Preparation of Aspergillus niger 426 naringinases for debittering citrus juice using of agro-industrial residues

Abstract Naringin (4,5,7-trihydroxy flavanone-7-rhamnoglucoside), considered as the main bitter component of grapefruit, requires the use of enzymes to reduce the level of this substance during juice processing. For this reason, it has been the focus of many studies. To increase the production of naringinase by Aspergillus niger cultivated in solid-state fermentation (SSF), it was verified whether the influence of agro-industrial residues as fermentation substrates and, finally, selected the best of the three inducers, or their mixtures to remove the bitterness of grapefruit juice. Cultivation with 2.3 g of grapefruit peel, 2.5 g of rice bran, and 5.2 g of wheat bran and medium supplementation with a mixture of naringin, rutin, and hesperidin in the concentration of (g / L): 2, 5, 4.5, and 3.0, respectively, leading to a maximum activity of 28 U / mL. The results indicate that the sequencing procedure, which allowed the definition of an optimal mixture of components, is a new way for microorganisms to have a high naringinase yield, in particular by SSF, since our data showed a 96% increase in the production of naringinase.