Food Lipids: Chemistry, Nutrition, and Biotechnology

Table 4 Possible Mechanisms of Chocolate Fat Bloom Formation
Procedure Blood mechanism
Poor tempering with good cooling and
storage at room temperature
Good tempering and good cooling and
storage at temperature >23�C and/or with
thermocycling
Mixed triacylglycerol systems leading to
solvation and recrystallization after
tempering
Source: Ref. 57.
Type IV crystals rapidly transform to type V,
resulting in excessive bloom
Type V crystals form and transform to type
VI crystals, resulting in variable levels of
bloom, usually over a longer time
Liquefied fat recrystallizing on chocolate
surface during and after cooling, resulting
in a variable rate of bloom formation
conversion, the condition is caused by liquefaction of fat and does not depend strictly
on the appearance of a specific polymorphic form. Regardless of the actual mechanism
or mechanisms of bloom formation, the polymorphism and phase behavior of
cocoa butter underlie the phenomenon.
3. Natural Fat Mixtures and Polymorphism
Although fat mixtures are not used in the confectionery industry alone, this chapter
emphasizes the confectionery fat blends specifically used in chocolate and chocolatelike
products. Cocoa butter is the primary fat used in chocolate. Its expense has led
to the development of other fats, used alone or in combination, to replace some or
all cocoa butter in cocoa containing confections. The general term applied to these
fats is ‘‘confectionery fat.’’ Two general subclassifications of cocoa butter replacers
(CBRs) exist: cocoa butter equivalents (CBE) and cocoa butter substitutes (CBS)
[59]. Essentially, a CBE is a mixed fat that provides a fatty acid and triacylglycerol
composition similar to those of cocoa butter. A CBS is a fat that provides some of
the desired physical characteristics to a confection independent of its dissimilar
chemical composition to that of cocoa butter. The development and use of these fats
successfully resulted only after the phase behavior of cocoa butter alone and in fat
mixtures had been assessed.
CBE fat blends must be tempered, since they will exhibit polymorphism similar
to that of cocoa butter. The most stable form is �. Production of these fats is achieved
by blending fractionated and natural fats to achieve a sn-2-oleoyl-disaturated triacylglycerol
composition equal to cocoa butter. Ideally, blends of CBE and cocoa butter
will be compatible in all proportions. (‘‘Compatibility’’ refers to the phase behavior
of the blend; complete compatibility implies no eutectic effect at any composition.)
A thermal eutectic is apparent when the melting point of a blend is lower than that
of any of the pure fats in the system.
Unlike CBE, CBS blends have been developed to mimic the hardness and
melting properties of cocoa butter only; they are chemically dissimilar to cocoa
butter. Palm kernel oil contains a fraction with a triacylglycerol composition that
forms a stable ��-2 polymorph but exhibits physical properties like that of cocoa
butter. However, the �-3 stable form of cocoa butter precludes substantial mixing of
cocoa butter and palm kernel oil, since the two fats develop incompatible polymorphic
arrangements that lead to softening [60].
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.