Abstract

This study involved the production of naringinase by twelve filamentous fungi in solid-state fermentation (SSF) using orange and grapefruit rind as substrates; these agro industrial residues contain naringin, an important inductor for this enzyme. The percentage of naringin hydrolyzed from grapefruit rind by Aspergillus foetidus,Aspergillus niger and Aspergillus niger HPD-2 was 81, 80 and 79% respectively. The volumetric and specific naringinase activity of each strain was influenced by temperature, pH and water activity (Aw). The culture conditions optimal for A. foetidus, A. niger and A. niger HPD2 were as follows: pH 5.4, 35°C, 0.5222 Aw; pH 5.4, 35°C, 0.7533 Aw; pH 5.4, 40°C, 0.7533 Aw; respectively. The highest volumetric activity was obtained using A. foetidus with 2.58 U ml^-1, when grew on grapefruit rind. Among the strains used, optimal naringinase production was with A. foetidus. The use of grapefruit rind as a substrate gave a higher yield of naringinase production than using orange rind.

Key words: Aspergillus foetidus, naringin, solid-state fermentation, grapefruit rind, naringinase.