Improving the acidification kinetics, structural and sensory properties of low-fat yoghurt using high-pressure homogenization treatment

In this study, the impact of high pressure homogenization at 50, 100 and 150 MPa, on the physicochemical, rheological, textural, microstructural, and sensory properties as well as acidification kinetics of low-fat yoghurt was investigated. The results showed that a shorter fermentation time was obtained for yoghurt samples produced from high-pressure homogenized milk compared to the control sample. Homogenization of milk at high pressures resulted in an increase in the water holding capacity from 42.83 to 52.67 % and firmness from 1.01 to 1.45 N of yoghurt samples. The viscosity (Ƞ50) of yoghurt increased up to 0.446 Pa.s by milk homogenization and all yoghurt samples showed shear thinning behaviour. Microstructural analyses revealed that control sample had a typical open porous gel network of casein, while fewer porous and more dense protein network was observed in yoghurts from high pressure homogenized milk. The positive effect of the milk homogenization treatment on the sensory properties of yoghurts was observed as well. Principal component analysis visualized the effect of high pressure homogenization treatment and confirmed the close relationship between structural properties and overall acceptability. Among the tested low-fat yoghurts, high pressure milk homogenization at 150 MPa had the greatest potential for improving yoghurt structure, whereas 100 MPa pressure imparted the most acceptable sensorial properties.