ing temperature fraction [i.e., pal

ing temperature fraction [i.e., palm stearin (PS), full or partially
hydrogenated oils] is interesterified with a particular vegetable
oil in the manufacture of trans-free margarine and vegetable
shortening (12,13).
An additional alternative involves the direct blending of a
high-melting temperature fraction with a vegetable oil (i.e.,
sesame oil). This last process has the additional advantage that
no chemical process is involved, consistent with the consumer
trend toward natural products. The aim of this study was to investigate the crystallization kinetics of PS, a palm oil fraction
constituted mainly by triglycerides of high-melting temperature, in blends with sesame seed oil. This process constitutes a
feasible alternative to expand the use of sesame oil through the
development of value-added products such as squeezable margarines, spreads, or low-fat margarines. According to the National Association of Margarine Manufacturers, the consumption of margarine-type products grew from 2.6 to 9.1 pounds
per capita for the period between 1930 and 1996 (10). In contrast, butter consumption dropped from 17.6 to 4.3 pounds per
person (10).
PS is obtained through fractional crystallization of refined,
bleached, and deodorized palm oil (12). Tripalmitin (TP) is the
triglyceride with the highest melting temperature in both palm
oil (5–10% w/w) and PS (12–56% w/w), depending on the
fractionation temperature) (14). As a consequence, TP should
affect crystallization kinetics and polymorphic behavior of
palm oil and PS. Our previous research (8,15) on crystallization has indicated that solutions of pure TP in sesame oil behave like binary solutions formed by saturated triglycerides
(i.e., TP) and unsaturated triglycerides (i.e., sesame oil). In the
present study, we evaluate whether this behavior holds in a
more complex crystallization system, i.e., mixtures of PS in
sesame oil.
MATERIALS AND METHODS
Materials.Whole-seed refined sesame oil was obtained from a
local company (DIPASA de México, Celaya, Gto., México).
The oil was stored at 4°C in the dark. The same batch was used
in all the experiments.
Pure TP (>99% pure, experimentally confirmed by gas chromatography and DSC) was obtained from Sigma Chemical Co.
(St. Louis, MO). Refined, bleached, and deodorized PS was
provided by the Palm Oil Research Institute of Malaysia (Kuala
Lumpur, Malaysia). Both TP and PS were used without further
purification.
Chemical analysis.The fatty acids composition of sesame
oil and PS was determined by gas chromatography utilizing a
Shimadzu chromatograph GC-9A (Shimadzu Corp., Kyoto,
Japan) with flame-ionization detector and a Supelco (Bellefonte, PA) glass column (2.6 m ×2.1 mm) packed with GP 10%
SP 2330 on Chromosorb 100/120. The analysis conditions have
been previously reported (8).
The triglyceride profile for PS was determined by high-performance liquid chromatography (HPLC) following the conditions described previously by Che Man et al.(14) utilizing a
Waters 600 E instrument (Waters Millipore Co., Milford, MA)
with a refractive index detector and a Nova Pack C18
column
(3.9 ×300 mm) (Water Millipore Co.). Triglyceride peaks were
assigned based on the retention time of triglyceride standards.
The particular concentration of TP in PS was determined by
gas chromatography of the saturated triglyceride fraction isolated by silver ion thin-layer chromatography (TLC) following
the conditions described by Nikolova-Damyanova (16)
DSC. A PerkinElmer differential scanning calorimeter
(model DSC-7; PerkinElmer, Norwalk, CT) equipped with a
dry box was used in all cases. The temperature calibration of
the equipment was done with indium (onset temperature for
melting = 429.8 K) and n-hexatriacontane (onset temperature
for melting = 349.3 K), and the baseline was developed with
an empty aluminum pan. The calibration for heat involved in
phase changes (i.e., melting/crystallization) was made only
with indium (∆Hfor melting = 28.45 J/g).
Nonisothermal DSC analysis.For dynamic runs, ≈12 mg of
TP solution in sesame oil (0.00, 0.32, 0.98, 1.80, 2.62, 10, and
25% wt/vol) or PS blend in sesame oil (0.00, 26, 42, 60, and
80% wt/vol) was sealed in a pan and held at 353 K for 30 min
before each DSC scan. The system was cooled at a rate of 10
K/min until a temperature of 243 K was achieved. After 2 min
at this temperature, the melting curve was obtained by heating
the system at 5 K/min until reaching 353 K. The temperature in
the maxima of both the exothermal peak of crystallization (T
Cr
)
and the endothermal melting peak (T
s
) were calculated using
the DSC-7 software library. In the same way, the heating and
cooling thermograms of pure TP and PS were determined.
The ideal behavior of the TP crystallization/melting in both
systems, TP/sesame oil and PS/sesame oil, was evaluated using
the Hildebrand equation (17):
ln(x) = ∆Hf
/R(1/T
s
−1/T
p
) [1]
where ∆Hf
is the enthalpy of fusion per mole of pure TP, T
p
and
T
s
are the melting temperature of pure TP and in the oil solutions, respectively (i.e., the temperature in the peak maximum
in the DSC endotherm), xis the mole fraction of TP in the system (i.e., TP/sesame oil and PS/sesame oil solutions), and Ris
the universal gas constant. An average molecular weight for
sesame oil triglycerides (874.93) and PS triglycerides (842.15)
was calculated from the fatty acid composition.
Isothermal DSC analysis.The PS/sesame oil solution (26,
42, 60, and 80% wt/vol) was heated at 353 K for 30 min and
then cooled (1.0 K/min) to a preset temperature (297.5–309 K)
and held at that temperature for crystallization. After complete
crystallization, the system was left at the isothermal temperature for additional 35 min. Afterward, the melting thermogram
was obtained by heating the system at a rate of 1.0 K/min. The
induction time for crystallization (T
i
) was calculated from the
isothermal thermogram as the time from the start of the isothermal process to the beginning of crystallization (i.e., time where
the heat capacity of the sample had a significant departure from
the baseline) using the DSC-7 software library. The cooling
rate was selected according to conditions used in previous stud-

Hasil (Bahasa Indonesia) 1:

ing suhu fraksi [yaitu, palm stearin (PS), penuh atau sebagianterhidrogenasi minyak] interesterified dengan sayuran tertentuminyak dalam pembuatan margarin bebas trans dan sayurmemperpendek (12,13).Alternatif tambahan melibatkan langsung campuranFraksi suhu mencair tinggi dengan minyak sayur (yaitu,minyak wijen). Proses ini terakhir memiliki tambahan keuntungan yangtidak ada proses kimia terlibat, yang konsisten dengan konsumenkecenderungan produk alami. Tujuan dari penelitian ini adalah untuk menyelidiki kinetika kristalisasi PS, sebagian kecil minyak sawitdibentuk terutama oleh trigliserida suhu mencair tinggi, dengan minyak biji wijen. Proses ini merupakanalternatif yang layak untuk memperluas penggunaan minyak wijen melaluipengembangan produk bernilai tambah seperti margarines dipengaruhi, menyebar, atau rendah lemak margarines. Menurut Asosiasi Nasional margarin produsen, konsumsi produk-produk margarin-jenis tumbuh dari 2.6 9.1 Poundsper kapita untuk periode antara tahun 1930 dan 1996 (10). Sebaliknya, mentega konsumsi turun 17,6 4.3 pound perorang (10). PS yang diperoleh melalui pecahan kristalisasi halus,dikelantang, dan deodorized palm oil (12). Tripalmitin (TP) adalahtrigliserida dengan suhu mencair tertinggi di sawitminyak (5-10% w/w) dan PS (12-56% w/w), tergantung padasuhu fraksinasi) (14). Sebagai akibatnya, TP harusmempengaruhi kristalisasi kinetika dan perilaku polimorfikminyak sawit dan PS. Penelitian kami sebelumnya (8,15) pada kristalisasi telah menunjukkan bahwa solusi murni TP dalam minyak wijen berperilaku seperti solusi biner yang dibentuk oleh jenuh trigliserida(yaitu, TP) dan jenuh triglycerides (yaitu, minyak wijen). DalamPenelitian ini, kami mengevaluasi apakah perilaku ini memegang dalamkristalisasi sistem yang lebih kompleks, yaitu, campuran PS diminyak wijen.BAHAN DAN METODEMinyak wijen halus Materials.Whole-benih Diperoleh dariperusahaan lokal (DIPASA de México, Celaya, Gto., México).Minyak disimpan pada 4° C dalam gelap. Kumpulan yang sama digunakandalam semua percobaan.TP murni (> 99% murni, eksperimental dikonfirmasi oleh kromatografi gas dan DSC) Diperoleh dari Sigma kimia Co(St. Louis, MO). PS halus, dikelantang dan deodorized adalahdisediakan oleh sawit Penelitian Institut Malaysia (KualaLumpur, Malaysia). TP dan PS digunakan tanpa lebih lanjutpemurnian.Analisis kimia. Komposisi asam lemak wijenminyak dan PS ditentukan dengan memanfaatkan kromatografi gasShimadzu chromatograph GC-9A (Shimadzu Corp, Kyoto,Jepang) dengan api-ionisasi detektor dan kolom kaca Supelco (Bellefonte, PA) (2.6 m × 2.1 mm) dikemas dengan GP 10%SP 2330 pada Chromosorb 100/120. Memiliki kondisi analisistelah dilaporkan sebelumnya (8).Profil trigliserida untuk PS ditentukan oleh kromatografi cair kinerja tinggi (HPLC) mengikuti kondisi yang dijelaskan sebelumnya oleh Che Man et al.(14) memanfaatkanInstrumen Waters 600 E (perairan Millipore Co, Milford, MA)dengan detektor indeks bias dan Nova Pack C18kolom(3.9 × 300 mm) (Air Millipore Co.). Puncak-puncak trigliserida ituditetapkan berdasarkan waktu penyimpanan trigliserida standar.Konsentrasi tertentu TP di PS ditentukan olehkromatografi gas fraksi jenuh trigliserida terisolasi oleh perak ion kromatografi lapis tipis (TLC) berikutkondisi yang dijelaskan oleh Nikolova-Damyanova (16)DSC. PerkinElmer Diferensial pemindaian kalorimeter(model DSC-7; PerkinElmer, Norwalk, CT) dilengkapi dengankotak kering digunakan dalam semua kasus. Kalibrasi suhuperalatan dilakukan dengan indium (onset suhu untukmencair = 429.8 K) dan n-hexatriacontane (onset suhuuntuk melelehkan = 349.3 K), dan dasar dikembangkan denganpanci aluminium kosong. Kalibrasi untuk terlibat dalam panasperubahan fase (yaitu, mencair/kristalisasi) dibuat hanyadengan indium (∆Hfor mencair = 28.45 J/g).Analisis DSC nonisothermal. Untuk berjalan dinamis, ≈12 mgTP solusi dalam minyak wijen (0.00 0,32 0,98, 1.80, 2,62, 10, dan25% wt/vol) atau PS berbaur minyak wijen (0.00, 26, 42, 60, dan80% wt/vol) disegel dalam panci dan diadakan di 353 K selama 30menitsebelum setiap DSC scan. Sistem didinginkan pada tingkat 10K/menit sampai suhu 243 K dicapai. Setelah 2 menitpada suhu ini, kurva mencair diperoleh oleh pemanasansistem di 5 K/menit sampai mencapai 353 K. Suhu dimaxima kedua puncak exothermal kristalisasi (TCR)dan puncak mencair endothermal (Ts) dihitung menggunakanDSC-7 software Perpustakaan. Dengan cara yang sama, pemanasan danpendingin thermograms murni TP dan PS bertekad.Perilaku ideal TP kristalisasi/mencair di keduasistem, TP wijen minyak dan minyak PS wijen, dievaluasi menggunakanpersamaan Hildebrand (17):LN (x) = ∆Hf /R(1/Ts−1/Tp) [1]mana ∆Hfadalah entalpi fusi per mol TP murni, TpdanTsadalah temperatur leleh TP murni dan solusi minyak, masing-masing (yaitu, suhu di puncak maksimumdalam DSC endotherm), xis fraksi mol TP dalam sistem (yaitu, TP wijen minyak dan PS wijen minyak solusi), dan Riskonstanta gas yang universal. Rata-rata berat molekul untukwijen minyak trigliserida (874.93) dan triglycerides PS (842.15)dihitung dari komposisi asam lemak.Analisis DSC isotermal. PS wijen minyak solusi (26,42, 60 dan 80% wt/vol) dipanaskan pada 353 K untuk 30 menit dankemudian didinginkan (1.0 K/min) dengan suhu preset (297.5-309 K)dan diselenggarakan di suhu bahwa untuk kristalisasi. Setelah menyelesaikankristalisasi, sistem ditinggalkan pada suhu isotermal untuk tambahan 35 min. sesudahnya, thermogram mencairDiperoleh dengan sistem pada tingkat 1.0 K min. pemanasinduksi waktu untuk kristalisasi (Tsaya) dihitung darithermogram isotermal sebagai waktu dari awal proses isotermal ke awal kristalisasi (yaitu, waktu manakapasitas panas sampel telah signifikan keberangkatan daribaseline) menggunakan DSC-7 software Perpustakaan. Pendinginantingkat dipilih sesuai dengan kondisi yang digunakan dalam sebelumnya stud-