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

Abstract

Naringin, 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. In this study, to increase the production of naringinase by Aspergillus niger cultivated in solid-state fermentation (SSF), a three-component simplex-centric mixing design along with a response surface methodology (RSM) was applied to generate statistical models and analyze the dataset. First, grapefruit peel, rice bran, and wheat bran were used for substrate selection for naringinase production 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 2, 5, 4.5, and 3.0 g/L, respectively, resulted in 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. This dataset can help other researchers apply a mixing design to increase enzyme production.