Broad-Spectrum Antibody-Based Immunochromatographic Strip Assay for Rapid Screening of Bisphenol A Diglycidyl Ether and Its Derivatives in Canned Foods.

Bisphenol A diglycidyl ether (BADGE) is widely present in the inner coating of metal food cans, from which it can migrate into food and generate harmful derivatives during storage, such as bisphenol A (2,3-dihydroxypropyl) glycidyl ether, bisphenol A (3-chloro-2-hydroxypropyl) glycidyl ether, and bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) glycidyl ether. Here, a gold-nanoparticle-based immunochromatographic strip assay based on a broad-spectrum polyclonal antibody was developed for the simultaneous detection of BADGE and its derivatives, which could be accomplished within 15 min. The quantitative analysis of the visualization results was performed using Adobe Photoshop CC 2021, and the detection limit, defined as the concentration causing 15% inhibition, was 0.97 ng/mL. The recoveries of BADGE and its derivatives at various spiking levels in canned food samples ranged from 79.86% to 93.81%. The detection results of the proposed immunochromatographic strip assay were validated via high-performance liquid chromatography, showing a good correlation coefficient (R2 = 0.9580).

Antibacterial and Antibiofilm Activities of Chlorogenic Acid Against Yersinia enterocolitica.

Nowadays, developing new and natural compounds with antibacterial activities from plants has become a promising approach to solve antibiotic resistance of pathogenic bacteria. Chlorogenic acid (CA), as a kind of phenolic acid existing in many plants, has been found to process multifunctional activities including antibacterial activity. Herein, the antibacterial and antibiofilm activities of CA against Yersinia enterocolitica (Y. enterocolitica) were tested for the first time, and its mechanism of action was investigated. It was demonstrated that CA could exert outstanding antibacterial activity against Y. enterocolitica. Biofilm susceptibility assays further indicated that CA could inhibit biofilm formation and decrease the established biofilm biomass of Y. enterocolitica. It was deduced that through binding to Y. enterocolitica, CA destroyed the cell membrane, increased the membrane permeability, and led to bacterial cell damage. In addition, the transcriptomic analysis revealed that CA could disorder many physiological pathways, mainly including the ones of antagonizing biofilms and increasing cell membrane permeability. Finally, the spiked assay showed that the growth of Y. enterocolitica in milk was significantly inhibited by CA. Taken together, CA, as an effective bactericidal effector with application potential, exerts antagonistic activity against Y. enterocolitica by mainly intervening biofilm formation and membrane permeability-related physiological pathways.

Progress in Nanomaterials-Based Enzyme and Aptamer Biosensor for the Detection of Organophosphorus Pesticides.

With the improvement of people's safety awareness, the requirement of pesticide detection is gradually increasing, and many new detection methods toward Organophosphorus pesticide (OPs) has been further developed and applied. Nanomaterials-based biosensors have played an important role in the trace detection of OPs. This article mainly introduces the detection principle of enzymes and aptamers as the identification element of biosensors. Various nanomaterials (i.e., metals and metal oxides, carbon nanotubes, graphene and graphene oxide, quantum dots, metal organic frameworks, molecular imprinted polymers, etc.) possess their unique properties and play different roles in the enzyme and aptamer-based biosensors toward OPs: (a) to produce the optical or electrochemical signal; (b) as a carrier to load the enzyme or aptamer; (c) to enhance the signal response. Besides, the intelligent portable devices provide the possibility to realize the onsite and real-time detection. The limitations of some nanomaterials and the future development are discussed. Finally, the future of enzyme and aptamer-based biosensors has prospected.

Integrated metabonomic-proteomic analysis reveals the effect of glucose stress on metabolic adaptation of Lactococcus lactis ssp. lactis CICC23200.

A combined proteomic and metabonomic approach was used to investigate the metabolism of Lactococcus lactis ssp. lactis subjected to glucose stress treatment. A proteomic method was used to determine 1,427 altered proteins, including 278 proteins with increased expression and 255 proteins with decreased expression. A metabonomic approach was adopted to identify 98 altered metabolites, including 62 metabolites with increased expression and 26 metabolites with decreased expression. The integrated analysis indicated that the RNA and DNA mismatch repair process and energy metabolism were enhanced in response to high-glucose stress in L. lactis. Lactococcus lactis responded to glucose stress by up-regulating oxidoreductase activity, which acted on glycosyl bonds, hydrolase activity, and organic acid transmembrane transporter activity. This led to an improvement in the metabolic flux from glucose to pyruvate, lactate, acetate, and maltose. Down-regulation of amino acid transmembrane transporter, aminoacyl-transfer RNA ligase, hydroxymethyl-, formyl-, and related transferase activities resulted in a decrease in the nitrogen metabolism-associated metabolic pathway, which might be related to inhibition of the production of biogenic amines. Overall, we highlight the response of metabolism to glucose stress and provide potential possibilities for the reduced formation of biogenic amines in improved level of sugar in the dairy fermentation industry. Moreover, according to the demand for industrial production, sugar concentration in fermented foods should be higher, or lower, than a set value that is dependent on bacterial strain and biogenic amine yield.

Research advances of DNA aptasensors for foodborne pathogen detection.

Aptamers, referring to single-stranded DNA or RNA molecules can specifically recognize and bind to their targets. Based on their excellent specificity, sensitivity, high affinity, and simplicity of modification, aptamers offer great potential for pathogen detection and biomolecular screening. This article reviews aptamer screening technologies and aptamer application technologies, including gold-nanoparticle lateral flow assays, fluorescence assays, electrochemical assays, colorimetric assays, and surface-enhanced Raman assays, in the detection of foodborne pathogens. Although notable progress (more rapid, sensitive, and accurate) has been achieved in the field, challenges and drawbacks in their applications still remain to be overcome.

Determination of the geographical origin of maize (Zea mays L.) using mineral element fingerprints.

BACKGROUND: Maize (Zea mays L.) is a staple cereal crop and feed crop throughout the world. In this article, a mineral element fingerprinting technique was applied to single out suitable element indicators to determine the geographical origin of maize. A total of 90 fresh maize samples were collected in 2107 from Jilin, Gansu, and Shandong provinces in China. The contents of 25 mineral elements in all maize samples were measured by inductively coupled plasma mass spectrometry (ICP-MS). The composition of mineral elements was analyzed by multivariate statistical analysis, including one-way analysis of variance (one-way ANOVA), principal component analysis (PCA), k-nearest neighbor (KNN) analysis, and stepwise linear discriminant analysis (SLDA). RESULTS: As compared by one-way ANOVA, the contents of 19 mineral elements in maize samples were significantly different among three provinces. Principal component analysis based on these 19 elements could obtain preliminary visual classification groups of maize samples. K-nearest neighbor analysis produced a total correct classification rate of 83.9% on the training set, and 82.2% on the prediction set. The SLDA model, based on eight indicative elements (Na, Cr, Rb, Sr, Mo, Cs, Ba, and Pb) obtained a total correct classification rate of 92.2% with cross-validation. CONCLUSION: The mineral element fingerprinting technique combined with multivariate statistical analysis could be a helpful method to identify the geographical origin of maize. © 2019 Society of Chemical Industry.

An Enhanced Stability Nanoparticle Preparation by Corn Protein Hydrolysate-Carboxymethyl Chitosan Maillard Conjugates Loaded with Rutin.

Rutin-loaded corn protein hydrolysate-carboxymethyl chitosan (CPH-NOCC) Maillard conjugate nanoparticles (NPs) with superior stability under different NaCl concentrations (0-0.25 mol/L) and pH levels (7.0 to 3.0) were investigated. Results showed that the degree of glycosylation of 53.3%, browning index of 0.6, and SDS-PAGE lane of CPH-NOCC conjugates were obtained after dry heating for 48 hr (60 °C, 79% RH). The high encapsulation efficiency (EE, 97.8%-98.8%) and CPH-NOCC-rutin (98.8%) was significantly higher than CPH-rutin (97.8%) and CPH/NOCC-rutin (98.4%) NPs illustrated that hydrolysis was positive for zein encapsulation, and conjugation of NOCC to CPH increased the EE. Hairy carbohydrate protrusions on the surface of CPH-NOCC-rutin NPs produced a stronger steric effect and hampered the formation of salt bridges and the particle aggregation under CPH isoelectric point at pH 4.0. Therefore, the CPH-NOCC conjugate NPs may be suitable carrier for hydrophobic bioactive substances in a board range of business foodstuffs.

Applications of SERS in the Detection of Stress-Related Substances.

A wide variety of biotic and abiotic stresses continually attack plants and animals, which adversely affect their growth, development, reproduction, and yield realization. To survive under stress conditions, highly sophisticated and efficient tolerance mechanisms have been evolved to adapt to stresses, which consist of the variation of effector molecules playing vital roles in physiological regulation. The development of a sensitive, facile, and rapid analytical methods for stress factors and effector molecules detection is significant for gaining deeper insight into the tolerance mechanisms. As a nondestructive analysis technique, surface-enhanced Raman spectroscopy (SERS) has unique advantages regarding its biosensing applications. It not only provides specific fingerprint spectra of the target molecules, conformation, and structure, but also has universal capacity for simultaneous detection and imaging of targets owing to the narrow width of the Raman vibrational bands. Herein, recent progress on biotic and abiotic stresses, tolerance mechanisms and effector molecules is summarized. Moreover, the development and promising future trends of SERS detection for stress-related substances combined with nanomaterials as substrates and SERS tags are discussed. This comprehensive and critical review might shed light on a new perspective for SERS applications.

Dual Effects of Creatinine on the Formation of 2-Amino-1-Methyl-6-Phenylimidazo [4,5-b]pyridine (PhIP).

Creatinine was found to not only act as a precursor of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) formation but also inhibit PhIP formation in a creatinine/phenylalanine model system. The dual mechanistic effects of creatinine on PhIP formation were then investigated in a model system. Adducts of creatinine-PhIP were detected by quadrupole-time-of-flight mass spectrometry and were found to be a likely explanation for the substantial decrease in the yield of PhIP when excess creatinine was supplied. Structures of probable adducts were predicted in molecular docking studies, which showed that hydrogen bonds were formed between creatinine and PhIP in 1:1 and 2:1 ratios. Furthermore, the active sites during creatinine-PhIP adduct formation (the primary amino groups [N2 -] and sp2 nitrogen atoms [N3 ] of creatinine and PhIP) match the active sites of PhIP metabolism and adducts of PhIP/lipid-derived reactive carbonyls. This verifies that creatinine inhibits PhIP production via the formation of adducts with hydrogen bonds at the N2 and N3 sites. PRACTICAL APPLICATION: This study enhances the understanding of how creatinine affects PhIP formation, reveals a new PhIP inhibition mechanism, and will be useful for developing technology to control PhIP formation during food processing.

Inhibition of 2-Amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) Formation by Alkoxy Radical Scavenging of Flavonoids and Their Quantitative Structure-Activity Relationship in a Model System.

The inhibitory effect of 10 flavonoids on the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in a creatinine-phenylalanine model system was investigated through electronic spin resonance and a quantitative structure-activity relationship. Alkoxy radicals were observed during the heating process, providing evidence for a radical pathway in the formation of PhIP. The alkoxy radical scavenging capability of the flavonoids was proportional to their inhibition of PhIP formation (IC50 ). We deduced that flavonoid inhibition of PhIP generation occurs via scavenging of alkoxy radicals during the heating process. Multiple linear regression and partial least squares models were used to elucidate the relationship between PhIP inhibition activity and structure characteristics of the flavonoids. The lipo-hydro partition coefficient and molecular fractional polar surface area of the flavonoids were found to be predictive of the inhibition effect.

Effects of antioxidants of bamboo leaves and flavonoids on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation in chemical model systems.

The inhibitory effects of antioxidants of bamboo leaves (AOB) and flavonoids against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation were investigated in creatinine and phenylalanine model systems. AOB and the tested flavonoids (orientin, homoorientin, vitexin, isovitex, apigenin, luteolin, isorhamnetin, fisetin, and hesperetin) had significant dose-dependent inhibition effects on PhIP formation with different IC50 values. The superoxide anion (O2(•-)) scavenging activities of these nine flavonoids were evaluated using the pyrogallol autoxidation system. The EC50 values of compounds that showed antioxidant activity were found to correlate well (R(2) = 0.8003) with the corresponding IC50 values representing their inhibition of PhIP formation. It was assumed that the inhibitory effects of flavonoids on PhIP formation were probably achieved by scavenging free radicals generated in the reaction system. These findings provide valuable information for the development of effective strategies to minimize heterocyclic amine content in thermally processed food.

Formation and mitigation of heterocyclic aromatic amines in fried pork.

Heterocyclic aromatic amines (HAAs) are potent mutagens and carcinogens generated during the heat processing of meat. HAAs, which are abundant in processed meat products, include 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), and 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP). The content of these three HAAs in fried pork was determined by LC-MS/MS. The effects of frying time and temperature, sample shape, and addition of antioxidants on the generation of HAAs were investigated. The results show that HAAs were produced during frying, and their levels increased with increasing frying time and temperature. Pork patties had the highest concentration of HAAs compared with pork meatballs and pork strips. The addition of antioxidant of bamboo leaves (AOB), liquorice extract, tea polyphenol, phytic acid and sodium iso-ascorbate to pork before frying had an inhibitory effect on HAA generation, with AOB being the most effective antioxidant. Inhibition levels of nearly 69.73% for MeIQx, 53.59% for 4,8-DiMeIQx and 77.07% for PhIP in fried pork were achieved when the concentrations of AOB added were 0.02, 0.01 and 0.10 g kg⁻¹, respectively.

Tube-immunoassay for rapid detection of carbaryl residues in agricultural products.

An antibody-based rapid, quantitative, and qualitative tube enzyme-linked immunosorbent assay (tube-ELISA) was developed and used to determine carbaryl (1-naphthyl methylcarbamate) residues in agricultural products (apple, Chinese cabbage, rice, and barley). The tube-ELISA is a competitive immunoassay in which the antibody is coated in the polystyrene tube, with a dynamic range between 0.7 and 46.3 microg kg(-1). Carbaryl was extracted from each agricultural sample by hand-shaking with methanol and examined for application to on-site analysis. After the liquid extraction, the sample extracts diluted with buffer were analyzed by rapid tube-ELISA directly. The overall test time was around 15-30 min, including sample preparation and assay performance. The results obtained from tube-ELISA correlated well with high-performance liquid chromatography (R2 > 0.9). The study shows that tube-ELISA is useful as a quality control tool and can be used to quantitatively detect carbaryl as well.

Enzyme immunoassay for the determination of carbaryl residues in agricultural products.

Carbaryl is one of the most important N-methyl carbamate insecticides used all over the world. To determine carbaryl residues in agricultural products (apple, pear, Chinese cabbage, rice and barley), a competitive enzyme-linked immunosorbent assay (ELISA) method was employed, and a simple and efficient extraction method for the rapid detection of carbaryl in agricultural products was developed with recoveries greater than 90%. After liquid extraction, sample extracts diluted with buffer were analysed by ELISA directly. Matrix effects can be avoided when a 1:20 dilution of apple, pear, rice and barley samples and a 1:50 dilution of Chinese cabbage samples with 0.5% fish skin gelation in phosphate-buffered saline containing 5% methanol. Sample extracts were analysed by ELISA and HPLC, and results obtained by two methods correlated well; the correlation was greater than 0.9.