338 Chapter 13
product, especially lactate, aroma compounds
(acetaldehyde, acetoin, and diacetyl), and
texture (through production of exopolysac-
charides (EPS), as well as to provide wider
varieties of health products (Tamime and
Robinson 2007 ).
Fruits and sweetening agents are usually
added to enhance the versatility of taste, color,
and texture of yogurt (O ’ Rell and Chandan
2006 ). The level of sweetener or fruit added
to the yogurt mix depends on the brix of
the fruit or the fl avoring ingredients and the
level of sweetness in the fi nished products.
These sweeteners include saccharin, aspar-
tame, Neotame^ ™^ , Acesulfame - K ® , sucralose,
corn sweeteners, and maltodextrins. They are
either solely added or added as a mixture
of two or more sweeteners (Chandan and
O ’ Rell 2006a ). The addition of these artifi cial
sweeteners may affect the culture growth,
product quality, and consumer acceptance.
Stabilizers such as gelatin, whey protein
concentrate, and various food gums are nor-
mally added to yogurt mixes to enhance and
maintain the desirable characteristics of
yogurt such as body and texture, viscosity
and consistency, appearance, and mouth feel.
During yogurt manufacture, the yogurt coag-
ulum is often subjected to mechanical treat-
ments such as stirring, pumping to the cooler,
mixing with other ingredient such as fruits
and fl avors, and post - fermentation heat treat-
ment in the case of pasteurized, ultra - high -
temperature (UHT), and long - life yogurt.
These treatments may cause the product to
become less viscous or even show whey
separation; hence, the addition of stabilizers
is to overcome these problems (Tamime and
Robinson 2007 ). A combination of several
stabilizers is usually employed to avoid
defects that may result from the use of a
single stabilizer (Nauth 2006 ).Yogurt Manufacture
Yogurt manufacture includes various key
steps such as standarization of milk fat, for-
tifi cation of milk solids, homogenization,goats, mares, and buffalo are also used in
different parts of the world.
Whole milk, partially skim milk, con-
densed skim milk, nonfat dry milk, whey
compositions, and cream can be used to for-
mulate and standardize various yogurt mixes.
These mixes should be formulated to comply
with regulations as well as meet consumer
expectations. The solids content of separated
milk or whole milk can also be raised to 12%
and 15%, respectively, by evaporation (Nauth
2006 ) or mixing in milk powder or whey
protein concentrate. At present, premix
yogurt mixes are available in various fl avors,
and are ready to be used at home, the offi ce,
and in food establishments.
The milk from small ruminants such as
goats and sheep (Haenlein 2001 ) as well as
milk from mares, camels, and water buffalo
is commonly used in the Balkan, Middle
Eastern, Indian subcontinent, and other Asian
regions for yogurt manufacture. These milks
are usually processed similar to cow ’ s milk,
but they contain different casein fractions due
to numerous breeds among goat and sheep as
compared to the few among cows. The quan-
tities of casein in decreasing order of these
milks are cow, sheep, buffalo, and goat for
minor caseins. For κ - casein: buffalo, goat ’ s,
cow ’ s, and sheep ’ s milk; for β - casein: goat ’ s,
sheep ’ s, cow ’ s, and buffalo milk; for α (^) s -
casein: sheep ’ s, buffalo, cow ’ s, and goat ’ s
milk (Tamime and Robinson 2007 ).
The starter cultures used in commercial
manufacture of yogurt consist of a mixture
of lactic acid bacteria such as Str. thermophi-
lus and Lb. delbrueckii subsp. bulgaricus.
However, other cultures are also used in
yogurt manufacture. In dahi preparation, for
instance, Str. thermophilus , Lc. lactis biovar
diacetylactis , and Lc. lactis subsp. cremoris
are used (Tamime and Marshall 1997 ), while
Lactobacillus , Bifi dobacterium , and Entero-
coccus species are used in probiotic yogurts
either as single or mixed cultures (Tamime
et al. 2005 , Tamime et al. 2007 ). Different
cultures are used in yogurt manufacture to
achieve desired fl avor characteristics of the