Chemistry Reference
In-Depth Information
Chapter 12
b
-Lactoglobulin Aggregates from Heating
with Charged Cosolutes: Formation,
Characterization and Foaming
Gerlinde Unterhaslberger,
1
Christophe Schmitt,
1
Sabrina
Shojaei-Rami
1
and Christian Sanchez
2
1
NESTLE
´
RESEARCH CENTER, P.O. BOX 44, CH-1000 LAUSANNE
26, SWITZERLAND
2
LABORATOIRE DE PHYSICO-CHIMIE ET GE
´
NIE ALIMENTAIRES,
INPL-ENSAIA, 2 AVENUE DE LA FORE
ˆ
T DE HAYE, BP 172,
F-54505, VANDOEUVRE-LE
`
S NANCY CEDEX, FRANCE
12.1 Introduction
Foamed products are gaining more importance in the food industry because of
their smooth and light texture. Food foams can be stabilized by emulsifiers and
fats, but proteins are the most commonly used foaming agents. Globular
proteins (e.g., whey proteins) exhibit good foaming properties, but in order
to achieve sufficient shelf-life stability of foamed food products and to maintain
consumer acceptability, the addition of food stabilizers (polysaccharides, sug-
ars, gelatin) is often needed.
Foam stability is governed by very complex (de)stabilization mechanisms.
1
Surface activity, molecular properties (protein size, flexibility, secondary struc-
ture and surface charge) and environmental conditions like pH and ionic
strength all play an important role in determining protein adsorption and
protein packing density at the interface.
2,3
It is known that proteins exhibit the
highest foam stability and the lowest drainage rates around their isoelectric
point and/or in the presence of ions. These influencing factors reduce repulsive
forces due to charge neutralization between the protein molecules allowing
dense packing at the air-water interface and leading to stable films.
4,5
In
addition, globular proteins are able to form cross-links (by SH-group activa-
tion, and hydrophobic and electrostatic interactions) and stable interfacial
networks that can prevent interbubble gas diffusion.
6-8
177
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