yogurt samples containing 6% and %6 jujube fruit pulp have high bioactive components and sensory acceptability, and can be preferred in the production of fruit yogurt with high antioxidant content.