Cold plasma suppresses fungal spoilage in packaged beef jerky

Authors: Niemira, Brendan; Sites, Joseph; Boyd, Glenn

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/2/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Introduction: Beef jerky is a popular snack food. Spoilage, though uncommon, manifests as outgrowth of fungi. Cold plasma is a relatively novel food processing intervention suitable for application to low-moisture foods. This study evaluated two types of cold plasma (pre- and post-packaging) as control strategies for fungal spoilage of beef jerky. Samples of commercially prepared beef jerky (42g) were inoculated with a mixed culture of spoilage fungi, including Aspergillus app., Penicillium spp., and Rhizopus spp. Methods: 1) Inoculated samples were loaded into clean commercial packaging, pouches sealed, and loaded into a corona discharge plasma system. Preliminary experiments at 45V input, 36kV output confirmed the generation of plasma inside the pouches with no loss of packaging integrity. Samples were treated for 3 minutes, or held without plasma treatment (control). 2) Inoculated samples were loaded onto a lab-scale conveyor belt and treated with a plasma jet apparatus consisting of 4 plasma emitter heads. Samples were passed under the plasma heads, 540 watts, 9cm gap spacing, for 1 minute, flipped, treated again for an additional minute, total treatment time was 2 minutes. Control samples received no plasma. Samples were loaded into clean commercial packaging, pouches sealed. Treatments were confirmed by IR camera to be nonthermal. Samples were stored at 25C for up to 16 days. Results: At 5 days of storage, slight mold growth was visible on control samples. This increased rapidly during storage, with complete fungal contamination and extensive growth by day 7. Corona discharge treated samples remained clean at 5 days, but showed slight signs of mold growth by 7 days, with more rapid growth thereafter. Plasma jet treated samples remained clean until 12 days, when single points of fungal growth were visible. Mold growth expanded on treated samples until complete contamination was observed on Day 14. Significance: in-package corona discharge cold plasma treatment of inoculated beef jerky had a slight suppressive effect on mold growth, while pre-package plasma jet treatment was much more effective, extending time in storage from 5 days to 13. Cold plasma has potential as a processing intervention for beef jerky and related low-moisture products.