Malays. Appl. Biol. (2006) 35(2): 53–57
EFFECT OF DEFATTING AND OIL ADDITION ON THE GELATINIZATION PROPERTIES OF WHEAT, RICE AND SAGO FLOUR
SALMA, M.Y., *MASKAT, M.Y. and WAN AIDA, W.M.
Food Science Program, School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
ABSTRACT
Effect of defatting and addition of oil on the thermal properties of wheat, rice and sago flour were studied using Differential Scanning Calorimetry (DSC). To determine the effect of defatting, batter solutions were prepared by mixing wheat, rice or sago flour with water at a ratio of 1:1.2 (flour:water) and were then freeze-dried for 15 hr. Defatting was done by Soxhlet extraction using hexane as solvent for 2 hr. For determining the effect of oil addition, batter solutions were prepared by mixing wheat, rice or sago flour with water at a ratio of 1:1.2 (flour:water). Five mg of frying oil was added to each batter solution which were then freeze-dried for 15 hr. Untreated and treated samples were analyzed by Differential Scanning Calorimetry (DSC) in the range of 25°C – 120°C at a scanning rate of 10°C/min. Parameters recorded were onset, peak and end temperatures along with enthalpy during gelatinization. In each of the wheat, rice and sago flour, it was shown that defatting and oil addition to the batter did not result in any major effects on the onset (To), peak (Tp) and end (Te) temperatures and also enthalpy of gelatinization (?H).
ABSTRAK
Kesan langkah nyahlemak dan penambahan minyak kepada cecair penyalut terhadap tepung gandum, beras dan sagu telah dikaji menggunakan Kalorimeter Pembias Kebedaan (DSC). Bagi penentuan kesan langkah nyahlemak, cecair penyalut telah disediakan dengan mencampurkan tepung gandum, beras atau sagu kepada air pada nisbah 1:1.2 (tepung:air) dan kemudian dikenakan pengeringan sejuk-beku selama 15 jam. Langkah nyahlemak dijalankan menggunakan pengekstrakan Soxhlet selama 2 jam dengan heksana sebagai pelarut. Bagi penentuan kesan penambahan minyak, cecair penyalut telah disediakan dengan mencampurkan tepung gandum, beras atau sagu kepada air pada nisbah 1:1.2 (tepung:air). Sebanyak 5 mg minyak masak ditambah ke dalam cecair penyalut tersebut dan dikenakan pengeringan sejuk-beku selama 15 jam. Sampel kawalan dan sampel yang dikenakan perlakuan dianalisis menggunakan Kalorimeter Pembias Kebedaan (DSC) dalam julat 25°C – 120°C pada kadar pemanasan 10°C/min. Parameter yang direkodkan adalah suhu awal, puncak dan akhir pengelatinan serta entalpi pengelatinan ternormal. Bagi setiap jenis tepung yang digunakan, langkah nyahlemak dan penambahan minyak kepada cecair penyalut tidak memberi kesan yang besar terhadap suhu awal (To), puncak (Tp), akhir (Te) dan entalpi pengelatinan (?H).
Key words: defatting, gelatinization
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