(^122) DAIRY CHEMISTRY AND BIOCHEMISTRY
Figure 3.28 Examples of butter churns.
quality - a fine dispersion of water droplets reduces the risk of microbial
growth and other spoilage reactions (most water droplets are < 5 pm).
Working is also necessary to reduce the water content to the legal limit,
i.e. < 16%. The length of time required to churn cream, fat losses in the
buttermilk and the moisture content of the butter are influenced by
various factors, as summarized schematically in Figures 3.29 and 3.30.
- Modern 'churns' operate continuously ~- by either of two principles:
processes using about 40% fat cream (i.e. the Fkz piocess, e.g.
Westfalia Separator AG) in which air is whipped into a thin film of
cream in a Votator (Figure 3.31). The process of phase inversion in
this process is essentially similar to that of traditional churning
methods.
Processes using highfat cream (80% fat); although the fat in 80% fat
cream is still in an oil-in-water emulsion, it is a very unstable
emulsion and is destabilized easily by chilling and agitation.