Concerning Table 1. Dijkstra has rightly pointed out
that columns 4 and 5, showing values for FAME before and
after mixing, do not accurately show the composition of the
50:50 blend of palm olein and methyl oleate and that this is
due to incompleteness of the reaction in the analysis of
FAME, especially when methyl oleate was present in the
mixture. These two columns were inadvertently placed into
the table by mistake and we did not discuss the values in
the two columns. The discussion was based on comparing
the feed oil and the high-oleic oil obtained. From the table,
the high-oleic palm oil (HOPO) composition did not
deviate too far from the calculated average mixture.
When discussing the results of the fatty acid compositions before and after randomization, we actually referred
to the comparison of the feed oil and the HOPO, and not to
the data from the two columns representing before and
after reaction.
For FAME preparation, the sample size was about
0.05 g. The reagent used was 0.5 M sodium methoxide and
is therefore a liquid. We did not mention the details for
preparing sodium methoxide because it is a commonly
known reagent prepared from sodium metal and methanol.
The mixture separated into two layers when water was
added.
The standard deviations of Tables 1 and 5 were generally higher than those of Tables 3 and 6. This is because
data from Tables 1 and 5 were from pilot plant experiments, while Tables 3 and 6 were from laboratory experiments. The variability in the pilot-plant experiments was
higher than in the laboratory experiments where better
control can be achieved. The laboratory experiments were
included at a later stage when requested by the reviewers
for data on palm oil. It was no longer possible to run pilotplant trials because methyl oleate in large quantities was
no longer available. Perhaps, the authors should havementioned this, although it was not the intention to mislead
readers. In fact, Table 3 actually show more consistent
results, where HOPO reflects the calculated average composition and that of the mixture after interesterifications.
The data on iodine values (IV) in Table 1 reflected the
FAME data, as they were calculated based on the unsaturated fatty acids. As for the standard deviations, they reflect
the standard deviations of the particular fatty acids used in
the calculations. The values given for HOPO were from the
three pilot-plant trials, and thus the variation was larger
than for RBD palm olein and methyl ester, where it would
be indicative of the consistency in the two raw materials
being used for the trials.
The triacylglycerol (TAG) compositions were presented
only for the major TAG found in the oils. Those familiar
with the HPLC method used, which was reverse-phase
HPLC using 75:25 v/v ratio acetone acrylonitrile as mobile
phase, would know that the TAG mentioned as POP, POO,
etc., do not mean the absolute POP isomer. It is well known
to those familiar with the method that the method does not
separate the isomers.
It is true that the TAG shown in the mixture columns are
actually of the sample (which includes the methyl oleate,
diacylglycerols, etc.). The HOPO data are reflective of the
oil, without the methyl oleate present.
Dijkstra rightfully pointed out the typographical errors
in the axes in Fig. 1. Upon further reflection, the slight FFA
increase could be due to the formation of a small amount of
soaps in the reaction, and some of which could be hydrolyzed in the presence of citric acid to form FFA. The data
are reported as obtained from pilot-plant experiments
which cannot be as easily controlled as in laboratory trials.
We cannot explain why the oleic increased and then
appeared to decrease.
The paper attempts to present a case study of the possibility of preparing a high-oleic oil from palm oil and to
further enhance the oleic content through fractionation.
While Dijkstra has put up a full process, as he envisions it,
the authors felt that such a process may be possible for
companies having fully integrated processes including a
methyl ester plant, etc. In other cases, one may be only
interested in purchasing the methyl oleate and starting from
that as raw material. In the latter case, the methyl oleate
and palmitate mixture at the end of the reaction could be
sold as methyl ester for biodiesel. The high-oleic palm
stearin (HOPS) as Dijkstra saw it was to be recycled back
to be mixed with RBD palm oil. In fact, the authors felt that
there could be a better use for HOPS oil, because it is also a
high-oleic oil having sufficient solids to be utilized in
margarine or shortenings. The authors have evaluated
HOPS for applications as margarines and shortenings. The
authors thank Dijkstra for his keen interest in the work and
for calling attention to the areas which the authors had
overlooked.
The objectives of the paper were to provide information
for a process to produce a high oleic palm-based oil
through chemical interesterificat