Abstract An economical preparation of amyloglucosidase (AMG) is obtained from a transglucosidase-nonproducing mutant of Aspergillus awamori by qualitative and quantitative optimization of the ingredients of its production medium as well as production parameters. Further, it is upgraded by filtration and 14-fold concentration through an ultrafiltration membrane. Finally, its maximal stabilization during storage at ambient temperature is attained by using 14% (w/v) partial hydrolysate of starch as a stabilizer. While the concentrated preparation without stabilizer showed less than 50% of the original activity after 24 weeks of storage, the concentrated preparation, fortified with 14% (w/v) partial hydrolysate of starch, showed 80% stabilization during the same period. This stabilizer could be substituted by 1 × 10 −3 M thiomersal for comparable stabilization of concentrated amyloglucosidase preparation. This enzyme preparation afforded efficient (96% DX, w/w) saccharification of 35% (w/w) tapioca starch in 48–54 h. Thus, these steps have cumulatively provided an economical, upgraded, stabilized and efficient alternative to commercially available AMG preparations.