Researching Palm Oil Crystallization in Margarine

Fat crystallization is an important property in many food products, such as margarine-style spreads. To further delve into the science behind fat crystallization, Malaysian scientists examined the mechanism related to crystallization and emulsification of palm oilbased margarine fats. The researchers also looked at the main triacylglycerol (TAG) responsible for primary crystal formation and the best level of palm oil stearin that gives the required microstructure properties and body to finished products such as margarine, shortening and butter.

As hydrogenated fats have fallen out of favor due to their trans fatty-acid content, margarine manufacturers have turned to palm oil and its fractions. The major TAGs in palm oil are dipalmitoyl-oleoyl-glycerol (and dioleoyl-palmitoyl-glycerol). Dipalmitoyl-glycerol develops crystals quickly, palmitoyl-oleoyl-glycerol slows crystal formation and dioleoyl-glycerol has no effect. In addition, the TAGs crystallize in different polymorphic forms that differ from crystal to crystal by melting point and crystal structure.

The research, published in the Journal of Food Science, found that TAG composition, solid fat index (SFC), thermal behavior and microstructure properties of palm-oil-based MFs were significantly affected by blending and emulsification. The scientists combined palm oil and palm stearin in different ratios to margarine-like emulsions. They then looked at their microstructure properties and analyzed them for triacylglycerols, solid fat content (SFC) and thermal behavior.

The researchers found that blending and emulsification at palm stearin levels over 40% significantly changed the physicochemical and microstructure properties of experimental margarine fats. They found that the formation of granular crystals in the margarine fats was dominated by the high-melting triacylglycerol (dipalmitoyl-oleoyl-glycerol) and that a low level of monoacylglycerol emulsifier slowed crystallization rate.