Pacific white shrimp (Litopenaeus vannamei) is heavily aquacultured globally due to the desirable qualities of its meat, including tenderness, high nutritional content of protein, amino acids and minerals (Li et al., 2022). However, its high moisture content makes it prone to microbial contamination and endogenous enzyme activity during harvesting, transportation, storage and sale, leading to quality deterioration (Zhang, Deng, & Wang, 2015). Listeria monocytogenes, a psychrophilic, gram-positive pathogen capable of surviving a wide temperature and pH range, is ubiquitous in foods and the environment (Mohan et al., 2021). Over 80% of shrimp is frozen for export to inhibit activity for preservation, but freezing alone cannot eliminate pathogens like L. monocytogenes and Vibrio parahaemolyticus, a halophilic gram-negative pathogen prevalent in shellfish (20–50%) that can cause septicemia and gastroenteritis when ingested. In recent years, V. parahaemolyticus has emerged as the primary source of food poisoning in coastal China (Ndraha, Huang, Wu, & Hsiao, 2022). Given that refrigeration alone is insufficient to meet safety requirements, more efficacious and eco-friendly preservation techniques are warranted for shrimp and other seafoods to inhibit microbial growth and extend shelf life.

Both thermal and non-thermal techniques could be used for aquatic food products preservation. Thermal processing extends aquatic food products shelf-life by inactivating microbes and enzymes, yet adversely affects the quality attributes like texture, flavor, color, and nutrients (Viji, Madhusudana Rao, Debbarma, & Ravishankar, 2022). Non-thermal techniques such as high pressure processing, irradiation, ozone treatment and bio preservatives can also inactivate microbes effectively at ambient temperatures, but each technique has its own drawbacks including reduced sensory quality, high costs, limited antimicrobial duration, or introduction of potentially harmful chemical residues (Wei, Mei, & Xie, 2022). Atmospheric cold plasma (ACP) technology offers high antimicrobial efficacy, low energy use and no chemical residues, making it a promising alternative (Olatunde, Shiekh, & Benjakul, 2021). As the fourth sate of matter beyond solids, liquids and gases, ACP is a highly ionized gas containing charged particles, neutral particles, free radicals, electromagnetic fields and photons (Chizoba Ekezie, Sun, & Cheng, 2017). Abundant reactive oxygen and nitrogen species (RONS) generated in ACP, including hydroxyl radicals (•OH), singlet oxygen (1O2), ozone (O3), nitric oxide (NO) and nitrogen dioxide (NO2), confer antimicrobial effects (Hertwig, Meneses, & Mathys, 2018; Moutiq, Misra, Mendonça, & Keener, 2020).

In recent years, numerous studies have examined the use of ACP for inactivating various foodborne pathogens on a variety of foods. ACP has been proven effective in significantly reducing Escherichia coli, Salmonella, and Staphylococcus aureus on chicken, pork, beef, lettuce, and fruits (Lee et al., 2016; Kim, Lee, Choi, & Kim, 2014; S. Choi, Puligundla, & Mok, 2016; Ermis, Yagci, & Durak, 2021). However, limited studies have investigated ACP treatment on aquatic food products. Moreover, existing ACP research on aquatic food products has focused primarily on preservation effects for shelf-life extension rather than pathogens inactivation (Albertos et al., 2019; Shiekh & Benjakul, 2020). Notably, the antimicrobial efficacy of ACP specifically on frozen seafoods has not yet been reported in the literature, yet seafoods are often sold in frozen and pathogens like listeria monocytoses can still survive at freezing temperatures(Alves et al., 2020).

The objective of this study was to investigate the inactivation efficacy of ACP treatment against two major pathogens, L. monocytogenes and V. parahaemolyticus, in suspension and on fresh and frozen pacific white shrimp. Additionally, the preservation effects of ACP treatment on shrimp quality and sensory attributes during refrigerated storage were evaluated. ACP treatment parameters, including treatment time and operating voltage, were assessed based on the generation of reactive gas species via optical absorption spectroscopy, as well as their impacts on pathogen inactivation.