Effect of Carrot Juice on the Texture Properties, Rheology, and Microstructure of Yoghurt

Abstract

In the present study, carrot juice prepared was added into skimmed milk before fermentation to produce 10% and 20% (w/w) carrot-fortified skim milk. The influence of carrot juice on the lactic acid content, chemical composition, syneresis, texture, rheology property, and microstructure was evaluated along with a potential of carrot juice as an ingredient with rich dietary fiber and a firm structure with interaction of milk protein and a complex matrix under acidification. The results showed that the pH of yoghurt significantly ( $P<0.01$ ) reduced with carrot juice addition, minimizing fermentation time by nearly 1 h and brought about an enhanced postacidification during the storage period while titratable acidity increased. Moreover, carrot juice addition had no significant effect on ferric reducing power and phenolic content ( $P>0.05$ ). With 10% and 20% level carrot juice added, the total phenolic content (mg GAEkg−1) increased (37.86 and 38.92, respectively) compared with control (36.91) ( $P<0.05$ ). Besides, the addition of carrot juice also showed reduced syneresis, increased apparent viscosity and viscoelastic modulus, stable texture, and a refined microstructure. Overall, this study confirmed that carrot juice has a potential as natural and nutrient composition to obtain firm and compact texture and enhance the beneficial quality of yoghurt.