Influence of homogenisation and the degradation of stabilizer on the stability of acidified milk drinks stabilized by carboxymethylcellulose

- Carboxymethylcellulose (CMC) is an effective stabiliser for acidified milk drinks.
- Homogenization and degradation of CMC significantly influences stability of drinks.
- Qualified choice for homogenisation pressure is required to achieve good stability.
- Degradation of CMC occurs during homogenisation and storage of drinks at low pH.

The present work deals with the influences of both homogenisation and the degradation of carboxymethylcellulose (CMC) on the stability of two kinds of acidified milk drinks (AMDs), directly acidified milk drinks and yoghurt drinks. The effect of homogenisation pressure for direct acidification process was investigated and evaluated. The experimental results showed that homogenisation was required to achieve a significantly small particle size (0.7 μm in the present work) and to prevent sedimentation and serum separation. However, homogenisation at too high pressures was not beneficial for the stability of the colloidal systems. The occurrence of degradation of CMC during homogenisation weakened the stabilisation effect of CMC. A qualified homogenisation pressure of 20 MPa should be chosen to achieve a good stability when a usually practical pressure range of 0-30 MPa was applied. In addition, the stability of directly acidified milk and yoghurt drinks prepared under the same homogenisation pressure was also investigated. While their stability increased with increasing CMC concentration, the degradation of CMC at low pH during storage gave rise to instability of the final products.