Food Lipids: Chemistry, Nutrition, and Biotechnology

Figure 10 Practical example of interesterification kinetics with palm oil. The SFI (at 40�C)
served as a measure of interesterification. Reaction temperatures 60�C (�), 52�C (●), and 45�C
(▫). (Adapted from Ref. 41.)
reaction, since the activation energy was higher for catalyst formation than for the
interesterification reaction itself.
Lo and Handel [61] observed that interesterification of soybean oil and beef
tallow was complete after 30 minutes (Fig. 11). Reaction completion was determined
by lipase hydrolysis analysis. Results by Konishi et al. [45] showed that in certain
cases the interesterification reaction can progress for as long as 24 hours, even with
catalyst preactivation. Thus, depending on conditions, randomization can proceed for
many hours.
Other factors that may influence interesterification onset include agitation intensity,
catalyst particle size, and temperature. Studies by many, including Konishi
et al. [45], Laning [14], and Wiedermann et al. [23] have shown that interesterification
kinetics are temperature dependent (Fig. 12).
IX. ASSESSING THE EFFECTS OF INTERESTERIFICATION ON
LIPID PROPERTIES
Fats and oils are usually modified to attain a certain functionality, such as improved
spreadability, a specific melting point, or a particular solid fat content–temperature
profile. However, changes in triacylglycerol structure may constitute the purpose of
the reaction, as in the synthesis of a particular structure. For that purpose, the fatty
acid distribution constitutes the reaction goal. Methods described to assess physical
properties include cloud point, Mettler dropping point, pulsed nuclear magnetic resonance,
differential scanning calorimetry, cone penetrometry, X-ray diffraction, and
polarized light microscopy. Chromatographic methods include thin-layer chromatography
(TLC), high pressure liquid chromatography (HPLC), and gas–liquid chro-
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