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

Received: 11 April 2013/Accepted: 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

REFERENCES

Bashaiwoldu, A.B., Podczeck, F. & Newton, J.M. 2004. A study on the effect of drying techniques on the mechanical properties of pellets and compacted pellets. European Journal of Pharmaceutical Sciences 21(2-3): 119-129.

Castellano, I., Gurruchaga, M. & Goni, I. 1997. The influence of drying on the physical properties of some graft copolymers for drug delivery systems. Journal of Carbohydrate Polymers 34(1-2): 83-89.

Chawla, P.R., Bajaj, I.B., Survase, S.A. & Singhal, R.S. 2009. Microbial cellulose: Fermentative production and applications. Food Technol. Biotechnol. 47(2): 107-124.

Clasen, C., Sultanova, B., Wilhelms, T., Heisig, P. & Kulicke, W.M. 2006. Effects of different drying processes on the material properties of bacterial cellulose membranes. Macromol. Symp. 244: 48-58.

Czaja, W., Romanovicz’, D. & Brown, R.M. Jr. 2004. Structural investigations of microbial cellulose produced in stationary and agitated culture. Cellulose 11: 403-411.

Gardner, A.W. 1982. Industrial Drying. Texas: Gulf Publishing Company.

Geankoplis, C.J. 2003. Transport Processes and Separation Processes Principles (Includes Unit Operations). USA: Prentice Hall.

Iuliana, M.J., Anicuta, S.G. & Marta, S. 2012. Controlled release of sorbic acid from bacterial cellulose based mono and multilayer antimicrobial films. LWT - Food Science and Technology 47: 400-406.

Jagannath, A., Raju, P.S. & Bawa, A.S. 2010. Comparative evaluation of bacterial cellulose (Nata) as a cryoprotectant and carrier support during the freeze drying of probiotic lactic acid bacteria. LWT - Food Science and Technology 43: 1197-1203.

Jie, X., Cao, Y., Qin, J.J., Liu, J. & Yuan, Q. 2005. Influence of drying method on morphology and properties of asymmetric cellulose hollow fibre membrane. Journal of Membrane Science 246(2): 157-165.

Keshk, S. & Sameshima, K. 2006. Influence of lignosulfonate on crystal structure and productivity of bacterial cellulose in a static culture. Enzyme and Microbial Technology 40: 4-8.

Maneerung, T., Tokura, S. & Rujiravanit, R. 2008. Impregnation of silver nanoparticles into bacterial cellulose for antimicrobial wound dressing. Carbohydrate Polymers 72: 43-51.

Mihranyan, A., Llagostera, A.P., Karmhag, R., Stromme, M. & Ek, R. 2004. Moisture sorption by cellulose powders of varying crystallinity. International Journal of Pharmaceutical 269(2): 433-442.

Nadia, H., Mohd Cairul Iqbal, M.A. & Ishak, A. 2012. Physicochemical properties and characterization of nata de coco from local food industries as a source of cellulose. Sains Malaysiana 41(2): 205-211.

Norihiro, K. & Gehrke, S.H. 2004. Microporous, fast response cellulose ether hydrogel prepared by freeze-drying. Journal of Colloid and Surfaces 38(3-4): 191-196.

Okiyama, A., Shirae, H., Kano, H. & Yamanaka, S. 1992. Bacterial cellulose: Two-stage fermentation process for cellulose production by Acetobacter aceti. Food Hydrocolloids 6: 471-477.

Pa'e, N., Hui, C.C. & Muhamad, I.I. 2007. Shaken culture fermentation for production of microbial cellulose using pineapple waste. Proceeding of International Conference on Waste to Wealth. 26-28 November. Kuala Lumpur. Malaysia Nuclear Agency (MINT).

Phisalaphong, M. & Jatupaiboon, N. 2008. Biosynthesis and characterization of bacteria cellulose-chitosan film. Carbohydrate Polymers 74: 482-488.

Segal, L., Creely, J.J., Martin, Jr. A.E. & Conrad, C.M. 1959. An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer. Textile Research Journal 29(10): 786-794.

Sheng, C.W. & Ying, K.L. 2008. Application of bacterial cellulose pellets in enzyme immobilization. Journal of Molecular Catalyst B: Enzymatic 54: 103-108.

Sheu, F., Wang, C.L. & Shyu, Y.T. 2000. Fermentation of Monascus purpureus on bacterial cellulose-nata and the color stability of Monascus-nata complex. Journal of Food Science (Food Microbiology and Safety) 65(2): 342-345.

Thakhiew, W., Devahastin, S. & Soponronnarit, S. 2010. Effects of drying methods and plasticizer concentration on some physical and mechanical properties of edible chitosan films. Journal of Food Engineering 99: 216-224.

Wei, B., Yanga, G. & Hong, F. 2011. Preparation and evaluation of a kind of bacterial cellulose dry films with antibacterial properties. Carbohydrate Polymers 84: 533-538.

Yeoh, Q.L., Lee, G.L. & Fatimah, H. 1985. Teknologi pengeluaran Nata. Jurnal Teknologi Makanan 4(1): 36-39.

Zhang, C., Wang, L., Zhao, J. & Zhu, P. 2011. Effect of drying methods on structure and mechanical properties of bacterial cellulose films. Advanced Materials Research 239-242: 2667-2670.

*Corresponding author; email: idayu@cheme.utm.my