Characterization of Ochratoxin A Producing Fungi from Grape Pomace

B. D. Karlton-Senaye, J. Yu2, L. L. Williams


Background: Recently, grape pomace is gaining use as a nutritional and functional food ingredient. Aspergillus carbonarius and Aspergillus niger, known for their ochratoxin A (a nephrotoxic and carcinogenic agent) producing ability in a variety of agricultural products including grape pomace is creating food safety concerns. The purpose of this study was to determine the safety of grape pomace as a food ingredient. Materials: Molds isolates were identified macroscopically on Czapek Yeast Extract (CYA), Potatoes Dextrose Agar (PDA) and Malt Extract Agar (MEA) according to Pitt and Hocking (1997). Isolates were confirmed by Random Amplified Polymorphic DNA (RAPD) analysis using ITS1/NIG and ITS1/CAB in combination with eight OPC primers. Results: Fungal counts ranged from 4.27±0.05 to 5.35±0.04 log CFU/mL. Out of thirty-eight isolates of molds found in the pomace cultivars 81.1% was A. niger, 13.51% A. carbonarius, and 5.39% was A. fumigatus. Pomaces derived from Chardonay and Merlot grape cultivars were mostly populated with all three Aspergillus strains detected. No mold was detected in pomace from Cabernet Franc, and Sangiovese grapes. RAPD analysis confirmed the presence of A. carbonarius and A. niger. RLFP analysis showed differentiation between strains detected. Conclusion: The findings from this study suggests that pomaces obtained from some grape cultivars could be unsafe as a food ingredient due to contamination by ochratoxin A producing molds that could be harmful to human health.


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Full conference title: 

115th General Meeting of the American Society for Microbiology
    • ASM 115th (2015)