Biotechnol. Bioprocess Eng. 1997, 2, 19-22 Production of Maltooligosaccharides from Starch and Separation of Maltopentaose by Adsorption of Them on Activated Carbon (I) I1-Shik Moon* and Gyoujin Cho Department of Chemical Engineering, Sunchon National University, Sunchon, Chonnam 540-742, Korea For the selective production ofmaltopentaose (Gs)over other oligosaccharides, enzymatic hy- drolysis conditions of starch by commercial a-amylase (Termamylj~') were investigated. The determined optimum condition was 29.6 KNU (Kilo Novo a-amylase Unit) enzyme loading in 150 mL of 0.3% starch solution under pH level of 5 at 40"C for 30 min. About 40% of G.~ selectivity can be attained using the determined optimum condition. For further enhancing G.~ selectivity, an activated carbon adsorption process has been attached after the enzymatic hydrolysis. From the adsorption process, G~can be enriched up to 72% in the solution. Key words: maltooligosaccharides, maltopentaose, a-amylase, starch, activated carbon INTRODUCTION After starting research on the production of oli- gosaccharides around 1970-75 in Japan, the investi- gation of oligisaccharides has been grown up rapidly to the commercialization during 1980s. Various kinds of biologically active oligosaccharides have been de- veloped from raw materials such as starch, sucrose, lac- tose, xylan, agar, chitin, chitosan, etc [1-7]. Among those oligosaccharides, maltooligosacchrides which have c~-1,4 glucosidic linkage with 2 to 10 glucopyra- nosyl units have been used in a number of food in- dustries as low sweetner, anti-hygroscopic agent, tun- icating agent, humeetant, etc. In particular, malto- pentaose which has five glucopyranoses is highly demanded as a high value-added material in the med- ical field since the pure maltopentaose can be used as a diagnostic reagent to examine the activity of (x-amyl- ase in serum [8-11]. Recently, Fuji-Oligo Ga a: and Fuji-Oligo G4 "~ con- taining more than 50% of pure maltotriose (Ga) and maltotetraose (G4) respectively in the syrup of starch hydrolyzed products have already been commerc- ialized. In addition, although the other maltooligo- saeeharides predominate, maltopentaese (Gs) and mal- tohexaose (G-6) enhanced syrup (Sun-Oligo 5- 6q;) has been in market as well [12]. Therefore, the separation of pure oligosaccharide from the reaction mixture is a key technique for the practical use. Up to the present, fine partiete and ion exchange resin packed columns are commonly used in the chromatographic separation of oligosaccharides [13]. However the separation tech- niques using those packing materials still have major problems such as high operation cost and low separa- tion efficiency. Therefore, more effective and con- venient process to attain a pm'e form of each G3, G4, Cx,5, Ga, etc. should be developed. In this paper, the new results of hydrolysis of starch * Corresponding author Te1:0661-50-3581 Fax:0661-50-3508 e-mail: ismoon@sunchon.sunchon.ac.kr using Termamyl ~ (c~-amylase) and enhanced selec- tivity of Gs from the produced maltooligosaecharides via an activated carbon adsorption process will be brief- ly reported. MATERIALS AND METHODS Materials An enzyme (a-amylase, (x-l-4-D-Glucan glucano- hydrolase; E.C. 3.2.1.1) used in this work was Ter- mamyl~ (Novo Nordisk A/S) with the specific activity of 120 KNU/g. One Kilo Novo a amylase Unit (1 KNU) is the amount of enzyme which breaks down 5.26 g starch (Merk, Amylum Soluble, Erg. B 6) per hour at pH level of 5.6 and 37~ Soluble starch was purchased from Sigma and used without further purification. Buffer solutions were prepared by using Na~HPO4- NaH2P04 and sodium acetate-acetic acid. Emzymatic Hydrolysis The Hydrolysis reactions were carried out in a 250 mL Erlenmeyer flask containing 150 mL of reaction mixtures. The reaction mixture consisted of 50 mL of the substrate and 100 mL of enzyme solution. The sub- strate concentraion was defined as the starch con- centration in 150 mL of the mixture. The resulting mix- tures were reacted for appropriate time under 40~ thermostatic agitating bath. After appropriate time, the reaction was stopped by inactivating the enzyme using an autoclave. The resulting sugars were analyz- ed by HPLC. Analytical Method Deionized water and analytical grade acetonitrile (Aldrich) were mixed as a ratio of 65:35 (v/v), filtered, and degassed to use as an mobile phase. The resulting sugars were analyzed at 40~ on a Shimadzu model LC- 6AD HPLC System equipped with a refractive index detector and Shimpaek CLC-NH~ column under the