Comparative Effects of Iranian Native and Commercial Probiotic Incorporation on Rheological Behavior and Syneresis Characteristics of Yogurts

Background and Objectives: The aim of the present study was to investigate effects of incorporating Iranian native and commercial probiotic strains (Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium lactis) on the rheological and syneresis properties of yogurts. Materials and Methods: Samples were heated (90 °C, 15 min) after reconstituting in milk (13% SNF). After cooling down, the starter culture and probiotics were incorporated. Incubation was carried out at 42 °C until the pH decreased to 4.5. Syneresis was assessed based on Amatayakul et al. method. Rheological characteristics were assessed using dynamic oscillation (strain sweep and frequency sweep) and rotation assays. Results: Results revealed significant improvement in characteristics of the probiotic yogurts, compared to the control sample. Based on the results of rheological assessments, yogurts showed viscoelastic behaviors. In general, yogurts containing the native strain of L. acidophilus provided further desirable rheological and syneresis characteristics. Conclusions: Therefore, it is strongly recommended to use native Iranian L. acidophilus in probiotic yogurt production.