399 399 International Journal of Research & Review (www.ijrrjournal.com) Vol.6; Issue: 8; August 2019 International Journal of Research and Review www.ijrrjournal.com E-ISSN: 2349-9788; P-ISSN: 2454-2237 Original Research Article Simple Determination of Inulin Polymerization Degree Average from Dahlia Tuber Using Spectrophotometer Iren Gusni Yanti 1 , Minda Azhar 2 , Anni Faridah 3 , Budhi Oktavia 2 1 Chemistry Department, Faculty of Mathematics and Natural Sciences, Universitas Negeri Padang 2 Jl. Prof. Dr. Hamka, Air Tawar, Padang, Indonesia 3 Faculty of Tourism and Hospitality, Universitas Negeri Padang Corresponding Author: Minda Azhar ABSTRACT Degree of polymerization (DP) of inulin is the number of monomer units in inulin polymer strand. DP of inulin can be determined simply using spectrophotometer. This study aims to determine DP of inulin from fresh dahlia tubers and dahlia tubers that stored for fifteen days. Inulin extraction from dahlia tuber was based on the solubility of inulin in hot water and precipitation in ethanol by adding ethanol to final concentration of 80% solution. Reducing sugars of inulin was determined using the DNS method. The absorbances were measured using spectrophotometer at maximum wavelength of 490 nm. Total sugar of inulin was determined using Phenol-sulphate method, the absorbance was measured at λ max 350 nm. Inulin from fresh dahlia tubers had higher DP than inulin from dahlia tuber that stored for fifteen days. Inulin that found in this research belongs to the fructooligosaccharide (FOS) group. Keywords: Degree of polymerization (DP), dahlia tubers, DNS, phenol-sulphate, reducing sugars, spectrophotometer. INTRODUCTION Inulin is fructant group polysaccharide, which consists of the main unit β-(21) fructofuranosil (Fm) and one α-glycopiranose (12) (GFn) terminal unit. The DP of inulin varies from 2 to 70, whereas inulin molecules with DP 2-10 are called oligofructose or fructooligosaccharides (FOS) (Petkova & Denev, 2015). Natural sources of inulin include chicory roots, Jerusalem artichokes, dahlia tuber, yacon, asparagus, leeks, onions, bananas, wheat and garlic (Shoaib et al., 2016). Most commercial inulin is produced from chicory, dahlia tubers and Jerusalem artichoke because it has high inulin content. Inulin is widely used in the food industry to modify textures, replace fat or as low-calorie sweetener. Generally, inulin is used as prebiotic for the development of functional foods to improve health. In addition, it has several applications in other fields such as pharmacy. Mostly inulin is used as diagnostic agents for kidney function and as protein stabilizer (Mensink et al., 2015; Shoaib et al., 2016). DP of inulin has effect on inulin function (Shoaib et al., 2016). Inulin with low DP is suitable to be used as prebiotic, whereas inulin with a high DP can be hydrolyzed into FOS. In this regard, the development of analytical methods for determining of DP of inulin is very important for the inulin characterization and its derivatives in plant samples (Saengkanuk et al., 2011). Some simple methods for determining of DP of inulin are fast, specific and suitable for analysis