Polymorphic form is determined by processing conditions.
Fatty acids crystallize in a double- or triple-chain
form depending on triglyceride composition and positional
distribution. Form IV crystallizes in a double-chain form,
form V in a triple-chain system that enables closer packing
and greater thermodynamic stability. Unstable lower polymorphic
forms (II and III) transform into higher melting,
more stable forms, with closer packing and lower volume.
These changes can be observed in terms of overall contraction
of the chocolate, appearance, or undesirable fat bloom
formation at rates dependent on relative stabilities of the
polymorphic forms and temperature (Talbot, 1999). For
chocolate to be in an appropriate polymorphic form, tempering
is crucial, influencing final quality characteristics
such as colour, hardness, handling, finish and shelf-life
characteristics.