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Sains Malaysiana 42(12)(2013):
1707–1714
Rheological
Properties of Different Degree of Pregelatinized Rice Flour Batter
(Sifat Reologi bagi Larutan Bater Tepung Beras Tergelatin)
M.S. ROHAYA, M.Y. MASKAT*& A.G.
MA'ARUF
School of Chemical Sciences and Food Technology, Faculty of
Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi,
Selangor, Malaysia
Received: 28 November 2012/Accepted: 15 August 2013
ABSTRACT
The effect of using rice flour at different degree of
gelatinization on rheological properties of a batter system was studied. Rice
flour was gelatinized by heated for 20, 40, 60 and 90 min. The treated rice
flour was used to prepare batters by stirring it for 2 min. The batter were
subjected to determination of apparent viscosity, consistency and flow behavior
index and storage modulus G’. The results showed that degree of gelatinization, DG of
rice flour increased with the increased heating period up to 60 min. All rice
flour batter shown shear thinning behavior since the viscosity decreased with
increasing shear rate. The behavior was proven by the value of consistency
coefficient, K more than 0 and flow behavior index, n less than 1. Rice flour
batter heated in a longer period has higher viscosity and could be attributed
by lower water content. The storage modulus, G’ of heated rice flour were lower
than G’ of commercial and unheated rice flour. This result was probably because
of the lower amylose and protein content in the modified starch pastes.
Keywords: Degree of gelatinization; gelatinization; rheology; rice
flour
ABSTRAK
Kesan menggunakan tepung beras pada darjah pengelatinan
yang berbeza terhadap sifat reologi sistem bater telah dikaji. Tepung beras digelatinkan dengan memanaskannya
selama 20, 40, 60 dan 90 min. Tepung beras yang terawat ini digunakan
untuk menghasilan larutan bater dengan mengacaunya selama 2 min.
Larutan bater ini digunakan untuk penentuan kelikatan, indeks
konsistensi, indeks kelakuan aliran dan moduli keelastikan G'.
Keputusan menunjukkan darjah pengelatinan, DG bagi
tepung beras adalah meningkat apabila dipanaskan sehingga 60 min.
Kesemua larutan bater tepung beras menunjukkan kelakuan penipisan
ricihan disebabkan oleh kelikatannya menurun dengan peningkatan
kadar ricihan. Kelakuan penipisan ricihan
ini dibuktikan dengan nilai indeks konsistensi, K yang lebih daripada
0 dan indeks kelakuan aliran yang kurang daripada 1. Larutan bater beras yang dipanaskan lebih lama mempunyai kelikatan
yang lebih tinggi dan mungkin disebabkan oleh kandungan lembapan
yang kurang. Sifat kekenyalan, G' bagi
tepung beras adalah lebih rendah daripada G' bagi tepung beras
komersil dan tepung beras yang tidak dipanaskan. Penemuan
ini mungkin disebabkan oleh kandungan amilosa dan protein yang
rendah di dalam larutan kanji terubahsuai.
Kata kunci: Darjah pengelatinan; pengelatinan;
reologi; tepung beras
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*Corresponding author; email: maskatmy@yahoo.com
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