This study was intended to produce turanose and resistant starch (RS) using recombinant amylosucrase from Neisseria subflava (NsAS). Turanose production yield maximally reached to 76% of sucrose substrate at 40 °C by NsAS treatment. To evaluate turanose as a low-calorie functional sweetener, its hydrolysis pattern was investigated in continuous artificial digestion system. When turanose was consecutively exposed through small intestinal phase, only 8% of disaccharide was hydrolyzed. Structural modification of gelatinized corn or rice starch was carried out by NsAS with sucrose as a glucosyl donor. Non-digestibility of enzyme-modified starches increased to 47.3% maximally through branch-chain elongation, enough for chain-chain association and recrystallization. Obviously, NsAS-modified starches had higher gelatinization peak temperatures than native counterparts, and their paste viscosity was inversely related to their digestibility due to elongated-chain induced retrogradation. These results suggested that NsAS could be a vital biocatalyst candidate in food industry to produce next generation low-calorie carbohydrate food materials.