The antimicrobial effects of ozonated water in a recirculating concurrent reactor were evaluated against four gram-positive and four gram-negative bacteria, two yeasts, and spores of Aspergillus niger. More than 5 log units each of Salmonella typhimurium and Escherichia coli cells were killed instantaneously in ozonated water with or without addition of 20 ppm of soluble starch (SS). In ozonated water, death rates among the gram-negative bacteria--S. typhimurium, E. coli, Pseudomonas aeruginosa, and Yersinia enterocolitica--were not significantly different (P > 0.05). Among gram-positive bacteria, Listeria monocytogenes was significantly (P < 0.05) more sensitive than either Staphylococcus aureus or Enterococcus faecalis. In the presence of organic material, death rates of S. aureus compared with L. monocytogenes and E. coli compared with S. typhimurium in ozonated water were not significantly (P > 0.05) affected by SS addition but were significantly reduced (P < 0.05) by addition of 20 ppm of bovine serum albumin (BSA). More than 4.5 log units each of Candida albicans and Zygosaccharomyces bailii cells were killed instantaneously in ozonated water, whereas less than 1 log unit of Aspergillus niger spores was killed after a 5-min exposure. The average ozone output levels in the deionized water (0.188 mg/ml) or water with SS (0.198 mg/ml) did not differ significantly (P < 0.05) but were significantly lower in water containing BSA (0.149 mg/ml).

Light-emitting diode (LED) technology is an emerging nonthermal food processing technique that utilizes light energy with wavelengths ranging from 200 to 780 nm. Inactivation of bacteria, viruses, and fungi in water by LED treatment has been studied extensively. LED technology has also shown antimicrobial efficacy in food systems. This review provides an overview of recent studies of LED decontamination of water and food. LEDs produce an antibacterial effect by photodynamic inactivation due to photosensitization of light absorbing compounds in the presence of oxygen and DNA damage; however, such inactivation is dependent on the wavelength of light energy used. Commercial applications of LED treatment include air ventilation systems in office spaces, curing, medical applications, water treatment, and algaculture. As low penetration depth and high-intensity usage can challenge optimal LED treatment, optimization studies are required to select the right light wavelength for the application and to standardize measurements of light energy dosage.

Shewanella putrefaciens is an important specific spoilage organism (SSO) in seafood under low-temperature storage and can form biofilms on seafood processing-related contact surfaces, which exacerbates seafood spoilage and causes food safety problems. The characterization of and dynamic change in biofilms formed by Shewanella putrefaciens on three seafood processing-related contact surfaces were investigated in this study. An effective strategy to eliminate mature biofilms by acidic electrolysis water (AEW) was provided. Shewanella putrefaciens can form biofilms on glass, stainless steel and polystyrene, which are closely connected with surface properties such as hydrophilicity/hydrophobicity and surface roughness. AEW can be an excellent choice to clean mature biofilms formed by S. putrefaciens. AEW at a concentration of 3 g/L can remove almost all biofilms on the three common food contact materials tested. There is a bactericidal effect on the biofilm, reducing the possibility of secondary contamination. This study will contribute to promoting the application of AEW for controlling biofilms during seafood processing.

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 NO₂⁻ and NO₃⁻ 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.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.

The efficacy of electrolyzed water (EW) to inactivate Listeria monocytogenes on stainless steel surfaces was evaluated and modelled in the present study. L. monocytogenes was inoculated on stainless steel coupons and subsequently subjected to Neutral EW (NEW, pH = 7.0) and Slightly Acid EW (SAEW, pH = 5.0) with different Available Chlorine Concentration (ACC, 50–200 mg/L) for different exposure times (0–6 min). The number of viable cells on coupons decreased as the exposure time increased at all ACC concentrations. Treatments with SAEW resulted in higher reductions of L. monocytogenes, i.e., 2.30 ± 0.16 to 5.64 ± 0.11 log cfu/cm², in comparison with NEW treatments (1.55 ± 0.11 to 5.22 ± 0.12 log cfu/cm²), probably due to the synergistic bactericidal effect between the acidic pH, higher oxidation-reduction potential and the effective form of chlorine, reported in previous studies. Since SAEW was the most effective against L. monocytogenes, two approaches were tested to model the survival data: the one- and two-step modelling procedures. The Weibull model was suitable to describe the survival data and both approaches produced suitable survival models (adj-R²>0.92 and MSE<0.2). EW is effective in reducing bacterial contamination on food-contact surfaces and the survival data and models derived from this study are relevant to optimize its use as an environment-friendly sanitizer in the food industry.

The synthesis of new chitin derivatives through ultrasound-assisted treatment of the chitin with 1-azido-3-chloropropan-2-ol under Green Chemistry conditions is described. This is the first example of ultrasound-assisted polymer analogues transformation of chitin unaccompanied by noticeable backbone degradation or deacetylation. The obtained water-soluble azido chitin derivatives are characterized by high antibacterial activity, which is comparable with that of commercial antibiotics ampicillin and gentamicin. At the same time, they were demonstrated almost identical in vitro toxicity as unmodified chitin and chitosan. The antibacterial activity of the obtained polymers is mainly provided by azido moiety in their macromolecules. The conjugation of azido moiety to chitin backbone strongly diminishes the toxicity of the azido pharmacophore, but preserves its antibacterial properties. The most potent chitin derivative was used for the film coating of Ricotta cheese samples. This food coating proved to be efficient for the prolongation of shelf life of Ricotta cheese.

Phenols are plant metabolites characterised by several interesting bioactive properties such as antioxidant and bactericidal activities. In this study the application of a phenols concentrate (PC) from olive vegetation water to two different fresh products – gilt-head seabream (Sparus aurata) and chicken breast – was described. Products were treated in a bath of PC (22 g/L; chicken breast) or sprayed with two different solutions (L1:0.75 and L2:1.5 mg/mL; seabream) and then stored under refrigeration conditions. The shelf life was monitored through microbiological analyses – quality index method for seabream and a specific sensory index for raw breast. The secondary products of lipid-peroxidation of the chicken breast were determined using the thiobarbituric acid reactive substances (TBARs) test on cooked samples. Multivariate statistical techniques were adopted to investigate the impact of phenols and microbiological data were fitted by DMfit software. In seabream, the levels of PC did not highlight any significant difference on microbiological and sensory features. DMfit models suggested an effect only on H₂S producing bacteria with an increased lag phase compared to the control samples (C: 87 h vs L2: 136 h). The results on chicken breast showed that the PC bath clearly modified the growth of Pseudomonas and Enterobacteriaceae. The phenol dipping was effective in limiting lipid-peroxidation (TBARs) after cooking. Treated samples disclosed an increase of shelf life of 2 days. These could be considered as preliminary findings suggesting the use of this concentrate as preservative in some fresh products.

Previous studies have confirmed that electrolyzed water had disinfection potential and enrich functional nutrients during seed germination. However, the effect of slightly acidic electrolyzed water (SAEW) on the quality and safety of peanut sprouts is poorly understood. In this study, the influence and mechanism of SAEW on the antibacterial, antioxidant capacity, and allergenicity of peanut sprouts were investigated. Although SAEW‐3 with 33.85 mg/L available chlorine concentration (ACC) showed better antibacterial effect, the SAEW‐2 (23.74 mg/L ACC) group has a 20% and 50% increase in phenolic acid and γ‐aminobutyric acid content, respectively. Moreover, SAEW‐2 induced peanut sprout has the best antioxidant capacity by eliminating free radicals and improving peroxidase activity. SAEW‐2 or SAEW‐3 treatment contributed to decreasing Ara h 1 and Ara h 2 content thus reduce allergenicity. Therefore, SAEW with appropriate ACC could be a promising application in food safety, nutrients enrichment, and health‐improvement of peanut products. NOVELTY IMPACT STATEMENT: Slightly acidic electrolyzed water (SAEW) with 23.74 mg/L available chlorine concentration (ACC) has a significant positive effect on the enrichment of phenolic and γ‐aminobutyric acid in germinated peanut. With the help of SAEW, the germination process can further reduce the content of Ara h 1 and Ara h 2, thereby reducing allergenicity. SAEW with appropriate ACC could be a promising application in food safety, nutrients enrichment, and health‐improvement of peanut products.

The disinfection efficacy of slightly acidic electrolyzed water (SAEW) has been recognized in food industry. However, the application of single SAEW limited its disinfection potential. The efficacy of the two-step disinfection with SAEW for the reduction of L. monocytogenes contamination on different food raw materials was evaluated compared to the one-step disinfection with SAEW in this study. Results demonstrated that SAEW could reduce both the natural aerobic bacterial count and inoculated L. monocytogenes population on endive and chicken immediately after processing and SAEW with approximately 60 mg/L of available chlorine concentration (ACC) had equal or higher antibacterial efficacy compared to NaClO solutions with approximately 150 mg/L of ACC. Moreover, SAEW treatments could control the growth of microbial populations of L. monocytogenes during storage and the efficacy on the microbial reduction was associated to the initial populations. In addition, the SAEW-treated food raw materials were stored and disinfected again after storage and the results showed that the two-step disinfection method could decrease the survival populations of L. monocytogenes by 24.8%–99.6% compared to the one-step disinfection of SAEW. Therefore, considering storage habits, the two-step disinfection of SAEW may be a better choice in the disinfection of non-consumed-directly food raw materials.

Compatibility of CNF with three polysaccharides having different surface charges and backbones (chitosan, methyl cellulose, and carboxymethyl cellulose) was investigated. Chitosan (CH) incorporation reduced water absorption (WA) of CNF films (P < 0.05). CH molecular weight (Mw) (68, 181, 287 kDa) and amount (10 and 20 g/100 g CNF in dry basis) impacted moisture barrier, mechanical, antibacterial, thermal, and structural properties of CNF films. Regardless of Mw, CH incorporation (20 g/100 g CNF) decreased (P < 0.05) WA of CNF films, and high Mw (287 kDa) CH (20 g/100 g CNF) incorporation resulted in lower film water solubility while increasing film water vapor permeability compared with low Mw CH (68 kDa) incorporation (P < 0.05). CNF film with low Mw CH (20 g/100 g CNF) exhibited antibacterial activity against L. innocua and E. coli. Interaction mechanisms between CH and CNF were investigated through thermal, structural, and morphology analyses using DSC, FTIR, and SEM, respectively. CNF films with low or high Mw CH incorporation (20 g/100 g CNF) were further validated as surface contact films for fresh beef patties, showing effectiveness to prevent moisture transfer between the layered patties. This study demonstrated the potential of using CNF-CH composite films as water resistant and antibacterial packaging for foods with high moisture surfaces.