037: Optimization of Plasma-Activated Brine (PAB) for the Reduction of Listeria Innocua: Advancing Cheese Brining Processes

Introduction

This study explores the application of cold plasma technology to activate brine, offering potential for enhanced cheese brining processes. Plasma activation generates antibacterial reactive species in liquid. For this study, a high-voltage atmospheric cold plasma (HVACP) system was employed, utilizing two different electrode configurations: single and multi-donut electrode.

Methods

Brine solutions at concentrations 15%, 19%, and 23% were spiked with non-pathogenic surrogate Listeria innocua and subjected to dry air plasma treatment at 50 kV and 60 kV for various treatment time intervals (30, 60, and 90 seconds). Following treatments, one set of the treated plasma activated brine (PAB) samples were analyzed immediately, while the other set was kept for a 24-hour storage prior to microbial analysis.

Results

This study revealed that the brine sample with a 23% concentration, treated using cold plasma treatment and stored for 24 hours, achieved a consistent 6 log CFU/ml reduction (p < 0.05) of Listeria innocua across all treatment combinations, regardless of voltage, treatment time and type of electrode used. These findings demonstrated the importance of extended storage time to enhance microbial reduction by allowing prolonged interaction between reactive species and microorganisms. The antimicrobial efficiency of PAB was determined through the quantification of reactive species (NO3-, NO2-, and H2O2) present in them. While increased voltage and treatment time generated more reactive antimicrobial species, the brine concentration played a more dominant role in the generation of reactive species. Reactive nitrogen species increased significantly (p < 0.05) from 15% to 19 % brine concentration but showed a decrease at 23%, while H2O2 levels decreased progressively from 15% to 23 %. This trend could be attributed to the varying dissolution of reactive species in different brine concentrations.

Significance

Plasma activation of brine solution is a novel and promising method for microbial reduction, offering significant potential for enhancing the safety of cheese brining processes. Similar to the application of plasma activated water, PAB also holds considerable promise for broader applications within the food sector, paving the way for innovative and safer food processing techniques.

Authors: Dharini Manoharan, Zifan Wan and Rani Govindasamy-Lucey