Starch derived oligosaccharides such as isomalto and nigero oligosaccharides are usually produced from starch by the combination of hydrolysis and transglucosylation. 1,2) As a first step, starch is liquefied by thermostable α amylase at around 100 C. This gelatinized starch is then cooled to around 50 65 C and hydrolyzed to maltose and maltotriose by β amylase and starch debranching enzymes. α Glucosidase is added and catalyzes the transglucosylation toward maltose and maltotriose to produce glucosidic linkage other than α 1,4 linkage at the non reducing end of maltooligosaccharides. The type of linkage produced is dependent on the specificity of α glucosidase for the glucosidic linkage. For example, α glucosidases from Aspergillus niger (ANG) and Acremonium strictum (ASG) produce isomalto (α 1,6 linkage) and nigero (α 1,3 linkage) oligosaccharides, respectively.3,4) These enzymes are utilized in industrial oligosaccharide production.The degree of polymerization (DP) of these oligosaccharides is usually 2 4. This is because the substrate for transglucosylation is mainly maltose and maltotriose produced from starch by β amylase. It is very difficult to introduce glucosidic linkage other than α 1,4 linkage at the non reducing end of longer maltooligosaccharides by the usual hydrolysis transglucosylation process because long maltooligosaccharides are immediately insoluble in water due to retrogradation. In addition, it is very difficult to produce long maltooligosaccharides efficiently with no production of short maltooligosaccharides by α amylase since this enzyme produces short maltooligosaccharides even in the initial stages of starch degradation.Cyclodextrin glucanotransferase (CGTase), which is a type of glycosyl transferase belonging to glycoside hydrolase family 13, 5,6) produces CDs from starch via intramolecular transglycosylation.7) This enzyme is known to catalyze four reactions: (i) CD production, (ii) transglycosylation of maltooligosaccharides to other maltooligosaccharides (disproportionation), (iii) the opening of circular CDs and the subsequent transfer to maltooligosaccharides (coupling), and (iv) hydrolysis.7) The hydrolytic activity of CGTase is generally lower than the transglycosylation activity.7) CGTase are thought to degrade starch more mildly than α amylase and CGTase is an appropriate enzyme to produce long maltooligosaccharides from starch.The sweetness of the starch derived glucan generally depends on its chain length. Shorter chain length glucans have a stronger sweetness than longer chain glucans. Although the sweetness of long chain glucans is weak, these substances are capable of masking the bitter tastes of foods and beverages and providing a rich taste. Abstract: The isomalto-and nigero-oligosaccharides are usually produced from starch by the combination of α-glucosidase and starch degrading enzymes, such as α-and β-amylases. In this study, a new reaction system for the production from starch of two α-1,4 glucans having α-1,6-and α-1,3-linked glucosyl residues at or near the non-...