High voltage atmospheric cold plasma (HVACP) treatment of Listeria monocytogenes from ready-to-eat deli-style, chicken breast meat inside a package

Objectives

The goal of this project was to evaluate high voltage atmospheric cold plasma (HVACP) treatment on ready-to-eat (RTE) deli-style, chicken breast meat for reduction of spot inoculated pathogen, Listeria monocytogenes (LM) and its impact on product quality.

Objective 1: Demonstrated the HVACP technology can eliminate inoculated LM populations on tryptic soy agar (TSA) under direct and indirect treatment.

Objective 2: Evaluated the HVACP process optimized in Objective 1 to significantly reduce natural spoilage organisms and inoculated LM populations on RTE deli-style, chicken breast meat. Quality changes were characterized using color measurement and Thiobarbituric acid reactive substances (TBARS) for oxidation measurement.

Objective 3: Examined the penetration effect of the HVACP process upon shingled RTE meat under both direct and indirect treatment.

Conclusions

Objective 1 results demonstrated 30 s direct and indirect HVACP treatment of tryptic soy agar (TSA) in air-filled packages achieved greater than 5 log reductions of LM. Objective 2 results showed HVACP treatment of LM inoculated RTE deli-style, chicken breast meat gave1.71 log/g reductions in 300 s in MA65 gas inside a sealed package. Additional HVACP treatments of LM inoculated on TSA with added ingredients (protein, oil, salt) similar to RTE chicken breast, showed a reduced effectiveness. In particular, for HVACP treatment in air the added oil provided a complete protection to the inoculated LM populations from the reactive gas species (RGS) with no measureable reductions. Objective 3 results showed indirect HVACP treatment of stacked shingles of RTE chicken breast meat led to no measureable LM reduction between shingles. Direct HVACP treatment of stacked shingles of RTE chicken breast meat in MA65 showed measureable RGS penetration within the layered product, although bacterial reductions of only 0.2 log/g were observed. HVACP treatment of RTE chicken breast meat in MA65 showed an immediate increase in TBARS after treatment but there was no significant change over 21 days of refrigerated storage.

Deliverable

 HVACP treatment is effective for achieving 3.5 log/g LM reductions on raw meat, but these same HVACP treatments showed only a 1.71 log/g reductions on RTE fully cooked chicken breast. Further research on HVACP treatment is needed using different gas blends; examining the protective effect provided from surface oil and protein exudate on LM in cooked meat; and quantifying the RGS generation within the shingled RTE meat.