Effect of carrot juice and stabilizer on the physicochemical and microbiological properties of yoghurt

• Carrot juice fortified yoghurt with gelatin as stabilizer was processed and characterized.
• Carrot juice at 10–15% fortification and 0.7% gelatin resulted in suppressed yoghurt syneresis.
• Yoghurt total carotenoid content was significantly increased with carrot juice fortification.
• Functional properties of yoghurt can be enhanced by carrot juice fortification.

Yoghurt fortification with fruits and vegetables has high potential to improve the nutrients and health promoting effects of the yoghurt. The effects of carrot juice (0, 10, 15 and 20%) and gelatin stabilizer (0.5, 0.6 and 0.7%) (w/w, base milk) addition on the properties of 12 yoghurt samples in a 3 × 4 factorial arrangement were investigated. Addition of carrot juice increased pH and syneresis significantly, but decreased titratable acidity (TA) and total viable counts (TVC). The TA and TVC were higher than minimum recommended of 0.6% lactic acid and 6 log10 CFU g−1, respectively for yoghurt. Coliform, yeast and mold counts were <10 CFU g−1. Syneresis decreased with stabilizer addition (p < 0.01). With 10 to 20 percent carrot juice addition, the total carotenoid content (mg/kg) increased (6.73 and 10.26, respectively) compared to control (3.05) (p < 0.05). However, the effects of carrot juice and stabilizer additions on total phenolic contents and antioxidant ferric reducing power were insignificant (p > 0.05). The results showed that yoghurt with suppressed syneresis and improved nutritional and total carotenoids contents can be processed from 10 to 15 percent carrot juice and 0.7 percent stabilizer additions.