High voltage atmospheric cold plasma treatment of Listeria innocua and Escherichia coli K-12 on Queso Fresco (fresh cheese)

High voltage atmospheric cold plasma (HVACP) is a non-thermal technology for effective decontamination of foods, resulting in safer and extended shelf-life products. Queso fresco (QF: fresh cheese) is a food product prone to Listeria monocytogenes contamination. Once QF gets contaminated post-manufacture, there is no additional treatment to remove pathogen contaminants. In this study, 10 g QF were inoculated with L. innocua and E. coli K12 and treated with HVACP under direct mode of exposure in dry air and MA65 (65% O-2, 30% CO2, 5% N-2) gas blends for up to 5 min at 60 kV, 80 kV, and 100 kV. After 5 min treatment in dry air at 100 kV, a reduction of 1.4 log(10) CFU/g and 3.5 log(10) CFU/g was observed for L. innocua and E. coli K-12 after 24 h storage at 4 degrees C, respectively. Increasing voltage from 60 to 100 kV resulted in a higher production of reactive antimicrobial species, which led to greater bacterial reductions with minimal effects on product quality. Overall, minimal quality changes in pH, moisture, color and lipid oxidation were observed, while no significant (p >= 0.05) difference was found in the cheese texture profile after HVACP treatment.

Automated summary

High voltage atmospheric cold plasma (HVACP) is an effective non-thermal technology for decontamination of food products, with minimal effects on product quality. The study demonstrated that HVACP treatment resulted in significant reductions of L. innocua and E. coli K-12 in queso fresco, while maintaining product quality and safety.