engleski

Influence of high intensity ultrasound on milk fermentation by yoghurt culture

The aim of this study was to investigate the effect of high intensity ultrasound on the activation of a commercially available yoghurt culture YC-380, on milk fermentation as well as on the properties of the produced yoghurts. Milk samples intended for fermentation were prepared by combining ultrasonic treatments with nominal input power of 270 W for 8 or 10 min and pasteurization at 72°C for 30 s. Control sample was prepared by standard pasteurization at 95°C for 10 min. Subsequently, milk samples were inoculated either with untreated yoghurt culture or a yoghurt culture that was previously activated by applying an ultrasonic treatment (102 W / 75 s). Hence, a total of 6 different yoghurt samples were produced. All of the produced yoghurts were subjected to analyses including determination of the protein content, the electrical conductivity, the titratable acidity, rheological properties, syneresis and sensory properties evaluation. According to the obtained results, ultrasonic treatments showed no significant effect on shortening the milk fermentation in comparison to conventional fermentation. However, sonicated yoghurt samples were characterised by poorer sensory properties in terms of higher acidity, but showed lower syneresis than the control sample.

ultrasound; yoghurt; fermentation; syneresis; sensory properties; composition

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