Table 4.

Application of electrolyzed water (EW) technology to fish products; main results and limitations of the technology considered.

Fish Product	Treatment Conditions	Tested Microorganisms	Results	Limit	Reference
Salmon fillets	The anolyte contained approximately 300 mg/L of free chlorine, an oxidation-reduction potential of 850 mV, a neutral pH (7.0 ± 0.1) and a residual chloride level of <0.5%. The solution was diluted to 50% and 15% (v/v).	Total aerobic counts Coliform Pseudomonas spp.	The use of the 15% or 50% solution for treatment significantly reduced the initial microbiota (approx. 1–2 log colony-forming units) during storage and significantly extended the shelf-life of the fillets by 2 and 4 days, without affecting the overall quality of the fillets, both raw and cooked.	No negative effects were found, instead, the significant increase in shelf-life and quality of fillets was corroborated by raw and cooked sensory evaluation.	[112]
Live clam (Venerupis philippinarum), mussel (Mytilus edulis)	Two types of acidic electrolyzed water (AEW) were used for treatment time, strong (SAEW), with an available chlorine concentration of 20 mg/L, pH 3.1 and an oxidation–reduction potential of 1150 mV, and weak (WAEW), with 10 mg/L of chlorine, pH 3.55 and potential of 950 mV.	Escherichia coli O104:H4 Listeria monocytogenes Aeromonas hydrophila Vibrio parahaemolyticus Campylobacter jejuni	SAEW and WAEW showed significant inhibitory activity against inoculated bacteria in each shellfish species. SAEW showed the highest antimicrobial activity, with reductions from 1.4 to 2.2 logarithmic cycles for the different microorganisms.	Weak electrolysed water showed fewer effective results than strong electrolysed water.	[113]
Atlantic Salmon (Salmo salar)	Acidic electrolysed water with pH 2.7, oxidation–reduction potential 1150 mV and free chlorine concentration of 60 ppm (generated at 9–12 V direct current for 15 min). Neutral electrolyzed water (NEW) with active hypochlorous acid (275 ppm) was electrochemically generated and diluted to obtain a solution with an available free chlorine content of 60 ppm, a pH of 6.8 and a potential of 786 mV.	L. monocytogenes	AEW and NEW showed strong antimicrobial properties against L. monocytogenes. The initial inoculation was 7.9 log CFU/g, which was reduced to 2.3 log CFU/g in samples treated with NEW at 65 °C for 10 min. By increasing the temperature and exposure time, the efficacy of electrolysed water increased significantly.	Further studies are needed on the effect of NEW and mild heat treatment on lipid oxidation, changes in amino acids, nutritional value and product preservation.	[114]
Shrimps	The samples were inoculated with Vibrio parahaemolyticus and subsequently treated using AEW1, with 51 mg/L chlorine, AEW2, with 78 mg/L chlorine, or organic acids (2% AA and 2% LA), for 1 min or 5 min under different treatment conditions.	V. parahaemolyticus	AEW treatment at 50 °C revealed a 3.1 log CFU/g reduction in V. parahaemolyticus.	The treatment significantly influenced the physico-chemical properties (pH, ORP, ACC).	[106]
Shrimp (Litopenaeus vannamei)	AEW was obtained by electrolysis of a 0.1% sodium chloride solution using a strongly acidic electrolyte water generator. AEW was frozen for 24 h	Total viable count	AEW ice was able to inactivate the bacterial load on raw shrimp; the total viable bacterial populations were reduced by 1.5 log CFU/g after 24 h. AEW ice also inhibited TVBN formation and PPO activity.	No negative effects were found.	[115]
American shad (Alosa sapidissima)	The electrolyzed oxidizing water (EOW) was generated with NaCl (0.1%) and deionised water, with a pH of 2.4, a potential of 1185 mV and a free chlorine level of 70 and 80 ppm. Dietary chitosan was used as a 2% (w/v) coating solution.	Total viable count Total aerobic count	The results of microbiological, physico-chemical (pH, TVBN, TBA, texture and colour) and sensory analyses revealed that the combined treatment successfully inhibited microbial growth, protein degradation and lipid oxidation and did not change texture, colour, or sensory characteristics during storage. This treatment extended the shelf-life of American shad fillets by 9–10 days during refrigerated storage.	No negative effects were found.	[101]
Pacific white shrimp (Litopenaeus vannamei)	In this study, weakly acidic electrolyzed water (WAEW) was used in combination with the modified atmosphere packaging (MAP). The WAEW had a pH of 6.4 and 6.6, an oxidation–reduction potential between 520 and 540 mV and an available chlorine concentration of 6.4 and 6.5 mg/L.	Total aerobic count Staphylococcus aureus	WAEW and MAP (40% CO2, 0% O2, 50% N2; 30% CO2, 20% O2, 50% N2) exerted a significant effect on spoilage inhibition, controlling microbial growth, increase in TVBN, TMA and TBARS and degradation of sensory properties.	No negative effects were found.	[116]
Raw trout	Acid electrolyte oxidising water (pH 2.30 and free chlorine 38 ppm), sterile distilled water was tested for 0 (control), 1, 3, 5 and 10 min at 22 °C.	E. coli O157:H7 Salmonella Typhimurium L. monocytogenes	The use of AC-EW was found to be the most effective treatment in reducing E. coli O157:H7, S. Typhimurium and L. monocytogenes. The level of reduction ranged between ca. 1.5 and 1.6 logs for E. coli O157:H7 and S. Typhimurium, and 1.1–1.3 logs reduction for L. monocytogenes.	There was no complete elimination of inoculated pathogens after treatment.	[117]
Cold smoked atlantic salmon (Salmon salar)	Electrolysed water (pH 2.7; ORP 1150 mV; free chlorine 60 ppm) was generated at 9 and 12 V DC for 15 min. Samples inoculated with the target bacteria, were treated with EW at different temperatures (20, 30 and 40 °C) and at different times (2, 6 and 10 min).	L. monocytogenes	Treatment prior to cold smoking at 40 °C for 10 min was able to reduce the cellular load of L. monocytogenes by 2.85 log CFU/g without causing any significant change in sensory properties.	No negative effects were observed.	[104]
Squid	The slightly acidic electrolyzed water (SAEW) was prepared by electrolysis of an aqueous mixture containing 0.2% NaCl and 0.04% HCl, then frozen immediately.	Endogenous microbiota	SAEW ice has been shown to be able to inhibit bacterial reproduction during storage by 1.46 log CFU/g, extend shelf-life and maintain good squid quality for the entire observation period (6 days).	No negative effects were found.	[118]
Raw salmon fillets	Electrolytic acidified water (AEW) was obtained at a constant current of 10 A by electrolysis of a sodium chloride solution (0.1%, w/v), pH (2.6 ± 0.2) and oxidation/reduction potential of 0.1140 ± 30 mV. The fillets were treated for 1, 5, or 10 min at room temperature.	L. monocytogenes Natural microbiota	The treatment reduced microbial contamination; with reductions of 0.75–0.79 log CFU/g for L. monocytogenes (compared to 0.17 log CFU/g in control) and about 0.59–0.64 log CFU/g for total viable count.	A strong deterioration in the sensory quality of the product was observed; the colour and odour of salmon were significantly affected after treatments, whereas the texture and firmness of tissue were not significantly changed.	[82]
Catfish fillets	Near-neutral electrolysed water (anolyte) (pH 6.0 to 6.5 ± 0.02; oxidation reduction potential > 700 mV; residual chlorine concentration of 10 to 200 ppm) was applied for 3 min.	Salmonella spp. L. monocytogenes	Treatment with anolyte resulted in a 1 log reduction for Salmonella and this reduction was maintained even after 8 days of refrigerated storage.	No reduction in L. monocytogenes was observed.	[119]
Shrimps	AEW was prepared by electrolysis of 0.1% sodium chloride (NaCl) solution and frozen.	Autochthonous microbiota	AEW ice showed a good ability to limit pH and colour changes and the formation of total volatile basic nitrogen (TVBN). Bacterial growth was controlled (reduction >1.0 log CFU/g, i.e., >90%) after 6 days.	No negative effects were observed.	[120]
Farmed puffer fish (Takifugu obscurus)	The WAEW was generated by electrolysing a solution of hydrochloric acid (3%). The hypochlorous acid content, oxidation–reduction potential and pH value were 21 ppm, 947.6 mV and 6.1, respectively. The treatment was combined with modified atmosphere and vacuum packaging.	Total viable count H2S-producing bacteria (including Shewanella putrefaciens) Pseudomonas spp. Lactic acid bacteria	The combined effect of WAEW and MAP of 60% CO₂/5% O₂/35% N₂ proved to be the most effective in maintaining better quality and prolonging shelf-life to 18 days against 9 days of untreated samples.	No negative effects were found.	[121]
Brown sole (Pleuronectes herzensteini)	Slightly acidic electrolysed water was produced by electrolysis of a 6% HCl solution and used in combination with a 5% w/v grapefruit seed extract solution after freezing.	Pseudomonas spp. Total viable count H2S-producing bacteria	Microbial growth was controlled, shelf-life was extended to 12–13 days and sensory characteristics were improved.	No negative effects were found.	[102]