Effects of chemical interesterification on physicochemical properties of palm stearin and palm kernel olein blends

Fat and oil blends, formulated by mixing palm stearin (PS) and palm kernel olein (PKOo) in different ratios from 20:80 to 80:20 (wt%), were subjected to chemical interesterification with sodium methoxide as catalyst. The slip melting point (SMP), soild fat content (SFC), triglyceride (TG) profile, melting thermogram, polymorphic form and crystal morphology of the interesterified and non-interesterified mixtures were evaluated. Results indicated that all the interesterified blends had lower SMP than their non-interesterified blends. The melting thermogram confirmed a product of lower melting point being formed in interesterified blends with the disappearance of the high melting TGs. The TG profile of the interesterified blends of PS and PKOo also showed a decrease in the concentration of the high melting TGs. Chemical interesterification altered the PS and palm kernel blend fat-crystal morphology significantly. X-ray diffraction analysis revealed that all the interesterified blends were exclusively β′ polymorph. Hence, interesterification of blends of PS and PKOo resulted in the formation of β′ polymorphic oil, yielding mixtures with lower SMP and SFC. Such oil could be used for the production of margarine, shortening, non-temper-type confectionery fats, whip creams and other similar products.