Abstract

The present study aimed to prepare a functional set-type yogurt fortified with turnip extract (TE) (0.0, 0.25, 0.5, and 1%) and evaluate its physicochemical properties, total phenolic content (TPC), antioxidant capacity, microstructure, and rheological, microbiological, and sensory characteristics. The results showed that the addition of TE did not significantly change the protein, fat, and solid non-fat contents, as well as the viability of starters in yogurt (P > 0.05). The acidity, b* value, chroma, and browning index increased by elevating the level of TE, whereas decreasing trends were observed in pH, L*, and a* values (P < 0.05). There were significant changes in the syneresis and water holding capacity (WHC) of yogurt containing 1% of TE compared to the control at the end of storage (13.96% vs. 11.81% for syneresis and 55.17% vs. 60.72% for WHC). The TE caused a significant increase in TPC (357.4–893.33 mg GAE/g.d.m) and antioxidant activity (16.06–26%) of yogurts compared to the control (182.91 mg GAE/g.d.m for TPC and 6.87% for antioxidant activity) on 1st day (P < 0.05). TE also affected the viscoelastic properties and the viscous behavior prevailed over elastic in the yogurt with 1% TE at higher frequencies. The microstructure of yogurts with TE was more uneven and with empty spaces. Although TE decreased the taste score in sensory evaluation, the overall acceptance of yogurts with 0.25% and 0.5% of TE were satisfactory. Therefore, TE up to 0.5% has the potential to develop a functional yogurt with high antioxidant capacity and appropriate quality characteristics.