Viscoelastic properties of orange fiber enriched yogurt as a function of fiber dose, size and thermal treatment

The effect of orange fiber addition on yogurt viscoelastic properties was studied, the following factors were evaluated: (i) fiber doses (0, 0.2, 0.4, 0.6, 0.8 and 1 g/100 ml) (ii) fiber particle size (0.417–0.7 and 0.701–0.991 mm) (iii) fiber addition prior or after pasteurization. (i) In yogurts with pasteurized fiber G′, G″ and complex viscosity increased with fiber dose, whereas in non-pasteurized fiber yogurts smaller fiber particles (<0.4 g/100 ml) rheological parameters decreased due to the disruptive effect of the fiber, and over 0.6 g/100 ml rheological parameters increased. The presence of particles alters yogurt structure but when the fiber dose is high enough the water absorption compensates the weakening effect of the fiber. (ii) G′, G″ and viscosity were higher in yogurts with large particles than in yogurts with fiber of smaller size. The higher the number of fiber particles, the higher the disrupting effect. (iii) Fiber pasteurization in the mix enhances its integration in the gel matrix.