Physical properties of lipase‐catalyzed interesterification of palm stearin with canola oil blends

Interesterified blends of hard palm stearin (IV of 11) and canola oil (hPS/CO) in ratios of 20 : 80, 30 : 70, 40 : 60, 50 : 50, 60 : 40 and 70 : 30 were prepared using immobilized Thermomyces lanuginosus lipase (Lipozyme TL IM). Comparison of physical properties was carried out between non‐interesterified and enzymatically interesterified products by monitoring their slip melting point (SMP), solid fat content (SFC), melting thermogram and polymorphism behavior. The Lipozyme TL IM‐catalyzed interesterification significantly modified the physical properties of the hPS:CO blends. The results showed that all the interesterified blends had lower SMP and SFC than their unreacted blends. The SMP result showed that the interesterified blends of hPS/CO 40 : 60, 50 : 50 and 60 : 40 could be useful for stick margarine and shortening applications, respectively. From the SFC analysis, the interesterified blends of hPS/CO 40 : 60 have SFC curves similar to vanaspati. The interesterified blends of hPS/CO 50 : 50 and 60 : 40 have SFC curves similar to margarines, puff pastry margarine and shortening. Interesterification had replaced the higher‐ and lower‐melting triacylglycerols by the middle‐melting triacylglycerols, yielding mixtures of lower SMP and SFC, compared to the original palm stearin. X‐ray diffraction analysis indicated the appearance of β' crystals in all the interesterified hPS/CO blends from predominantly β‐type oils.