ABSTRACT
The crystallization of multicomponent triacylglycerol (TAG) mixtures, for example, edible fats, is of paramount importance in the manufacture of products such as chocolate, ice cream, and butter (Garside, 1978; Hartel, 2001). The crystallization behavior and structure of these materials is extremely sensitive to heat and mass transfer conditions and compositional changes (Chapman, 1962; Timms, 1984; Kellens et al., 1992; Herrera et al., 1999; Sato, 1999, 2001; Herrera, 2002; Martini et al., 2002a,b; Mazzanti et al., 2003, 2004, 2005, 2007, 2009; Sato and Ueno, 2005) and will ultimately affect mechanical strength, †ow behavior, and sensory texture (Herrera and Hartel, 2000a,b,c; Campos et al., 2002; Campos and Marangoni, 2010; Brunello et al., 2003; Dibildox Alvarado et al., 2004). Of particular interest is the nucleation behavior of these systems, since important structural features are a direct consequence of nucleation behavior, such as crystallite number, size, and morphology, as well as the spatial distribution of mass (Marangoni and McGauley, 2003). In what follows, we will review theoretical formalisms used to characterize both the nucleation and crystallization behavior of edible fats. An excellent and widely read review on fat crystallization was written in 1988 by Boistelle (1988) and Kashchiev’s book on nucleation is a must read for more advanced students of the art (Kashchiev, 2000). Philippe Rousset (2002) wrote an excellent review on modeling crystallization kinetics of triacylglycerols and is a highly recommended material. The most current critical review of the art has recently been written by Keshra Sangwal (2012), who summarizes most serious efforts in modeling crystallization processes in triacylglycerols. The purpose of this chapter is to offer the reader this author’s view on how to model the kinetics of crystallization of fats from a basic knowledge of the kinetic theory of gases. The approach is rather phenomenological and highly practical, however stressing fundamental understanding of what is being done, with the undergraduate and early graduate students in mind.
