Next we come tophase transitions. Chapter 14 mentions the various
phase transitions that may occur, such as crystallization, gas bubble
formation, or separation of a polymer solution in two layers; it then treats
the nucleation phenomena that often initiate phase transitions. Chapter 15
discusses crystallization, a complicated phase transition of great importance
in foods. It includes sections on crystallization of water, sugars, and
triacylglycerols. Chapter 16 introduces glass transitions and the various
changes that can occur upon freezing of aqueous systems.
Finally, Chapter 17 is aboutsoft solids, a term that applies to the
majority of foods. It gives an introduction into solids rheology and fracture
mechanics, but otherwise it makes use of many of the theories treated in
earlier chapters to explain properties of the various types of soft solids
encountered in foods.
1.2.2 What Is Not Treated
Some aspects are not covered. This includes analytical and other
experimental techniques. A discussion of these is to be found in specialized
books. Basic principles of some methods will be given, since this can help the
reader in understanding what the results do represent. Possible pitfalls in the
interpretation of results are occasionally pointed out.
Aspects that are generally treated in texts on food chemistry are for the
most part left out; an example is the mechanism and kinetics of enzyme-
catalyzed reactions. Some subjects are not fully treated, such as rheological
and other mechanical properties, since this would take very much space, and
several books on the subject exist.
Basic theory is treated where needed, but it does not go very deep:
giving too much may cause more confusion than enlightenment. We will
generally not go to atomic scales, which implies that quantum mechanics
and electron orbitals are left out. We also will not go into statistical
thermodynamics. Even classical chemical thermodynamics is restricted to a
minimum. Theories that involve mathematical modeling or simulation, such
as Brownian dynamics, are not discussed either. Equations will be derived
only if it helps to understand the theory, and if the derivation is relatively
simple.
1.2.3 For Whom It Is Intended
The book is written as a text, with clear and full explanations; illustration of
trends rather than giving precise research results; not too many details,
although details cannot always be left out; numerous cross-references in the