Om. Lai et al., PHYSICAL-PROPERTIES OF PSEUDOMONAS AND RHIZOMUCOR-MIEHEI LIPASE-CATALYZED TRANSESTERIFIED BLENDS OF PALM STEARIN PALM KERNEL OLEIN, Journal of the American Oil Chemists' Society, 75(8), 1998, pp. 953-959
The physical properties of Pseudomonas and Rhizomucor miehei lipase-ca
talyzed transesterified blends of palm stearin:palm kernel olein (PS:P
KO), ranging from 40% palm stearin to 80% palm stearin in 10% incremen
ts, were analyzed for their slip melting points (SMP), solid fat conte
nt (SFC), melting thermograms, and polymorphic forms. The Pseudomonas
lipase caused a greater decrease in SMP (15 degrees C) in the PS:PKO (
40:60) blend than the R. miehei lipase (10.5 degrees C). Generally, al
l transesterified blends had lower SMP than their unreacted blends. Ps
eudomonas lipase-catalyzed blends at 40:60 and 50:50 ratio also showed
complete melting at 37 degrees C and 40 degrees C, respectively, wher
eas for the R. miehei lipase-catalyzed 40:60 blend, a residual SFC of
3.9% was observed at 40 degrees C. Randomization of fatty acids by Pse
udomonas lipase also led to a greater decrease in SFC than the rearran
gement of fatty acids by R. miehei lipase. Differential scanning calor
imetry results confirmed this observation. Pseudomonas lipase also suc
cessfully changed the polymorphic forms of the unreacted blends from a
predominantly beta form to that of an exclusively beta' form. Both be
ta and beta' forms existed in the R. miehei lipase-catalyzed reaction
blends, with beta' being the dominant form.