Sains Malaysiana 40(4)(2011): 359–367
Effect of Super Olein and Sunflower Oil on the
Rheological Properties of Chocolate Syrup
(Kesan Minyak Super Olein
dan Bunga Matahari ke Atas Ciri Reologi Sirap Coklat)
Nazaruddin Ramli*
& Foo Shih Ying
School of Chemical
Sciences and Food Technology, Faculty of Science and Technology
Universiti
Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
Diserahkan: 9
Disember 2009 / Diterima: 21 Oktober 2010
ABSTRACT
This study was carried out to determine the effect of super
olein (POo) and sunflower oil (SFO) on the rheological
properties of chocolate syrup. The formulation of chocolate syrup was modified
from that used in a preliminary study consisting of 49.1% water, 30% sugar, 15%
cocoa powder, 5% vegetable fats (POo and SFO), 0.5% lecithin and 0.4%
vanilla flavour. The rheology of chocolate syrup was measured at a shear rate
of 0.01-60 s-1 using a rotational rheometer equipped with a parallel
plate at 4°C and 25°C. The shear stress and shear rate data were entered into
the Power Law model to determine the apparent viscosity, flow behaviour index
(n) and consistency index (K) of the chocolate syrup. In this study, the apparent
viscosity of the chocolate syrup was determined at a shear rate of 30 s-1.
The apparent viscosity of POo chocolate syrup was the highest at 14.62 ± 1.97
Pa.s (4°C) and 3.91 ± 0.21 Pa s (25°C), followed by SFO chocolate
syrup, with apparent viscosities of 5.42 ± 0.40 Pa s (4°C) and 1.203 ± 0.076 Pa
s (25°C). The apparent viscosity of Hershey’s chocolate syrup was the lowest,
at 2.15 ± 0.070 Pa.s (4°C) and 0.6734 ± 0.027 Pa s (25°C). All of the chocolate
syrups exhibited shear-thinning behaviours with n<1 at 4°C and 25°C. The
consistency index of chocolate syrup increased in the order of KHershey<KSFO<KPOo at
4°C and 25°C. For sensory evaluation, it was found that POo and SFO chocolate
syrups were preferred by the panellists over Hershey’s syrup (p<0.05). There
was no significant difference between the POo and SFO chocolate
syrups with respect to panellists’ preferences. In conclusion, POo and SFO can
be potentially utilised in the preparation of chocolate syrups.
Keywords: Chocolate syrup; rheology; sunflower oil; super olein;
viscosity
ABSTRAK
Kajian ini dijalankan untuk menentukan kesan minyak super olein
(POo) dan bunga matahari (SFO) ke atas ciri reologi sirap
coklat. Formulasi sirap coklat adalah diubahsuai daripada kajian awal yang
mengandungi 49.1% air, 30% gula, 15% serbuk koko, 5% lemak sayuran (POo dan SFO),
0.5% lesitin dan 0.4% perisa vanilla. Reologi sirap coklat diukur pada kadar
ricihan 0.01-60 s-1 menggunakan reometer berputar yang
dilengkapi dengan plat selari pada 4°C dan 25°C. Data tekanan ricihan dan kadar
ricihan dimasukkan ke dalam model Hukum Kuasa untuk menentukan kelikatan
ketara, indeks kelakuan aliran (n) dan indeks konsistensi (K) sirap coklat.
Dalam kajian ini, kelikatan ketara bagi sirap coklat ditentukan pada kadar ricihan
30 s-1. Kelikatan ketara bagi sirap coklat POo adalah yang tertinggi,
pada 14.62 ± 1.97 Pa s (4°C) dan 3.91 ± 0.21 Pa.s (25°C), diikuti dengan sirap
coklat SFO, dengan kelikatan ketara 5.42 ± 0.40 Pa.s (4°C) dan
1.203 ± 0.076 Pa s (25°C). Kelikatan ketara bagi sirap coklat Hershey adalah
yang terendah, pada 2.15 ± 0.070 Pa s (4°C) dan 0.6734 ± 0.027 Pa s (25°C).
Kesemua sirap coklat mempunyai kelakuan ricihan penipisan n<1 pada 4°C dan
25°C. Indeks konsistensi bagi sirap coklat meningkat mengikut urutan KHershey<KSFO<KPOo pada
4°C dan 25°C. Bagi penilaian sensori, didapati sirap coklat POo dan SFO lebih
disukai oleh ahli panel berbanding sirap Hershey (p<0.05). Tiada perbezaan
ketara diantara sirap coklat POo dan SFO dengan kesukaan ahli panel.
Kesimpulannya, POo dan SFO adalah berpotensi untuk digunakan
di dalam penyediaan sirap coklat.
Kata kunci:
Kelikatan; minyak bunga matahari; reologi; sirap coklat; super olein
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*Pengarang untuk surat-menyurat; email:
naza@ukm.my
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