Composition and crystallization behavior of solvent-fractionated palm stearin

Palm stearin (PS) is an extensively used trans-free hardstock. Depending on process parameters, fractions with unique compositions, hardness, and solid fat content can be tailored toward specific applications. In this work, the composition and crystallization of PS fractionated with acetone at 30 degrees C, 35 degrees C, or 40 degrees C into various liquid (LF) and solid (SF) fractions were investigated. After fractionation, iodine value (IV) of PS changed from 37 to values ranging from 24 to 51. The IV of the LF increased with a decrease in fractionation temperature whereas that of the SF (similar to 24) was unaffected. The main fatty acids of all PS fractions were palmitic and oleic acids, with the LF having a lower palmitic acid but higher oleic acid content than the SF. LF and SF obtained at higher fractionation temperatures showed more rapid crystallization rates. Under the microscope, the LF fractionated at 30 degrees C and 35 degrees C consisted of spherulites whereas those fractionated at 40 degrees C exhibited dendritic crystals. All SF consisted of spherulites comprised of large rod-like crystals. All samples existed as mixtures of beta' and beta crystals. This study serves as the basis for the development of baking margarines and pastry shortenings using fractionated PS.