Efficacy optimization of plasma-activated water for food sanitization through two reactor design configurations. (December 2021)

• Record Type: Journal Article
• Authors: Hadinoto, Koentadi; Astorga, Javiera Barrales; Masood, Hassan; Zhou, Renwu; Alam, David; Cullen, Patrick J.; Prescott, Stuart; Trujillo, Francisco J.
• Is Part Of: Innovative food science & emerging technologies. Volume 74(2021)
• Publication Date: 2021-12
• Subjects: Plasma-activated water -- Conductivity -- Plasma-bubble discharge -- Pin-to-liquid discharge -- Reactive nitrogen species -- Reactive oxygen species; Food -- Biotechnology -- Periodicals; Food industry and trade -- Technological innovations -- Periodicals; Aliments -- Biotechnologie -- Périodiques; Food -- Biotechnology; Periodicals; Electronic journals; 664.005
• DOI: 10.1016/j.ifset.2021.102867
• Languages: English
• ISSNs: 1466-8564

Abstract

Abstract: The chemistry, antimicrobial efficacy and energy consumption of plasma-activated water (PAW) was optimized by altering the discharge frequency, ground-electrode configuration, gas flow rate and initial water conductivity for two reactor configurations, i.e., air pin-to-liquid discharge and air plasma-bubble discharge in water. The ratio of NO 2 − and NO 3 − formation was altered to optimise the antimicrobial effects of PAW, tested against two Gram-negative bacteria. An initial solution conductivity of 0.2 S·m −1 and 2000-Hz discharge frequency with the ground electrode positioned inside the pin reactor showed the highest antimicrobial effect resulting in a 3.99 ± 0.13-log10 reduction within 300 s against Escherichia coli and 5.90 ± 0.24-log10 reduction within 240 s for Salmonella Typhimurium. An excellent energy efficiency of reactive oxygen and nitrogen species (RONS) generation of 10.1 ± 0.1 g·kW −1 ·h −1 was achieved. Industrial relevance: Plasma-activated water (PAW) is deemed as an eco-friendly alternative to chemical disinfection because its bactericidal activity is temporary. Optimizing the design and operation of PAW reactors to achieve high inactivation rates of more than 5-log10 reductions, as demonstrated in this work, will support the industrial application of this technology and the scaleup at industrial level. Highlights: Increasing discharge frequency from 1000 to 2000 Hz improved the antimicrobial characteristics of PAW by the pinreactor Increasing initial liquid conductivity in the pin reactor increased the bacterial inactivation to 1.74–4.4-log10 reduction Ground electrode inside the pin reactor caused higher E. coli (3.99-) and S . Typhimurium (5.90-log10 reduction) inactivations Altering ground-electrode position from inside to outside the bubble reactor changed the NO 2 − / NO 3 − ratio from 0.92 to 2.69 The optimal PAW configuration, achieving more than 5-log reduction of S . Typhimurium, was the pin-to-liquid discharge