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Traditional foods (TFs) inherit a long history and colorful cultures and are closely bound with the dietary patterns of indigenous people. They are either homemade or commercially made and purchased from local food outlets, which provide distinctive textural and sensory properties, nutritional values, and bioactive functions. However, the science and wisdom of TFs are not thoroughly understood by local people in their historical context. Today's scientific knowledge and technical capabilities provide opportunities for scientists, industries, and consumers to understand the scientific ingenuity behind TFs, which may significantly promote the transition of TFs from homemade to scaled and standardized manufacturing with global availability and acceptance. In addition, the science of TFs may open new vistas for developing modern foods and new lifestyles. This review summarizes and provides insights into the science of TFs, covering food chemistry, food quality, food safety, health function, food processing, and its implications for future food systems. • Modern science revealed the sciences and benefits of TFs. • Scientific knowledge promoted TFs into global availability. • Science of TFs inspired the development of modern foods and new lifestyles. • Advanced methodologies provide new opportunities in TF studies. [ABSTRACT FROM AUTHOR]

Determination of the minimum free chlorine concentration needed to prevent pathogen survival/cross-contamination during produce washing is essential for the development of science-based food safety regulations and practices. Although the trend of chlorine concentration-contact time on pathogen inactivation is generally understood, specific information on chlorine and the kinetics of pathogen inactivation at less than 1.00 s is urgently needed by the produce processing industry. However, conventional approaches to obtain this critical data have been unable to adequately measure very rapid responses. This paper reports our development, fabrication, and test of a novel microfluidic device, and its application to obtain the necessary data on pathogen inactivation by free chlorine in produce wash solution in times as short as 0.10 s. A novel microfluidic mixer with the capability to accurately determine the reaction time and control the chlorine concentration was designed with three inlets for bacterial, chlorine and dechlorinating solutions, and one outlet for effluent collection. The master mold was fabricated on a silicon wafer with microchannels via photopolymerization. Polydimethylsiloxane replicas with patterned microchannels were prototyped via soft lithography. The replicas were further assembled into the micromixer on glass via O 2 plasma treatment, and the inlets were connected to a syringe pump for solution delivery. To determine the kinetics of free chlorine on pathogen inactivation, chlorine solutions of varying concentrations were first pumped into the micromixer, together with the addition of bacterial suspension of Escherichia coli O157:H7 through a separate inlet. This was followed by injection of dechlorinating solution to stop the chlorine-pathogen reaction. The effluent was collected and the surviving bacteria cells were enumerated using a modified ‘Most Probable Number’ method. Free chlorine concentration was determined using a standard colorimetric method. The contact time was experimentally set by adjusting the solution flow rate, and was estimated by computational fluid dynamics modeling. Results showed that 1) pathogen inactivation was significantly affected by free chlorine concentration (P < 0.0001) and subsecond reaction time (P < 0.0001) and their interactions (P < 0.0001); and 2) the current industry practice of using 1.0 mg/L free chlorine will require more than 1.00 s total contact to achieve a 5-log 10 reduction in an E. coli O157:H7 population, whereas a 10.0 mg/L free chlorine solution will achieve 5-log 10 reduction in as little as 0.25 s. Information obtained from this study will provide critical insight on kinetics of bacterial inactivation for a broad range of sanitizers and produce wash operational conditions, thus facilitating the development and implementation of science-based food safety regulations and practices for improving food safety. [ABSTRACT FROM AUTHOR]

Physics and chemistry underpinned the remarkable advances in materials science that occurred during the 20th century, while biology is poised to provide the scientific underpinning for materials science advances of the 21st century. Biofabrication is the emerging approach to broadly apply biology's materials and mechanisms to create structure and function. Here, we describe one such biofabrication methodology, the use of tyrosinase to graft phenolics to the aminopolysaccharide chitosan. Phenolics are a broad class of abundant natural products and we provide results from a single phenolic reactant, caffeic acid, to illustrate the potential for enzymatically imparting functional properties to chitosan. We show that tyrosinase oxidation mediates the grafting of caffeic acid to chitosan and possibly even results in the covalent crosslinking of chitosan. When this enzymatic reaction is performed in a chitosan solution (pH<6), it is observed to induce a sol-gel transition. At higher pHs, chitosan forms an insoluble film and this enzymatic reaction can alter the film's mechanical properties. Importantly, caffeic acid grafting also confers redox-activity to the chitosan film, enabling the film to accept, store and donate electrons. The broader efforts to enlist tyrosinase to build macromolecular structures and impart functions are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Recently, food safety application of microfluidic device has drawn increasing attentions, whereas the research in this field is still limited due to the complexity of food systems. Most of immunosensor technology has endeavored to improve the sensitivity of the assay. However, the major challenges in food allergen detection are to simplify detection by creating a device with both rapid and broaden detection range from threshold to the real-world concentration. In this work, an ELISA-based colorimetric detection of allergen in food systems was achieved using microfluidic device and regular optical microscope. Casein, the major allergen in milk, was selected as a model analyte. The results indicated that the device was superior to the traditional method and substantially simplified the allergen detection, by demonstrating rapid detection, wide detection range from threshold to real-world concentration. The total detection time was reduced substantially from 45min to 15min without diminishing the detection limit. The linear detection range of antigen was also increased by 5-log difference. Moreover, this study also investigated the mechanism and kinetic study of TMB in-channel oxidation, and established a protocol to determine microfluidic channel size and TMB incubation time for allergen detection in food systems. Therefore, this work not only demonstrated the capability and superiority of microfluidic device for food safety application, but also provided a general optimization method for rapid allergen detection in food systems. [Copyright &y& Elsevier]

Abstract: The current use of silver is limited to certain medical applications owing to two major toxicity concerns, namely low haemocompatibility and silver release-induced skin discoloration, both of which have been attributed to the interaction between silver and blood cysteine. To address these challenges, in this study silver/protein nanocomposites were prepared using α-lactalbumin (ALA), a high-cysteine protein. The effect of the cysteine redox state of ALA on physicochemical characteristics was evaluated, and the nanocomposites were formed by Ag–S or Ag–N coordination bonds and electrostatic attractions. The optimum balance between antimicrobial efficacy and toxicity was achieved by treating freshly prepared silver and reduced ALA (ALAred) nanocomposite with ultraviolet radiation, which resulted in a dramatic reduction in toxicity and maintenance of antimicrobial activity. We anticipate that these promising results may have a great impact on broadening the clinical application of silver-based antimicrobial agents. [Copyright &y& Elsevier]

Abstract: Chitosan (CS) nanoparticles coated with zein has been newly demonstrated as a promising encapsulation and delivery system for hydrophilic nutrient with enhanced bioactivities in our previous study. In this study, a hydrophobic nutrient, α-tocopherol (TOC), was successfully encapsulated into zein/CS complex. The fabrication parameters, including zein concentration, zein/CS weight ratio, and TOC loading percentage, were systematically investigated. The physicochemical and structural analysis showed that the electrostatic interactions and hydrogen bonds were major forces responsible for complex formation. The scanning electron microscopy study revealed the spherical nature with smooth surface of complex. TOC encapsulation was also evidenced by differential scanning calorimetry. The particle size and zeta potential of the complex varied from 200 to 800nm and +22.8 to +40.9mV, respectively. The kinetic release profile of the TOC showed burst effect followed by slow release. Compared with zein nanoparticles, zein/CS complex provided better protection of TOC release against gastrointestinal conditions, due to CS coatings. Zein/CS complex is believed to be a promising delivery system for supplementation or treatment of hydrophobic nutrients or drugs. [Copyright &y& Elsevier]

Abstract: Five pH levels were experimented to study their effect on zein structural, rheological, and antioxidant properties. Structural changes, including secondary structures, surface charge, molecular weight, particle size distribution, and morphology were evaluated using a spectrum of instruments. Zein rheology, including the viscosity and viscoelastic property, was examined by a rheometer. The antioxidant efficacy was determined by measuring the scavenging activity of 1,1-diphenyl-2-picrylhydrazyl free radical and the reducing power of 1,10-phenanthroline-iron with a spectrophotometer. Results indicated that under proper acidic or basic conditions, zein structures, rheological behaviour, and antioxidant properties changed significantly. Decreased contents for α-helix, β-sheet, and β-turn were detected by the Fourier transform infrared spectroscopy for zein samples at acidic and basic conditions comparing to those in a near neutral condition, which were attributed to the deamidation of glutamine to glutamic acid/glutamate in zein. However, no obvious zein fragmentation or oligomerization was detected by the sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The mild deamidation without fragmentation led to a decreased viscosity and an improved antioxidant property of zein. Modified rheological behaviour and enhanced antioxidant properties resulting from a pH treatment may facilitate novel application development of zein in food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Abstract: The selenite-loaded chitosan (CS) nanoparticles using tripolyphosphate (TPP) as a cross-linking agent with or without zein (a water insoluble corn protein) coating were prepared to obtain selenite supplement formulations with low toxicity and improved antioxidant property. Scanning electron microscopy observation showed selenite-loaded CS/TPP nanoparticles had a spherical shape with uniform diameter (100–300nm). The results demonstrated that particle size, surface charge, encapsulation efficiency, and release profile could be modulated by fabricating conditions. After coated with zein, the particle size maintained nanoscale (200–400nm) while encapsulation efficiency increased from 60% to 95%. The release profile was also prominently improved with zein coating, the released selenite reduced from 85% to 30% within 4h in PBS. In simulated gastrointestinal condition with enzymes, 93% of selenite released from non-coated CS/TPP nanoparticles into gastric fluid, however, the releasing rate decreased to 46% after coated with zein. Moreover, due to high antioxidant activity of CS, the in vitro antioxidant properties of selenite-loaded CS/TPP nanoparticles were significantly enhanced, compared with pure selenite. [ABSTRACT FROM AUTHOR]

Why was the work done: Diastatic variants of Saccharomyces cerevisiae are unusual in producing an extracellular glucoamylase which enables the breakdown of starch to fermentable sugars. Diastatic S. cerevisiae has long been viewed negatively as a contaminant of especially beer packaged in cans or bottles. However, this view is being reconsidered due to the opportunities that diastatic strains present for niche fermented products and distillation applications. What are the main findings: This review highlights the utilisation of diastatic S. cerevisiae for its flavour potential, and processing applications in the brewing, distilling, and biofuel industries. Further, genetic differences are compared with non-diastatic strains of S. cerevisiae, together with commonly employed and emerging methods of detection. Why is the work important: Diastatic yeast strains can be used to create flavour profiles that resemble traditional beverages and can be used to achieve fermentation with higher attenuation. This offers greater fermentation efficiency in, for example, the development of low-calorie beers. Additionally, the ability of diastatic strains of S. cerevisiae to convert non-fermentable oligosaccharides to fermentable sugars enables applications that range from novel beverages using unusual raw materials to more efficient distillation and biofuel production. The negative attributes that are associated with diastatic S. cerevisiae yeasts can be managed through co-inoculation or hybridisation with standard strains. [ABSTRACT FROM AUTHOR]

Belgian Saisons and Lambics are two well‐known examples in the brewing industry of mixed fermentations, combination of two or more yeast and/or bacteria strains. The purpose of this study was to determine the impact different pitch rates of Saccharomyces cerevisiae (traditional brewing yeast) and S. cerevisiae var. diastaticus (a variant associated with Belgian styles) had on the fermentation kinetics and concentration of the volatile compounds in the finished beers. A series of brews were performed utilizing ratios of S. cerevisiae and diastaticus. The fermentations were heavily monitored, and a model was used to fit fermentation variables. It was found that mixed fermentations produced behaviors that were predictable and proportional to the mixture ratios. As expected, the pure cultural fermentations of diastaticus had a slower fermentation midpoint (M) at 45.45 h versus 28.28 h for S. cerevisiae with the mixed ones falling in between the two. Flavor and aroma play a key role in the acceptability of beer. The mixed fermentations showed a combination of the two different yeast strains aromatic profiles. When combined, there was a strong linearity between alcohols (R2 = 0.94), esters (R2 = 0.89), and the overall total (R2 = 0.91) volatile compounds. Practical Application: Modeling is a widely utilized tool in several different fields. The purpose of this research is to apply modeling techniques to describe the fermentation speed and flavor profile of a mixed fermentation between S. cerevisiae and diastaticus. The equations from this data can be used by brewers for product development purposes to make beers with certain flavor profiles within a desired timeframe. [ABSTRACT FROM AUTHOR]

Romaine lettuce in the U.S. is primarily grown in California or Arizona and either processed near the growing regions (source processing) or transported long distance for processing in facilities serving distant markets (forward processing). Recurring outbreaks of Escherichia coli O157:H7 implicating romaine lettuce in recent years, which sometimes exhibited patterns of case clustering in Northeast and Midwest, have raised industry concerns over the potential impact of forward processing on romaine lettuce food safety and quality. In this study, freshly harvested romaine lettuce from a commercial field destined for both forward and source processing channels was tracked from farm to processing facility in two separate trials. Whole-head romaine lettuce and packaged fresh-cut products were collected from both forward and source facilities for microbiological and product quality analyses. High-throughput amplicon sequencing targeting16S rRNA gene was performed to describe shifts in lettuce microbiota. Total aerobic bacteria and coliform counts on whole-head lettuce and on fresh-cut lettuce at different storage times were significantly (p < 0.05) higher for those from the forward processing facility than those from the source processing facility. Microbiota on whole-head lettuce and on fresh-cut lettuce showed differential shifting after lettuce being subjected to source or forward processing, and after product storage. Consistent with the length of pre-processing delays between harvest and processing, the lettuce quality scores of source-processed romaine lettuce, especially at late stages of 2-week storage, was significantly higher than of forward-processed product (p < 0.05). • Romaine lettuce from local (source) and remote (forward) processing chains were tracked and tested. • Forward-processed lettuce had higher microbial loads than source-processed product. • Quality score of fresh-cut lettuce in cold storage declined with delayed processing. • A shift in microbiota was detected between source and forward-processed lettuce. [ABSTRACT FROM AUTHOR]

The requirement of a large input amount (500 ng) for Nanopore direct RNA‐seq presents a major challenge for low input transcriptomic analysis and early pathogen surveillance. The high RNA input requirement is attributed to significant sample loss associated with library preparation using solid‐phase reversible immobilization (SPRI) beads. A novel solid‐phase catalysis strategy for RNA library preparation to circumvent the need for SPRI bead purification to remove enzymes is reported here. This new approach leverages concurrent processing of non‐polyadenylated transcripts with immobilized poly(A) polymerase and T4 DNA ligase, followed by directly loading the prepared library onto a flow cell. Whole transcriptome sequencing, using a human pathogen Listeria monocytogenes as a model, demonstrates this new method displays little sample loss, takes much less time, and generates higher sequencing throughput correlated with reduced nanopore fouling compared to the current library preparation for 500 ng input. Consequently, this approach enables Nanopore low‐input direct RNA‐seq, improving pathogen detection and transcript identification in a microbial community standard with spike‐in transcript controls. Besides, as evident in the bioinformatic analysis, the new method provides accurate RNA consensus with high fidelity and identifies higher numbers of expressed genes for both high and low input RNA amounts. [ABSTRACT FROM AUTHOR]

The foodborne pathogen Listeria monocytogenes (L. monocytogenes) can form very persistent biofilms on food contact substances, either in monospecies, or in conjunction with background microflora. Although some studies have investigated how bacterial symbiosis facilitates L. monocytogenes survival in complex cocktail biofilms, very little is known about how this core symbiotic relationship is affected by environmental factors. Here, we investigate how L. monocytogenes persistence is affected by symbiosis with Escherichia coli O157:H7, Pseudomonas fluorescens , and Ralstonia insidiosa , and how these relationships are impacted by environmental factors, including food contact surface topography and chemistry, and microbial nutrition. We find that symbiosis can significantly enhance L. monocytogenes persistence in four-species cocktail biofilms (5.71 ± 0.03 Log CFU/cm2) by up to 1.9 Log CFU/cm2 compared to monospecies biofilms (3.81 ± 0.08 Log CFU/cm2). We also report that surface topography and chemistry, microbial nutrition, and symbiont species significantly impact the symbiotic relationships involving L. monocytogenes , revealing the adaptability of bacterial symbiosis to changing environmental conditions and the complex nature of cocktail pathogen biofilms. Antagonistic and synergistic interactions involving pathogens in cocktail biofilms, and factors affecting those interactions, are elucidated and can establish a foundation to study symbiosis and its role in mitigating pathogen persistence in food systems, and helping identify unanticipated increased food safety risks of pathogens due to enhanced persistence. • L. monocytogenes biofilm is affected by symbiosis with background microflora. • Symbiosis in a biofilm is affected by surface, nutrition, and symbiont species. • P. fluorescens shows synergies with L. monocytogenes in biofilm formation. • E. coli O157:H7 and R. insidiosa show changing symbiosis with L. monocytogenes. • Leveraging biofilm symbiosis mitigates synergisms or facilitates antagonisms against pathogens. [ABSTRACT FROM AUTHOR]

Biohazards, which may occur at all supply chain stages, pose significant threats to food safety and public health. Addressing these concerns and enhancing food safety necessitates a nondestructive pathogen surveillance approach capable of continuously and simultaneously detecting multiple pathogens. Detecting and differentiating low concentrations of pathogenic bacteria amid high background microflora levels in foods is challenging, requiring technology with high sensitivity and robust discriminatory capability. This study introduces an artificial neural network-driven paper chromogenic array sensor (ANN-PCA) technique developed for the nondestructive, continuous, and simultaneous detection of Salmonella Enteritidis (SE) and Escherichia coli O157:H7 (Ec) from a high background microflora in shredded cheddar cheese. This method enables accurate detection of SE and Ec in monoculture and cocktail culture while distinguishing them from a high level of background microflora (∼7.5 log CFU/g), with accuracies ranging from 72 ± 11% to 92 ± 3%. In addition, SE and Ec were successfully identified at concentrations as low as 1 log CFU/g within one day, with an accuracy of 72 ± 11%. This approach exhibits promising potential for integration into a digitalized, smart, and resilient nondestructive surveillance system for real-time pathogen detection in foods throughout the supply chain without enrichment, incubation, or other sample preparation steps. [Display omitted] • Development of a machine learning-driven paper chromogenic array sensor approach. • Non-destructive, continuous, and simultaneous detection of multiple pathogens. • Detection of pathogenic bacteria from a high level of background microflora. • The approach provided potential detection for pathogens throughout the food supply chain. [ABSTRACT FROM AUTHOR]

Global food systems can benefit significantly from continuous monitoring of microbial food safety, a task for which tedious operations, destructive sampling, and the inability to monitor multiple pathogens remain challenging. This study reports significant improvements to a paper chromogenic array sensor - machine learning (PCA-ML) methodology sensing concentrations of volatile organic compounds (VOCs) emitted on a species-specific basis by pathogens by streamlining dye selection, sensor fabrication, database construction, and machine learning and validation. This approach enables noncontact, time-dependent, simultaneous monitoring of multiple pathogens (Listeria monocytogenes , Salmonella , and E. coli O157:H7) at levels as low as 1 log CFU/g with over 90% accuracy. The report provides theoretical and practical frameworks demonstrating that chromogenic response, including limits of detection, depends on time integrals of VOC concentrations. The paper also discusses the potential for implementing PCA-ML in the food supply chain for different food matrices and pathogens, with species- and strain-specific identification. [ABSTRACT FROM AUTHOR]

This study aimed to develop self-assembled gelatin-chitosan (Gel-CS) nanocapsules as a water-soluble delivery system for alcohol-soluble compounds. Eugenol (Eug) selected as the model molecule for its high solubility in alcohol and insolubility in water. The study also examined different reaction conditions and reagent loading ratios to optimize eugenol-embedded gelatin-chitosan nanocapsules (Eug-Gel-CS NPs) formation. The optimal loading ratio of Gel, CS, and Eug was 3:1:2, which yielded an average particle size of 229.09 nm and an encapsulation efficiency of 50.69%. The morphological characteristics of Eug-Gel-CS NPs were further demonstrated by transmission electron microscopy. The prepared Eug-Gel-CS NPs also exhibited potential controlled-release properties in aqueous phase with the in vitro release percentage of 69.47 ± 1.24% over 36 h. This nanocapsule system may provide a platform to expand the potential applications of Eug in food and nutrition. [ABSTRACT FROM AUTHOR]

Abstract Battling meat adulteration is essential in preserving both public health and a fair market. This study depicts a method of reducing adulteration in meats, in which Electronic-nose (E-nose) and gas chromatography-mass spectrometer (GC-MS) were applied to identify adulterants in mutton. Duck meat was selected as a model adulterant due to its lower cost and similarity in flavor to mutton, as well as being frequently adulterated in China. Qualitative and quantitative analysis were conducted using linear regression, fisher linear discriminant analysis (FLDA), and multilayer perceptron neural networks analysis (MLPN) on E-nose signals. Several fingerprint volatile organic chemicals (VOC) were identified by GC-MS to validate the E-nose results. Multivariate partial least square regression (PLS) was carried out to study the relationships between GC-MS and E-nose. The results of GC-MS confirmed that E-nose can be used to identify duck adulteration in mutton, with a minimum detection ratio of 10%. This method proved that rapid detection of mutton adulterated duck meat using E-nose has a high accuracy, which has reduced detecting time and improved detection efficiency. Highlights • E-nose and GC-MS can be used to identify duck adulteration in mutton. • Detection of mutton adulterated duck meat using E-nose has a high accuracy. • E-nose detection was coupled with statistical analysis (MLPN, FLDA, PLS and LDA) for modeling. • E-nose can be used to identify duck adulteration in mutton, with a minimum detection ratio of 10%. [ABSTRACT FROM AUTHOR]

Abstract The increasing demand for safety and quality in food products has stimulated research on developing natural preservatives and their carrier systems as a novel preventive control strategy. In this study, metal-organic framework (MOF) was investigated, for the first time, as a carrier for volatile antimicrobial essential oils. Zinc metal-organic framework (Zn@MOF) was synthesized with zinc nitrate hexahydrate and 2-aminoterephthalic acid in N, N-dimethylformamide (DMF). Thymol was then loaded into the Zn@MOF at a loading rate of 3.96% as measured by thermogravimetric analysis (TGA). The crystal structure of porous MOF was confirmed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Antibacterial activity of thymol loaded Zn@MOF (T-Zn@MOF) with active thymol loading of 0.029 g/100 g was assessed against a three-strain cocktail of E. coli O157:H7 in a tryptic soy broth (TSB). E. coli O157:H7 growth in T-Zn@MOF exhibited growth inhibition without an exponential growth phase after 24 h of incubation, which could be attributed to the sustained release of thymol by incorporating it in the porous Zn@MOF through noncovalent interactions. This research demonstrates that Zn@MOF loaded with the essential oil thymol is an effective antimicrobial and may have potential indirect applications in food. Highlights • Metal-organic framework (MOF) was investigated for food safety application. • Antimicrobial essential oil, thymol, was selected as a model bioactive substance. • Zn@MOF was synthesized and characterized with a thymol loading at 3.96%. • Thymol loaded MOF showed promising antimicrobial activity against E. coli O157:H7. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Small immune magnetic particles with diameter of ∼12 nm were fabricated. • The specific surface area of immune magnetic particles was 96.5 m2/g. • The distribution of antibody on the surface of magnetic particles was 25.8 μg/m2. • More than 3 × 108 of E. coli cells can be collected by 1 mg magnetic particles. • The QS signal was amplified ∼3 times than nature QS signal at total cell OD 0.08. Abstract Quorum sensing (QS) enables intercellular communication after bacterial cells sense the autoinducers have reached or exceeded a critical concentration. Selectively amplifying specific bacterial "quorum" activity at a lower cell density is still a challenge. Here, we propose a novel platform of immune magnetic nano-assembly to amplify specific bacterial QS signaling via improving the bioavailability of autoinducers-2 (AI-2, furanosyl borate) from sender (wide-type, WT cells) to receiver (reporter cells). Antibody coated magnetic nanoparticle (MNPAB) was fabricated with an average diameter of 12 nm and a specific surface area of 96.5 m2/g. The distribution efficiency of the antibody on the surface was 25.8 μg/m2 of magnetic nanoparticles. It was found that more than 3 × 108 of K12 serotype Escherichia coli (E. coli) reporter or WT cells were collected using 1 mg fabricated MNPAB at a saturated condition. The MNPAB not only captured E. coli WT cells but also brought them into proximity of E. coli (CT104, pCT6+pET-DsRed) reporter cells via magnetic attraction. The amplified QS signaling of the reporter cells by this immune magnetic nano-assembly was approximately 3 times higher than the nature QS signaling in cell suspension at optical density (OD) 0.08. This study foresees potential applications in amplifying specific biological QS signals based on a preprogrammed design. [ABSTRACT FROM AUTHOR]

Abstract Preservatives in processed meat raise significant concerns associated with bowel cancer and diabetes, and implicate various public health issues. This introduces the need for safer preservatives to uphold public health standards. However, developing safer alternatives to these preservatives poses a significant challenge to food industry. A potential solution to this issue is the use of loaded nanoparticles as preservative agents. This study investigated antimicrobial and antioxidant effects of sorbic acid-loaded chitosan/tripolyphosphate nanoparticles (SAN) in Chinese Sausage. SAN were prepared through ionic gelation, followed by natural air-drying for 20 days. After preparation, the antimicrobial and antioxidant activities of various treatment groups were analyzed intermittently during storage at room temperature. SAN-treated samples had significantly lower levels of surviving bacteria, molds, and yeasts than the blank control (p < 0.05) over the entire 72 days of storage. Additionally the SAN-treated samples also had lower levels of surviving bacteria than the chitosan/tripolyphosphate samples after 31–56 days of storage (p < 0.05). The thiobarbituric acid value and pH of the SAN-treated samples were also significantly lower than the blank control (p < 0.05). These results indicated that SAN could be a good intervention strategy to retard lipid oxidation and inhibit microbial growth in Chinese Sausage. Highlights • SAN were developed as alternatives to carcinogenic preservatives in processed meat products for the first time. • Chinese sausage was selected in evaluation of antimicrobial and antioxidant activities of SAN. • SAN exhibits superior activities to retard lipid oxidation and inhibit microbial growth in processed meat. [ABSTRACT FROM AUTHOR]

Summary: Quorum sensing (QS) exists widely among bacteria, enabling a transition to multicellular behaviour after bacterial populations reach a particular density. The coordination of multicellularity enables biotechnological application, dissolution of biofilms, coordination of virulence, and so forth. Here, a method to elicit and subsequently disperse multicellular behaviour among QS‐negative cells is developed using magnetic nanoparticle assembly. We fabricated magnetic nanoparticles (MNPs, ∼5 nm) that electrostatically collect wild‐type (WT) Escherichia coli BL21 cells and brings them into proximity of bioengineered E. coli [CT104 (W3110 lsrFG− luxS− pCT6 + pET‐DsRed)] reporter cells that exhibit a QS response after receiving autoinducer‐2 (AI‐2). By shortening the distance between WT and reporter cells (e.g., increasing local available AI‐2 concentrations), the QS response signalling was amplified four‐fold compared to that in native conditions without assembly. This study suggests potential applications in facilitating intercellular communication and modulating multicellular behaviours based on user‐specified designs. [ABSTRACT FROM AUTHOR]

Determining the minimal effective free chlorine (FC) concentration for preventing pathogen survival and cross-contamination during produce washing is critical for developing science- and risk-based food safety practices. The correlation between dynamic FC concentrations and bacterial survival was investigated during commercial washing of chopped Romaine lettuce, shredded Iceberg lettuce, and diced cabbage as pathogen inoculation study during commercial operation is not feasible. Wash water was sampled every 30 min and assayed for organic loading, FC, and total aerobic mesophilic bacteria after chlorine neutralization. Water turbidity, chemical oxygen demand, and total dissolved solids increased significantly over time, with more rapid increases in diced cabbage water. Combined chlorine increased consistently while FC fluctuated in response to rates of chlorine dosing, product loading, and water replenishment. Total bacterial survival showed a strong correlation with real-time FC concentration. Under approximately 10 mg/L, increasing FC significantly reduced the frequency and population of surviving bacteria detected. Increasing FC further resulted in the reduction of the aerobic plate count to below the detection limit (50 CFU/100 mL), except for a few sporadic positive samples with low cell counts. This study confirms that maintaining at least 10 mg/L FC in wash water strongly reduced the likelihood of bacterial survival and thus potential cross contamination of washed produce. [ABSTRACT FROM AUTHOR]

Chlorine, the most commonly used sanitizer for fresh produce washing, has constantly shown inferior sanitizing efficacy in the presence of organic load. Conventionally this is attributed indirectly to the rapid chlorine depletion by organics leading to fluctuating free chlorine (FC) contents. However, little is known on whether organic load affects the sanitization process directly at well-maintained FC levels. Hereby, a sustained chlorine decay approach was employed to study the inactivation of Escherichia coli O157:H7 under stabilized washing conditions. Chlorine solution was first incubated with organic load for up to 4 h, modeling the chlorination in produce washing lines. The FC level was then stabilized at five targeted values for sanitization study. Our study showed decreased sanitizing efficacy as the organic load increased. At 5 s residence time and pH 6.5, a minimum of 0.5 and 7.5 mg/L FC were needed to achieve a 5 log reduction at 0 and 900 mg/L chemical oxygen demand (COD), respectively. The decrease was more pronounced at lower FC, higher COD, higher pH, and shorter residence time values. The organics-associated interference with FC measurement and disruption of chlorine/bacteria interaction, together with the chlorine demand of concentrated inoculum per se, collectively resulted in inadequate sanitization. Finally, our results were compared with existing studies conducted under dynamic conditions in the context of different experimental settings. This study provided a feasible method for studying the bacteria/sanitizer interaction while ruling out the confounding effect from fluctuating FC levels, and it indicated the direct, negative impact of organic load. [ABSTRACT FROM AUTHOR]

[Display omitted] • Paper chromogenic array (PCA) integrated with machine learning (ML) was developed. • PCA exhibit distinguishable pattern shifts when reacting volatile metabolites. • PCA pattern recognition achieved using a cross-validated neural network. • PCA accurately identify multiplexed pathogens from indigenous microflora. • The nondestructive PCA-ML holds great potential as a smart food safety system. Non-destructive detection of human foodborne pathogens is critical to ensuring food safety and public health. Here, we report a new method using a paper chromogenic array coupled with a machine learning neural network (PCA-NN) to detect viable pathogens in the presence of background microflora and spoilage microbe in seafood via volatile organic compounds sensing. Morganella morganii and Shewanella putrefaciens were used as the model pathogen and spoilage bacteria. The study evaluated microbial detection in monoculture and cocktail multiplex detection. The accuracy of PCA-NN detection was first assessed on standard media and later validated on cod and salmon as real seafood models with pathogenic and spoilage bacteria, as well as background microflora. In this study PCA-NN method successfully identified pathogenic microorganisms from microflora with or without the prevalent spoilage microbe, Shewanella putrefaciens in seafood, with accuracies ranging from 90% to 99%. This approach has the potential to advance smart packaging by achieving nondestructive pathogen surveillance on food without enrichment, incubation, or other sample preparation. [ABSTRACT FROM AUTHOR]

In this research, winter jujubes were treated with X-ray doses of 0, 0.3, 0.5 kGy and stored at 0 °C. Then jujubes from early (day 0) and late (day 60) storage were transferred to 20 ± 1 °C and qualities were evaluated every 3 days to explore the preservation effect of X-ray. Results indicated that 0.3 kGy X-ray inhibited the jujube decay by preventing 8.20% of fungal and 29.12% of aerobic bacterial growth. The pectin decomposition was prevented (0.21% on day 60), softening was alleviated, and reddening was delayed for 5 days correspondingly. Microscopic observation validated the integrity of the treated jujube tissue. Furthermore, the highest inhibition rates of 0.3 kGy X-ray on the activities of polygalacturonase (PG), cellulase and β-glucosidase (β-Glu) were 47.32%, 74.71% and 68.00%, respectively. Research demonstrated X-ray's potential in winter jujube preservation, which can provide a solid theoretical reference for the development and industrial application. • 0.3 kGy X-ray extends the shelf-life of winter jujube stored at room temperature to 12 days. • 0.3 kGy X-ray inhibits 8.20% of fungal and 29.12% of aerobic bacterial growth. • 0.3 kGy X-ray decreases the activities of polygalacturonase (PG), cellulase and β-glucosidase (β-Glu) by 47.32%, 74.71% and 68.00%, respectively. • Winter jujube discoloration is positively correlated with softening decreases. [ABSTRACT FROM AUTHOR]

A novel nanocomposite of silver/titanium dioxide/chitosan adipate (Ag/TiO 2 /CS) was developed through photochemical reduction using a chitosan adipate template. Chitosan served as a reducing agent anchoring the metal ions through Ag–N coordination bonds and electrostatic attractions, thus stabilizing the Ag/TiO 2 /CS product observed by Fourier transform infrared spectroscopy and X-ray diffraction patterns. Scanning electron microscopy observations revealed that the nanocomposite particles (50–100 nm) were deposited onto the chitosan adipate layer. The product exhibited high ζ-potentials from 30.1 mV to 33.0 mV during 60 days of storage. In addition, the nanocomposite demonstrated higher antimicrobial activity than AgNO 3 or nano-Ag particles at similar concentrations, as evidenced by the inhibition zone, minimum inhibitory concentrations (MIC), and growth curve. The nanocomposite reduced the Escherichia coli population by 6 logs after 24 h of incubation, and had an MIC value of 0.38 μg Ag/mL. These results suggest that Ag/TiO 2 /CS has the potential to be used as an antibacterial protective coating for fruit storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Long term effect of thymol chitosan nanoparticles (TMO-CSNPs) were evaluated in the preservation of chestnut quality. • TMO-CSNPs reduce the loss of soluble sugar and starch by limiting the chestnut's metabolism. • TMO-CSNPs can significantly inhibit the growth of molds and yeasts during the storage. • TMO-CSNPs prolong the storage time of the chestnuts by inhibiting spoilage. Thymol (TMO) was loaded into chitosan nanoparticles (CSNPs) to inhibit chestnuts decay during storage. Three chestnut treatments were evaluated, including the CK (uncoated control), CSNPs (coated with chitosan nanoparticles), and TMO-CSNPs (coated with thymol-loaded chitosan nanoparticles). Quality assessments of chestnuts were conducted periodically for up to 180 days, which included starch content, amylase activity, water content, respiration rate, weight loss rate, microbiological indicators, decay rate, and quality evaluation. Results indicated that TMO-CSNPs had significantly less nutrient loss in soluble sugar (10.61%) and starch content (27.72%) compared with CK, which was attributed to low metabolic activities as evident in low amylase activity and respiration rate. Moreover, TMO-CSNPs significantly inhibited the growth of mold and yeast (4.17 log CFU g−1 on day 180) and kept the lowest decay rate (5.33%). This study demonstrates the potential of food nanomaterial as an alternative strategy to promote food security and supply chain resilience. [ABSTRACT FROM AUTHOR]

Sensor-based chemical analyses commonly enlist either the molecular recognition capabilities of biology (e.g., enzyme biosensors) or advanced information processing algorithms (e.g., the electronic nose). Here, a hybrid approach is proposed in which an enzyme is used to 'filter' chemical information and write this information to a film which then serves as a permanent storage medium that can be 'read' repeatedly, interactively, and by multiple sensor modalities. This approach is demonstrated by analyzing common dietary phenols that are reported to offer health benefits. Specifically, the enzyme tyrosinase is used to convert these phenols into reactive quinones that graft (i.e., write) to a chitosan film. Grafting can be detected by optical, mechanical, and electrochemical sensors. Importantly, grafting confers redox activity to the films and this redox activity can be probed interactively by advanced electrochemical methods that allow the intrinsic redox reactivities to be compared, redox interactions to be identified, and biologically relevant redox activities to be examined. The transfer of chemical and biological information to a film is envisioned to provide broader access to the extensive capabilities offered by sensor technologies and signal processing methodologies. [ABSTRACT FROM AUTHOR]

Cationicβ-lactoglobulin (CBLG) was developed as a bioavailabilityenhancer for poorly absorbed bioactives. At most 11 anionic aminoacid residues of β-lactoglobulin (BLG) were substituted by ethylenediamine(EDA), resulting in a highly positive surface charge (zeta potentialup to 39 mV at pH 7.0) and significantly increased surface hydrophobicity.These changes conferred CBLG with desirable water solubility and improvedmucoadhesion by at most 252%, according to quartz crystal microbalance(QCM) study. Furthermore, CBLG inherited the unique resistance togastric digestion from BLG, while the digestion under simulated intestinalcondition was significantly improved. The latter was possibly dueto the formation of aspartic acid-EDA conjugates, together with therandomization of protein conformation related with decreased percentageof β-sheet. Compared to BLG, CBLG formed smaller (75–94nm), more uniform nanoparticles by the acetone-desolvation method.These merits made CBLG a useful material that provides desirable solubility,controlled release, and enhanced absorption to nutraceuticals or drugs. [ABSTRACT FROM AUTHOR]

The opportunistic pathogen Pseudomonas aeruginosa (P. aeruginosa) is associated gastrointestinal (GI) inflammation and illness; however, factors motivating commensal-to-pathogen transition are unclear. Excessive zinc intake from supplements is common in humans. Due to the fact that zinc exposure enhances P. aeruginosa colonization in vitro, we hypothesized zinc exposure broadly activates virulence mechanisms, leading to inflammation and illness. P. aeruginosa was treated with excess zinc and growth, expression and secretion of key virulence factors, and biofilm production were determined. Effects on invasion, barrier function, and cytotoxicity were evaluated in Caco-2 cells co-cultured with P. aeruginosa pre-treated with zinc. Effects on colonization, mucosal pathology, inflammation, and illness were evaluated in mice infected with P. aeruginosa pre-treated with zinc. We found the expression and secretion of key virulence factors involved in quorum sensing (QS), motility (type IV pili, flagella), biosurfactants (rhamnolipids), toxins (exotoxin A), zinc homeostasis (CzcR), and biofilm production, were all significantly increased. Zinc exposure significantly increased P. aeruginosa invasion, permeability and cytotoxicity in Caco-2 cells, and enhanced colonization, inflammation, mucosal damage, and illness in mice. Excess zinc exposure has broad effects on key virulence mechanisms promoting commensal-to-pathogen transition of P. aeruginosa and illness in mice, suggesting excess zinc intake may have adverse effects on GI health in humans. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes (L. monocytogenes) biofilm formation on food-contact surfaces is a significant food safety concern. However, research on the ability of contact surfaces to resist fouling by L. monocytogenes biofilm is limited. With the objective of assessing the combined effects of substrate topography and coating composition on L. monocytogenes biofilm formation, we used stainless steel 304 with three surface topographies (native finish, #4 commercial brushed finish, and native finish with microfabricated pillars developed by a new process), in each case either uncoated or coated with one of five FDA-approved food-contact substances (chromium nitride, titanium nitride, Dursan, Ni–P-polytetrafluoroethylene (Ni–P-PTFE), and Lectrofluor 641). Results indicate that surface topography and composition significantly affected fouling resistance. Significant enhancement of resistance to L. monocytogenes fouling was observed on native finish coated by Ni–P-PTFE, which reduced L. monocytogenes by 1.5 Log CFU/cm2. Coating the brushed finish with Ni–P-PTFE, Lectrofluor 641, or Dursan reduced L. monocytogenes fouling by 0.5, 0.4, and 0.9 Log CFU/cm2, respectively. The greatest reductions in L. monocytogenes biofilm formation were obtained with Dursan coated on the native finish (3.4 Log CFU/cm2) and on the micropillar-modified native finish (2.8 Log CFU/cm2). The combined variation of substrate topography modification and coating composition provides a new approach to enhance fouling resistance of stainless steel against L. monocytogenes biofilm for improved sanitary design of food processing equipment. • Nonfouling enhancement of stainless steel against Listeria monocytogenes biofilm. • Combination of topography modification and food contact substances (FCS) coating. • Dursan coating demonstrates the strikingly good fouling-resistant effect. • The new strategy can be applied for improved food processing equipment design. [ABSTRACT FROM AUTHOR]

Zein is a corn prolamin that has broad industrial applicationsbecause of its unique physical properties. Currently, the high costof extraction and purification, which is directly related to the dispersionof zein in different solvents, is the major bottleneck of the zeinindustry. Solution behaviors of zein have been studied for a longtime. However, the physical nature of zein in different solvents remainsunclear. In this study, small-angle X-ray scattering (SAXS), staticlight scattering (SLS), and rheology were combined to study the structureand protein–solvent interaction of α-zein in both aceticacid and aqueous ethanol solutions. We found that the like-dissolve-likerule, the partial unfolding, and the protonation of zein are all criticalto understanding the solution behaviors. Zein holds an elongated conformation(i.e., prolate ellipsoid) in all solutions, as revealed from SAXSdata. There is an “aging effect” for zein in aqueousethanol solutions, as evidenced by the transition of Newtonian rheologicalprofiles for fresh zein solutions to the non-Newtonian shear thinningbehavior for zein solutions after storage at room temperature for24 h. Such shear thinning behavior becomes more pronounced for zeinsolutions at higher concentrations. The SLS results clearly show thatacetic acid is a better solvent to dissolve zein than aqueous ethanolsolution, as supported by a more negative second virial coefficient.This is majorly caused by the protonation of the protein, which wasfurther verified by the dissolution of zein in water (a nonsolventfor zein) with the addition of acids. [ABSTRACT FROM AUTHOR]

[Display omitted] • The FPZC is composed of a ZIF-67 encapsulating photothermal cores and carvacrol. • Laser-irradiation rapidly triggers carvacrol release from the developed FPZC. • Photo-triggered release of carvacrol vapor effectively inactivates bacteria. • The developed FPZC achieves a non-contact antibacterial strategy. • The FPZC has recyclability and no safety concerns by nanomaterial migration. Foodborne illness outbreaks have significantly impacted public health. The contact antibacterial nanomaterials may have potential migration of nanomaterials and thus bring safety concerns. In this work, we develop photo-triggered nano-generators for on-demand release of antibacterial essential oil vapor to achieve a non-contact antibacterial strategy between nanomaterials and target bacteria. This photo-triggered nano-generator (Fe 3 O 4 @PDA-COOH@ZIF-67/carvacrol, FPZC) is composed of photothermal Fe 3 O 4 @PDA-COOH cores in a zeolitic imidazolate framework-67 (ZIF-67) shell with loaded antibacterial carvacrol. Briefly, these nano-generators have magnetic transfer and immobilization, photo-thermal conversion, and controlled carvacrol vapor release capacities. Under laser irradiation at wavelength of 808 nm for 60 s, 80 mg FPZC can rapidly release carvacrol vapor to 171.0 μg/L in the air to completely inactivate Staphylococcus aureus and Escherichia coli at initial amount of 5 log CFU. Photo-triggered nano-generators exhibit flexible carvacrol release property, high photo-triggered killing rate (100%), and good recyclability (5 cycles). Compared to conventional contact antibacterial strategy, nano-generators cannot bring safety concerns with potential nanomaterial migration into sterilized material, and therefore provides promise in practical applications especially in food-related sterilization. [ABSTRACT FROM AUTHOR]

We have developed an inexpensive, standardized paper chromogenic array (PCA) integrated with a machine learning approach to accurately identify single pathogens (Listeria monocytogenes , Salmonella Enteritidis, or Escherichia coli O157:H7) or multiple pathogens (either in multiple monocultures, or in a single cocktail culture), in the presence of background microflora on food. Cantaloupe, a commodity with significant volatile organic compound (VOC) emission and large diverse populations of background microflora, was used as the model food. The PCA was fabricated from a paper microarray via photolithography and paper microfluidics, into which 22 chromogenic dye spots were infused and to which three red/green/blue color-standard dots were taped. When exposed to VOCs emitted by pathogens of interest, dye spots exhibited distinguishable color changes and pattern shifts, which were automatically segmented and digitized into a ΔR/ΔG/ΔB database. We developed an advanced deep feedforward neural network with a learning rate scheduler, L 2 regularization, and shortcut connections. After training on the ΔR/ΔG/ΔB database, the network demonstrated excellent performance in identifying pathogens in single monocultures, multiple monocultures, and in cocktail culture, and in distinguishing them from the background signal on cantaloupe, providing accuracy of up to 93% and 91% under ambient and refrigerated conditions, respectively. With its combination of speed, reliability, portability, and low cost, this nondestructive approach holds great potential to significantly advance culture-free pathogen detection and identification on food, and is readily extendable to other food commodities with complex microflora. • A paper chromogenic array (PCA) - machine learning approach was developed to accurately identify multiple pathogens in background microflora. • PCAs, fabricated via photolithography, react with volatile organic compounds to exhibit distinguishable color pattern shifts. • An advanced neural network demonstrated excellent performance with a learning rate schedule, L2 regularization, and shortcut connections. • This nondestructive approach holds great potential to significantly advance culture-free pathogen detection and identification on food. [ABSTRACT FROM AUTHOR]

Retail display of highly perishable foods behind glass doors ensures uniform product temperatures below the FDA Food Code threshold of 5 °C, resulting in better-preserved foods while reducing energy costs. However, only a handful of studies have evaluated the effect of repeated door openings on product temperatures and energy consumption with contrasting reports. In this paper, we evaluated the effects of two frequencies (doors opened every 5 or 15 min) and four durations (doors held ajar for 5, 15, 30 or 60 s) on product simulator temperatures in a display case installed in our research supermarket. At ambient conditions (19.6–20.9 °C, 63% RH), with a case thermostat setting of 0.6 °C and a daily 30-min defrost cycle, the only statistically significant fluctuation in product simulator temperatures was found for the most aggressive opening schedule where the door was opened every 5 min for 60 s at each opening. Pairwise comparisons demonstrated that this treatment resulted in product simulator temperatures (up to 6.6 °C during defrost cycle) that were significantly higher (p < 0.001) or somewhat significantly higher (p < 0.03) compared to product exposed to all other combinations. Product exposed to all other treatment combination resulted in temperatures that either never exceeded 5 °C or briefly exceeded it only during the single 30-min defrost cycle. As a result, we selected an average opening sequence (every 10 min for 12 s) to perform an energy consumption assessment of the case. Energy consumption was determined to be 66% lower than that compared to an open-retail display case (same model, mark, size, operating schedule and thermostat setting). Even with the most extreme schedule where three of the six doors remained open continuously, there was still a measured 45% reduction in energy consumption as compared to that of the open-retail display case. • Enclosed refrigerated display cases support compliance with US Food Code. • Typical door opening regimes do not impact product temperature uniformity in display cases. • Typical door opening regimes still provide significant energy savings compared to an open display case. [ABSTRACT FROM AUTHOR]