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This study undertakes a comprehensive exploration of the impact of slightly acidic electrolyzed water (SAEW) on Listeria monocytogenes, a common foodborne pathogen, with a particular focus on understanding the molecular mechanisms leading to the viable but nonculturable (VBNC) state. Given the widespread application of SAEW as an effective disinfectant in the food industry, uncovering these molecular pathways is crucial for improving food safety measures. We employed tandem mass tags (TMT), labeling proteomic techniques and LC-MS/MS to identify differentially expressed proteins under two doses of SAEW conditions. We indicated 203 differential expressed proteins (DEPs), including 78 up-regulated and 125 down-regulated DEPs. The functional enrichment analysis of these proteins indicated that ribosomes, biosynthesis of secondary metabolites, and aminoacyl-tRNA biosynthesis were enriched functions affected by SAEW. Further, we delved into the role of protein chlorination, a potential consequence of reactive chlorine species generated during the SAEW production process, by identifying 31 chlorinated peptides from 22 proteins, with a dominant sequence motif of Rxxxxx[cY] and functionally enriched in translation. Our findings suggest that SAEW might prompt alterations in the protein translation process and trigger compensatory ribosome biosynthesis. However, an imbalance in the levels of elongation factors and AARSs could hinder recovery, leading to the VBNC state. This research carries substantial implications for food safety and sanitation, as it adds to our understanding of the SAEW-induced VBNC state in L. monocytogenes and offers potential strategies for its control.

The effects of lipid peroxidation products 4-Hydroxy-2-nonenal (4-HNE) and 4-oxo-2-nonenal (4-ONE) were evaluated using bovine heart mitochondria. Oxygen consumption rate (OCR), ultrastructure, antioxidant activity, and membrane permeability were examined to compare their effects on isolated mitochondria from beef cardiac muscle. For the mitochondrial morphology, the final concentration of mitochondria and 4-ONE or 4-HNE in the reaction tube were 10 mg/ml and 1 mM, respectively. For the OCR experiment, mitochondria (2.5 mg/ml) were incubated with 0.20 mM ONE or in a Clark electrode chamber at 25°C. Mitochondrial membrane permeability was determined by incubating 0.5 mg/ml of mitochondrial protein with either 0.05 mM ONE or HNE or ethanol control at pH 5.6 and 7.4 at 25°C. Transmission electron microscopy (TEM) revealed that the size of 4-ONE treated mitochondria at pH 7.4 increased (

Photocatalysis disinfection has great potential for irrigation water disinfection to improve fresh produce safety. Titanium dioxide (TiO2) nanoparticle (NP)-embedded cellulose acetate (CA) film has shown effectiveness against Escherichia coli (E. coli) O157:H7 in water. The current study evaluated the effect of natural water compounds on the photo-disinfection efficacy of TiO2 NP-embedded CA film. Humic acid, calcium carbonate (CaCO3), and kaolin clay solutions were prepared at four concentrations, respectively. When concentration increased from 0 to 20 ml/L, inactivation of E. coli O157:H7 in humic acid, CaCO3, and kaolin clay solutions decreased from 6 log to 5, 4, and 2 log CFU/ml, respectively after 3 h treatment. Turbidity, UVT-254, water hardness, total suspended solids (TSS), and total organic carbon (TOC) of the solutions were measured. UVT-254 and turbidity had the highest correlation with the inhibition effect of water compounds on photo-disinfection efficacy. A prediction equation was developed with UVT-254 and water hardness as independent variables to predict photo-disinfection efficacy in natural water. E. coli O157:H7 decreased by 1 and 2.5 log CFU/ml in unfiltered and filtered natural creek water samples after treatment. The results from this study showed promise in the use of TiO2 NP-embedded CA film to inactivate pathogens in natural water. HIGHLIGHTS Natural water compounds affect TiO2 photo-disinfection efficacy in different degrees.; UV transmittance and water hardness are important water quality parameters that can affect TiO2 photo-disinfection efficacy.; Prediction equation was developed to predict TiO2 photo-disinfection efficacy in natural water.; Filtration is an effective pre-treatment method for improving TiO2 photo-disinfection in natural water.

HighlightsPhoto-disinfection using TiO2 NP-embedded CA film showed great potential.TiO2 loading, water depth, and light intensity affected TiO2 photo-disinfection.Bacterial reduction can be predicted based on water depth and light intensity.Durability of the TiO2 NP-embedded CA film has been demonstrated.Abstract. Photocatalysis disinfection has great potential for food and water safety applications. TiO2 NP-embedded cellulose acetate (CA) film has shown effectiveness in inactivating Escherichia coli (E. coli) O157:H7 in water. This study evaluated the effect of several operational parameters such as TiO2 load, light intensity, and water depth on photo-disinfection efficacy of TiO2 NP-embedded CA film. Effect of TiO2 load on photocatalysis disinfection efficacy was investigated by assessing the disinfection rate of the films at different TiO2 levels in inoculated water at a weak UV-A light intensity. The individual and interaction effects of light intensity and water depth on photocatalysis disinfection were evaluated using the response surface methodology (RSM). Based on a central composite design, 13 runs of experiments were conducted with the combination of the two factors at three levels. The effect of film size on photo-disinfection efficacy was also investigated. Results showed that CA film with a TiO2 load of 0.82 mg/cm2 yielded the highest disinfection rate. An empirical model was established to predict the effect of light intensity and water depth on bacterial reduction with a high coefficient of determination (R2 = 0.98). An increased water depth or a decreased light intensity reduced photo-inactivation efficacy. A 5 log reduction was achieved during a 3-h treatment at a light intensity of 1 mW/cm2 and water depth at 1.6 cm. The photo-disinfection efficacy of the film was not significantly (p>0.05) affected by film size. The CA film was able to maintain antimicrobial efficacy after four repeated uses. Results from this study demonstrated that UV-A assisted photo-disinfection using TiO2 NP-embedded CA film has great potential to inactivate pathogens in water. Keywords: Cellulose Acetate, E. coli O157:H7, Photocatalysis, TiO2 nanoparticles, Water Treatment.

Longan fruit loses its market value rapidly due to postharvest pathogenic infestation and quality deterioration. Here, we hypothesized that acidic electrolyzed water (AEW) could maintain higher quality of P. longanae-inoculated longans via regulating energy metabolism. Results indicated that AEW reduced fruit disease index and decay incidence. Significantly, AEW treatment retained higher levels of ATP, ADP, and energy charge, and higher activities of Ca

Black tea powder was used to make tea infusion using a Keuring coffee maker. Effect of tea particle size (0.30 or 0.60 mm), water volume for brewing (118, 177, or 236 ml), and the amount of tea powder (1.0, 1.5, or 2.0 g) on tea infusion quality were evaluated. The concentration of four chemical compounds (soluble sugars, total amino acids, polyphenols, and caffeine) in tea infusion was measured. In general, the concentration of the four compounds in tea infusion increased with the amount of tea powder used and decreased with increasing water volume and tea particle size. Using 2.0 g of 0.30 mm tea powder and 118 ml of water per brew, the concentration of the above four components was 412.3, 251.6, 208.9, and 205.3 μg/ml, respectively, and higher than tea infusion prepared by traditional method (312.4, 204.1, 211.6, and 175.9 μg/ml). The highest extraction efficiency (mg/cup.g) for the four chemical components per unit weight of tea powder was at using 1.0 g of 0.30 mm tea powder with 236 ml water for soluble sugars (32.3 μg/ml) and caffeine (16.3 μg/ml), at using 1.5 g tea powders for polyphenols (22.3 μg/ml) and at using 2.0 g tea powders for amino acid (13.6 μg/ml). This study suggested using a single‐serve coffee maker can be a convenient and effective way to prepare the tea infusion with high quality., Results obtained from this study demonstrated that the single‐serve coffee maker can be a convenience tea brewing method and tea infusion quality can be optimized based on consumer preference.

Bactericidal effects of various concentrations of phenyllactic acid on Shiga toxin-producing Escherichia coli (STEC), including E. coli O157:H7, O26:H11, O103:H2, and O121:H19, and on Salmonella Typhimurium DT104 in pure culture and microplates assays were studied. Beef cuts were surface sprayed with phenyllactic acid or lactic acid for inactivation of E. coli O157:H7 and Salmonella Typhimurium. The 1.5% phenyllactic acid inactivated all inoculated E. coli O157:H7, O26:H11, O103:H2, and O121:H19 and Salmonella Typhimurium DT104 (>6-log reduction) within 1 min of contact at 21°C, whereas 1.5% lactic acid did not result in microbial reduction. Microplate assays (for STEC and Salmonella Typhimurium DT104 at 10 to 100 CFU per well) indicated that concentrations of 0.25% phenyllactic acid or 0.25% lactic acid inhibited the growth of STEC and Salmonella Typhimurium DT104 incubated at 37°C for 24 h. Treatment of beef with 1.5% lactic acid or 1.5% phenyllactic acid reduced E. coli O157:H7 by 0.22 and 0.38 log CFU/cm2, respectively, within 5 min and reduced Salmonella Typhimurium DT104 by 0.12 and 0.86 log CFU/cm2, respectively. When meat treated with 1.5% phenyllactic acid was frozen at -20°C, inactivation of E. coli O157 and Salmonella Typhimurium DT104 was enhanced by 1.06 and 1.46 log CFU/cm2, respectively. Thus, treatment of beef with 1.5% phenyllactic acid significantly reduced the population of E. coli O157:H7 and Salmonella.

The effects of pathogen inoculum concentration, pH and organic load of electrolyzed oxidizing (EO) water treatment on the culturability and viability of Listeria monocytogenes and Escherichia coli O157:H7 was examined. Inoculum concentrations (8, 6, and 4 log CFU/mL), EO water at pH between 2.7 and 8.5 and two lettuce-to-EO water ratios (1:20 and 1:10 w/v) were tested by exposing pathogens to EO water for 5 min, followed by culturing on nonselective media and viability assessment through flow cytometry and resuscitation attempts. Treating pathogens at high initial populations with EO water led to maintenance of culturability, while lower populations lost culturability at free chlorine concentrations (FCC) above 1 mg/L. The pH of EO water significantly affected the reduction of viable populations of both pathogens (p

This study aimed to elucidate the mechanism of ferrous and alkaline activated persulfate in inactivating Escherichia coli O157:H7 and Listeria monocytogenes. A five-strain cocktail of each pathogen was treated with activated persulfate for 5 min. The treated pathogens were plated on both selective and non-selective agars. DNA and protein leakage, TTC-dehydrogenase relative activity, and cellular ultrastructure were analyzed. The results showed there were significant (P

The beef industry utilizes blade tenderization (BT) to enhance tenderness; however, foodborne outbreaks have been associated with BT beef. Therefore, antimicrobials that reduce the risks associated with BT while maintaining quality are desired. The objective of this study was to assess the effects of pulse ultra-violet light (PUV), 5 mL/dL levulinic acid + 0.5 g/dL sodium dodecyl sulfate (LVA + SDS), and electrolyzed oxidizing water (EOW; 50 mg/L) on beef strip loins before BT for their impact on quality and sensory characteristics compared to 4.5 mL/dL lactic acid (LA) and no antimicrobial interventions (CON). Beef strip loins were independently subjected to treatments prior to BT. After BT, two steaks were removed from the anterior end for sensory and Warner-Bratzler shear force analysis, and six roasts were assigned to retail display for determination of shelf life characteristics. Aerobic plate count bacteria were lower (P ≤ 0.05) for LVA + SDS and LA compared to CON, EOW, and PUV. Treatment did not affect color, cooking, or sensory characteristics (P > 0.05). Lipid oxidation showed no difference among treatments (P > 0.05) until day 7 of display (P ≤ 0.05). These results suggest that LVA + SDS could be an alternative to LA without impacting quality and shelf life.

This study aimed to investigate the difference between ‘Fuyan’ longan (Dimocarpus longan Lour. cv. Fuyan) fruit and ‘Dongbi’ longan (Dimocarpus longan Lour. cv. Dongbi) fruit in term of their aril breakdown and respiratory metabolism. As compared to ‘Fuyan’ longans, the ‘Dongbi’ longans exhibited lower fruit respiration rate, lower aril breakdown index, higher NADK activity, higher total activities of G-6-PDH and 6-PGDH, higher contents of NADP and NADPH, lower activities of AAO, CCO, PPO, PGI, and SDH, and lower contents of NAD and NADH in aril. These findings suggest that better storability and lower aril breakdown index in ‘Dongbi’ longans than ‘Fuyan’ longans might be due to lower activities of respiratory terminal oxidases, and lower respiratory metabolic pathways of EMP-TCA cycle related-enzymes in ‘Dongbi’ longan aril, which decreased respiratory rate and reduced the consumption of substrates, and subsequently maintained the integrity of the aril of ‘Dongbi’ longans during storage.

The efficacy of Infra-red radiation (IR) and Pulsed UV (PUV) for the inactivation of parent (Par) and Nalidixic acid adapted (Nal) strains of Escherichia coli O157:H7, top six shiga-toxin producing E. coli (E. coli O26, E. coli O45, E. coli O103, E. coli O111, E. coli O121, and E. coli O145 and E. coli O104) along with nonpathogenic surrogates were evaluated. It was observed that significant (P

This study aimed to investigate the effects of acidic electrolyzed oxidizing water (AEW) treatment on storability and metabolism of reactive oxygen species (ROS) in blueberries cv. ‘Brightwell’ during storage at 4 °C. Results showed that, compared with the control blueberries, AEW treated-blueberries exhibited lower incidence of fruit decay, higher rate of commercially acceptable fruit, higher fruit firmness and skin hardness, and higher anthocyanin and total phenolics contents, along with higher activities of SOD, CAT and APX, higher antioxidant activity, but lower generation rate of superoxide anion and cell membrane permeability. These results demonstrated that AEW treatment for enhancing storability of harvested blueberries during storage may be mediated by regulating ROS metabolism, manifested as AEW increasing ROS scavenging capacity and reducing ROS accumulation, and thereby maintained the structural integrity of cellular membrane, which indicated that AEW treatment was a facile postharvest method for extending the shelf life of harvested blueberries.

With the growing demand for safe and nutritious foods, some novel food nonthermal sterilization technologies were developed in recent years. Electrolyzed oxidizing water (EOW) has the characteristics of strong antimicrobial ability, wide sterilization range, and posing no threat to the humans and environment. Furthermore, EOW can be used as a green disinfectant to replace conventional production water used in the food industry since it can be converted to the ordinary water after sterilization. This review summarizes recent developments of the EOW technology in food industry. It also reviews the preparation principles, physical and chemical characteristics, antimicrobial mechanisms of EOW, and inactivation of toxins using EOW. In addition, this study highlights the applications of EOW in food preservation and safety control, as well as the future prospects of this novel technology. EOW is a promising nonthermal sterilization technology that has great potential for applications in the food industry.

The development of innovative antimicrobial materials is crucial in thwarting infectious diseases caused by microbes, as drug-resistant pathogens are increasing in both number and capacity to detoxify the antimicrobial drugs used today. An ideal antimicrobial material should inhibit a wide variety of bacteria in a short period of time, be less or not toxic to normal cells, and the fabrication or synthesis process should be cheap and easy. We report a one-step microwave-assisted hydrothermal synthesis of mixed composite CuxFeyOz (Fe2O3/Cu2O/CuO/CuFe2O) nanoparticles (NPs) as an excellent antimicrobial material. The 1 mg/mL CuxFeyOz NPs with the composition 36% CuFeO2, 28% Cu2O and 36% Fe2O3 have a general antimicrobial activity greater than 5 log reduction within 4 h against nine important human pathogenic bacteria (including drug-resistant bacteria as well as Gram-positive and Gram-negative strains). For example, they induced a &gt, 9 log reduction in Escherichia coli B viability after 15 min of incubation, and an ~8 log reduction in multidrug-resistant Klebsiella pneumoniae after 4 h incubation. Cytotoxicity tests against mouse fibroblast cells showed about 74% viability when exposed to 1 mg/mL CuxFeyOz NPs for 24 h, compared to the 20% viability for 1 mg/mL pure Cu2O NPs synthesized by the same method. These results show that the CuxFeyOz composite NPs are a highly efficient, low-toxicity and cheap antimicrobial material that has promising potential for applications in medical and food safety.

Apple juice, known as a good antioxidant source, may partially protect the body from oxidative stress. In this report, the effect of apple juice reconstituted with alkaline electrolyzed water (EO-apple juice) on HT-29 cells was investigated. Specifically, the total antioxidant capacity (ORAC and TEAC) of EO-apple juice, and the effects this EO-apple juice on cell proliferation (MTT assay), DNA fragmentation, and oxidative DNA damage (comet assay) of HT-29 cells were evaluated. The TEAC value of EO-apple juice was higher (2773 μM TE vs. 1739 μM TE) than apple juice reconstituted with ultra pure water (Water-apple juice). EO-apple juice also had a higher ORAC value (15446 μM TE) than that Water-apple juice (13908 μM TE). After 72 h cell incubation, HT-29 cell proliferation was more effectively reduced by the EO-apple juice than the Water-apple juice. Induction of apoptosis was determined using a DNA fragmentation method, and apoptotic cells increased in a dose-dependent manner after treatment with both reconstituted apple juices. In conclusion, EO-apple juice had a stronger antioxidant effect than water-apple juice and can inhibit HT-29 cell proliferation plus induce apoptosis.

Compared to P. longanae-inoculated longan fruit, DNP-treated P. longanae-inoculated longans displayed higher fruit disease index, pericarp browning index and cell membrane permeability. Moreover, they exhibited higher activities of phospholipase D, lipase and lipoxygenase, lower amounts of phosphatidylcholine, phosphatidylinositol and USFA (unsaturated fatty acids) as well as higher amounts of phosphatidic acid and SFA (saturated fatty acids). Additionally, lower ratio of USFA to SFA and USFA index were shown in DNP-treated P. longanae-inoculated longans. However, ATP-treated P. longanae-inoculated longans exhibited the opposite results. These findings indicated that DNP stimulated longan pericarp browning and disease development caused by P. longanae resulted from the increases in activities of membrane lipids-degrading enzymes, promoting degradation of membrane phospholipids and USFA, and disruption of membrane structural integrity. Whereas, the opposite results observed in ATP-treated P. longanae-inoculated longans were due to the reduction in activities of membrane lipids-degrading enzymes and the maintenance of membrane structural integrity.

Concerns have been on the rise regarding the use of chlorine-based sanitizers for fresh produce sanitation due to the production of toxic disinfection by-products (DBPs). This study was undertaken to evaluate the efficacy of activated persulfate in inactivating Escherichia coli O157:H7 and Listeria monocytogenes in pure culture. The objectives were to study the effect of persulfate to activator ratios and determine the major contributing radical in pathogen inactivation. A five-strain cocktail of each pathogen was treated with sodium persulfate activated by ferrous sulfate or sodium hydroxide for 60 s or 120 s. Non-selective agars supplemented with sodium pyruvate were used for pathogen enumeration. The steady-state concentrations of free radicals were quantified using HPLC-DAD. Radical scavengers (tert-butanol, isopropanol, and benzoquinone) were used to determine the major contributing radical in pathogen inactivation. The results showed more than 7 log CFU/mL reductions can be achieved in 120 s for both pathogens at appropriate activation conditions. For ferrous activation, the persulfate to ferrous ratio played an important role in the overall inactivation efficacy. The maximum pathogen reduction (7.77 log CFU/mL for E. coli O157:H7 and 7.25 log CFU/mL for L. monocytogenes) was achieved at persulfate to ferrous molar ratio of 1:0.33 when the initial persulfate concentration was set at 40 mmol/L. Further increase or decrease of ferrous ratio always leads to lower pathogen reductions. For alkaline activation, the inactivation efficacy increased with more initial sodium hydroxide. The maximum reduction was achieved at 40 mmol/L persulfate with 30 mmol/L sodium hydroxide for E. coli O157:H7 (6.21 log CFU/mL reduction) and at 500 mmol/L persulfate with 350 mmol/L sodium hydroxide for L. monocytogenes (8.64 log CFU/mL reduction). Also, persulfate activated by sodium hydroxide always achieved significantly (P 0.05) higher microbial reductions than sodium hydroxide or persulfate alone. L. monocytogenes was generally more resistant against the activated persulfate treatment compared with E. coli O157:H7, which might be due to the different cell envelop structures between Gram-positive and Gram-negative bacteria. Hydroxyl radical was demonstrated to be the major radical to inactivate both pathogens in ferrous activation while superoxide radical was demonstrated to be the major radical to inactivate both pathogens in alkaline activation.

The aim of this meta-analysis was to develop an overall estimate of the pathogen reductions achieved when food products are treated with electrolyzed (EO) water. A literature search and systematic review was conducted to identify EO water intervention studies to reduce Escherichia coli O157:H7, Salmonella and Listeria monocytogenes on poultry, eggs, meat, fish and produce. Pathogen reduction data from the included studies were utilized in the estimation of effect sizes (mean log reductions) and heterogeneity assessment between studies (I2). Twenty-seven studies (294 observations) were obtained and the sanitizers identified as controls were water and sodium hypochlorite. Summary effects of 0.66, 1.12, 1.15, 2.41, 4.45 and 5.34 log reductions were estimated for EO water treatments on poultry, fish, meats, lettuce, eggs and tomatoes, respectively. Highest reductions were estimated for smooth-surfaced foods (eggs, tomatoes) while pathogen reductions were lower on muscle foods. I2 ranged between 60 and 99%, indicating high heterogeneity and necessitating the use of meta-regressions to assess the variations. Free chlorine concentration (FCC), time and temperature were significant variables (p

TiO2 nanoparticles embedded polymer films were fabricated by solution casting method using three biodegradable polymers (cellulose acetate (CA), polycaprolactone (PCL) and polylactic acid (PLA)). Optical and physical properties of the films were assessed by measuring the thickness, color, UV–vis absorption spectra and UV-A transmission. Photodegradation of methylene blue was used to evaluate photocatalytic activity of different TiO2 embedded polymer films. Photocatalytic bactericidal property of the films was evaluated by inactivation of Escherichia. coli O157:H7 under UV-A light illumination at a light intensity of 1.30 ± 0.15 mW/cm2 for 2 h. CA film incorporated with 5 wt% TiO2 NPs had highest bactericidal activity and achieved 1.69 log CFU/ml reduction. Whereas, TiO2 embedded PCL and PLA composite films did not show significant bactericidal property. TiO2 embedded CA film has the potential to be used as antimicrobial food packaging.

The goals of this study were to evaluate the antimicrobial efficacy of Neutral electrolyzed oxidizing (NEO) water on E. coli O157:H7, Salmonella Enteritidis and Yersinia enterocolitica in both pure culture and on inoculated pork chops and skin samples, and to investigate the formation of viable but nonculturable (VBNC) pathogens after treatments. Both the plate count method and flow cytometry were used to evaluate antimicrobial efficacy on pure cultures. Different concentrations of NEO water were prepared by diluting the original NEO water (100%) with sterilized deionized water. The antimicrobial efficacy increased as the concentrations of NEO water increased. The flow cytometry results showed that treating with diluted NEO water led to the formation of VBNC cells. No VBNC cells formed when treating pure cultures with 50% or 100% NEO water. Yersinia cultures were found to be more resistant to NEO treatments than Salmonella and E. coli O157:H7 cultures, with Yersinia cultures showing lower reductions and higher levels of VBNC cells after treatments. The antimicrobial efficacy of NEO water was significantly better on skin samples than on pork chops. The differences in protein content and structure between pork chops and skin samples serve as major factors impacting the NEO water's efficacy.

Brown rice is prone to be contaminated by microorganism and it is a common problem during brown rice soaking and germination. In this study, efficacy of acidic electrolyzed water (AEW) and slightly acidic electrolyzed water (SAEW) with different available chorine concentrations (ACC) on inactivation of natural microbiota and inoculated Bacillus cereus spores on brown rice was determined. Effect of replacing treatment solution during soaking and properties of brown rice after treatment was also determined. Brown rice was treated with AEW and SAEW at ACC of 50, 100 and 150 mg/L for 30 or 60 min at the ratio of 1: 5 (w/v) to remove the natural microbiota and then soaked in sterilized deionized water for the following 24 h. The results showed AEW with ACC of 150 mg/L for 30 or 60 min treatment decontaminated natural microbiota completely with no significant impact on properties of brown rice and could be used to remove microbiota on brown rice for the following inoculation trials. AEW and SAEW with ACC of 50, 100 and 150 mg/L were used to soak brown rice for 24 h and achieved the reduction of B. cereus spores inoculated on brown rice about 1.6–3.3 logs. AEW and SAEW with ACC of 50 and 100 mg/L replaced for 5 times during brown rice soaking achieved additional 2.40, 2.87 and 2.80, 2.78 log reductions respectively, in comparison with electrolyzed oxidizing (EO) waters with the same ACC soaked brown rice without replacement. However, germination potential and germination rate of brown rice were negatively affected by AEW for 24 h soaking. Results suggested that the application of SAEW to soak brown rice could reduce the microorganism with no adverse effect or even promote the properties of brown rice and hence could be used safely in food industry for brown rice soaking. Other approaches will be needed to combine with EO water for brown rice germination to reduce microbiota.

The use of electrolyzed oxidizing (EO) water to inactivate microorganisms on foods has been extensively studied and shown to be effective. However, the prospect of the formation of “viable but nonculturable” (VBNC) cells in pathogens after low free chlorine concentration (FCC) treatments under high organic loads presents safety concerns. This study investigated the effect of EO water FCC on inducing Escherichia coliO157:H7 and Listeria monocytogenesinto the VBNC state and studied possible resuscitation triggering procedures of the VBNC cells. A 5‐strain cocktail of each pathogen (106colony forming units [CFU]/mL) was exposed to EO water (FCC of 20, 10, 5, 2.5, 1.25, 0.625 mg/L) and allowed to stand for 1 and 5 min, followed by the addition of neutralizing broth. Treated samples were plated on nonselective agar and analyzed using flow cytometry. For resuscitation, samples treated with identified VBNC induction conditions were exposed to elevated temperatures (37 °C) as well as addition of sodium pyruvate (SP) and Tween® 20 (T20) solutions. The initial culturing procedures suggested complete inactivation of both pathogens at 2.5 and 1.25 mg/L FCC in the growth medium. However, flow cytometry profiles showed VBNC cells were present. Subjecting samples to the recovery procedures further proved that VBNC E. coliO157:H7 can be resuscitated after exposure to SP and T20 at 37 °C, while L. monocytogenesdid not resuscitate. These findings show that treating pathogens at low FCC can induce the VBNC state, and culturability of E. coliO157:H7 can be restored under appropriate conditions. VBNC induction conditions for foodborne pathogens during chlorine washing treatment were determined in a broth system and the information can serve as a basis for future studies that address the prevention of VBNC formation during produce wash treatments.

Bacteria treated with chlorine-based sanitizer could enter into viable but non-culturable (VBNC) state, which may be underestimated its health risk. In this study, E. coli O157: H7 was treated with slightly acidic electrolyzed water (SAEW), acidic electrolyzed water (AEW) and sodium hypochlorite with different available chlorine concentrations (ACC). The reduction of population was determined, as well as the status of treated cells (viable and culturable, VBNC, dead) was assayed using flow cytometry combined with plate counting. Finally, the cell which cannot be detected using routine media was cultured in p-TSB to resuscitate. The results showed that the reduction of E. coli O157: H7 increased with increasing ACC of SAEW, AEW and sodium hypochlorite and the antimicrobial effect of electrolyzed oxidizing (EO) waters was much higher than sodium hypochlorite. SAEW, AEW and sodium hypochlorite with ACC of 30, 20 and 60 mg/L achieved E. coli O157: H7 colonies to non-detectable level on solid media. The results obtained from flow cytometric assay indicated that culturable cells after EO water and sodium hypochlorite treatments with increasing ACC firstly enter VBNC state and then transferred to dead status. VBNC E.coli was able to be resuscitated in p-TSB and therefore regarded as a potential risk for human health. E. coli O157: H7 in VBNC state after EO water treatment should be taken into consideration and complete inactivation could be achieved by elevated chlorine concentration.

The residual free chlorine level in fresh produce wash solution is closely correlated to the chemical and microbial safety of produce. Excess amount of free chlorine can quickly react with organic matters to form hazardous disinfection by-products (DBPs) above EPA-permitted levels, whereas deficiency of residual chlorine in produce wash solution may result in incompletely removing pathogens on produce. The purpose of this study was to develop a chlorine dosing strategy to optimize the chlorine dosage during produce washing process without impacting the microbial safety of fresh produce. Prediction equations were developed to estimate free chlorine needed to reach targeted residual chlorine at various sanitizer pH and organic loads, and then validated using fresh-cut iceberg lettuce and whole strawberries in an automated produce washer. Validation results showed that equations successfully predicted the initial chlorine concentration needed to achieve residual chlorine at 10, 30, 60, and 90 mg/L for both lettuce and strawberry washing processes, with the root mean squared error at 4.45 mg/L. The Escherichia coli O157:H7 reductions only slightly increased on iceberg lettuce and strawberries with residual chlorine increasing from 10 to 90 mg/L, indicating that lowering residual chlorine to 10 mg/L would not compromise the antimicrobial efficacy of chlorine-based sanitizer. Based on the prediction equations and E. coli O157:H7 reduction results, a chlorine dosing strategy was developed to help the produce industry to maintain microbial inactivation efficacy without adding excess amount of free chlorine.The chlorine dosing strategy can be used for fresh produce washing process to enhance the microbial food safety and minimize the DBPs formation potential.

Effects of Lasiodiplodia theobromae on reactive oxygen species (ROS) production-scavenging system during L. theobromae-induced pericarp browning and disease development of harvested "Fuyan" longans were investigated. Compared with control longans, L. theobromae-inoculated longans exhibited higher pericarp browning index and fruit disease index, higher pericarp O2- generation rate and MDA content. Moreover, L. theobromae infection also resulted in lower contents of pericarp AsA and GSH, lower levels of pericarp DPPH radical scavenging ability and reducing power. Additionally, L. theobromae infection decreased the activities of pericarp SOD, CAT and APX from day 2 to day 5. These findings suggested that L. theobromae-induced pericarp browning and disease development of harvested longans might be due to reduction of ROS scavenging ability and increase in ROS production, which might stimulate membrane lipid peroxidation, disrupt cellular membrane structure, and cause the loss of cellular compartmentalization and disease resistance, in turn, resulting in pericarp browning and disease development.

To investigate the effect of decontamination treatment on the nutritional attributes of fresh-cut produce, fresh-cut slices of immature bell peppers were soaked in sodium hypochlorite solutions or slightly acidic electrolyzed water with varying concentrations of effective free chlorine. Changes in the residual ratios of the water-soluble nutrients, vitamin C (L-ascorbic acid, L-AsA) and potassium, were measured, as well as aerobic plate counts (APCs), after decontamination. The L-AsA ratios of the samples that were decontaminated with the sodium hypochlorite solutions exhibited a gradual decrease when higher concentrations of detergent and longer soaking times were employed. In contrast, the potassium ratio remained mostly constant around 50% after 1 min of soaking. A decrease in the L-AsA ratio to 80% was observed within 5 min of a soak in deionized water (a 0 ppm solution). Soakings in the slightly acidic electrolyzed water also resulted in a decrease in L-AsA ratios, yet the trend was not similar to that associated with the sodium hypochlorite solutions. These results indicate that water-soluble nutrient contents of fresh-cut produce decrease during a decontamination process that uses chlorine-based solutions according to the free chlorine concentration and the soaking time. Moreover, the reduction in nutrient content varied depending on the disinfectant used, even if the free chlorine concentration was the same for the different disinfectants.

Washing treatment with effective sanitizer is one of the critical steps in ensuring fresh produce safety. This study was to evaluate the efficacy of peracetic acid (PAA; VigorOx® 15 FV L. monocytogenes on romaine lettuce and cantaloupe; S. Typhimurium DT104 on lemons, tomatoes, cantaloupe, and blueberries). PAA at 45, 85, and 100 mg/L; AEO, NNEO, and bleach at 100 mg/L of free chlorine; lactic acid at 2%; and DI water were used for washing inoculated produce in an automated produce washer for 5 min. In general, PAA at 100 mg/L achieved the highest microbial inactivation of E. coli O157:H7 (lettuce, lemon, tomato, and blueberry at 2.2, 5.7, 5.5, and 6.7 log CFU/g, respectively), S. Typhimurium DT104 (lemon, tomato, cantaloupe, blueberry at 5.4, 6.8, 4.5, and 5.9 log CFU/g, respectively), and L. monocytogenes (lettuce and cantaloupe at 2.4 and 4.4 log CFU/g, respectively). Efficacy of sanitizers on produce with coarse surface (for example, lettuce and cantaloupe) was lower than produce with smooth texture (lemon, tomato, and blueberry). Cross-contamination of E. coli O157:H7 among romaine lettuce heads during simulated retail crisping process was greatly reduced by the application of PAA and NNEO. Practical application NNEO and PAA showed high efficacy in foodborne pathogen removal from fresh produce. Produce surface texture plays an important role in pathogen removal. NNEO and PAA effectively prevented cross-contamination during the crisping process.

Conventional water disinfection with chlorine is limited by the inconvenience of their transportation and storage and by the production of potentially harmful disinfection by-products (DBPs). Electric field treatment (EFT), formally studied for food processing, inactivates pathogens by damaging cell membranes through irreversible electroporation. Electroporation is a physical phenomenon, which potentially avoids the use of chemical disinfectants and the formation of DBPs. Nevertheless, EFT has rarely been considered to disinfect water, let alone large-scale industrial applications. In this article, we aim to discuss the feasibility of EFT as an alternative drinking water disinfection technology. We briefly summarize the recent advances of EFT for pathogen inactivation with a focus on industrial applications in food processing. Subsequently, we introduce the basics of EFT and analyze its feasibility to be implemented in water disinfection. We believe that EFT has the potential to become a competitive candidate in the technology toolbox of water disinfection. High energy consumption is identified as the major barrier, which can potentially be overcome by reducing the distance between the electrodes or applying a locally enhanced electric field. Lastly, we discuss the research needs and call for actions of researchers in different disciplines to promote the implementation of EFT in water disinfection.

Chlorine-based sanitizers have seen wide spread use in food sanitation. The reaction of chlorine species with organic matter is a concern for two reasons. Available chlorine can be “used up” by organic compounds resulting in a lower amount of chlorine available for disinfection. Another concern is that some forms of chlorine can react with some organic compounds to form toxic halogenated disinfection byproducts (DBPs). Many studies have been conducted to evaluate the role of hypochlorous acid (HOCl) and hypochlorite ion (OCl−) in the production of DBPs with a particular interest in the production of trihalomethanes (THMs) and haloacetic acids (HAAs). Since most of the chlorine reactions are pH dependent, pH is found to have a significant effect on the formation of chlorine DBPs. In many cases, the concentration of THMs decreases and HAAs increases as pH decreases. pH also plays an important role in the determination of the type and amount of DBPs formed, with lower, more acidic, pHs resulting in the formation of less chloroform. This review summarizes the information from the literature on the role of chlorine-based sanitizers as affected by pH in the formation of different types of DBPs. Alternative novel strategies to minimize the formation of DBPs are also discussed.

Effects of postharvest biocontrol treatment with antagonistic bacteria Bacillus amyloliquefaciens LY-1 on quality attributes and storability of harvested litchi fruit were investigated. “Wuye” litchi fruit were immersed in 1.0 × 108 colony-forming units (CFU) mL−1 B. amyloliquefaciens LY-1 culture broth (BLCB) or sterile water (control) for 5 min, respectively. Litchi fruit were then air-dried and stored at 25 ± 1 °C and 85%–90% relative humidity. Comparing to control litchi fruit, the BLCB-treated litchi fruit exhibited lower pericarp browning index, and percentages of fruit decay and weight loss. Moreover, the BLCB-treated litchi fruit maintained higher contents of total soluble solids, titratable acidity, total soluble sugars and vitamin C in pulp, as well as higher activities of disease resistance-related enzymes (phenylalanine ammonia lyase, chitinase, and β-1, 3-glucandase) and higher content of natural disease-resistive material like lignin in pericarp. Thus, it can be concluded that the 1.0 × 108 CFU mL−1 BLCB treatment delayed the progress of pericarp browning, lowered fruit decay and weight loss, and maintained higher quality of harvested “Wuye” litchi fruit during storage, which might suggest that the BLCB treatment was a promising and effective biological control method for prolonging the shelf-life of harvested litchi fruit.

This study was to evaluate the effect of acidic electrolyzed oxidizing water (AEW) on extending the shelf-life of blueberries during postharvest storage. On day 0, two cultivars of blueberries (Brightwell and Camellia) were washed by AEW with available chlorine concentration (ACC) of 48 mg/L at pH 2.8 for 5 min, and then stored at 4 °C until analyzing. Quality attributes of blueberries including firmness, cell wall composition and cell wall degrading enzymes were analyzed on days 0, 3, 6, 9, 12 and 15. Results showed that Brightwell softened faster than Camellia. AEW treatment slowed down the softening of both cultivars, while it had higher efficacy on delaying the softening of Camellia blueberries than the Brightwell blueberries. In addition, AEW treatment deactivated different cell wall degrading enzymes (CWDEs, polygalacturonase (PG), cellulase and β-galactosidase) and prevented the degradation of cell wall components including Na2CO3-soluble pectin (NSP), hemicellulose and cellulose. These results suggested that AEW treatment can be used as a postharvest technique to delay the softening process of blueberries during storage through lowering CWDEs activities and preventing degradation of cell wall components.

The main objective of this study was to determine the effects of 8-week storage on the consumer acceptability and volatile compound profile of roasted peanuts. Normal-oleic Georgia 06G kernels (06G), high-oleic Georgia 13M (13M), georgia runner (mixed) in-shell (InR) & kernels (R), and virginia (mixed) in-shell (InVA) & kernels (VA) were roasted to medium doneness and stored at 21 °C for consumer and chromatography-mass spectroscopy (GC–MS) tests conducted at week 0, 4 and 8. GC–MS results showed that 06G was the most oxidized samples followed by InVA after 8 weeks. Only InVA exhibited a decrease in consumer likings during storage. At week 8 InR was significantly (p ≤ 0.05) preferred over InVA. When compared high-oleic 13M to normal-oleic 06G, 13M had significantly (p ≤ 0.05) higher consumer likings than 06G at all three time points with a better ability to retain pyrazines and resist to lipid oxidation.

Sixty-four whole pork loins (Institutional Meat Purchase Specifications 413) were procured from a national supplier and randomly assigned to 4 treatments across 2 replications to evaluate the use of alkaline electrolyzed reduced water as a replacement for traditional salt and phosphate based enhancement solutions. Treatments included: alkaline electrolyzed reduced water (EOH; pH≈11.5), EOH plus 2.5% potassium lactate (EOK), industry standard (IS; 0.35% Sodium Tri-polyphosphate, 0.14% sodium chloride, 2.5% potassium lactate), and no enhancement (CON). After enhancement to a target of 110% raw loin weight, chops were cut (2.54-cm), vacuum packaged, and placed in simulated retail display for 30 d to determine treatment effects on objective and subjective shelf life color and lipid oxidation. Despite the alkaline nature of the enhancement solution, EOH chops were lighter in color (L*; P < 0.05) and less red (P < 0.05) but had greater proportions of deoxymyoglobin (P < 0.01) than IS chops across all days of retail display. Subjective color panelists rated the average color of EOH chops as brighter purplish-pink (P < 0.05) with less muscle darkening (P < 0.05) than both IS and CON. Additionally, EOH enhanced chops exhibited greater (P < 0.05) lipid oxidation than all other treatments. Although the addition of potassium lactate to EOH (EOK) was intermediate to EOH and IS for most measures, the use of alkaline electrolyzed reduced water as a pork enhancement solution was not able to maintain similar color or lipid oxidation properties when compared to a traditional salt and phosphate based enhancement solution and is therefore not recommended.

Kitchen cutting boards are one common source of microbial cross-contamination in foods. In this study, a method was developed to create an antimicrobial coating on HDPE cutting board using UV-activated TiO2 nanoparticles (NPs). The antimicrobial efficacy of the developed coatings was tested against E. coli O157: H7 for 3 h at 0.5 ± 0.05 mW/cm2 UVA light intensity. In addition, the effect of NP loading (0.0125, 0.0625, and 0.125 mg/cm2), and surface treatment of coatings by oxygen plasma for 1–15 min on the bactericidal efficacy was investigated. Further, the bactericidal efficacy of the TiO2 coated cutting board on repeated use (i.e. 1, 2, 3 and 5 times) was also evaluated. The results showed that by increasing the NP loading from 0 to 0.125 mg/cm2 has increased the log reduction from 0.37 to 1.18 CFU/cm2. However, no significant difference (P > 0.05) in the reduction was observed between NP loadings at 0.0625 and 0.125 mg/cm2. Oxygen plasma treatment of the coated surfaces for 5–15 min significantly increased (P ≤ 0.05) the log reduction compared to control sample without plasma treatment. Under the tested conditions, TiO2 coating with 0.0625 mg/cm2 NP loading followed by oxygen plasma treatment for 5 min was found to achieve the greatest reduction up to 2.67 log CFU/cm2. Also, the coated-surfaces were found to retain the original bactericidal property even after up to 5 times washing treatment. The developed TiO2 coating on cutting board showed promise to mitigate the risk of microbial cross-contamination by providing a stable antimicrobial activity for extended use. Plasma treatment further enhanced the bactericidal property of the developed coatings without affecting physical stability.

Chlorine-based sanitizers are widely used in fresh produce industry. However, maintaining sufficient free chlorine residual in wash solution in the presence of organic matter is a challenge. The purpose of this study was to evaluate the effects of organic load, sanitizer pH and initial chlorine concentration on chlorine demand of fresh produce wash water. A full factorial design was used to study the chlorine demand of romaine lettuce wash water with different organic load when reacting with NaOCl solution at different pH (2.5, 4.0, 6.0, 8.0 and 9.5) and initial chlorine concentration (50, 75 and 100 mg L−1 free chlorine residual). The results showed that the chlorine demand of lettuce wash water significantly increased (P ≤ 0.05) with increasing organic load. The significant effect (P ≤ 0.05) of initial chlorine concentration on chlorine demand was only detected at high organic load. Increasing the pH of NaOCl from 2.5 to 9.5 led to decrease in the chlorine demand except slight increase from 6.0 to 8.0. Equations for predicting chlorine demand of various fresh produce wash waters at different organic load for different sanitizer pH and initial chlorine concentration were developed, and verified using four types of produce (romaine lettuce, iceberg lettuce, strawberry and grape) and two types of chlorine-based sanitizers (NaOCl and electrolyzed water). Our study demonstrated that organic load, sanitizer pH and initial chlorine concentration all affected the chlorine demand of produce wash water, and chlorine demand prediction equations developed can be used for different types of fresh produce and chlorine-based sanitizers.

Cross-contamination of foods with pathogenic microorganisms such as bacteria, viruses, and parasites may occur at any point in the farm to fork continuum. Food contact and nonfood contact surfaces are the most frequent source of microbial cross-contamination. In the wake of new and emerging food safety challenges, including antibiotic-resistant human pathogens, conventional sanitation and disinfection practices may not be sufficient to ensure safe food processing, proper preparation, and also not be environmentally friendly. Nanotechnology-enabled novel food safety interventions have a great potential to mitigate the risk of microbial cross-contamination in the food chain. Especially engineered nanoparticles (ENPs) are increasingly finding novel applications as antimicrobial agents. Among various ENPs, photocatalyst metal oxides have shown great promise as effective nontargeted disinfectants over a wide range of microorganisms. The present review provides an overview of antimicrobial properties of various photocatalyst metal oxides and their potential applications as surface coatings. Further, this review discusses the most common approaches to developing antimicrobial coatings, methods to characterize, test, and evaluate antimicrobial efficacy as well as the physical stability of the coatings. Finally, regulations and challenges concerning the use of these novel photocatalytic antimicrobial coatings are also discussed.

The aim of this study was to use acidic electrolyzed water (AEW) to treat longan fruit and evaluate the effects of AEW treatment on storability, quality attributes and nutritive properties of longans during storage. The data indicated that, as compared to the control samples, AEW treatment could effectively reduce the respiration rate and pericarp cell membrane permeability, retard the occurrences of pericarp browning, pulp breakdown and fruit disease, keep a higher rate of commercially acceptable fruit. Additionally, AEW treatment could suppress the decrease of chromaticity values of L*, a* and b* of the fruit surface, keep higher amounts of pericarp carotenoid, chlorophyll, flavonoid and anthocyanin, maintain higher amounts of pulp total soluble solid (TSS), total soluble sugars, sucrose and vitamin C. These results demonstrated that AEW treatment at pH of 2.5, ACC of 80 mg/L could maintain higher quality attributes and nutritive properties, and display better storability of harvested longans.

Efficacy of pulsed ultraviolet (PUV) to inactivate Salmonella pure culture and on inoculated black peppercorns was evaluated. Black peppercorns inoculated with Salmonella were subjected to PUV treatment (0.28 J/cm2 /pulse) using two different sample holders, on a traditional flat surface or on a wave-shaped surface to increase surface exposure of peppercorns to PUV through light reflection. The temperature change on black peppercorns surface during treatment was recorded, and the effect of cooling period during PUV treatment was studied. PUV treatment of two pulses reduced Salmonella population by more than 6 log CFU/mL in phosphate-buffered saline. Continuous PUV treatment (80 pulses on each side) using a wave-shaped surface was able to reduce Salmonella by 1.9 log CFU/g; same treatment using flat surface reduced Salmonella by less than 1.5 log CFU/g. The temperature on peppercorns surface increased to 65 °C after 80 pulses continuous PUV treatment. Adding 280 s cooling time after every 20 pulses reduced the temperature from 65 to 40 °C and achieved similar Salmonella inactivation (P > 0.05) as the continuous PUV treatment. Results from this study showcase the effectiveness of PUV treatment for reducing Salmonella level on black peppercorns surface and provided insights on the potential implementation of PUV treatment at the industrial level. PRACTICAL APPLICATION: Results from this study showcased the effectiveness of PUV treatment for reducing Salmonella level on black peppercorns surface and provided insights on the potential implementation of PUV treatment at the industrial level.

Mycelial growth of Aspergillus parasiticus NRRL 2667 and aflatoxin production on Florunner peanuts grown under different calcium supplementation levels (CSL) (550, 1,100, 2,200 and 4,400 kg gypsum/ha) with initial spore loads of 102, 104 and 106 spores/g were investigated. Growth at 25°C for 0, 4, 7 and 14 days was determined by viable plate counts on Aspergillus flavus/parasiticus agar (AFPA) medium. Irrespective of the initial spore load, maximum growth of 108 to 109 CFU/g was attained after 14 days except for the 4,400 kg/ha Ca-supplemented nuts on which the maximum populations were one log less. Aflatoxins B1 and G1 concentrations measured by thin layer chromatography (TLC) ranged from 0-3460 (μg/g and 0-3740 (μg/g, respectively. Toxin production was highest in single peanuts with CSL of 2,200 kg/ha. A reduction of 50% or higher was observed as CSL was increased to 4,400 kg/ha.