Dairy Chemistry And Biochemistry

138 DAIRY CHEMISTRY AND BIOCHEMISTRY

1

• 1 margarine
  I
  before working

lo a butter 1

c

F

.- LA

O' 0 2 4 6 a

Days after working

Figure 3.38 Effect of microfixing on the hardness of butter and conventional margarine (from
Mulder and Walstra, 1974).

be removed by centrifugation (special centrifuges have been developed) or
filtration. Early studies on fractional crystallization involved removing the
high-melting point fraction for use in other applications, the mother liquor
being used as a modified butter spread. This approach shifts the melting
point-temperature curve to lower temperatures without significantly chang-
ing its shape (Figure 3.39). While the resulting butter has acceptable
spreadability at low temperatures, its 'stand-up' properties are unsatisfac-
tory, i.e. it becomes totally liquid at too low a temperature. A better
approach is to blend low and high melting point fractions, by which an ideal
melting curve can be approached. The problem of finding economic uses for
the middle melting point fraction remains.

Blending. Blends of vegetable oils and milk fat offer an obvious solution
to the problem of butter hardness - any desired hardness values can be
obtained. Such products were introduced in the 1960's and are now used
widely in many countries. These products may be produced by blending an