Efficacy of low concentration acidic electrolysed water and levulinic acid combination on fresh organic lettuce (Lactuca sativa Var. Crispa L.) and its antimicrobial mechanism

Metabolic and protein expression responses of Shewanella baltica in golden pomfret broths to slightly acidic electrolysed water

Shewanella baltica is a specific spoilage organism of golden pomfret. This study aims to explore the antibacterial mechanism of slightly acidic electrolysed water (SAEW) against S. baltica (strains ABa4, ABe2 and BBe1) in golden pomfret broths by metabolomics, proteomics and bioinformatics analyses. S. baltica was decreased by at least 3.94 log CFU/mL after SAEW treatment, and strain ABa4 had the highest resistance. Under SAEW stress, amino acids and organic acids in S. baltica decreased, and nucleotide related compounds degraded. Furthermore, 100 differentially expressed proteins (DEPs) were identified. Most DEPs of strains ABe2 and BBe1 were down-regulated, while some DEPs of strain ABa4 were up-regulated, especially those oxidative stress related proteins. These results suggest that the modes of SAEW against S. baltica can be traced to the inhibition of amino acid, carbon, nucleotide and sulphur metabolisms, and the loss of functional proteins for temperature regulation, translation, motility and protein folding.

Recent advances in activated water systems for the postharvest management of quality and safety of fresh fruits and vegetables

Over the last three decades, decontamination management of fresh fruits and vegetables (FFVs) in the packhouses and along the supply chains has been heavily dependent on chemical-based wash. This has resulted in the emergence of resistant foodborne pathogens and often the deposition of disinfectant byproducts on FFVs, rendering them unacceptable to consumers. The management of foodborne pathogens, microbial contaminants, and quality of FFVs are a major concern for the horticultural industries and public health. Activated water systems (AWS), such as electrolyzed water, plasma-activated water, and micro-nano bubbles, have gained significant attention from researchers over the last decade due to their nonthermal and nontoxic mode of action for microbial inactivation and preservation of FFVs quality. The aim of this review is to provide a comprehensive summary of recent progress on the application of AWS and their effects on quality attributes and microbial safety of FFVs. An overview of the different types of AWS and their properties is provided. Furthermore, the review highlights the chemistry behind generation of reactive species and the impact of AWS on the quality attributes of FFVs and on the inactivation/reduction of spoilage and pathogenic microbes (in vivo or in vitro). The mechanisms of action of microorganism inactivation are discussed. Finally, this work highlights challenges and limitations for commercialization and safety and regulation issues of AWS. The synergistic prospect on combining AWS for maximum microorganism inactivation effectiveness is also considered. AWS offers a potential alternative as nonchemical interventions to maintain quality attributes, inactivate spoilage and pathogenic microorganisms, and extend the shelf-life for FFVs.

Synergistic effect of electrolyzed water generated by sodium chloride combined with dimethyl dicarbonate for inactivation of Listeria monocytogenes on lettuce

BACKGROUND

Electrolyzed water (EW) is recognized as an effective way to control and reduce pathogens in vegetables. However, the disinfection efficacy of EW alone is limited. In this work, the bactericidal activity and biofilm removal capability of EW, generated by adding NaCl to a portable EW generator, were investigated with special reference to Listeria monocytogenes. Furthermore, the impact of EW in combination with dimethyl dicarbonate (DMDC) in reducing the microbial load and improving the overall quality of lettuce during refrigerated storage was evaluated.

RESULTS

EW with 0.3% NaCl (SEW) had the highest bactericidal activity against L. monocytogenes. The pathogen treated with SEW exhibited lower superoxide dismutase activity and more leakage of proteins and nucleic acids than in the case of EW. Furthermore, the use of SEW resulted in changes in the cell permeability and morphology of L. monocytogenes. A decrease in adhesion and collapse of the biofilm architecture were also observed, indicating that SEW was more effective for inactivating L. monocytogenes cells compared to EW. For untreated lettuce, the populations of the total plate count and inoculated L. monocytogenes decreased by 2.47 and 2.35 log CFU g-1 , respectively, after the combined SEW/DMDC treatment for 3 min. The use of SEW alone or combined with DMDC did not negatively impact the lettuce color values, titratable acid, ascorbic acid and soluble solids compared to the control group.

CONCLUSION

SEW in combination with DMDC can be used as a novel and potentially effective disinfection strategy for ensuring the safety of vegetable consumption. © 2023 Society of Chemical Industry.

A multi-omics analysis strategy reveals the molecular mechanism of the inhibition of Escherichia coli O157:H7 by anthocyanins from Aronia melanocarpa and its application

Water pollution causes the propagation of pathogenic microorganisms, which poses a serious threat to human life. Escherichia coli O157:H7, as a representative organism that can directly exhibit molecular response to stress, was selected as the indicator bacteria for the study. Tandem mass tag (TMT) quantitative proteomics and non-targeted metabolomics were used to study the response of Escherichia coli O157:H7 to Aronia melanocarpa anthocyanin (AMA) treatment. The results showed that 628 proteins and 1338 metabolites changed significantly after treatment with AMAs. According to bioinformatics analysis, integrated proteomics and metabolomics analysis differentially expressed proteins (DEPs) and metabolites participate in pyruvate metabolism, glycolysis/gluconeogenesis, alanine, aspartate and glutamate metabolism and the pentose phosphate pathway. This study preliminarily proposed the inhibition mechanism of AMAs on Escherichia coli O157:H7 from the perspective of multi-omics, providing a theoretical basis for the application of natural preservatives in fresh cut vegetables.

The Effect of Different Organic Acids and Their Combination on the Cell Barrier and Biofilm of Escherichia coli

Organic acids are natural antimicrobial compounds commonly used in the food industry. In this study, acetic, lactic, butyric, citric, and malic acid at minimum inhibitory concentrations and their combinations at optimal inhibition concentrations were used to treat E. coli, and the effects on the cell barrier and biofilm of E. coli were evaluated. Acetic acid showed the highest membrane-damaging effect, while citric acid and malic acid could specifically damage the cell wall of E. coli, leading to alkaline phosphatase leakage. The RT-qPCR results showed that organic acids upregulated the membrane-protein-related genes of E. coli, and the combination of organic acids had a wider range of effects than single organic acid treatment. Moreover, organic acids inhibited the formation of E. coli biofilm and cellular activity within the biofilm. This study showed that the combination of organic acids plays a synergistic inhibitory role mainly through multiple destructive effects on the cell barrier and exhibited synergistic anti-biofilm effects. The three-three combination of acetic, lactic acid, and a third organic acid (butyric, citric, or malic) can play a better synergistic antibacterial effect than the two-pair combination of acetic and lactic acid. These findings have implications for the usage, development, and optimization of organic acid combinations.

Generation, mechanisms, kinetics, and effects of gaseous chlorine dioxide in food preservation

Food preservation is a critical issue in ensuring food safety and quality. Growing concern around industrial pollution of food and demand for environmentally sustainable food has led to increased interest in developing effective and eco-friendly preservation techniques. Gaseous ClO2 has gained attention for its strong oxidizing properties, high efficacy in microorganism inactivation, and potential for preserving the attributes and nutritional quality of fresh food while avoiding the formation of toxic byproducts or unacceptable levels of residues. However, the widespread use of gaseous ClO2 in the food industry is limited by several challenges. These include large-scale generation, high cost and environmental considerations, a lack of understanding of its mechanism of action, and the need for mathematical models to predict inactivation kinetics. This review aims to provide an overview of the up-to-date research and application of gaseous ClO2 . It covers preparation methods, preservation mechanisms, and kinetic models that predict the sterilizing efficacy of gaseous ClO2 under different conditions. The impacts of gaseous ClO2 on the quality attributes of fresh produce and low-moisture foods, such as seeds, sprouts, and spices, are also summarized. Overall, gaseous ClO2 is a promising preservation approach, and future studies are needed to address the challenges in large-scale generation and environmental considerations and to develop standardized protocols and databases for safe and effective use in the food industry.

Inactivation of Staphylococcus aureus by Levulinic Acid Plus Sodium Dodecyl Sulfate and their Antibacterial Mechanisms on S. aureus Biofilms by Transcriptomic Analysis

The combination of levulinic acid (LVA) and sodium dodecyl sulfate (SDS) in recent years has shown a considerable potential to use as an antimicrobial intervention. The objectives of this study were to evaluate the antimicrobial efficacy of the combination against Staphylococcus aureus in both planktonic and biofilm states and to investigate the transcriptional changes in S. aureus biofilms coincubated with sublethal concentrations of LVA and/or SDS. The minimum inhibitory concentrations (MICs) of LVA and SDS determined by the microdilution method were 3.125 and 0.039 mg/mL, respectively. An additive bacteriostatic interaction (fractional inhibitory concentration index = 1) between the two compounds was observed by the checkerboard assay, whereas a synergistic bactericidal activity was displayed by the time-kill assay. The biomass and viable cells in the biofilms were reduced by both antimicrobials either alone or in combination in a dose-dependent manner. Transcriptomics indicated that more differentially expressed (DE) genes were observed in the biofilm treated with SDS (103 up- and 205 downregulated DE genes) and LVA + SDS (187 up and 162 down) than that coincubated with LVA (34 up and 32 down). The SDS and LVA + SDS treatments mainly affected the expression of genes responsible for cell surface proteins, virulence factors, adhesins, and capsular polysaccharides. Both the antibiofilm assay and the transcriptomics indicated that SDS, not LVA, was the major chemical contributing to the antibacterial efficacy of the combination. This study reveals the behavioral responses and protective mechanisms of S. aureus to LVA and SDS applied individually or in combination.

The influences of acidic electrolyzed water on quality and bacteria community of fresh-cut jackfruit in storage

This study evaluated the effects of acidic electrolyzed oxidizing water (AEW) on the quality and bacterial communities of fresh-cut jackfruit during storage. The result showed that AEW treatment, as compared to the CK group (without AEW treatment), could effectively inhibit the browning, maintain higher firmness and higher amounts of total titratable acidity (TTA) (0.21%), sugars (58.30 g/kg), ascorbic acids (28.72 mg/kg) and total phenolics (35.47 mg/kg) of fresh-cut jackfruits, and suppress the decrease of antioxidant ability during 4–8 days of storage. Additionally, the bacterial communities were significantly affected by AEW during storage. In particular, the AEW treated samples showed lower abundance of Pseudomonas and Lactobacillus than the CK group after storage of 8 day. And energy metabolism, nucleotide metabolism has the significantly lower (p < 0.05) relative abundance in the AEW group than in CK group. These results suggested that AEW (pH: 4.2–4.5, ACC: 35–38 mg/L) treatment could maintain the quality of fresh-cut jackfruit during storage. It could be attributed to that AEW treatment affect the growth and metabolism of bacterial communities, resulting in the decrease of nutrients consumption.

Dual-Species Biofilms Formed by Escherichia coli and Salmonella Enhance Chlorine Tolerance

Outbreaks of Escherichia coli and Salmonella in food might be associated with the cross-contamination of biofilms on food-contact surfaces. The knowledge of the sanitization of mono-species biofilm on the food-contact surface is well established, while mixed-species biofilm occurs more naturally, which could profoundly affect the efficacy of sanitizer.

Microbial inactivation of milk by low intensity direct current electric field: Inactivation kinetics model and milk characterization

Microbial inactivation by pulsed electric field (PEF) has been studied widely although with high operational risk, while few studies on the potential of low intensity electric fields for microbial inactivation have been reported. In this study, the feasibility of inactivating microorganisms in milk by low intensity direct current (DC) electric field was investigated. Then a kinetics model was proposed based on the inactivation curves. Finally, the effect of electric field on the microflora and physicochemical properties of milk was analyzed. Results showed that the bacterial reduction >5 log CFU/mL could be achieved at 50–55°C, 0.3 A–0.6 A, and with 5 min starting intensity of 5 V/cm-9 V/cm. The inactivation kinetics consisted of three stages, therein, the middle stage, main part of the inactivation curve, followed 1st-order reaction kinetics, and the effect of temperature on it was consistent with the Arrhenius Law, which implied that the electric field itself can inactivate bacteria without thermal inactivating effect. The microflora analysis showed that naturally occurring bacteria in the milk contained typical potential pathogenic bacteria (e.g., 56.9% of Acinetobacter spp.) and spoilage bacteria (e.g., 27.5% of Pseudomonas spp.), and the electric field can inactivate them. Moreover, the inactivation chemically preserved the milk's fresh-like characteristics (according to indexes of whey protein denaturation rate, furosine content), and physical stability (turbidity, zeta potential, particle size, color and so on). Therefore, a promising approach is provided for microbial inactivation in dairy industry.

•

Microbial inactivation of milk in low intensity direct current electric field was verified.

•

The bacteria (7.5 log CFU/mL) in milk were completely inactivated.

•

The main part, middle stage, of inactivation followed 1st-order reaction kinetics.

•

For Acinetobacter spp. and Pseudomonas spp., inactivation of the electric field was non-selective.

•

Inactivation on the physicochemical properties of milk was at an acceptable level.

Application of sonodynamic technology and sonosensitizers in food sterilization: a review of developments, trends and challenges

Food safety and food waste have always been hot topics of discussion in recent years. However, the infection of human pathogenic bacteria and the waste of food resources caused by microbial-contaminated food remains common. Although traditional sterilization technology has been very mature, it causes changes in food flavor and excessive energy consumption to a certain extent. Moreover, the widespread bacterial resistance has also sounded a warning for researchers and finding a new alternative to antibiotics is urgently needed. The application of sonodynamic sterilization technology in medical treatment has aroused the interest of researchers. It provides ideas for new food sterilization technology. As a new non-thermal sterilization technology, sonodynamic sterilization technology has strong penetration, safety, less residue and by-products, and will less change the quality of the food itself. Therefore, sonodynamic sterilization technology has great potential applied in food sterilization technology. This review describes the concept of sonodynamic sterilization technology, the sterilization mechanism of sonodynamic sterilization and the inactivation mechanism of various pathogens, the classification and application of sonosensitizers, and the ultrasonic technology in sonodynamic sterilization in the application over the recent years. It provides a scientific reference for the application of sonodynamic sterilization technology in the field of food sterilization.

Antimicrobial activity of cyanidin-3-O-glucoside-lauric acid ester against Staphylococcus aureus and Escherichia coli

Enzymatic acylation of anthocyanin with fatty acid improves its lipophilic solubility and application potential. Nevertheless, evaluation of functional properties of product is premise for application. This study investigated the antimicrobial potential and the underlying mechanisms of an acylated anthocyanin, namely, cyanidin-3-O-glucoside-lauric acid ester (C3G-LA), to provide guidelines for its application. C3G-LA exhibited outstanding antibacterial activity against Staphylococcus aureus [minimum inhibitory concentration (MIC) = 0.3125 mg/mL] and modest activity against Escherichia coli (MIC = 5 mg/mL). Moreover, C3G-LA manifested bactericide ability against S. aureus at 0.625 mg/mL. Decreases in membrane integrity (by 96% and 92% at MIC in S. aureus and E. coli, respectively), intracellular ATP concentration (by 96% and 92%) and intracellular pH (by 11% and 9%) and changes in cellular morphology altogether indicated the dysfunction of cell membrane under C3G-LA treatment. These findings demonstrated that C3G-LA could be adopted as an alternative food preservative against foodborne pathogens.

Dual bacterial strains TTI for monitoring fish quality in food cold chain

Most microbial time-temperature indicators (TTIs) considered only one spoilage strain. This research compared single and dual spoilage strains-based microbial TTI for quality changes of chilled grouper fish (Epinephelus fuscoguttatus x E. lanceolatus) fillet products during distribution. The next-generation sequencing (NGS) and traditional plate count approach showed that Pseudomonas fragi and Vibrio parahaemolyticus were specific spoilage bacteria at 7 and 15°C. A dual-strain TTI response provides more accurate results than a single-strain TTI and provides an irreversible color change from yellow to reddish-brown, showing levels of fish freshness. The microbial TTI comprises fish spoilage bacteria strains with 3 log CFU/ml, a nutrient broth supplemented with 2% NaCl as a medium, and phenol red with 0.25 mg/ml as a pH indicator. Overall, this study points to the applicability of a dual-strain microbial TTI as a valuable tool for monitoring fish quality changes during cold chain break condition.

Effect of chlorine sanitizer on metabolic responses of Escherichia coli biofilms "big six" during cross-contamination from abiotic surface to sponge cake

The effect of chlorine on Escherichia coli biofilm O157:H7 are well established; however, the effect on biofilm adhesion to food as well as the six emerging E. coli serotypes ("big six") have not been fully understood. Chlorine sanitization with 1-min 100 mg/L was applied against seven pathogenic E. coli (O111, O121:H19, O45:H2, O26:H11, O103:H11, O145, and O157:H7) biofilms on high-density polyethylene (HDPE) and stainless steel (SS) coupons, respectively. Using sponge cake as a food model, the adhesion behavior was evaluated by comparison of bacteria transfer rate before and after treatment. Besides, the metabolic profiles of biofilms were analyzed by nuclear magnetic resonance (NMR) spectrometer. A significant decrease in transfer rate (79% decline on SS and 33% decline on HDPE) was recorded as well as the distinctive pattern between SS and HDPE coupons was also noticed, with a low population (6-7 log CFU/coupon) attached and low survivals (0-3 log CFU/coupon) upon chlorine on SS, while high population (7-8 log CFU/coupon) attached and high survivals (5-7 log CFU/coupon) on HDPE. Moreover, O121:H19 and O26:H11 demonstrated the highest resistance to chlorine with the least metabolic status and pathways affected. O103:H11, O145, and O111 followed similar metabolic patterns on both surfaces. Distinct metabolic patterns were found in O45:H2 and O157:H7, where the former had more affected metabolic status and pathways on SS but less on HDPE, whereas the latter showed an opposite trend. Overall, a potential contamination source of STEC infection in flour products was demonstrated and metabolic changes induced by chlorine were revealed by NMR-based metabolomics, which provides insights to avoid "big six" biofilms contamination in food.

Effects of electrolysed water and levulinic acid combination on microbial safety and polysaccharide nanostructure of organic strawberry

This study aimed to better understand the effects of acidic electrolysed water (AEW, 4 mg/L) and levulinic acid (LA, food grade, 2%) combination on organic strawberry over 7 days. This combined method reduced the population of strawberry's natural microbiota by 1-2 log CFU/g and kept the level of inoculated Escherichia coli O157:H7 and Salmonella below the detection limit (2 log CFU/g) during the whole storage period. Meanwhile, AEW + LA did not affect the physicochemical qualities of strawberries significantly, maintaining most texture and biochemical attributes at an acceptable level (e.g., firmness, colour, soluble solids content and organic acid content). Atomic force microscopy further revealed that the treatment containing LA preserved the sodium carbonate soluble pectin (SSP) nanostructure best by maintaining their length and height, and slowed the breakdown of SSP chains by promoting acid-induced bonding and soluble pectin precipitation. These results demonstrated that low concentration AEW and LA combination is a promising sanitising approach for organic strawberry preservation.

Dual Inhibitory Activity of Petroselinic Acid Enriched in Fennel Against Porphyromonas gingivalis

Increasing evidence has shown that a major periodontal pathobiont, Porphyromonas gingivalis, triggers oral dysbiosis leading to deterioration not only of periodontal health, but also of several systemic conditions. In the present study we identified remarkable anti-P. gingivalis activity of Foeniculum vulgare (fennel), an herbal plant used in Asian cuisine as well as in traditional medicine, by screening of 92 extracts prepared from 23 edible plants. The n-hexane-extracted fennel (HEF) showed a rapid lethal action toward P. gingivalis, while it was rather ineffective with a wide range of other oral commensal bacterial species. Morphological analysis using both high-speed atomic force microscopy and field emission scanning electron microscopy revealed that a low concentration of HEF (8 μg/mL) resulted in formation of protruding nanostructures composed of outer membrane vesicle (OMV)-like particles, while a high concentration of HEF (64 μg/mL) induced bacteriolysis with overproduction of OMVs with unusual surface properties. Interestingly, HEF treatment resulted in deprivation of two outer membrane transporter proteins, RagA and RagB, which is essential for nutrient acquisition in P. gingivalis, by extracellularly releasing RagA/RagB-enriched OMVs. Furthermore, HEF showed gingipain-inhibitory activity toward both arginine-specific (Rgps) and lysine-specific (Kgp) gingipains, resulting in blocking oral epithelial cell rounding and the subsequent detachment from culture dishes. Finally, we isolated petroselinic acid as a major bactericide as well as a gingipain inhibitor through a bioassay-guided fractionation of HEF. Taken together, our findings suggest clinical applicability of HEF and petroselinic acid for periodontitis therapy to eliminate P. gingivalis and its major virulence factors on the basis of the dual anti-P. gingivalis activity, i.e., rapid bacteriolysis and gingipain inhibition.

The Efficacy of Conventional Spray, Electrostatic Spray, and Dip with a Combination of Hydrogen Peroxide and Peroxyacetic Acid To Inactivate Listeria monocytogenes on Apples

ABSTRACT

This study aimed to evaluate the efficacy of a hydrogen peroxide (H2O2) and peroxyacetic acid (PAA) mixer delivered by conventional garden spray (GS), electrostatic spray (ES), and dip methods to inactivate Listeria monocytogenes on apples. Organic Honeycrisp, Fuji, and Pink Lady apples were dip inoculated with L. monocytogenes (two strains, serotype 1/2b), which were then kept untreated (control), sprayed with water only, or treated with the H2O2-PAA mixer (0.0064, 0.1, 0.25, and 0.50%) for 20 s via GS, ES, or dip, followed by draining (for 2 min) on aluminum foil. Surviving bacteria were recovered on modified Oxford agar. Atomic force microscopy was used to detect the structural changes of inactivation of L. monocytogenes in broth medium by the H2O2-PAA mixer solution. Data (two replicates, with six samples per replicate) were analyzed using the mixed model procedure of SAS (P = 0.05). Initial counts of L. monocytogenes on untreated apples were 6.80 to 6.90 log CFU per apple. The dip method was the most effective treatment (P < 0.05) for pathogen reductions (2.31 to 2.41 log CFU per apple), followed by GS (1.44 to 1.70 log CFU per apple) and then ES (0.84 to 1.20 log CFU per apple). Reductions of L. monocytogenes were greatest (P < 0.05) when apples were treated with H2O2-PAA mixer -0.25 and -0.50%. Atomic force microscopy analyses indicated that inactivation of L. monocytogenes cells in H2O2-PAA mixer solutions resulted from disruption of the outer membrane. The H2O2-PAA mixer-treated cells had increased width and height and decreased roughness compared with the untreated cells. Results suggested that applying a H2O2-PAA mixer by dip or GS methods is better for pathogen reduction than ES on apples.

HIGHLIGHTS

Ultrasound assisted aqueous two-phase extraction of polysaccharides from Cornus officinalis fruit: Modeling, optimization, purification, and characterization

Ultrasound assisted aqueous two-phase extraction of polysaccharides from Cornus officinalis fruit was modeled by response surface methodology (RSM) and artificial neural network (ANN), and optimized using genetic algorithm coupled with ANN (GA-ANN). Statistical analysis showed that the models obtained by RSM and ANN could accurately predict the Cornus officinalis polysaccharides (COPs) yield. However, ANN prediction was more accurate than RSM. The optimum extraction parameters to achieve the highest COPs yield (7.85 ± 0.09)% was obtained at the ultrasound power of 350 W, extraction temperature of 51 ℃, liquid-to-solid ratio of 17 mL/g, and extraction time of 38 min. Subsequently, the crude COPs were further purified via DEAE-52 and Sephadex G-100 chromatography to obtain a homogenous fraction (COPs-4-SG, 33.64 kDa) that contained galacturonic acid, arabinose, mannose, glucose, and galactose in a molar ratio of 34.82:14.19:6.75:13.48:12.26. The structure of COPs-4-SG was also characterized with UV-vis, fourier-transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), scanning electron microscopy (SEM), Congo-red test, and circular dichroism (CD). The findings provide a feasible way for the extraction, purification, and optimization of polysaccharides from plant resources.

Polycaprolactone/polyvinyl pyrrolidone nanofibers developed by solution blow spinning for encapsulation of chlorogenic acid

Study on the application of nanofibers in food active packaging has been a research hotspot in recent years. In this work, the solution blow spinning (SBS) was applied to rapidly fabricate the polycaprolactone (PCL), polyvinyl pyrrolidone (PVP), and PCL/PVP nanofibrous films to encapsulate chlorogenic acid (CGA). All the films showed uniform and smooth nanofibers, and the FTIR and XRD proved the success of mixed spinning of PCL and PVP. With the increase of PVP content, the thermal stability of the PCL/PVP nanofibrous films improved. The PCL/PVP (4:1) film possessed better mechanical properties than PCL and PVP films because of the stronger fiber-fiber interactions. The addition of PCL endowed the hydrophobic surfaces to the PCL/PVP films, and the PCL/PVP films had better water vapor barrier ability. The PCL/PVP (4:1) film exhibited the best long-term continuous release of CGA during 72 h. The PVP nanofibrous film exhibited no inhibition against S. aureus and E. coli due to the low encapsulation efficiency, but the PCL and PCL/PVP films exhibited good antimicrobial activity. The above results suggested that the nanofibrous films developed by SBS possessed the promising prospects in food packaging.

Development of Ultrasound-Assisted Extraction to Produce Skin-Whitening and Anti-Wrinkle Substances from Safflower Seed

In this study, ultrasound-assisted extraction (UAE) was applied to extract bioactive substances with skin-whitening, anti-wrinkle, and antioxidant effects from safflower seeds, and the extraction conditions were optimized by a central composite design. The independent variables, including extraction time (5.0~55.0 min), extraction temperature (26.0~94.0 °C), and ethanol concentration (0.0~100%), were optimized to increase tyrosinase activity inhibitory (TAI), collagenase activity inhibitory (CAI), and radical scavenging activity (RSA), which are indicators of skin-whitening, anti-wrinkle, and antioxidant effects. An extraction time of 26.4 min, extraction temperature of 52.1 °C, and ethanol concentration of 50.7% were found to be optimum conditions of UAE, under which TAI, CAI, and RSA were 53.3%, 91.5%, and 27.7%, respectively. The extract produced by UAE was analyzed by LC-MS/MS, and maleic acid and levulinic acid were identified as the main substances. Therefore, UAE is evaluated as an effective process to extract skin-whitening, anti-wrinkle, and antioxidant substances from safflower seeds at lower temperatures and shorter extraction times compared to the conventional extraction methods. Overall, safflower seeds extract can be used as a material for value-added cosmetics, including maleic acid and levulinic acid, which have bioactive functions.

LC-MS/MS method for the simultaneous quantification of pyriproxyfen and bifenthrin and their dissipation kinetics under field conditions in chili and brinjal

Bifenthrin, a synthetic pyrethroid, and pyriproxyfen, a plant growth regulator, are used extensively in agriculture for controlling the different insect pests. The present study was undertaken to examine the dissipation behavior of a formulation with a combination of pyriproxyfen and bifenthrin on chili and brinjal under field conditions at four different locations. Dissipation study of combination of pyriproxyfen and bifenthrin revealed swift degradation in both crops with a half-life of 2.5-2.6 and 2.0-2.1 days in brinjal and chili, respectively. Also, a simple method for simultaneous quantification of pyriproxyfen and bifenthrin was developed and validated using modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) technique on liquid chromatography with tandem mass spectrometry (LC-MS/MS). Recovery of the method was found to be under an acceptable range of 90.0%-93.5% and 88.7%-94.3% in chili and 92.4%-96.6% and 97.4%-100.9% in brinjal for pyriproxyfen and bifenthrin, respectively. At harvest time, the terminal residues of bifenthrin and pyriproxyfen were below the maximum residue limits set by European Union in chili and brinjal, respectively, suggesting that the use of this pesticide formulation is safe and does not impose harmful effects on human health. PRACTICAL APPLICATION: In this paper, dissipation behavior of a pesticide formulation with a combination of pyriproxyfen and bifenthrin was undertaken under field conditions at four different locations on chili and brinjal in India. The simultaneous quantification of pyriproxyfen and bifenthrin using LC-MS/MS technique has been validated incorporating modified QuEChERS extraction method with limit of detection at 0.005 µg/g and limit of quantification at 0.01 µg/g, which is well below the EU-MRLs (European Union legislation Maximum Residue Level) of pyriproxyfen and bifenthrin in both chili and brinjal. Furthermore, dissipation kinetics of a formulation undertaken under field conditions at four different locations on chili and brinjal suggested that the terminal residues of both bifenthrin and pyriproxyfen were below the maximum residue limits set by European Union in chili and brinjal, respectively, at the time of harvest and that the use of this pesticide formulation is safe.

In vitro and in silico approaches to investigate antimicrobial and biofilm removal efficacies of combined ultrasonic and mild thermal treatment against Pseudomonas fluorescens

A combined ultrasonic and thermal (US-TM) treatment was developed in this study to achieve a high efficacy of P. fluorescens biofilm control. The present study demonstrated that combined a moderate ultrasound treatment (power ≥ 80 W) and a mild heat (up to 50 °C) largely destroyed biofilm structure in 15 min and removed>65.63% of biofilm from a glass slide where cultivated the P. fluorescens biofilm. Meanwhile, the viable cell count was decreased from 10.72 to 6.48 log10CUF/mL. Differences in biofilm removal and lethal modes of US-TM treatment were confirmed through microscopies analysis in vitro. The ultrasound first contributed to releasing the bacteria in the biofilm to the environment and simultaneously exposing inner bacteria at the deep layer of biofilm depending on shear force, shock waves, acoustic streaming, etc. When the biofilm structure was destroyed, US-TM treatment would synergistically inactivate P. fluorescens cells. In silico studies adopted COMSOL to simulate acoustic pressure and temperature distribution in the bioreactor; both of them were significantly influenced by various factors, such as input power, sonotrode position, materials and volume of container, etc. Facing the biofilm issue existing on the surface of container, boundary conditions were exported and thereby pointing out potential "dead ends" where the ultrasound may not be effectively transduced. Both in vitro and in silico results may inspire the food industry to adopt US-TM treatment to achieve biofilm control.

Recent trends and applications of electrolyzed oxidizing water in fresh foodstuff preservation and safety control

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.

Research Trends on the Application of Electrolyzed Water in Food Preservation and Sanitation

Electrolyzed water (EW) has been proposed as a novel promising sanitizer and cleaner in recent years. It is an effective antimicrobial and antibiofilm agent that has several advantages of being on the spot, environmentally friendly, cheap, and safe for human beings. Therefore, EW has been applied widely in various fields, including agriculture, food sanitation, livestock management, medical disinfection, clinical, and other fields using antibacterial technology. Currently, EW has potential significance for high-risk settings in hospitals and other clinical facilities. The research focus has been shifted toward the application of slightly acidic EW as more effective with some supplemental chemical and physical treatment methods such as ultraviolet radiations and ultrasound. This review article summarizes the possible mechanism of action and highlights the latest research studies in antimicrobial applications.

Synergistic combination of Sapindoside A and B: A novel antibiofilm agent against Cutibacterium acnes

Sapindus saponins extracted from Sapindus mukorossi Gaertn. have been reported to exert antibacterial activity against Cutibacterium acnes (C. acnes). However, there are no reports about their potentials against its biofilm, which is a major contributor to the antibiotic resistance of C. acnes. This study aimed to investigate the synergistic antibiofilm activity and action of the combination of Sapindoside A and B (S_AB) against C. acnes. S_AB with sub-MICs significantly inhibited the early-formed and mature biofilm of C. acnes and decreased the adhesion and cell surface hydrophobicity (p < 0.05). Also, S_AB greatly reduced the production of exopolysaccharide and lipase (p < 0.05), and the binding mode of S_AB and lipase was predicted by molecular docking, via hydrogen bonds and hydrophobic interactions. Biofilm observed with electron microscopies further confirmed the high antibiofilm activity of S_AB against C. acnes. Furthermore, a significant down-regulation of biofilm biosynthesis-associated genes was observed. The combination index explained the synergistic effects of S_AB leading to the above results, and the contribution of S_A was greater than that of S_B. The current results showed that S_AB had synergistic antibiofilm activity against C. acnes, and the Sapindoside A played a major role, indicating that S_AB could be a natural antiacne additive against C. acnes biofilm-associated infections.

Application of a 360-Degree Radiation Thermosonication Technology for the Inactivation of Staphylococcus aureus in Milk

Milk is easy to be contaminated by microorganisms due to its abundant nutrients. In this study, a 360-degree radiation thermosonication (TS) system was developed and utilized for the inactivation of Staphylococcus aureus in milk. The 360-degree radiation TS system-induced inactivation kinetics of S. aureus was fitted best by the Weibull model compared with biphasic and linear models. The treatment time, the exposure temperature, and the applied ultrasound power was found to affect the bactericidal efficacy of the 360-degree radiation TS system. Additionally, the TS condition of 200 W and 63°C for 7.5 min was successfully applied to achieve complete microbial inactivation (under the limit of detection value) in raw milk. The treatment of 360-degree radiation TS can enhance the zeta potential and decrease the average particle size of milk. It also exhibited better retainment of the proteins in milk compared with the ultrahigh temperature and conventional pasteurization processing. Therefore, the 360-degree radiation TS system developed in this study can be used as an alternative technology to assure the microbiological safety and retain the quality of milk, and the Weibull model could be applied for the prediction of the inactivation levels after exposure to this technology.

Combined an acoustic pressure simulation of ultrasonic radiation and experimental studies to evaluate control efficacy of high-intensity ultrasound against Staphylococcus aureus biofilm

This study evaluated efficacy of high-intensity ultrasound (HIU) on controlling or stimulating Staphylococcus aureus biofilm. Acoustic pressure distribution on the surface of glass slide cultivated S. aureus biofilm was first simulated as a standardized parameter to reflect sono-effect. When the power of HIU was 240 W with acoustic pressure of -1.38×105 Pa, a reasonably high clearance rate of S. aureus biofilm was achieved (96.02%). As an all-or-nothing technique, the HIU did not cause sublethal or injury of S. aureus but inactivate the cell directly. A further evaluation of HIU-induced stimulation of biofilm was conducted at a low power level (i.e. 60 W with acoustic pressure of -6.91×104 Pa). The low-power-long-duration HIU treatment promoted the formation of S. aureus biofilm and enhanced its resistance as proved by transcriptional changes of genes in S. aureus, including up-regulations of rbf, sigB, lrgA, icaA, icaD, and down-regulation of icaR. These results indicate that the choose of input power is determined during the HIU-based cleaning and processing. Otherwise, the growth of S. aureus and biofilm formation are stimulated when treats by an insufficiently high power of HIU.