Fortification of yogurt with encapsulated chia seed oil and mucilage: optimization and evaluation of physicochemical and rheological properties

The aim of the present study was to optimization of enriched yogurt with chia seed oil and mucilage. This purpose was done with the aim of maximizing omega-3 level and minimizing changes in physical and chemical properties (pH, titrate acidity, syneresis, dry matter, peroxide values and color changes) compared to the control sample. First, in order to increase the oxidative stability, chia seed oil was encapsulated with sodium alginate and chia seed mucilage using emulsification/ internal gelation method. The physical characteristics results showed that the enrichment caused a decrease in the syneresis, an increase in the water holding capacity and viscosity. Then, yogurt was enriched and optimized with free and encapsulated chia seed oil (0 to 4%) and chia seed mucilage (0 to 0.25%). The sample without chia seed mucilage and oil used as a control sample. The results of scanning electron microscopy images showed that the successful alginate-sodium-mucilage microfiber coating of chia seeds has been made with a uniform structure. Yogurt contained 3.41% encapsulated chia seed oil and 0.213% chia seed mucilage was selected as an optimum treatment. The results showed that the number of starter bacteria of optimum sample were not significantly different from the control (p˃0.05). The texture of the yogurts was found to be viscoelastic. The flow behavior index in all samples was less than one, which indicates the non-Newtonian (pseudoplastic) behavior of the samples. Herschel Balky model had R2 and lowest RMSE in both samples, which indicates the suitability of this model to investigate the shear flow behavior in terms of shear velocity of samples.