Food Safety Testing Research Articles

A label-free electrochemical sensor based on π-structured bipedal DNA walker-triggered hybridization chain reaction and AuPt NPs/Zr-MOF for OTA detection

BackgroundOchratoxin A (OTA) is a serious food contaminant, not easily degradable, and capable of causing irreversible damage to the human body. Therefore, it is of great practical significance to establish a sensitive and efficient OTA detection method. The electrochemical aptasensor has a broad development prospect in OTA detection with its advantages of fast response speed and low cost. ResultsHerein, a cascade signal amplification strategy based on AuPt NPs/Zr-MOF and π-structure bipedal DNA walker-triggered hybridization chain reaction (HCR) was designed for the detection of ochratoxin A (OTA). AuPt NPs/Zr-MOF was employed as the electrode modification material, providing a large number of active sites and high conductivity, achieving 1.47 times signal amplification. Interestingly, bipedal DNA walker binds to hairpin 1 (H1) to form the π-structure. Under the activation of Pb2+, one bipedal DNA walker can simultaneously bind and cleave two H1. It exhibits a wide walking range and high recognition efficiency. After H1 is cleaved, the trigger sequence was exposed to trigger HCR and a large amount of methylene blue was loaded on the electrode. Under the optimal conditions, the linear range of the determined OTA is 1 × 10−3–500 ng/mL, and the limit of detection is as low as 0.525 pg/mL. SignificanceThe experimental results demonstrate that the constructed electrochemical aptasensor is a sensitive and efficient platform for OTA monitoring. The applicability in food samples was also confirmed, and the strategy was efficiently selective and reproducible for different analytes. This provides ideas for subsequent food safety testing.

Contact-electro-luminescence triggered by triboelectric charge

Luminol, a prominent chemiluminescent reagent, is extensively employed in biochemical and environmental analyses for its ability to produce rapid luminescence through oxidation in aqueous solutions. However, the lack of comprehensive studies on the observation and regulation of intermediate species during this luminescent reaction may limit its effectiveness in detection applications. Understanding these intermediates is crucial for enhancing the accuracy and reliability of luminol-based detection methods. To solve the above problems, this work proposes a straightforward and effective approach to directly oxidize luminol via reactive oxygen species (ROS) generated from contact electrification (CE) between inert solid dielectrics and deionized (DI) water, termed contact-electro-luminescence (CEL). Metal-free, cost-effective solid dielectrics present a promising alternative to expensive metal-based catalysts, aligning well with the principles of green chemistry and sustainable development. In such reaction system, ROS can be regulated by various solid dielectrics and additives (such as xylitol and p-benzoquinone), thereby tuning the luminol reaction. More importantly, two distinct luminescent emission peaks are directly observed and the intensity of the emission peaks of the two intermediate states can be regulated. The observation of intermediate is beneficial to reveal the intrinsic of luminescence reactions, exploiting the effective and tunable luminescence system. Moreover, CEL provides a new mechanical-photonic conversion paradigm to study luminol luminescence via triboelectric charge from the CE effect. CEL can offer distinct characteristic signals, offering potential applications in high-efficiency and specific detection for environmental monitoring, biomedical diagnosis and food safety testing etc.

Dual-Indicator loaded porous polymer microneedle patches for rapid and colorimetric detection of water-injected meat

Water-injected meat leads to microbial growth, which affects the health of consumers. A colorimetric porous polymer microneedle patch was designed and prepared using photopolymerization of an acrylate monomer with porogen to be the substrate, and cobalt (II) chloride as color change indicator and tartrazine as the reference. The color of the microneedle patch changed from green to yellow green and to yellow as the increase of moisture concentration. Furthermore, the discoloration trend of the microneedle patch during the moisture measurement of meat is very regular. The moisture measurement of meat in range of 66.9 %–75.7 % exhibited a good linear dependence on RGB values. The results indicate that the microneedle patch can visually determine the moisture content of meat in 3 min. In addition, the microneedle patch can be combined with smartphone to achieve accurate detection of water-injected meat, making it a wonderful tool in the field of food safety testing.

Probe-based dual-chip digital loop-mediated isothermal amplification for the simultaneous detection of Staphylococcus aureus and Salmonella enteritidis in livestock and aquatic products

Staphylococcus aureus and Salmonella are common pathogens causing foodborne diseases, posing a serious threat to food safety. Accurate detection of foodborne pathogens is particularly critical. This study developed a probe-based dual-chip digital loop-mediated isothermal amplification (cdLAMP) technique that enables the simultaneous detection of Staphylococcus aureus and Salmonella in food samples. The chip contains 20,000 wells, each with a micro-reaction unit volume of approximately 1 nL. The dual-detection is achieved through the dual-color fluorescence channel equipped on the imaging analyzer. Compared with qPCR, the cdLAMP demonstrates superior sensitivity. In the detection of pure cultures and spiked food samples, the detection limit of two foodborne pathogens is 2 CFU/mL. In the detection of field samples, it is capable of detecting single colonies of both pathogens. The dynamic detection range spans 5 logs. In conclusion, the probe-based cdLAMP technique emerges as a user-friendly tool for detecting foodborne pathogens, providing a powerful platform for food safety testing.

Refractive index sensing characteristics of PCF-SPR based on dual-plasmon materials

Abstract In this paper, a photonic crystal fiber (PCF) refractive index sensor based on surface plasmon resonance with dual plasmonic materials (indium tin oxide and gold) is proposed. We innovatively designed a dual-core PCF structure and pore arrangement effectively enhancing the coupling effect. Using two different plasma materials, phase matching is achieved at two different wavelengths for the evanescent and surface plasmon waves, resulting in dual resonance peaks. The refractive index sensing is accomplished by measuring the dual-peak resonance shift, which expands the detection wavelength and RI detection ranges. The sensor can detect analytes with refractive indices ranging from 1.32 to 1.43 at wavelengths between 0.4 µm and 1.4 µm. We optimized the PCF structure and studied the sensing performance of the sensor, improving its sensitivity. Simulation results indicate that the designed PCF sensor exhibits outstanding maximum dual-peak shift sensitivity, reaching up to 28 000 RIU−1, along with maximum amplitude sensitivity and wavelength sensitivity of 18 500 RIU−1 and 34 500 RIU−1, respectively, in the direction of y-polarization. Furthermore, the sensor achieves high resolution, and the figure of merit (FOM) values can reach up to 5.134 × 10−7 and 2758. Consequently, the proposed sensor can provide high-precision and extensive-range measurements of solution refractive indices within the visible and infrared light spectrum, and it holds potential application prospects in numerous fields, such as food safety testing and chemical substance detection.

Rapid identification of antibiotic residues in bovine kidney using coated blade spray-mass spectrometry

The use of certain antibiotics in food-producing animals is allowed in Europe following Regulation (EU) 2017/625. However, use could result in antibiotic residues in foodstuffs of animal origin. Maximum residue limits (MRLs) are in place to protect consumers. For monitoring purposes, animal matrices are tested to verify their compliance with these MRLs. Initially, matrices of (slaughtered) food animals are screened, often using a microbiological assay. Faster screening tests for antibiotics would be an advantage for control laboratories. Therefore, the present study describes, for the first time, the use of coated blade spray (CBS) followed by direct mass spectrometry (MS) analysis for the screening of tetracyclines, sulfonamides, quinolones, and macrolides residues from the renal area of intact bovine kidneys. An optimized workflow using two different desorption/ionization solutions per blade allowed screening of target compounds within 1 min per sample. The proof-of-principle of the CBS-MS method is validated according to (EU) 2021/808, presenting CCβ screening values of 0.1 × MRL for 43 analytes, 0.5 × MRL for 4 analytes, and 2.5 µg kg−1 for the prohibited substance dapsone, respectively. The developed method was successfully applied to seven official control samples of bovine kidneys. One of these samples was found to be positive using the CBS-MS method, which was confirmed as a true positive by LC-MSMS analysis. The developed method demonstrates that CBS devices can directly extract and analyze kidney samples for food safety testing.

Rapid and Ultrasensitive Detection of H. aduncum via the RPA-CRISPR/Cas12a Platform.

Hysterothylacium aduncum is one of six pathogens responsible for human anisakiasis. Infection with H. aduncum can cause acute abdominal symptoms and allergic reactions and is prone to misdiagnosis in clinical practice. This study aims to enhance the efficiency and accuracy of detecting H. aduncum in food ingredients. We targeted the internal transcribed spacer 1 (ITS 1) regions of Anisakis to develop a visual screening method for detecting H. aduncum using recombinase polymerase amplification (RPA) combined with the CRISPR/Cas12a system. By comparing the ITS 1 region sequences of eight nematode species, we designed specific primers and CRISPR RNA (crRNA). The specificity of RPA primers was screened and evaluated, and the CRISPR system was optimized. We assessed its specificity and sensitivity and performed testing on commercial samples. The results indicated that the alternative primer ADU 1 was the most effective. The final optimized concentrations were 250 nM for Cas12a, 500 nM for crRNA, and 500 nM for ssDNA. The complete test procedure was achievable within 45 min at 37 °C, with a limit of detection (LOD) of 1.27 pg/μL. The amplified product could be directly observed using a fluorescence microscope or ultraviolet lamp. Detection results for 15 Anisakis samples were entirely consistent with those obtained via Sanger sequencing, demonstrating the higher efficacy of this method for detecting and identifying H. aduncum. This visual detection method, characterized by simple operation, visual results, high sensitivity, and specificity, meets the requirements for food safety testing and enhances monitoring efficiency.

Development and application of a streamlined DNase-assisted DNA extraction method for the quantitative PCR of live bacterial counts in heated game meat

ABSTRACT In response to the growing need for effective food safety protocols in game meat, this study introduces a novel DNase I treatment and heat kill method to detect live bacterial pathogens in meat, particularly in game. Focusing on male wild boar shoulder meat, we tested the method’s efficacy under a stringent condition of 59°C for 60 minutes. The results demonstrate that DNase I remains active, enabling the accurate differentiation between viable and non-viable bacterial cells for precise pathogen quantification. This method’s simplicity and potential for high-throughput processing suggest it could be an invaluable tool for enhancing the safety and quality of game meat. These findings offer a practical approach to game meat safety, and can permit large-scale food safety testing across various meat types.

Reproducible, Accurate, and Sensitive Food Toxin On-Site Detection with Carbon Nanotube Transistor Biosensors.

Field-effect transistor (FET) biosensors based on nanomaterials are promising in the areas of food safety and early disease diagnosis due to their ultrahigh sensitivity and rapid response. However, most academically developed FET biosensors lack real-world reproducibility and comprehensive methodological validation to meet the standards of regulatory bodies. Here, highly uniform and well-packaged semiconducting carbon nanotube (CNT) FET biosensor chips were developed and assessed for the plug-and-play sensing for the rapid and highly sensitive detection of aflatoxin B1 (AFB1) in real food samples to meet international standards. In order to meet the requirements for reproducibility and stability, a scalable residual-free passivation and packaging process was developed for CNT FET biosensors. Portable detection systems were then constructed for on-site detection. The resulting packaged chips were functionalized with nucleic aptamers to enable highly selective detection of AFB1 in food samples with a detection limit (LOD) of 0.55 fg/mL (standard) for AFB1 and cross-reactivity coefficients to interferences as low as 1.8 × 10-7 in simulated solutions. Utilizing the portable detection system, on-site real food detection was achieved with a rapid response time less than 60 s, and LOD of 0.25 pg/kg (standard) in complex corn sample matrices. Single-blind tests demonstrated the ability of the chips to detect AFB1-positive food with 100% accuracy, using a set of 30 peanut samples. Validation experiments confirmed that the detection range, stability, and repeatability met international standards. This study showcased the accuracy, reliability, and potential practical applications of CNT FET biosensor chips in areas such as food safety and rapid biomedical testing.

A new method for the determination of Potassium sorbate via Photoelectron transfer using NIR fluorescence Silver-Copper nanocluster probe

Potassium sorbate (PS) is a widely utilized food preservative with bactericidal solid effects. However, it can cause serious side effects and health risks when the dosage is exceeded.Thus, developing an exceptional probe for detecting trace amounts of PS was significantly important. Bimetallic nanoclusters, compared to monometallic nanoclusters, possess better chemical performance. Herein, we introduce a novel fluorescence of Ag/CuNCs (at excitation/emission peaks of 395/680 nm)as a fluorescent probe, is quenched by PS due to electron-transfer (PET) between Ag/CuNCs and PS. the present sensor system exhibits a good linear response to PS ranging from 0.08 to 45 μM, and the limit of detection was found to be 3.7 nM. Its applicability has also been confirmed successfully in drinks. Due to its high stability, sensitivity, and selectivity, this bimetallic cluster-based sensing system shows great promise for application in food safety testing.

Monitoring foodborne pathogens of food served at an institutional cafeteria

The provision of food by cafeterias is an opportunity to promote health through a balanced diet and safe food, offering the prospect of sustainably developing the well-being a community and the local economy. This study assessed the hygiene conditions of an institutional cafeteria. The presence of foodborne pathogens and indicators of general hygiene in 143 food and environmental samples were analyzed using the TEMPO and VIDAS food safety testing machines. All food samples tested negative for Salmonella sp., and Staphylococcus aureus counts were below the GCC Standardization Organization (GSO) limit. Escherichia coli was detected at level above the set limit in six food samples. Sixteen food samples showed aerobic bacterial counts above the set limit. Total coliforms and Enterobacteriaceae were each detected above the set limits in eight food samples. Yeasts and molds were detected above the set limit in 14 food samples. Coliform bacteria, S. aureus, and mold were detected on the hands and white coats of cafeteria workers and on work surfaces, machines, and cutting boards. The hygiene conditions of the cafeteria are not suitable for food preparation, and to improve hygienic conditions in cafeterias, regular inspection of food and food preparation facilities is strongly recommended.

Bifunctional Nanocellulose@MOF composite aerogel for selective fluorescent detection and efficient removal of tetracycline

The antibiotic tetracycline (TC) significantly pollutes water bodies, adversely impacting ecosystems and human health. In this work, a bifunctional platform for simultaneous detection and removal of TC was successfully constructed by in-situ growth of Zr-MOF in BC microspheres. The in-situ growth ensured the stability, while the design of the aerogel microspheres improved the processability, convenience, and recyclability. The macropores and mesopores in the aerogel microspheres significantly improved the molecular mass transfer efficiency, and the sensitivity and selectivity of TC detection and adsorption were improved due to the size-sieving effect of the abundant micropores of Zr-MOF and the supramolecular interaction of the ligand. Owing to the hierarchical pore structure, the adsorption capacity reaches as high as 317.6 mg/g. The enrichment during the adsorption process enhances the interaction between TC and Zr-MOF, thereby significantly improving the detection sensitivity of TC. As expected, BMAT3H5 has a LOD as low as 28 ± 0.012 nM and a KSV as high as 1.89 ± 0.001 × 106 M−1, providing excellent detection performance compared to other work in recent years. The good selectivity to TC was theoretically validated through simulations with Materials Studio software (MS). It provides a novel and practical bifunctional platform for efficient fluorescence detection and adsorption of TC, which has a broad application prospect in the fields of environmental monitoring, water treatment, and food safety testing.

Highly sensitive electrochemical sensing of moxifloxacin based on molecularly imprinted and Au nanoparticle functionalized PEDOT composites

The misuse of antibiotics and continuous antimicrobial resistance is one of the critical challenges facing society today. It is therefore crucial for food safety and environmental protection to develop an analytical technique for the selective detection of trace antibiotics. In this paper, worm-like Au/Poly(3,4-ethylenedioxythiophene) (Au/PEDOT) composites were designed and imprinted with polypyrrole (Ppy) in the presence of moxifloxacin, and molecularly imprinted sensors (MIP/Au/PEDOT/GCE) were prepared for the ultrasensitive detection of moxifloxacin (MOX). It was found that the Au/PEDOT worm-like structure provided a large surface area, increased the number of molecularly imprinted recognition sites, and improved electrochemical sensitivity. The molecularly imprinted sensor has a linear detection range of 0.004–20 μM, a lower detection limit of 1.109 nM, good interference immunity and stability. In addition, the sensor demonstrated good recoveries for the detection of MOX in real samples, indicating the potential of the sensor to be suitable for food and drug safety testing. This work offers a new strategic solution for the accurate quantitative detection of MOX.

Nanozyme-catalyzed and zwitterion-modified swabs based for the detection of Listeria monocytogenes in complex matrices

In recent years, nanozymes have been widely used in the field of biosensing and food safety testing due to their advantages of low cost, high stability, easy modification and adjustable catalytic activity. However, how to reduce the signal interference generated by reducing substances, macromolecules and colored substances in the food matrix in nanozymes-based colorimetric sensing is still a major challenge. In this paper, using Listeria monocytogenes as a model analyte, sodium sulfonyl methacrylate (SBMA) polymers were modified onto cotton swabs by photothermal polymerization and combined with Listeria monocytogenes-specific aptamer (Apt1) to prepare swabs that can specifically capture and isolate Listeria monocytogenes from complex matrices (SBMA/Apt1 cotton swab). In addition, in combination with the inhibitory effect of the aptamer (Apt2) on the oxidase activity of Mn3O4 NPs, a colorimetric biosensor based on nanozymes that can quantitatively, sensitively, and specifically identify Listeria monocytogenes in food products was constructed. The results showed that the colorimetric signal of the method was linear with the concentration of Listeria monocytogenes in the range of 2.83–2.83 × 105 CFU/mL, and the limit of detection was 2.64 CFU/mL, which can be used for the detection of Listeria monocytogenes in complex environments and food samples.

Application of nanozymes in food safety testing

Application of nanozymes in food safety testing

Sensitive and specific detection of Listeria monocytogenes in food samples using imprinted upconversion fluorescence probe prepared by emulsion polymerization method

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen with high morbidity and mortality rates, necessitating rapid detection methods. Current techniques, while reliable, are labor-intensive and not amenable to on-site testing. We report the design and synthesis of a novel imprinted upconversion fluorescence probe through Pickering emulsion polymerization for the specific detection of L. monocytogenes. The probe employs trimethylolpropane trimethacrylate and divinylbenzene as cross-linkers, acryloyl-modified chitosan as a functional monomer, and the bacterium itself as the template. The developed probe demonstrated high specificity and sensitivity in detecting L. monocytogenes, with a limit of detection of 72 CFU/mL. It effectively identified the pathogen in contaminated salmon and chicken samples, with minimal background interference. The integration of molecular imprinting and upconversion fluorescence materials presents a potent and reliable approach for the rapid and specific detection of L. monocytogenes, offering considerable potential for on-site food safety testing.

A novel standard-free detection of adulteration method for sildenafil derivatives in dietary supplements.

The rapid and accurate detection of illegal adulteration of chemical drugs into dietary supplements is a big challenge in the food chemistry field. Detection of compounds without a standard reference is even more difficult; however, this is a common situation. Here in this study, a novel "standard-free detection of adulteration" (SFDA) method was proposed and phosphodiesterase-5 inhibitor derivatives were used as an example to figure out the possibility and reliability of this SFDA method. After analysis by quadrupole coupled time of flight-tandem mass spectrometry detection and multivariable statistics, six common fragment ions were chosen to indicate whether adulteration was present or not, while 20 characteristic fragment ions indicated whether adulteration was by nitrogen-containing heterocycles or by anilines. Furthermore, the quantitative methods were conducted by high-performance liquid chromatography-tandem mass spectrometry. In a word, this strategy allows for a quick determination of dietary supplement adulteration without any need for standard materials, improving the efficacy of food safety testing.

UV-triggered and temperature-control carrier transport regulation of ZnO/Ti3C2Tx MXene heterostructures for dual selective HCHO and triethylamine detection

Food safety is crucial to the health and life of every individual. Triethylamine and formaldehyde, as key indicators for assessing the freshness of seafood, are increasingly important for food safety. Consequently, this study has developed a dual-gas sensor that is easy to operate and can rapidly detect both formaldehyde and triethylamine. The ZnO-MXene based gas sensors were prepared by a two-step electrostatic adsorption method. Under irradiation with 450 nm LED light, the sensors can detect formaldehyde gas at room temperature. By adjusting the temperature, it is possible to detect 100 ppm triethylamine in the dark at 160 ℃, with a response value of 28.2, which is 5.2 times that of the pure ZnO based sensors. Additionally, it exhibits good selectivity, excellent stability, and reproducibility. This paper also provides a detailed discussion of the sensing mechanism for detecting dual gases. It is significant for the development of dual-gas or multi-gas sensors and has potential applications in food safety testing and addressing complex changes in air environments.

Advances in Microfluidic Paper-Based Analytical Devices (µPADs): Design, Fabrication, and Applications.

Microfluidic Paper-based Analytical Devices (µPADs) have emerged as a new class of microfluidic systems, offering numerous advantages over traditional microfluidic chips. These advantages include simplicity, cost-effectiveness, stability, storability, disposability, and portability. As a result, various designs for different types of assays are developed and investigated. In recent years, µPADs are combined with conventional detection methods to enable rapid on-site detection, providing results comparable to expensive and sophisticated large-scale testing methods that require more time and skilled personnel. The application of µPAD techniques is extensive in environmental quality control/analysis, clinical diagnosis, and food safety testing, paving the way for on-site real-time diagnosis as a promising future development. This review focuses on the recent research advancements in the design, fabrication, material selection, and detection methods of µPADs. It provides a comprehensive understanding of their principles of operation, applications, and future development prospects.

Detection of food harmful substances based on electrochemical biosensors

Food safety is related to everyone's health and life, so it is crucial to establish appropriate food systems and infrastructure, and develop efficient instruments for detecting food contaminants. Nowadays, many advanced detection technologies have emerged, playing a huge role in food safety testing, such as chromatographic analysis, spectral analysis, and electrochemical analysis. Among them, electrochemical biosensors have the advantages of superior selectivity, high sensitivity, convenient operation, low cost, and fast response, which are expected to develop into portable instruments for on-site rapid detection. Significant progress has been made in the electrochemical detection of food contaminants through the combination of nanotechnology and intelligent technology in recent years. This research summarizes the advancement of electrochemical biosensing technology for the detection of pesticides, heavy metals, illegal additives and mycotoxin by discussing the analytes, electrode materials, modification techniques, methods and detection limits for electrochemistry. Finally, the future development trends of the technology are discussed.