Sains Malaysiana 43(5)(2014): 767–773

Effect of Different Drying Methods on the Morphology, Crystallinity, Swelling Ability and

Tensile Properties of Nata De Coco

(Kesan Kaedah Pengeringan Berbeza pada Morfologi, Penghabluran, Kebolehan untuk Mengembang dan Kekuatan Tegangan Nata De Coco)

NORHAYATI PA'E, NUR IDAYU ABD HAMID, NOZIEANA KHAIRUDDIN, KHAIRUL AZLY ZAHAN, KOK FOOK SENG, BAZLUL MOBIN SIDDIQUE & IDA IDAYU MUHAMAD*

Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia

Diserahkan: 11 April 2013/Diterima: 3 September 2013

ABSTRACT

Nata de coco or bacterial cellulose produced by Acetobacter xylinum is a unique type of biocellulose. It contains more than 90% of water. Dried nata was preferred compared to wet form since it is more convenient and portable with stable properties. Therefore, drying process is necessary in order to produce dried nata de coco. Drying method is a key factor that influenced the properties of dried nata de coco produced. The aim of this study was to investigate the effect of different drying methods on morphology, crystallinity, swelling ability and tensile strength of dried nata de coco. Nata de coco samples were dried using three physical drying methods such as oven, tray dryer or freeze dryer until it achieved 3-5% moisture content. Obviously, the three drying techniques produced web-like structured nata de coco and quite similar crystallinity which was in range between 87 and 89%. Freeze dried sample showed the largest swelling capacity and tensile strength which was found to be 148 MPa. Different drying method gave different properties of nata de coco. Therefore, the present work proposed the most suitable drying method can be utilized based on the properties of end product needed.

Keywords: Acetobacter xylinum; bacterial cellulose; drying process; nata de coco

ABSTRAK

Nata de coco atau selulosa bakteria yang dihasilkan oleh Acetobacter xylinum merupakan bioselulosa yang unik. Ia mengandungi lebih daripada 90% air. Oleh itu, proses pengeringan sangat diperlukan untuk menghasilkan nata de coco kering. Kaedah pengeringan adalah faktor utama yang mempengaruhi sifat nata de coco yang telah dikeringkan. Kajian ini dijalankan untuk mengkaji kesan kaedah pengeringan yang berbeza pada morfologi, penghabluran, kebolehan untuk mengembang dan kekuatan tegangan nata de coco yang telah dikeringkan. Sampel nata de coco dikeringkan menggunakan tiga kaedah pengeringan fizikal iaitu ketuhar, pengering dulang atau pengering beku sehingga ia mencapai kurang daripada 5% kandungan lembapan. Jelas sekali, tiga teknik pengeringan tersebut menghasilkan nata de coco dengan struktur jaringan yang tersusun dan nilai penghabluran yang hampir sama iaitu dalam lingkungan 87-89%. Sampel daripada pengering beku menunjukkan kapasiti penyerapan air terbesar dan dengan kekuatan tegangan 148 MPa. Kaedah pengeringan yang berbeza memberikan sifat yang berbeza kepada nata de coco. Oleh itu, hasil kajian ini dapat mencadangkan kaedah pengeringan yang paling sesuai digunakan berdasarkan sifat produk akhir yang dikehendaki.

Kata kunci: Acetobacter xylinum; nata de coco; proses pengeringan; selulosa bakteria

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*Pengarang untuk surat-menyurat; email: idayu@cheme.utm.my