Mechanical properties of fat dispersions prepared in a mechanical crystallizer

Dispersions of hydrogenated palm oil (HP) in sunflower oil were crystallized in a scraped-surface heat exchanger (SSHE), where local strain rates are high. The HP crystallized completely or partially under shear, possibly followed by crystallization at rest. The Young's moduli scaled with the fraction solid fat to powers 2.5 and 1.5 for dispersions partially and completely crystallized under shear, respectively. Dispersions completely crystallized under shear leave the SSHE as a dispersion of compact aggregates in which the crystals are strongly sintered. The aggregates attract each other by relatively weak Van der Waals forces. Possibly, recrystallization causes a slow increase in consistency over about 16 days as a result of sintering between the aggregates. Dispersions partly crystallized under shear and partly at rest obtained their final consistency within 1 day. This is explained by ongoing crystallization at rest, which causes rapid sintering between aggregates and thereby formation of strong bonds. Any additional recrystallization then did not result in an increased consistency. The final consistency of the dispersions was comparable for both crystallization conditions