Sains Malaysiana 39(6)(2010): 969–973

Molecular Characterisation of Sago Starch Using Gel Permeation Chromatography Multi-Angle Laser Light Scattering

(Pencirian Molekul Kanji Sago Menggunakan Kromatografi Penelapan Gel Serakan Cahaya Laser Pelbagai Sudut)

Zainon Othman*

Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor, D.E., Malaysia

Saphwan Al-Assaf

Phillips Hydrocolloids Research Centre

Glyndwr University, Mold Road, Wrexham LL 2AW, United Kingdom

Osman Hassan

Food Science Programme, School of Chemical Sciences and Food Technology

Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E., Malaysia

Diserahkan: 8 April 2009 / Diterima: 1 Jun 2010

ABSTRACT

The molecular characteristics of sago starch (native and debranched) were determined using a gel permeation chromatograpy multi-angle laser light scattering (GPC-MALLS) method. The method involves the optimisation of sample solubilisation and GPC operating conditions. The weight-average molecular weight Mw of native and debranched sago starch determined was 29.1 ± 2.1 °— 106 and 1.87 ± 0.4 °— 105 gmol-1 respectively while radius of gyration Rg was 123.6 and 59.3 nm respectively. The reduction in Mw and Rg in debranched sago was attributed to the hydrolysis of α-1,6 glycosidic linkages by pullulanase to smaller oligosaccharides.

Keywords: GPC-MALLS; radius of gyration; sago starch; weight-average molecular weight

ABSTRAK

Pencirian molekul kanji sagu (asli dan dinyahcabang) telah dijalankan menggunakan kaedah kromatografi penelapan gel serakan cahaya laser pelbagai sudut (GPC-MALLS). Kaedah pencirian ini melibatkan pengoptimuman pelarutan sampel dan keadaan operasi kromatografi. Berat purata berat molekul Mw kanji sago asli adalah 29.1 ± 2.1 °— 106 berbanding 1.87 ± 0.4 °— 105 gmol-1 untuk kanji sago dinyahcabang dan legaran jejari Rg adalah 123.6 nm untuk kanji asli berbanding 59.3 nm untuk kanji dinyahcabang. Penurunan nilai Mw dan Rg dalam kanji sago dinyahcabang adalah hasil hidrolisis ikatan glikosidik α-1,6 oleh enzim pullulanase ke oligosakarida yang lebih kecil.

Kata kunci: Berat purata berat molekul; GPC-MALLS ; kanji sagu; legaran jejari

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*Pengarang untuk surat-menyurat; email: zainon@nuclearmalaysia.gov.my