Effects of emulsifiers on crystal behavior of palm oil blends on slow crystallization

The effects of sorbitan tristearate (STS) and soy lecithin on blends of palm oil (PO) and olein by slow crystallization were studied. The blends of PO and olein were melted at 80C for 30 min and slowly cooled at a rate of 0.7C/min for 32 min and at 20 +/- 0.1C for 48 min. Nuclear magnetic resonance was used to measure the solid fat content (SFC) development. Crystallization without emulsifier was influenced by trisaturated and disaturated triacylglycerol content of PO manifesting significant (P < 0.05) changes in SFC, crystal dispersion and viscosity, but emulsifiers in the blends disturbed these behaviors. The reaction of lecithin was very selective and was determined that at 0.03%, it generally served as a crystal promoter, while at 0.06-0.09%, it was a crystal inhibitor. Viscosity was closely related to the crystal dispersion in the liquid. The blends had low viscosity with 0.03% lecithin, while blends with high trisaturate content had high viscosity with 0.06% lecithin. STS was generally a crystal inhibitor, although at various levels, it was a crystal promoter for the middle-range saturates. Slow crystallization process of PO and olein blends with 0.03% lecithin produced homogenous crystals with low SFC and viscosity for fluidized products.