Cold plasma-activated solutions for Vibrio parahaemolyticus decontamination and melanosis inhibition of whiteleg shrimp (Penaeus vannamei)

As a major contributor to the global seafood market, whiteleg shrimp (Penaeus vannamei) is highly susceptible to contamination by pathogenic Vibrio species. Specifically, Vibrio parahaemolyticus represents a primary biological hazard in seafood safety, causing thousands of cases of acute gastroenteritis annually. Consequently, cold plasma has emerged as a promising non-thermal technology for food preservation due to its antimicrobial properties. Therefore, this study evaluated the efficacy of cold plasma-activated solutions (PAS) in decontaminating V. parahaemolyticus and inhibiting melanosis on whiteleg shrimp. Distilled water, ascorbic acid, and phosphoric acid solutions were activated using a dielectric barrier discharge system at 90 kV for 30 min to generate plasma-activated water (PAW), plasma-activated ascorbic acid (PAA), and plasma-activated phosphoric acid (PAP), respectively. The resulting PAS were characterized by quantifying peroxides and nitrates. The in vitro and in vivo antimicrobial effects were evaluated against a suspension of V. parahaemolyticus and artificially contaminated shrimp. Furthermore, melanosis was monitored throughout refrigerated (4°C) storage for 9 days. PAA exhibited the highest concentrations of plasma-generated reactive species among the treatments, with peroxide and nitrate levels of 2.93 mmol/L and 73.76 mg/L, respectively. In vitro exposure to PAW, PAA, and PAP for 20 s significantly reduced the V. parahaemolyticus population from an initial load of 7.00 log CFU/mL to 0.90, 0.96, and 0.70 log CFU/mL, respectively. For in vivo immersion trials, PAW, PAA, and PAP yielded residual bacterial counts of 3.09, 2.99, and 3.13 log CFU/g, respectively. PAA achieved the greatest overall microbial reduction, significantly outperforming the conventional industrial treatment of sodium metabisulfite (p < 0.05). Cold plasma activation of the acid solutions enhanced their bactericidal action, whereas the non-activated acid controls exhibited a limited antimicrobial efficacy. This enhanced inactivation is likely driven by a synergistic mechanism, wherein the acidic environment potentiates cell membrane damage induced by plasma-generated reactive species. Additionally, the application of PAA successfully reduced melanosis during storage, demonstrating its dual functionality as a sanitizer and quality enhancer. The utilization of plasma-activated solutions, particularly PAA, represents an innovative and effective hurdle technology for controlling foodborne pathogens and inhibiting melanosis in whiteleg shrimp, thereby extending its commercial shelf life.