The structure of the glucomannan was investigated by IR and NMR spectroscopy revealing that it consists of mannose and glucose units with a mannose/glucose ratio of about . The degree of crystallization was investigated by XRD diffraction revealing that the glucomannan was amorphous. The molecular weight was determined by viscosimetry to be of ×106 Da. | Journal of Science and Technology 54 (2) (2016) 224-230 DOI: CHARACTERIZATION OF GLUCOMANNAN FROM AMORPHOPHALLUS PANOMENSIS IN VIETNAM Nguyen Tien An1, *, Do Truong Thien2, Nguyen Thi Hoa1, Vu Thi Hue1, Vu Thi Minh Thu1, Lai Thi Thu Trang1 1 Thai Binh University of Medicine and Pharmacy, 373 Ly Bon, Thai Binh city, Vietnam 2 Institute of Chemistry, VAST, 18 Hoang Quoc Viet road, Hanoi, Vietnam * Email: nguyentienanvhh@ Received: 1 June 2015; Accepted for publication: 24 September 2015 ABSTRACT A glucomannan has been isolated from the tuber of Amorphophallus panomensis by a simple method without using toxic chemicals. The glucomannan content of the tuber was 4% (w/w). The structure of the glucomannan was investigated by IR and NMR spectroscopy revealing that it consists of mannose and glucose units with a mannose/glucose ratio of about . The degree of crystallization was investigated by XRD diffraction revealing that the glucomannan was amorphous. The molecular weight was determined by viscosimetry to be of ×106 Da. Keywords: Amorphophallus panomensis, glucomannan, konjac. 1. INTRODUCTION Amorphophallus sp. is a perennial herbaceous herb. It grows in mountain or hilly areas in subtropical regions mainly in the South East of Asia. It has been used as food and food additives in China and Japan for more than 1000 years. Glucomannan (GM) is a polysaccharide of the mannan family, very abundant in nature, specifically in softwoods (hemicellulose), roots, tubers and many plants bulbs. Despite the variety of sources, the most commonly used type of GM is named Konjac glucomannan (KGM), which is extracted from tubers of Amorphophallus plants. Irrespective of its origin, GM is composed of β-1,4-linked D-mannose and D-glucose monomers. However, the mannose/glucose monomer ratio may vary depending on the original source of GM. For example, it has been reported that Konjac GM has a molar ratio of around , whereas GMs .
