Butter and Butter Products 205either by holding it in a store at this tempera-
ture or by using microwave tunnel heaters. It
is then worked to blend and standardize the
salt and moisture content of the fi nal product.
An alternative process involves chopping the
frozen butter into thin strips while maintain-
ing the butter temperature at 0 ° C to 2 ° C
(32 ° F to 35.6 ° F). The butter is then worked
in the blender section several times and
deaerated before being packaged in retail
units. It is important to note that butter is
quite soft when it fi rst emerges from the
churn, but it will set or harden gradually over
a period of about four weeks. Freezing inter-
rupts the setting process, but setting resumes
when the butter is removed from frozen
storage. Re - working butter such as takes
place with bulk stored butter before retail
packaging also softens butter by disrupting
the three - dimensional structure. Recovery of
hardness, however, occurs during subsequent
storage at refrigerator temperatures.Low - fat Butter
The traditional process for producing low - fat
or half - fat butter (40% fat) is based on using
butter oil into which an aqueous phase
such as milk or buttermilk and stabilizers,
emulsifi ers, colorings, fl avors, and antioxi-
dants are blended. This mixture is then chilled
and crystallized in a scraped surface heat
exchanger (see the section on spreads). An
alternative process (APV patented method)
may be employed that uses standard butter
directly (Figure 9.5 ). In this process the butter
is worked and deaerated in a vacuum working
section, where it is also heated gently before
being pumped into a butter homogenizer. The
softened butter is fi rst dosed with a pasteur-
ized solution of sodium caseinate before the
mixture is homogenized to ensure that a
homogeneous blend of the butter and protein
solution is achieved, with small (approxi-
mately 5 microns) well dispersed water drop-
lets. The degree of homogenization depends
upon the milk fat composition of the originalthe amount of buttermilk expelled can be
regulated. Passing through the apertures of
the regulating gate greatly increases the
surface area of the butter; however, by apply-
ing a vacuum in the chamber connecting the
two working sections it is possible to reduce
the air content in the butter from 5% to 6%
to less than 0.5%. Deaeration improves shelf
life and appearance of the butter, resulting in
a more closely textured product than is found
in traditionally worked butter.
Working section 2, like the fi rst working
section, consists of augers and working ele-
ments; however, the auger speed is usually
two or three times higher than in working
section 1. The function of the second working
section is to carry out the fi nal working of the
butter and ensure that water and salt are
evenly distributed throughout the butter, with
water droplet size as small as possible,
approximately 5 microns, to prevent undesir-
able microbial growth during storage.
Overworking, however, produces a sticky
butter that is diffi cult to pack. Salt is intro-
duced into butter in modern equipment as a
slurry via a computer - controlled pump. The
slurry is a mixture of ultra fi ne salt grains
(less than 20 microns) and water in a 50 : 50
ratio. It is important that all salt particles
are dissolved in the moisture in the butter
by the end of working, otherwise color
and fl avor defects will occur in the fi nal
product.
Packing
Butter may be packed in bulk in 25 - kg
polythene - lined cardboard cartons for chill or
frozen ( - 18 ° C or - 25 ° C; - 0.4 ° F or - 13 ° F)
storage, printed as 250 - g or 500 - g retail
blocks, and wrapped in parchment or lined
foil, or extruded into attractive plastic tubs
similar to those used for margarines and other
spreadable fats. Re - packing bulk butter for
retail purposes usually requires reworking
the butter fi rst. The temperature of the bulk
butter is raised to 5 ° C to 8 ° C (41 ° F to 46.4 ° F)