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J Amer Oil Chem Soc (2007) 84:427–431
Hydrogenated vegetable oils, containing lower levels of
unsaturated fats and elevated levels of trans and satu-
rated fats, have traditionally been used to prepare base
feedstocks with the melting point ranges required [2, 3]
for structure and spreadability at refrigerator tempera-
tures (i.e. 50 ꢁF, 10 ꢁC). During the catalytic hydroge-
nation of edible oils, major TAG such as trilinolein and
trilinolenin are converted to elaidic acid-containing
TAGs such as EEO and EOE, higher-melting TAG
which contribute to the desired functional properties
(Phillipsburg, NJ, USA). All solvents were either HPLC
Grade (acetone, acetonitrile, methanol) or ACS Grade
[benzene, carbon tetrachloride, ethyl ether (EE), petroleum
ether (PE)], and were used as received.
Methods
1. Ag-HPLC: A Spectra-Physics P2000 solvent delivery
system (Spectra-Physics Analytical, San Jose, CA,
USA/now Thermo-Finnigan),
a Rheodyne 7125
(
spreadability) of the resultant spreads.
injector (Rheodyne, Inc., Cotati, CA, USA) with a
20 lL injection loop, and an ISCO V4 Absorbance
Detector (ISCO, Inc., Lincoln, Nebraska, USA) at a
wavelength of 206 nm was used. (A representative Ag-
HPLC chromatogram of a TAG fraction containing
Health, consumer-driven and recent FDA labeling
mandates have stimulated research aimed at reducing the
levels of trans and long-chain saturated fatty acids in
shortening and frying oils by such procedures as inter-
esterification, the blending of tropical and liquid vegeta-
ble oils, low-temperature fractionation and, more
recently, by development of structurally modified oils by
transgenic or conventional plant breeding methods [4].
After interesterification, as much as 50% of the sym-
metrical TAGs of structure ABA are converted to non-
symmetrical TAGs of structure AAB, a change which,
when coupled with lower levels of saturated fatty acids
both the EEO and EOE isomers is shown in Fig. 1.)
ꢀ
The ChromSpher
Lipids columns (4.6 mm
I.D. · 250 mm stainless steel; 5 micron particle size;
silver ion impregnated) were purchased from Varian-
Chrompack Int., Middelburg, The Netherlands, and
used as received.
2. Thin-Layer Chromatography (TLC): Formation of the
mono- or dielaidoyl and oleoylglycerol intermediates
and the final TAGs were followed by TLC [3].
Samples (5–10 mg) were dissolved in 1.0 mL hex-
ane and applied (ca.10 lL) to 1 in. · 3 in. silica gel
TLC [K6] plates (Whatman, Inc., Clifton, NJ, USA).
Eluting solvent: 80:20—Hexane: Ethyl Ether (v/v;
(
FAs) and the elimination of trans isomers, could account
for the observed changes in melting point ranges, solid
fat content profiles and other parameters contributing to
the poor ‘‘mouth feel’’ and loss of flavor observed in
commercially-available ‘‘low-trans’’ (<5%) TAG formu-
lations [1]. By careful selection of mono- or diacyl-
glycerol substrates, both the symmetrical (EOE) and
nonsymmetrical (EEO) TAG isomers can be chemically
synthesized [5, 6], their purities readily determined by
silver-ion HPLC (Ag-HPLC), and their drop point [7] and
heats of fusion values measured. These values, currently
not available, will be utilized as part of a study corre-
lating the sensory properties of TAG formulations with
TAG structures (ABA vs. AAB, etc.) and TAG FA
[8]); visualization by I vapor or by spraying with
2
10% CuSO in 8% H PO solution/ heating to120 ꢁC
4
3
4
(hot plate).
3. Gas Chromatography: Chemical purities of the 1(3)-
MAG or 1,3-DAG precursors and of the synthesized
TAGs were determined by gas chromatography after
conversion (5% HCl in methanol) to FAMEs [9]. A
Varian 3400 Gas Chromatograph (GC; Varian
Instruments, Palo Alto, CA, USA) equipped with a
100 m · 0.32 mm SP2380 (Supelco, Inc., Bellefonte,
PA, USA) capillary column, flame ionization detec-
tor (FID) and He as carrier gas (operating condi-
tions: injector, 240 ꢁC; split ratio, 100:1; oven
temperature programmed from 155 to 220 ꢁC at
3 ꢁC/min with an initial hold of 15 min; detector,
(
saturated vs. cis vs. trans) compositions.
Experimental
Materials
280 ꢁC) was utilized.
Oleic (O) and elaidic (E) acids, and 1-monoolein were
purchased from Nu-Chek-Prep (Elysian, MN, USA).
Sodium methoxide was obtained from Harshaw Chem. Co.
4. Acylglycerol Structures: The structural purities of the
isolated or purchased MAG and DAG starting mate-
rials (after conversion to di- or mono-acetate(s),
respectively) and of the synthesized TAGs were
determined by Ag-HPLC [10, 11].
(
Cleveland, OH, USA), N,N¢-dicyclohexylcarbodiimide,
p-toluenesulfonic acid and triolein from Sigma-Aldrich (St.
Louis, MO, USA), 4-dimethylaminopyridine from Eastman
Fine Chemicals (Rochester, NY, USA), Silica gel (60/200)
5. Drop Point: Drop points were determined by AOCS
Official Method Cc 18-80. The values listed in Table 1
represent the means of duplicate determinations.
ꢀ
and Florisil (100/200) from J.T. Baker Chemical Co.
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