Purpose: The purpose of this study is to evaluate the safety of grape pomace as food ingredient by (i) determining the fungal population in the pomaces, and (ii) identifying and characterizing ochratoxigenic-producing Aspergilli from the pomaces and (iii) studying the ability of the pomaces to produce OTA.
Methods: Molds isolates were identified macroscopically according to Pitt and Hocking (1997) and OTA was detected using ELISA method.
Results: The population of yeast and mold ranged from 4.27 ± 0.05 to 5.35 ± 0.04 log CFU/ml. Out of an average of 37 mold counts, OTA producing mold Aspergillus niger (81.1%) and Aspergillus carbonarius (13.51%) were found to be the most dominant molds identified. Other molds detected were Aspergillus fumigatus (5.39%). Pomace derived from Chardonnay 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. The level of OTA in the pomace varied with grape cultivars used for the pomaces. High levels of ochratoxin A exceeding the 2 ng/g allowed level were detected in the pomace samples of Chardonnay (159.99 ± 36.99), Cabernet Sauvignon (133.46 ± 22.99), Sangiovese (134.00 ± 23.08) and Merlot (20.06 ± 3.87 ng/g).
Significance: The findings from this study indicates that pomaces obtained from some grape cultivars may not be safe to be used as a food ingredient due to the contamination of pathogenic molds and presence of high levels of ochratoxin A.