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[Display omitted] • Hg (II) decreased the content of α-helix of croaker myosin. • The croaker myosin particles length increased after adding Hg (II). • The quenching between croaker myosin and Hg (II) was static quenching. • Hydrogen bonds, van der Waals forces were the main forces in complex formation. Heavy metals have long biological half-lives and are therefore a major threat to aquatic organisms, especially fish. Divalent mercury (Hg(II)) is an important form from a toxicological viewpoint. In this paper, we studied the interaction mechanism between large yellow croaker myosin and Hg(II) by multi-spectroscopies and molecular docking. Hg(II) had a positive effect on improving the elasticity of myosin gel, and the constant increase of charge would destroy the gel. Hg(II) caused myosin to aggregate, and the protein's apparent structure rapidly increased in length. The content of α-helix obviously decreased, β-turns and β-sheet increased. The myosin and Hg(II) quenching type was static quenching. Thermodynamic analysis suggested hydrogen bonding and van der Waals forces were the main forces for the combination. The molecular docking further confirmed the mechanism of action. This study provides a theoretical guidance for the preventions and control of marine heavy metals. [ABSTRACT FROM AUTHOR]

• Fluorescein acted as a response signal and rhodamine B acted as a reference signal. • Zein/RhB-Flu label displayed a sensitive fluorescent color change for biogenic amine. • Zein/RhB-Flu label showed excellent reusability and stability. • Fluorescent label realized accurate, visual, in situ detection of shrimp freshness. A zein-based film functionalized with fluorescent dyes was constructed for visual, real-time monitoring of seafood freshness. The addition of fluorescent dyes had no significant effect on the mechanical property or water sensitivity of the zein-based film, and the fluorescent film exhibited dual emission response. When exposed to ammonia, fluorescein fluorescence increased whilst the fluorescence of rhodamine B was undisturbed. The fluorescent film presented a clearly distinguishable color transition from pink to green. Sample detection tests showed the fluorescent film served successfully as a response label for on-site visual detection of seafood freshness. Development of this intelligent fluorescent film provides a new platform for food safety and quality monitoring, benefiting economic value and public health. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanism of cellulose nanocrystals (CNC) to improve film properties was proposed. • Adding CNC restricted water mobility and improved the viscoelasticity of films. • Incorporation of CNC enhanced hydrophobic and hydrogen bonding interactions. • CNC-induced conformational modifications promoted to form stronger film structures. • The obtained nanocomposite films can be used for pork and strawberry preservation. This study aimed to evaluate the effects of cellulose nanocrystals (CNC) on the basic properties of soy protein isolate films, and especially to propose the corresponding formation mechanism. Tensile strength, barrier properties, and water resistance were effectively improved after the formation of nanocomposite films. Incorporating CNC could restrict water mobility and improve the viscoelastic properties of films. Appropriate content of CNC (0.50% and 0.75%) promoted the construction of a more homogeneous and compact film structure, which may be attributed to the CNC-induced conformational modifications and the enhanced hydrophobic and hydrogen-bond interactions. While excessive CNC (1.00%) was not conducive to the integrity and continuity of film structures, resulting in the weakened functional properties. The obtained films were able to decrease total viable counts and total volatile basic nitrogen of stored pork, and extend the shelf-life of strawberry. This work offers a theoretical basis for the application of CNC in packaging industry. [ABSTRACT FROM AUTHOR]

The low solubility limits the utilization of other functional characteristics of wheat gluten (WG). This study effectively improved the solubility of WG through protease modification and explored the potential mechanism of protease modification to enhance the solubility of WG, further stimulating the potential application of WG in the food industry. Solubility of WG modified with alkaline protease, complex protease, and neutral protease was enhanced by 98.99%, 54.59%, and 51.68%, respectively. Notably, the content of β-sheet was reduced while the combined effect of hydrogen bond and ionic bond were increased after protease modification. Meanwhile, the reduced molecular size and viscoelasticity as well as the elevated surface hydrophobicity, thermostability, water absorption capacity, and crystallinity were observed in modified WG. Moreover, molecular docking indicated that protease was specifically bound to the amino acid residues of WG through hydrogen bonding, hydrophobic interaction, and salt bridge. [Display omitted] • Solubility of wheat gluten (WG) was improved after treatment by three proteases. • WG bound to proteases mainly through non-covalent interactions at specific sites. • Protease modification induced β-sheet changed into α-helix, β-turn and random coil. • Proteases enhanced the combined effect of hydrogen bond and ionic bond in WG. [ABSTRACT FROM AUTHOR]

Here, the influence and potential mechanism by which cellulose nanocrystals (CNC) collaborated with Ca2+ enhancing the heat-induced gelation of pea protein isolate (PPI) were investigated. It was found that the combination of 0.45% CNC and 15 mM Ca2+ synergistically increased the gel strength (from 14.18 to 65.42 g) and viscoelasticity of PPI while decreased the water holding capacity. The improved particle size, turbidity, and thermostability as well as the reduced solubility, crystallinity, and gel porosity were observed in CNC/CaCl 2 composite system. CNC fragments bind to specific amino acids in 11S legumin and 7S vicilin mainly through hydrogen bonding and van der Waals forces. Moreover, changes in the protein secondary structure and enhancement of the molecular interaction induced by CNC and Ca2+ could favor the robust gel network. The results will provide a new perspective on the functional regulation of pea protein and the creation of pea protein gel-based food. [Display omitted] • CNC and Ca2+ had a synergistic effect in the gelation of pea protein isolate. • CNC and Ca2+ affected the phase transition behavior of sol-gel. • Ca2+ strengthened cross-linking of CNC and proteins to form stable gel structure. • CNC combined with 7S vicilin and 11S legumin via hydrogen bond and Van der Waals. [ABSTRACT FROM AUTHOR]

• A novel fluorescent probe based on red emission carbon dots was fabricated. • It was applied colorimetric and fluorometric dual-mode detection of nitrite. • It had a high sensitivity and a low detection limit. • It was successfully applied in detecting nitrite in meat products with satisfactory recoveries. • This dual-mode probe presented great advantages for detection of nitrite in food samples. Nitrite (NO 2 –) is widely present in the human environment and accurate, sensitive and selective detecting of nitrite is of vital significance for food safety and water quality. Herein, a novel red emission carbon dots (r-CDs) fluorescent probe was fabricated for dual-mode detection of nitrite, which was capable of both convenient colorimetric analysis and accurate fluorometric detection. When NO 2 – is added to the rose-red r-CDs solution, NO 2 – interacts with the amino groups which on the surface of r-CDs to form diazotized substance, resulting in that the colorimetric color of r-CDs solution realizes the transition from rose red to light purple, and the red fluorescence is gradually quenched. The detection limits of colorimetric and fluorescence for NO 2 – were 0.193 μM and 0.149 μM, respectively. Furthermore, the dual-readout probe revealed satisfactory recovery and reliability when analyzing the concentration of NO 2 – in ham and bacon samples.. [ABSTRACT FROM AUTHOR]

In this study, the β-cyclodextrin encapsulated betanin (BET@β-CD) with improved thermal stability and retention as well as the berberine (BBR) with aggregate induced luminescence effect were incorporated into corn amylose (CA) biomatrix to develop colorimetric/fluorescent dual-channel smart film. Results shown that the added functional components were uniformly distributed in the film matrix. The high tensile strength (78.87%), low water solubility (31.15%) and water vapor permeability (1.24 × 10−10 g Pa−1 s−1 m−1) of the film predicted its acceptable stability. It was worth mentioning that the film displayed excellent responsiveness to volatile ammonia (0.025–25 mg/mL) with at least 4 times recyclability. Application experiment demonstrated that the film can achieve macroscopic dynamic monitoring of the freshness of shrimps stored at 25 °C, 4 °C, −20 °C under daylight (red to yellow) and UV light (yellow-green to blue-green). Thus, the study suggests an attractive and effective strategy for constructing dual-mode smart packaging materials for food freshness detection. [Display omitted] • Betanin@β-cyclodextrin inclusion complex was successfully prepared. • The AIE property of berberine was triggered for the fluorescence response signal. • The label displayed clear color response under daylight and ultraviolet light. • The label had potential to detect bioamines in colorimetric/fluorescent dual mode. • The label achieved accurate, real-time, and visual monitoring of shrimp freshness. [ABSTRACT FROM AUTHOR]

[Display omitted] • An enzyme-mediated ratiometric fluorescent probe was developed. • Ru@UiO-66 acted as a reference signal and thiamine acted as a response signal. • It integrated quenching effect, enzyme-like activity and enzyme inhibition. • It exhibited excellent analytical performance against dichlorvos and chlorpyrifos. • Ratiometric fluorescent hydrogels were developed for portable visual detection. In view of the potential hazards of organophosphorus pesticides (OPs), this paper constructed a ratiometric fluorescent probe utilizing a functionalized metal–organic framework to detect OPs. Ru(bpy) 3 Cl 2 was encapsulated inside UiO-66 as a reference signal, and MnO 2 nanosheets (MnO 2 NSs) were grown on the surface to obtain Ru@UiO-66@MnO 2 NSs. Acetylcholinesterase catalyzed the decomposition of acetylcholine into reductive thiocholine, which consumed MnO 2 NSs, thus restoring the Ru@UiO-66 fluorescence. Due to the enzymatic inhibition of OPs and the redox reaction between MnO 2 NSs and thiamine, this probe emitted blue fluorescence in the presence of OPs. The probe achieved linear responses to dichlorvos and chlorpyrifos with LODs of 9.99 × 10-6 μg mL−1 and 9.99 × 10-5 μg mL−1. The probe exhibited a satisfactory recovery rate for OPs in green tea. Furthermore, a hydrogel detection platform was developed by embedding the probe into sodium alginate. Overall, this work provides a visual approach to detect OPs in agricultural products. [ABSTRACT FROM AUTHOR]

• Wheat bran cellulose (WBC) strengthened heat-induced soy protein isolate (SPI) gel. • WBC improved gel properties by stabilizing water phase and filling effect. • WBC induced the formation of a regular three-dimensional gel network. • A conformation conversion from α-helix to β-sheet found in the composite gels. • The thermal stability of SPI gel was enhanced after WBC incorporation. The effect and mechanism of wheat bran cellulose (WBC) on the gelling characteristics of soy protein isolate (SPI) were evaluated. It was found that the water holding capacity, gel strength, and viscoelasticity of SPI gel were improved with the increase of WBC concentration. The addition of WBC (0.5–2.0%, w/v) stabilized the moisture phase and induced the construction of the regular and homogenous three-dimensional gel network. The Raman spectroscopy revealed that WBC addition caused a significant reduction in α-helix percentage (28.92–63.08%) (p < 0.05) with a concomitant increase in β-sheet (16.92–34.37%) (p < 0.05) and β-turn (8.09–13.54%) (p > 0.05) percentages of the pure SPI gel. Additionally, hydrogen-bonding interaction between SPI and WBC and the enhanced thermal stability were proposed in the composite gels. Overall, WBC is effective in improving the gel properties of SPI, suggesting its potential application as novel gel modifier in the food industry. [ABSTRACT FROM AUTHOR]

• The carbon selenide nanofilms modified carbon cloth (CSe 2 NF/CC) was fabricated. • CSe 2 nanofilms enhance the electrocatalytic oxidation activity of the electrode. • The CSe 2 NF/CC has been successfully used in food samples for nitrite detection. Large uptakes of nitrite have been proven to be detrimental to human health, therefore, the development of high-performance nitrite sensors is highly emergent. Herein, a carbon selenide nanofilms modified carbon fiber cloth (CSe 2 NF/CC) electrode was obtained via in-situ synthesis to detect nitrite. The electrode integrates the collective merits of macroporous CC and pleated carbon selenide nanofilms, possessing a low overpotential of 0.83 V, a high electrochemical active surface area (EASA) of 5.39 cm2, great electrical conductivity, and fast charge transport as well as ion diffusion. The proposed electrode achieved a low limit of detection of 0.04 μmol L−1 (S/N = 3), a high sensitivity of 2048.56 μA mmol L−1 cm−2, excellent selectivity, and long-term stability. Additionally, the CSe 2 NF/CC was successfully used for nitrite detection in different food samples such as pickled vegetables and sausage samples. [ABSTRACT FROM AUTHOR]

• Metal-polydopamine framework (MPF) based lateral flow assay (LFA) was developed. • MPF displayed excellent affinity with antibodies to detect tetracycline. • Assay performance of this LFA was 66-fold higher than that of traditional AuNP-LFA. • This work expands the application of MOFs as a novel label in immunoassays. Gold nanoparticles (AuNPs)-based lateral flow assay (LFA) enables a rapid detection of tetracycline (TET) in food samples but suffers from low sensitivity. Herein, metal-polydopamine framework (MPF), as a label, was employed to load monoclonal antibodies (mAbs) directly as the probe in LFA for highly sensitive sensing of TET. Combining zeolitic imidazolate framework (ZIF-67) and polydopamine (PDA), a stable MPF with large size, well water-dispersible, excellent affinity and optical properties was prepared through a versatile layer-by-layer assembly (LLA) strategy. Under optimized conditions, the biosensor (MPF-LFA) exhibited a great linear relationship in the range of 0.09–6 ng/mL and a detection limit of 0.045 ng/mL for TET detection, which was over 66-fold more sensitive than traditional AuNPs based LFA. Furthermore, the MPF-LFA was successfully applied to the screening of TET in fish, chicken, milk and shrimp samples with satisfied recoveries from 91% to 114%. [ABSTRACT FROM AUTHOR]

• A label-free and dual-readout biosensor was constructed to detect E. coli O157:H7. • The Fe 3 O 4 @CuS could capture targets directly and possessed PTEs to amplify signals. • An ideal analytical performance with high sensitivity and specificity was achieved. • The sensor were successfully used in food samples for E. coli O157:H7 detection. Herein, a label-free and dual-readout immunochromatographic test strip (ITS) for the sensitive detection of Escherichia coli (E. coli) O157:H7 by taking advantages of the strong capture ability of Fe 3 O 4 @CuS nanostructures (NSs) towards bacteria and their ultrahigh photothermal effects (PTEs) was reported. Especially, without the customarily antibody (Ab)-labeled probe, Fe 3 O 4 @CuS NSs could be adsorbed onto the surfaces of bacteria to form Fe 3 O 4 @CuS-bacteria conjugates and then trapped by immobilized Abs on the test line (T-line), forming a characteristic yellow band. After direct immunoreactions, the PTEs of Fe 3 O 4 @CuS NSs endowed T-line to be irradiated by an 808 nm infrared light, obtaining satisfactory sensitivity and accuracy. Under optimal conditions, E. coli O157:H7, as low as 103 and 102 CFU/mL, could be monitored in colorimetric and photothermal modes. Additionally, E. coli O157:H7 was successfully detected in beef, chicken, milk and honey samples by this proposed platform with a recovery of 80–120%. [ABSTRACT FROM AUTHOR]

• A novel, sensitive, and stable fluorescent sensor was developed for TET detection. • The synthesized MoS 2 NPs possessed superior solubility and strong blue fluorescence. • A low detection limit of 0.032 μM with good linear relationship was achieved. • This prominent technique could be applied in milk and bovine muscle samples. The wide use of tetracyclines (TCs) for prevention and therapy of animal diseases may result in excessive residues in animal products, which could pose serious risks to human health. A novel molybdenum disulfide nanoplates (MoS 2 NPs)-based fluorescent sensor for tetracycline (TET) is reported. The MoS 2 NPs, synthesized via a facile bottom-up hydrothermal route, showed blue fluorescence at 430 nm in aqueous solution. Interestingly, its fluorescence was quenched significantly upon addition of TET, which is mainly due to a combination of the inner filter effect and electron transfer. Thus, the MoS 2 NPs based fluorescence sensor was delineated for the detection of TET. The methodology here presented showed a low detection limit of 0.032 μM and satisfied recoveries from 88.46% to 108.62% in spiked milk, milk powder and bovine muscle samples. [ABSTRACT FROM AUTHOR]