Isomaltooligosaccharide (IMO), a well-known prebiotic, was produced from starch by a novel approach of simultaneous saccharification and transglucosylation (SST). The dosage of enzyme mixture consisting of Fungamyl 800L, for saccharification and alpha-glucosidase, for transglucosylation was optimized by Nelder-Mead simplex algorithm. The optimal conditions observed at the end of five iterations were 0.06 U for Fungamyl 800L and 1.05 U for alpha-glucosidase per 5 mL of liquefied slurry. The production of IMO from soluble starch using these optimal concentration of enzymes in SST was found to be 95.08 +/- 1.22 g/L at the end of 12 h in comparison to 89.66 +/- 2.64 that was obtained using consecutive saccharification and translucosylation (CST) at the end of 24 h. Thus produced IMO via SST comprised of (in g/L) isomaltose: 13.83, maltotriose: 5.58, panose: 39.40, tetrasaccharides (DP4): 16.1, pentasaccharides (DP5): 11.29 and other higher oligosaccharides (>= DP6): 8.86. The optimized SST process was also extrapolated to two sustainable starch sources viz., potato processing waste (PPW) and broken rice (BR). The IMO produced using PPW and BR as substrates were found to be 92.17 +/- 3.43 g/L and 85.11 +/- 4.30 g/L, respectively. These results indicate that SST could be a promising process intensification alternative for the sustainable production of IMO in comparison to existing methods. (C) 2016 Elsevier Ltd. All rights reserved.