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Nitrite (NO 2 −) is present in a variety of foods, but the excessive intake of NO 2 − can indirectly lead to carcinogenic, teratogenic, mutagenicity and other risks to the human body. Therefore, the detection of NO 2 − is crucial for maintaining human health. In this study, an integrated array sensor for NO 2 − detection is developed based on molybdenum single atom material (IMS Mo-SAC) using high-resolution electrohydrodynamic (EHD) printing technology. The sensor comprises three components: a printed electrode array, multichannels designed on polydimethylsiloxane (PDMS) and an electronic signal process device with bluetooth. By utilizing Mo-SAC to facilitate electron transfer during the redox reaction, rapid and efficient detection of NO 2 − can be achieved. The sensor has a wide linear range of 0.1 μM–107.8 mM, a low detection limit of 33 nM and a high sensitivity of 0.637 mA−1mM−1 cm−2. Furthermore, employing this portable array sensor allows simultaneously measurements of NO 2 − concentrations in six different foods samples with acceptable recovery rates. This array sensor holds great potential for detecting of small molecules in various fields. [ABSTRACT FROM AUTHOR]

The development of techniques and methods for rapidly and reliably detecting and analysing food quality and safety products is of significance for the food industry. Traditional machine learning algorithms based on handcrafted features normally have poor performance due to their limited representation capacity for complex food characteristics. Recently, the convolutional neural network (CNN) emerges as an effective and potential tool for feature extraction, which is considered the most popular architecture of deep learning and has been increasingly applied for the detection and analysis of complex food matrices. In the current review, the structure of CNN, the method of feature extraction based on 1-D, 2-D and 3-D CNN models, and multi-feature aggregation methods are introduced. Applications of CNN as a depth feature extractor for detecting and analyzing complex food matrices are discussed, including meat and aquatic products, cereals and cereal products, fruits and vegetables, and others. In addition, data sources, model architecture and overall performance of CNN with other existing methods are compared, and trends of future studies on applying CNN for food detection and analysis are also highlighted. CNN combined with nondestructive detection techniques and computer vision system show great potential for effectively and efficiently detecting and analysing complex food matrices, and the features based on CNN show better performance and outperform the features handcrafted or those extracted by machine learning algorithms. Although there still remains some challenges in using CNN, it is expected that CNN models will be deployed on mobile devices for real-time detection and analysis of food matrices in future. • The principle and architectures of convolutional neural network are presented. • Feature extraction methods based on convolutional neural network are investigated. • Recent applications of convolutional neural network in food are summarized. • Challenges and future work of convolutional neural network are discussed. [ABSTRACT FROM AUTHOR]

Most of existing methods mainly focus on the food image recognition which assumes that one food image contains only one food item. However, in this paper, we present a system to detect a diversity of foods in refrigerator where multiple food items may exist. In view of the refrigerator environment, we propose a food detection framework based on the supervised transformer network. More specifically, the supervised transformer network, dotted as RectNet, is first proposed to automatically select the irregular food regions and transform them to the frontal views. Then, based on the rectified food images, we further propose an end-to-end detection network that predicts the categories and locations of food items. The proposed detection network, called Lite Fully Convolutional Network (LiteFCN), is evolved from the advanced object detection algorithm Faster R-CNN while several significant improvements are tailored to achieve a higher accuracy and keep inference time efficiency. To validate the effectiveness of each component of our method, we build a real-world refrigerator dataset with 80 classes. Extensive experiments demonstrate that our methods achieve the state-of-the-art results, which improves the baseline by a large margin, e.g. , 3–5% in terms of F-measure. We also show that the proposed detection network achieve a competitive result on the public PASCAL VOC2007 dataset, which outperforms the Faster R-CNN by 2.3% with a higher speed. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3a and 3c are screened out from five D-A type dicyanoisophorone derivatives, which show high selectivity towards H 2 O 2. • 3a and 3c express colorimetric and fluorescent dual-signals towards H 2 O 2 with low detection limits (0.20 μM and 0.14 μM). • 3a and 3c are capable of H 2 O 2 detection in milk samples. • Low cytotoxicity allows 3a to be utilized as a H 2 O 2 fluorescence sensor in living HepG-2 cells and zebrafish. • A smartphone-based analysis method is utilized for the rapid quantitative detection of H 2 O 2 by 3c. Excessive residual hydrogen peroxide (H 2 O 2) disinfectant in food is harmful to human health. Therefore, it is necessary to develop efficient detection methods for H 2 O 2 detection. In this work, we designed and synthesized five D-A molecules 3a - 3e by introducing electron-donor substituents (–OCH 3 and –CH 3) to the electron-acceptor dicyanoisophorone skeleton in order to find out the suitable probes for H 2 O 2 detection. Among them, two promising probes, 3a and 3c , are screened out according to structure-property relationships. Based on the principle of intramolecular charge transfer (ICT), 3a and 3c express colorimetric and fluorescent dual-signals towards H 2 O 2 with low detection limits (0.20 μM and 0.14 μM) and rapid response (within 20 mins). The reaction mechanism between probes and H 2 O 2 is determined by 1H NMR and HRMS. Density functional theory (DFT) calculations are measured to study the regulation mechanism of structure adjustment on probs performance. Furthermore, a smartphone RGB analysis is utilized as a portable platform for the quantitative detection of H 2 O 2 without complicated instruments, indicating a high efficiency and on-site detection method for H 2 O 2. In addition, probes are applied to detect H 2 O 2 in milk samples, HepG-2 cells and zebrafish, suggesting the promising applications in food samples and physiological systems. [ABSTRACT FROM AUTHOR]

• An Ag-coated nanofiber SERS platform was prepared for rapid nitrite detection. • Electrospraying technique was firstly used to assemble SERS platform. • The Ag-coated nanofiber SERS platform has good homogeneity and reproducibility. • The EF and the LOD was 2.635 × 108, 2.216 × 10−12 M, respectively. • The SERS platform shows good compatibility in nitrite detection for real samples. Nitrite is commonly used as a preservative and color fixative in the meat industry. However, the risk of it transforming into N -nitrosamine restricts its intake. Herein, a novel sensitive Ag-coated nanofiber surface-enhanced Raman scattering (SERS) platform was developed for rapid nitrite detection. The electrospraying technique was firstly used to assemble Ag nanoparticles (NPs) on the nanofibers to obtaine SERS platform. The homogeneity and long-term stability of the SERS platform were evaluated. The limit of detection (LOD) of the SERS platform was estimated to be 2.216 × 10−12 mol/L, corresponding to 15.29 ng·L−1 and good linearity was shown between the relative SERS intensity and nitrite concentration range of 10–1 to 10−4 mol/L. The Ag-coated nanofiber SERS platform was utilized to assay-five common nitrite foods, and the results provided valid evidence for the compatibility of SERS platform in quantitative nitrite detection. [ABSTRACT FROM AUTHOR]

[Display omitted] We report herein a new highly selective fluorescent probe QVPB-DNP for selective evaluation of H 2 S in the solid states and food samples. In this probe, a quinoline-phenol vinylic conjugated skeleton as well as the expanded benzothiazole moiety (QVPB-OH) is selected as the fluorophore and a 2,4‑dinitrophenyl (DNP) ether is chosen as binding site of H 2 S. The probe shows significant variations in UV/visible absorption (Stokes Shift = 160 nm) and fluorescence emission enhancement at 605 nm for selective detection of H 2 S in DMSO/PBS system (v/v , 7:3, PBS buffer; pH 7.4). Moreover, probe QVPB-DNP -loaded test strips are successfully applied for the visual and real-time detection of gaseous H 2 S in practical food samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • L5 can achieve naked-eye recognition for I−. • The mechanism of subject-object recognition was elucidated. • The method can be used for I− detection in food. • L5 has lower detection limit and higher sensitivity. In this study, a cholesteric chiral artificial receptor L5 was synthesized and a rapid method for the detection of iodide ions was established. The addition of L5 to Ethanol/Tris (V/V = 1/1, pH 7.0) solution changed the iodide ion solution from colorless to light yellow to achieve the naked-eye identification. The identification pattern was confirmed with the help of spectral titration, job test and anti-interference test, and it was found that L5 bound to iodide ion in a 1:1 coordination ratio. It was also confirmed that the hydrogen atoms of the amide group of MeO-PhCONH in L5 and the hydrogen atoms of –COOCH 3 in L5 interacted with I− through hydrogen bonding force by 1H NMR titration, infrared spectroscopy, scanning electron microscopy and computer molecular simulation. The detection limit of L5 was 0.025 µmol/L, which could efficiently and conveniently detect iodide ions in food samples. [ABSTRACT FROM AUTHOR]

Formaldehyde (FA) is an environmental toxin and widely used in building and decorating materials, which is listed as a class 1 carcinogen. Silver ion (Ag+) has a beneficial bactericidal effect, while it can also cause silver poisoning and skin damage. Therefore, developing a quantitative detection technique for formaldehyde and Ag+ is necessary. In this study, a novel difunctional fluorescent probe (DBP) was designed and synthesized based on the natural product dehydroabietic acid, which could selectively detect formaldehyde and Ag+ through "turn-on" and "turn-off" fluorescence response, respectively. The probe DBP performed satisfactory nanomolar-level detection limit to formaldehyde (38 nM) and Ag+ (19 nM) in ethanol/PBS (3/7, v/v, pH = 7.4) solution. Furthermore, DBP could effectively recognize formaldehyde and Ag+ within a short response time (FA: 15 min, Ag+: 100 s) and a wide pH range (5–10). The sensing mechanisms of DBP to FA and Ag+ were well verified by 1H NMR titration, ESI-MS, DFT computation, and Job's plot analysis. What is more, the applications in bioimaging were carried out in MCF-7 cells and living zebrafish. Besides, the probe DBP was successfully applied in detecting FA and Ag+ in actual food and water samples, and the DBP -loaded filter paper was prepared for convenient tracking gaseous FA and Ag+. • A novel fluorescent probe DBP for detecting formaldehyde and Ag+ was synthesized. • DBP exhibits low LOD, short response time and wide pH range towards FA and Ag+. • DBP was utilized in food and water samples, filter paper test, and bioimaging. [ABSTRACT FROM AUTHOR]

The high quantum-yield (QY) lignin fluorescence material at solid state was obtained via the polymer confinement strategy, using polyvinyl alcohol (PVA) as polymer matrix and organic solvent lignin (OL) as luminescent material. The absolute QY of lignin/PVA film could reach 13.68 % by optimizing the raw material of OL, of which was even higher than that in THF medium due to their hydrogen bond interaction for inhibiting aggregation and rigid environment for decreasing molecular rotation and vibration. In addition, under the encapsulation of PVA, the resistance of photobleaching of lignin fluorescence was also enhanced. Finally, OL was proved as a natural ratiometric fluorescence pH sensor from the electronegativity change of phenylpropane unit, and the fluorescence of lignin/PVA film showed a naked-eye recognition for spoiled pork detection. This work provided a new perspective to lignin fluorescence for really using as a feedstock for luminescent materials. • High QY lignin fluorescent material at solid-state is obtained by polymer confinement. • Absolute QY of doping film could reach 13.68% by optimizing the raw material of OL. • A naked-eye recognition displays from the natural ratiometric pH response of lignin. [ABSTRACT FROM AUTHOR]

Acrolein is a highly toxic agent that can be generated exogenously and endogenously. Therefore, a highly specific and sensitive probe for acrolein with potential applications in acrolein detection must be developed. In this research, a novel fluorescent probe named "probe for acrolein detection" (Pr-ACR) was designed and synthesized based on a naphthalimide fluorophore skeleton, and a thiol group (-SH) was introduced into its structure for acrolein recognition. The -SH traps acrolein via Michael addition and the resultant interaction product of the probe inhibits the photoinduced electron transfer process and produce a strong fluorescence at 510 nm. The probe showed high sensitivity and specificity for acrolein. HPLC-MS/MS analysis verified that it can be used to quantify acrolein in foods, such as soda crackers, red wine, and baijiu, with a fluorescence spectrophotometer. After methyl esterification, the methyl esterified probe (mPr-ACR) successfully visualised acrolein in Hela cells under a laser scanning confocal microscope. This finding proved that Pr-ACR and mPr-ACR are potential tools for the detection and visualisation of acrolein from different sources. [Display omitted] • A napthalimide-based fluorescent probe was developed for sensitive detection of acrolein. • It recognized acrolein through thiol participation in Michael addition. • It was used to quantitatively determine acrolein in different foods. • It successfully tracked acrolein in Hela cells. [ABSTRACT FROM AUTHOR]

Abstract: Food safety problem has become a serious problem all over the world particularly in China. There is a rapid increasing requirement for more accurate and sensitive detection method to cope the more subtle adulterations in food. This paper reviewed and linked the scattered research activity about the application and research conditions of fingerprinting method in food detection mainly in China. The classification, application domain, strengthens and limitations of fingerprinting technology were discussed. The results bring out the benefits of both professionals and scientists. [Copyright &y& Elsevier]

Cr3+-doped Ca 3 Y 2 Ge 3 O 12 broadband near-infrared phosphor was synthesized by the high temperature solidstate reaction method. Under the excitation of 475 nm, the emission peak of Ca 3 Y 2 Ge 3 O 12 :Cr3+ is at 823 nm and the full width at half maximum (FWHM) is 155 nm. The introduction of Ce3+ as a sensitizer leads to the enhancement of CYG:Cr3+ emission intensity. The emission range of CYG:Ce3+, Cr3+ can perfectly cover the frequency doubling absorption band of C–H, O–H and other hydrogen groups. There is an energy transfer process between Ce3+ and Cr3+, and the energy transfer efficiency is as high as 94.21%. According to the near-infrared response to hydrogen group and Lambert-Beer law, the dependence of absorbance Lg(I 0 / I) on sugar content was explored, and then the reliability and accuracy of the method were verified. The results show that the phosphor Ca 3 Y 2 Ge 3 O 12 :Ce3+, Cr3+ phosphor has prospects for a potential application in nondestructive food detection. • There is the energy transfer from Ce3+ to Cr3+. • CYG:Ce3+, Cr3+ has certain application value in nondestructive food detection. • The best excitation wavelength of the sample is 475 nm, which can be effectively excited by the blue light chip, and the FWHM is 155 nm. [ABSTRACT FROM AUTHOR]

[Display omitted] • A unique SERS substrate processed by one-step femtosecond laser ablation in Argon. • S-Ag-Ar can detect 10-8mol/L R6G with enhancement factor up to 5.3 × 106. • S-Ag-Ar has high uniformity with relative standard deviation less than 11.97%. • S-Ag-Ar can be stored for more than seven months and shows good universality. • This unique SERS substrate demonstrates good potentials for food safety evaluation. Surface Enhanced Raman Scattering (SERS) is a reliable tool for detection of food additives due to its advantages including rapid detection, non-destructive and excellent sensitivity. Currently, the commercial SERS substrates are not yet satisfactory referring to cost, sensitivity, uniformity and stability. Herein, we report a unique SERS substrate processed by one-step femtosecond laser ablation in Argon. The substrate shows high sensitivity with limit of detection up to 10-8mol/L for Rhodamine 6G (R6G) and enhancement factor up to 5.3 × 106 due to laser induced more plentiful nanostructures and less oxidation in Argon, in addition to high uniformity with relative standard deviation less than 11.97% and long storage time more than seven months. This SERS substrate is capable of detecting the common food additives including malachite green (1 ppm), crystal violet (10-7mol/L), Sudan I (1 ppm), melamin (1 ppm), brilliant blue (1 ppm) and tartrazine (1 ppm). This unique Ag SERS substrate demonstrates good potentials for food safety evaluation. [ABSTRACT FROM AUTHOR]

The Western Antarctic Peninsula (WAP) has experienced rapid atmospheric and ocean warming over the past few decades and many marine-terminating glaciers have considerably retreated. Glacial retreat is accompanied by fresh meltwater intrusion, which may result in the freshening and acidification of coastal waters. Marian Cove (MC), on King George Island in the WAP, undergoes one of the highest rates of glacial retreat. Intertidal and shallow subtidal waters are likely more susceptible to these processes, and sensitive biological responses are expected from the organisms inhabiting this area. The gammarid amphipod Gondogeneia antarctica is one of the most abundant species in the shallow, nearshore Antarctic waters, and it occupies an essential ecological niche in the coastal marine WAP ecosystem. In this study, we tested the sensitivity of G. antarctica to lowered salinity and pH by meltwater intrusion following glacial retreat. We exposed G. antarctica to four different treatments combining two salinities (34 and 27 psu) and pH (8.0 and 7.6) levels for 26 days. Mortality, excluding cannibalized individuals, increased under low pH but decreased under low salinity conditions. Meanwhile, low salinity increased cannibalism, whereas low pH reduced food detection. Shelter use during the daytime decreased under each low salinity and pH condition, indicating that the two stressors act as disruptors of amphipod behavior. Under low salinity conditions, swimming increased during the daytime but decreased at night. Although interactions between low salinity and low pH were not observed during the experiment, the results suggest that each stressor, likely induced by glacial melting, causes altered behaviors in amphipods. These environmental factors may threaten population persistence in Marian Cove and possibly other similar glacial embayments. Image 1 • Glacial retreat induced by global warming can decrease salinity and pH of the Antarctic ocean. • The Antarctic amphipod Gondogeneia antarctica was exposed to low salinity (27 psu) and low pH (7.6) conditions. • Low salinity increased cannibalism and induced adjusted swimming. • Low pH increased mortality, impaired food detection and reduced daytime shelter use. • Ocean freshening and acidification act as independent stressors influencing behavior and physiology of Antarctic amphipods. [ABSTRACT FROM AUTHOR]