Safety Improvement of Grape Pomace by Pressure Cooking and Fermentation with Different Strains of Lactobacillus
Description
Grape pomace (GP) is a polyphenol and dietary fiber-rich byproduct of grapes from winemaking and has great potential to serve as food and feed ingredients. However, limited studies have found that GP is often contaminated with high levels of Ochratoxin A (OTA), which has been reported to cause nephrotoxicity and other diseases in various animal species. In this study, we examined the impacts of pressure-cooking at different pH and fermentation with five lactobacillus strains (L. paracasei, L. acidophilus, L. plantarum, lactiplantibacillus plantarum and Lactobacillus bulgaricus (LB6)) on OTA and different classes of polyphenols in the GP. The GP was deseeded and adjusted to pH 5-7 with NaHCO₃, spiked to OTA of 50ng/g GP, and then pressure cooked for 15-60 min. The GP obtained at optimal pressure- cooking condition was fermented anaerobically at 42 °C for 4-144 hours. The untreated GP served as control. Pressure-cooking only decreased the OTA content by 18- 36% (P< 0.05), while TP concentrations increased quadratically (R²=0.9642-0.9145, P< 0.05). TA concentration decreased exponentially with increasing treatment times (R²=0.995). In the pH range OF 5-7, pressure – cooking achieved 40-63% of OTA reductions (p< 0.05). OTA levels were further reduced by fermentation and a total OTA reduction of 98% was achieved.