The medium composition for the production of intracellular beta-fructofuranosidase (FFase, EC 3.2.1.26) by Aspergillus japonicus TIT-90076 was improved by using statistical experimental designs and the method of steepest ascent in shake batch cultures. Sucrose and yeast extract were the key nutritional factors affecting enzyme production. Improved media containing 24.05% sucrose and 2.75% yeast extract increased enzyme production by 180%.