The Effect of High-Voltage Atmospheric Cold Plasma Treatment on the Shelf-Life of Distillers Wet Grains

There are currently limitations to storing and feeding distillers wet grains (DWG) due to their potential for spoilage and mycotoxin contamination in storage. In this study, in-package treatments of DWG using high-voltage atmospheric cold plasma (HVACP) treatment and storage in modified atmosphere with carbon dioxide were investigated with the primary purpose of increasing product shelf-life. The conditions investigated were (1) HVACP treatment and modified atmosphere packaging (MAP) storage, (2) carbon dioxide-modified atmosphere storage, and (3) HVACP treatment and carbon dioxide-modified atmosphere storage, compared with a control sample with no treatment under MAP storage. Treated samples and controls were stored for 0, 7, 14, 21, and 28 days at 10 and 25 °C, after which treated samples were evaluated for their efficacy to control mold growth indicated by pH, microbial count (CFU/g)/log reduction, and peroxide (H2O2) level. There was a significant difference among the treatments indicated by CFU/g (P 60% moisture), DWG for up to 28 days of storage at 10 and 25 °C. Both HVACP and the combination treatment showed high peroxide levels (100 mg/L) after treatment, which degraded in storage over time. It is thought that a better strategy for the combination treatment would be to treat substrate using HVACP with MAP having a high O2 concentration (65%) and store samples post-treatment in-package in a high CO2 environment.