| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程研究所 === 83 === The interesterification of palm oil midfraction (POMF) and
stearic acid is an important method for the production of cocoa
butter equivalents. In the presence of lipase, acyl exchange
occurs primarily between the palmitoyl group of POMF and the
stearoyl group of stearic acid; and by carefully adjusting
reaction parameters, product with composition similar to that
of cocoa butter can be obtained. In this study, the
interestreification of POMF and stearic acid with Rhizopus
arrhizus lipase was carried out in reverse micelles. The
effects of surfactant concentration, water to surfactant molar
ratio (Wo), reaction temperature as well as enzyme loading on
the interesterification reaction between POMF and stearic acid
were investigated. It was found that a combination of AOT
concentration = 10 mM, Wo = 16, reaction temperature = 30 ℃
and enzyme loading = 11U yields optimal results in terms of
product sigma value. The interesterification reaction was
insensitive to pH in the range of 7.0 - 9.0 with Tris-HCl
buffer. The effects of molar ratio of stearic acid to POMF,
substrate concentration and stability of lipase on the
interesterification reaction were also examined. If POMF was
hydrolyzed for 30 minuters before stearic acid was added,the
reaction displayed a higher interesterification activity than
that obtained when POMF and stearic acid were added
simultaneous at the beginning of the reaction.
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