Ellagic Acid Recovery by Solid State Fermentation of Pomegranate Wastes by <i>Aspergillus niger</i> and <i>Saccharomyces cerevisiae</i>: A Comparison

• Main Authors: Federica Moccia, Adriana C. Flores-Gallegos, Mónica L. Chávez-González, Leonardo Sepúlveda, Stefania Marzorati, Luisella Verotta, Lucia Panzella, Juan A. Ascacio-Valdes, Cristobal N. Aguilar, Alessandra Napolitano
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Molecules
• Subjects: solid state fermentation; <i>aspergillus niger</i>; <i>saccharomyces cerevisiae</i>; ellagic acid; ellagitannins; ultrasound microwave-assisted extraction; acid hydrolysis
• Online Access: https://www.mdpi.com/1420-3049/24/20/3689

Fermentation in solid state culture (SSC) has been the focus of increasing interest because of its potential for industrial applications. In previous studies SSC of pomegranate wastes by <i>Aspergillus niger</i> has been extensively developed and optimized for the recovery of ellagic acid (EA), a high value bioactive. In this study we comparatively investigated the SSC of powdered pomegranate husks by <i>A. niger</i> and <i>Saccharomyces cerevisiae</i> and evaluated the recovery yields of EA by an ultrasound and microwave-assisted 7:3 water/ethanol extraction. Surprisingly enough, the yields obtained by <i>S. cerevisiae</i> fermentation (4% <i>w</i>/<i>w</i>) were found 5-fold higher than those of the <i>A. niger</i> fermented material, with a 10-fold increase with respect to the unfermented material. The EA origin was traced by HPLC analysis that showed a significant decrease in the levels of punicalagin isomers and granatin B and formation of punicalin following fermentation. Other extraction conditions that could warrant a complete solubilization of EA were evaluated. Using a 1:100 solid to solvent ratio and DMSO as the solvent, EA was obtained in 4% yields from <i>S. cerevisiae</i> fermented husks at a high purity degree. Hydrolytic treatment of <i>S. cerevisiae</i> fermented pomegranate husks afforded a material freed of the polysaccharides components that gave recovery yields of EA up to 12% <i>w</i>/<i>w</i>.