Effect of chemical and enzymatic interesterification on the physicochemical properties of palm oil and palm kernel oil blends

Abstract

Palm oil (PO) and palm kernel oil (PKO) have different chemical composition and physical properties. Both oils have limited application in their natural form. To widen their commercial values,PO and PKO were modified by blending and subsequently followed by interesterification (IE). Interesterification is the rearrangement of fatty acids within and among different triacylglycerols,using enzyme or chemical as the catalysts. Palm oil with iodine value (IV) of 52.6 and PKO (IV = 17.5) were mixed in different ratios from 25:75 to 75:25 (%wt/wt) at 25% increment. The blends were subjected to chemical and enzymatic interesterification using sodium methoxide and Lipozyme TL IM as catalysts,respectively. The effects of chemical and enzymatic interesterification on the triacylglycerols (TAG) composition,thermal properties,solid fat content (SFC) and slip melting point (SMP) were investigated. Chemical interesterification (CIE) caused significant changes in the TAG composition of the oil blend compared to enzymatic interesterification (EIE). This changes led to a significantly higher (p<0.05) SMP for the chemically-interesterified than the enzymatically-interesterified blends. The differential scanning calorimetry (DSC) melting thermograms confirmed that harder product with higher final complete melting temperature was obtained from the chemically-interesterified blends. Similar SFC profiles for all oil blends were observed with steep SFC slopes for blend with high proportion of PKO. Chemical interesterification reduced the eutectic interactions that occurred at 5 to 25°C in the non-interesterified and enzymatically-interesterified blends. Thus,CIE caused significant changes in physicochemical properties of the PO and PKO blends compared to EIE. Results from this study could improve the existing PO and PKO properties and widen their usage in food and non-food applications.