196 Chapter 8
In the pursuit of increased value from
lactose, the generation of derivatives from
lactose is of interest to the dairy industry. The
most relevant derivatives are enzymatic
hydrolysis products of lactose, lactulose,
tagatose, lactitol, lactobionic acid, lactic acid,
and galactooligosaccharides. Only a few of
these products have found commercial rele-
vance in the dairy industry. The enzymatic
conversion of lactose into glucose and galac-
tose in dairy products generates products that
are suitable for people suffering from lactose
intolerance. Lactulose is manufactured in
large scale from lactose by alkaline isomeri-
zation; its main application is in medicine as
a constipation regulator, a growth promoter
of bifi dobacteria, a treatment of hepatic
encephalopathy, and a treatment of salmonel-
losis (Affertsholt and Nielsen 2007 ).
Galactooligosaccharides are carbohydrates
comprising 2 to 10 monosaccharide units;
they can be produced by the same enzyme
that hydrolyzes lactose. Tagatose is a natu-
rally occurring ketohexose that has been sug-
gested as a low calorie sweetener. Despite
large investments in research and develop-
ment and a commercial plant, production by
Arla was halted in 2006 (Affertsholt and
Nielsen 2007 ).Acknowledgements
We would like to acknowledge the Fonterra
Co - operative Group and the New Zealand
Institute of Plant and Food Research for sup-
porting the publication of this chapter. We
would like to thank Tony Corbett for creating
the fi gures in this chapter.References
Abd El - Salam , M. H. , El - Shibinay , S. , and Salem , A.
2009. “ Factors affecting the functional properties of
whey protein products: A review. ” Food Reviews
International 25 ( 3 ): 251 – 270.
Affertsholt , T. , and Nielsen , M. D. 2007. The World
Market for Whey and Lactose Products 2006 – 2010.
3A Business Consulting.c. Amount of washing required (pro-
portional to the level of impurities)
d. Centrifuge design; the decanting
centrifuge is commonly used today- Drying of the crystals to a powder; the
temperature during drying should not
exceed 93 ° C (199 ° F) because β - lactose
is formed at higher temperatures (Bylund
1995 ). Drying times are also important
to avoid the formation of amorphous
lactose on the α - hydrate crystal. - The refi ning of lactose for higher grade
applications such as pharmaceuticals.
This involves rehydration in hot water to
50% solids and fi ltration in the presence
of active carbon, phosphate, and a fi ltra-
tion agent; followed by crystallization,
separation, and drying. An alternative
procedure is to use ion exchange to
remove mineral impurities from the
crude lactose (Harper 1992 ). - Grinding. The size of the lactose crystal
is relevant to the application.
Lactose is available in various grades:
crude lactose (purity between 95% and 98%);
edible and refi ned edible grade (99% to
99.5% purity); pharmaceutical grade (99.5%
to 99.9% purity).
Lactose is used in a variety of foods:
baked goods, dry soups and sauces, infant
formulas, meat products, confectionery, and
drinks. It is used for reduction in sweetness,
fortifi cation of aroma, improved color of
baked products (because lactose is not fer-
mented by Baker ’ s yeast, its functional prop-
erties are not lost during the fermentation
stages of the process), and improved shelf
life. The delayed crystallization of concen-
trated sucrose solutions when lactose is
added is useful in the coating of candies
(Harper 1992 ).
In the pharmaceutical industry, lactose is
used as a carrier for tablet making (where
fl ow and compressibility are the key proper-
ties), as a carrier in dry powder inhalers, and
as a fi lling agent in capsules.