Dairy Ingredients for Food Processing

202 Chapter 9

Ripened cream may be produced at this

stage for cultured butter. Usually such cream

is pasteurized at a higher temperature than

cream for sweet cream butter, cooled to rip-

ening temperature (20 ° C to 27 ° C; 68 ° F to

80.6 ° F), and inoculated with starter culture

(1% to 2%). Normally a mixed culture of

lactic microorganisms, for example, Lacto-

coccus lactis subsp. cremoris, Lactococcus

lactis subsp. lactis, and Lactococcus lactis

biovar. diacetylactis, is added to the cream to

ensure acid (pH 5.3 to 4.7) and fl avor (espe-

cially diacetyl) development. The primary

aroma producers are Lactococcus lactis

biovar. diacetylactis and Leuconostoc mesen-

teroides subsp. cremoris. Cooling the cream

controls the extent of the fermentation

process and strength of fl avor development,

and allows crystallization of the fat in the

cream to be completed before churning.

An alternative process developed in the

mid 1970s by the Netherlands Dairy Research

Institute is the NIZO method, which involves

adding a mixture of cultured whey concen-

trate and bacterial culture to sweet cream

butter during working. The concentrates,

which can vary in composition, add lactic

acid, aroma, and fl avor compounds to butter,

thus avoiding the production of lactic but-

termilk. The advantages of using concen-

trates to produce ripened or cultured butter

are that starter cultures need not be stored

or prepared in a factory laboratory, and

disposal of sweet cream buttermilk is both

easier and cheaper than disposal of lactic

buttermilk.

Butter Formation

Butter is now commonly manufactured using

continuous butter making machines. These

machines have the advantage over the older

batch churns (Figure 9.2 ) in terms of consis-

tent production of a butter of uniform quality

with low air content (better texture and less

oxidation), improved moisture distribution,

and smaller water droplet size (improved

desirable product properties (Wright et al.
2001 ).
The proportion of solid fat in butter is
highly correlated with product fi rmness and
strongly infl uenced by the cows ’ diet and
stage of lactation. The fatty acids in milk fat
(Table 9.2 ) originate from two main sources:
those acids synthesised de novo in the
mammary gland, C4 - C14 and a proportion of
C16 acids, and those arising directly from the
diet and taken up by the mammary gland
from the circulating blood, i.e., the remainder
of C16 and the longer - chain C18 acids. When
the dairy cows graze fresh pasture, this leads
to a softer, more unsaturated milk fat with a
reduction in content of saturated fatty acids,
especially C16 : 0, and an increase in mono-
unsaturated fatty acids, mainly C18 : 1. The
reverse occurs during winter feeding of con-
centrates and silage.
The cooled cream may be held in cream
aging tanks or, for larger operations, in silos.
Slow - moving agitators or intermittent mixing
are necessary to prevent separation, but care
should be taken to avoid aeration or damage
to the fat globules.

Table 9.2. Principal fatty acids in milk fat (g fatty
acid/100 g total fatty acids).

Fatty acid

(Carbon number)

Winter

butter *

Summer

butter *

C4 : 0 2.9 2.2

C6 : 0 1.7 1.5

C8 : 0 1.3 9.6

C10 : 0 2.9 2.0

C12 : 0 3.3 2.4

C14 : 0 11.5 9.7

C14 : 1 c 1.4 1.2

C16 : 0 33.0 26.6

C16 : 1 c 1.9 1.7

C18 : 0 11.0 12.6

C18 : 1 c 9 22.5 28.7

C18 : 1 t 2.2 3.6

C18 : 2 c 9,12 1.3 0.86

C18 : 2 conjugated * * 0.5 1.6

C18 : 3 c 9,12,15 0.8 1.4

• Winter diets of concentrates and silage; summer diets
  of mainly fresh grass


• 
  
  
  
  • Total conjugated linoleic acid, principally C18 : 2 c 9, t 11
    isomer