Detoxification of Grape Pomace Contaminated with Ochratoxin A by Thermal-Pressure Treatment in Combination with...

Grape pomace (GP), a polyphenol-rich byproduct of winemaking, holds considerable health benefits and potential as an antibiotic alternative for livestock animals. However, its utilization is compromised by the contamination of mycotoxins produced by pathogenic molds (with ochratoxin A (OTA) being the most frequently detected), which pose hidden health risks to both livestock animals and human beings. This study evaluated the efficacy of thermal-pressure treatment (pressure cooking) with and without the addition of acidic and alkaline agents, and the combined thermal-pressure and fermentation with four lactic acid bacteria (LAB) strains, including Lactobacillus bulgaricus (LB6), Lacticaseibacillus paracasei (previously Lactobacillus paracasei) (BAA-52), Lactobacillus acidophilus, and Lactiplantibacillus plantarum (previously Lactobacillus plantarum), on reducing OTA and preserving polyphenols in GP. The study found that pressure cooking alone reduced OTA by approximately 33-35% in 30-45 min. The addition of citric acid (CA) or acetic acid (AA) enhanced OTA reduction to 46.9-55.2% and 51.7-54%, respectively, while preserving more polyphenols, notably anthocyanins. Conversely, pressure cooking with the addition of NaHCO₃ facilitated greater OTA reductions (40.4-63%), but concomitantly resulted in substantial polyphenol loss, especially anthocyanins. Fermentation for 24 h with LAB following thermal-pressure treatment resulted in up to 97% OTA reduction for Lc. paracasei, L. acidophilus, and Lp. plantarum strains, which displayed similar high effectiveness in OTA reduction in GP. L. bulgaricus (LB6) was least effective (45%), even after 72 h of fermentation. These findings indicate that home-scale pressure cooking combined with lactic acid fermentation effectively detoxifies OTA-contaminated GP, thus enhancing its safety profile for consumption by livestock animals and humans, despite partial polyphenolic losses.