Dairy Ingredients for Food Processing

Butter and Butter Products 211

Figure 9.7. Anhydrous milk fat production from cream (method 1) and butter (method 2). Tetrapak Dairy
Processing Handbook, UK.

Whole milk

Centrifugal

separation

Cream 40%

Phase inversion

& butter making

Centrifugal

pre-separation

Cream 75% fat

Phase inversion

by means of a

homogenizer

Butter ~ 80% fat

Skim milk

Buttermilk

~ 1% fat

Buttermilk

~0.6-0.8% fat

Buttermilk

~20-30% fat

Method 1 Method 2

Final centrifugal

concentration

Butteroil ~99.5%

Vacuum

AMF 99.8% fat

Melting & holding

Final centrifugal

concentration

Butteroil ~99.5%

Vacuum

AMF 99.8% fat

Water phase

microbiological deterioration of the original
material has occurred to avoid transfer of off
fl avors into the concentrated product.
Cream is the starting point for AMF pro-
duction from either source, approximately
75% to 80% fat if cream rather than butter is
the starting material, or cream with a fat
content of approximately 40% for butter
manufacture. Usually the separated cream
is pasteurized at a minimum of 85 ° C (185 ° F)
to destroy bacteria and inactivate milk lipo-
lytic enzymes. This prevents formation of
free fatty acids (FFA) in the product, which
are associated with off fl avors. When using
cream as the starting material, a second
centrifugal concentration process is applied
to obtain cream of 75% to 80% fat. The
higher - fat cream ensures that effective phase

inversion can be readily achieved at the next

stage.

Phase inversion converts the oil - in - water

cream emulsion into a water - in - oil emulsion,

and although different types of devices are

available, they all involve forcing the cream

under pressure through narrow passages or

orifi ces, as found in homogenizers (Figure

9.8 ). This process ruptures the fat globules in

the absence of air, producing free fat and

resulting in a water - in - oil emulsion. The

product (99.5% fat) is then passed into a

vacuum dryer where the moisture content of

the oil is reduced to below 0.5%. This is

achieved by fi rst heating the oil to approxi-

mately 95 ° C to 98 ° C (203 ° F to 208.4 ° F)

before drying it under vacuum, removing dis-

solved oxygen at the same time (Figure 9.9 ).