Homogenization of yoghurt milk

Yoghurt is a dairy product that is well known around the world. When producing yoghurt, the homogenization process is one of the most energy demanding steps. In order to decrease the energy consumption the aim of this master thesis was to understand if the homogenization pressure, the homogenization temperature and the positioning of the homogenizer (upstream or downstream) affect the quality of the final yoghurt. When the yoghurt milk is homogenized, the fat globules are disrupted into smaller fat globules and are easier incorporated into the yoghurt gel. The gel formation in yoghurt is a complex process since the gel is sensitive to temperature changes, concentration of culture and vibrations during formation among other things. It is well known that homogenization of milk improves the storage stability and with this thesis, it was of interest to investigate if a partial homogenization of yoghurt milk would contribute to the same quality improvement. From the project, no effect of homogenization pressure on the proteins and the quality of the yoghurt could be found. This would mean that partial homogenization of yoghurt milk would be possible without compromising the quality. Another conclusion was that the higher homogenization temperature led to a decrease in the fat globule size but none of the quality parameters nor the sensory analysis showed to be affected by the temperature change. This project also showed that there was an indication of the upstream homogenization process to be preferred.