Om. Lai et al., Physical properties of lipase-catalyzed transesterified blends of palm stearin and anhydrous milk fat, FOOD CHEM, 70(2), 2000, pp. 215-219
Palm stearin (PS) and anhydrous milk fat (AMF) blends, formulated by mixing
40 to 80% PS in increments of 10% (w/w), were subjected to transesterifica
tion catalyzed by lipases from Pseudomonas sp. and Rhizomucor miehei (Lipoz
yme IM60). The physical properties of the transesterified products were eva
luated by slip melting point (SMP), differential scanning calorimetry (DSC)
, solid fat content (SFC) and X-ray diffraction (XRD) analyses. SMP results
indicated that the Pseudomonas sp. lipase caused a bigger drop in SMP (15.
6%) for a PS:AMF (40:60) blend compared to 12.5% reduction when R. miehei l
ipase was used. The same blend, when reacted with either of the lipases, ha
d a residual SFC of 7.1% at 40 degrees C. Generally, for all other ratios o
f PS:AMF blends, the % of reduction in SMP was higher in the Pseudomonas li
pase-catalysed blends compared to the R. miehei lipase-catalysed blends. Ps
eudomonas lipase also successfully changed the polymorphic form of unreacte
d PS:AMF blends from a mixture of beta and beta' crystals to a predominantl
y beta' mixture following transesterification. On the other hand, transeste
rification with R. miehei lipase resulted in a product that is beta' domina
ting (C) 2000 Elsevier Science Ltd. All rights reserved.