Utilization of dahlia tuber chips for preparation of difructose anhydride III (DFA III) by enzymatic reaction using inulin fructotransferase (IFTase)

Abstract

Dahlia tuber is known as an alternative source of inulin. Inulin is a substrate required for difructose anhydride (DFA) III preparation by an enzymatic reaction. Therefore, dahlia tuber can be used as a raw material for the preparation of DFA III. Our previous investigation successfully produced DFA III from fresh dahlia tuber extract and inulin isolate from fresh dahlia tuber with a yield of 1.86 and 3.56 %, respectively. In this study, we aimed to compare the yield and purity of DFA III produced from dahlia tuber crude extract and inulin fraction prepared from dried slices (chips) of dahlia tuber. The dahlia tuber chips crude extract and inulin isolate were prepared by soaking the dahlia tuber chips in 70 %-v/v ethanol at a ratio of 1:10. The soaked dahlia tuber chips were then further extracted and isolated to obtain the dahlia tuber chip crude extract and inulin isolate. The enzymatic reaction of DFA III was conducted at pH 5.5 and a temperature of 65 °C for 24 hours. The qualitative analysis of DFA III was carried out by thin layer chromatography (TLC). High-performance liquid chromatography (HPLC) coupled with a refractive index (RI) detector was conducted for quantitative analysis. The obtained syrup was decolorized and crystalized. The result showed that the extract gave a higher yield of DFA III (5.3 %) compare to inulin isolate (4.34 %). However, the extract showed a lower purity (93.4 %) compare to inulin isolate (94.35 %). This study confirmed the better potential of dahlia tuber chips than fresh dahlia tuber in producing DFA III.