查看更多>>摘要：Tropomyosin (TM), a major allergen in shellfish, has raised increasing concern in industrialized countries and resulted in an urgent need for accurate, simple, and sensitive methods for tracing its presence in food products. Herein, we proposed a sandwich biosensor that employed the rationally imprinted magnetic particles and aptamer modified carbon dots for the detection of TM in seafood products. The multi-point initiated polydopamine was employed as molecular imprinting polymer on magnetic particles, which was subjected to antifouling surface modification to achieve efficient separation of TM. By taking the aptamer modified carbon dots as signal probes, a sandwich assay was achieved with the limit of detection (LOD) being 30.76 ng mL(-1) (S/N = 3). The proposed method not only possessed excellent specificity towards TM but exhibited great accuracy. The sandwich biosensor was further used to quantitatively analyze TM in five shrimp and five shrimp processed products, which proved that the proposed biosensor could detect TM in commercial samples and had a great application prospect.
Neves, Marina De GeaPoppi, Ronei JesusBreitkreitz, Marcia Cristina
8页
查看更多>>摘要：This study aimed at developing a non-invasive and rapid method to determine the authenticity of plant-based protein powders (free of soy, lactose, and gluten), and classify possible adulterations in the powders using near-infrared spectroscopy (NIR) and chemometric tools. Three potential powder adulterants were investigated: soy protein, whey (lactose source), and wheat (gluten source). The goal was to achieve untargeted and targeted detection to solve problems related to the authentication of the protein powders and the classification of the adulterants. For this purpose, the OC-PLS (one-class partial least squares) model was used for authentication and the PLS2-DA (partial least squares discriminant analysis) model was used to classify the adulterants. VIP (variable importance in projection) scores were used to confirm the main relevant variables and spectral ranges were responsible for each class in PLS2-DA. Laboratory samples were prepared by adding 10, 15, 20, 25, 30, 35 and 40% (w/w) of each adulterant into pure plant-based protein powder samples. In total, 47 pure plant-based protein powder samples and 144 adulterated samples were analyzed. The analysis results indicate a promising way of combining one-class (OC-PLS) with multiclass (PLS-DA) methods, in tandem with NIR to investigate plant-based protein powders. Due to the speed, high sensitivity, and specificity of the methodology, and no requirement of sample preparation, the proposed methodology could be successfully used in a range of 10-40% of adulteration, to verify the authenticity of the plant-based protein powders and to classify adulterants into soy, whey, and wheat.
查看更多>>摘要：Drying processes can be performed using different methods, with the selected technique and operational conditions directly influencing the quality of the final product. The aim of this work was to evaluate the effect of the heating tray temperature (without temperature control, and controlled at 30, 40, and 50 degrees C) used for lyophilization of avocado (cv. Breda) pulp, considering the process drying time and the following quality parameters: dynamic equilibrium moisture, colorimetric indices, phenolic compounds, and antioxidant activity of the fruit pulp. Greater browning was observed for the dehydrated paste samples (82.48-139.15%), compared to the fresh fruit (64.27%). The best results for phenolic compounds (8 and 10.23 mg EAG/g db for slice and paste samples, respectively) and antioxidant activity (41.08 and 60.53% for slice and paste samples, respectively) were found for lyophilization with the heating tray temperature controlled at 50 degrees C. Control of the temperature was effective in decreasing the process drying time), achieving reductions of between 48 and 60% (about 12.5 and 6.3 h for slice and paste samples respectively), compared to lyophilization without temperature control.
查看更多>>摘要：Poly(butylene adipate-co-terephthalate) (PBAT), poly(butylene succinate) (PBS) and linear low-density poly-ethylene (LLDPE) were blended to produce bio-based packaging via blown-film extrusion. Blend ratios modified morphology, crystallinity and relaxation temperatures (T-alpha) of the films. Binary mixtures caused phase separation and non-homogeneous fibrous microstructures of immiscible polymers. Bio-based blend films containing LLDPE (LLDPE/PBAT and LLDPE/PBS) gave less homogeneous structures than PBAT/PBS films. The formation of ori-ented fibrous networks subsequently controlled mechanical and barrier properties of the blend films. LLDPE blending modified C=O carbonyl groups in PBAT and PBS, forming voids in topographic images indicating in-compatibility. PBAT and PBS blends showed good compatibility and adhesion of polymer interface, causing smooth and compact structures with minimal surface roughness. Incorporation of PBAT and PBS sharply reduced crystallinity of LLDPE/PBAT and LLDPE/PBS films. LLDPE/PBAT blends had lower T-alpha than neat PBAT and LLDPE, while T-alpha of PBAT/PBS blends proportionally decreased at increasing PBS which indicated diverse polymer miscibility and molecular mobility. Water vapor permeability (WVP) and oxygen permeability (OP) fitted with polynomial and exponential equations, respectively and depended on blend ratios. Films containing higher PBS had combined higher WVP and lower OP, delaying fungal growth in packaged bread due to dehy-dration. Ratios of PBAT, PBS and LLDPE blend films clearly affected mold growth and crumb hardness during storage. Regardless of film components, the firmness of bread crumbs increased linearly with package WVP. Conversely, mold growth had insignificant correlation with OP. Moisture loss from bread crumbs due to high WVP showed dominant effects on microbial growth. Blending PBAT and PBS modified the morphology and permeability of bio-based films and increased the shelf-life of packaged bread.
查看更多>>摘要：In this study, we designed a zinc-based porphyrin metal-organic framework (Zn-TCPP-MOF) for ultra-sensitive and quantitative detecting BPA as a novel luminescent sensor. The fluorescence experiments revealed that the detectable limit of Zn-TCPP-MOF against BPA was far lower than many other reportorial methods. Moreover, an apparent quenching merely occurs when Zn-TCPP-MOF encountered BPA compared with the other phenolic compounds that usually coexist with BPA in food plastic packaging and it will not be interfered as well. During the adsorption experiments, the Zn-TCPP-MOF exhibited the most evident adsorption performance for BPA, the zeta potential tests showed the other phenolic compounds could not significantly change the surface potential of Zn-TCPP-MOF except BPA. The highly sensitive and selective fluorescence quenching mechanism as follow, the structural characteristics of BPA and Zn-TCPP-MOF make them conducive to electrostatic interaction that strengthens the adsorption of Zn-TCPP-MOF to BPA. Furthermore, based on cyclic voltammetry (CV) and Kubelka-Munk diagram to calculate molecular orbital energies, we found that the excited state of the ligand (TCPP) in MOFs is at a higher energy level than the LUMO of BPA which allows existing a driving force for the transfer of excited electrons from TCPP to BPA, thus promote the occurrence of luminescence quenching.
查看更多>>摘要：Non typhoidal Salmonella spp. are among the leading causes of foodborne illness in the U.S. Some 20% of foodborne illnesses attributed to Salmonella can be associated with poultry and poultry products. Industry efforts to lower the incidence of Salmonella have been successful, but the number of illnesses from contaminated poultry has not seen a concomitant drop. In this review, the historical background of Salmonella assessment in poultry at the processing plant will be presented along with the problems inherent with current methods. In addition, opportunities for improvement via the availability of emerging detection and identification technologies as well as other food safety measures that can be taken such as consumer education.
查看更多>>摘要：Herein, a soluble tetramine phthalocyanine indium-decorated reduced graphene oxide (rGO-InTAPc) nano composite was prepared via non-covalent functionalization and used to construct a novel electrochemical sensor for sensitive determination of rutin in Tartary buckwheat tea. The rGO-InTAPc as an improved electrode material can significantly increase the electroactive surface area and electron transfer capacity. Moreover, the electrochemical response can be dramatically expanded by the enrichment effect of rutin through the adsorption of 7C-7C stacking. Under optimized conditions, the rGO-InTAPc sensor displayed a linear dependence for rutin concentration ranging from 0.005 to 100 mu M with a detection limit of 2.0 nM (S/N = 3). The proposed sensor with excellent selectivity and reproducibility was quantitatively validated in commercially available Tartary buckwheat tea with rutin level ranging of 9.06-13.87 mg/g, which results were highly consistent with these of HPLC. This strategy of rutin detection will address a long-standing analytical challenge to establishing facile and sensitive methods for quality monitoring in tea drinks.
查看更多>>摘要：The present study aimed to develop a novel enzyme immunoassay (EIA) for the tremorgenic mycotoxin, penitrem A (PTA). This competitive EIA, based on rabbit anti-PTA polyclonal antibodies and a PTA-bovine serum albumin conjugate, yielded a mean standard curve detection limit of 220 ng/mL. The PTA-EIA, together with two EIAs for paxilline (PAX) and ergoline alkaloids, were used to study the toxin profiles in culture of fungi isolated from some naturally infected food sample materials, including dairy products, citrus fruits, and walnuts. PTA was produced by eight out of 27 mycelium extracts from malt extract agar and Sabouraud glucose chloramphenicol selective agar (2-200 mu g/mL). Ten isolates from all types of food were also positive in the PAX-EIA (0.004-4 mu g/ mL). The EIA for ergoline alkaloids yielded positive results (0.0002-0.4 mu g/mL) in isolates from dairy products and from walnuts, but not from citrus fruits. Control analyses of selected fungal extracts by HPLC-MS/MS for PTA and PAX qualitatively confirmed the EIA results, poor quantitative agreement could be attributed to the presence of penitrems other than PTA, and to PAX analogues, respectively. Selected PTA-positive fungal isolates were subjected to sequencing of the internal transcribed spacer region and the beta-tubulin gene, and were identified as Penicillium polonicum and P. crustosum. In conclusion, Penicillium spp. capable to produce PTA, PAX, and ergoline alkaloids, either alone or in combination, appear to be quite common as contaminants on foods at the retail or production level. Some are capable to produce PTA in culture at high levels, which would have to be considered as toxic if present in food.
查看更多>>摘要：Controlled release of antimicrobial agents is an efficient and promising technology for food preservation. Halloysite nanotubes (HNTs) are a novel material that act as carriers of active agents, while also providing a pathway for sustained release. By using coatings that responded to their environment, we were able to obtain controlled release such that the desired amounts of active agents were delivered to the packaged food at the desired time. In this study, we loaded cinnamaldehyde into HNTs lumen, and used opposite charged poly electrolytes to cap the ends of the HNTs to control the release of cinnamaldehyde. Fourier transform infrared spectroscopy (FTIR), Brunauer, Emmett, Teller's test (BET) thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), cumulative release rate, and fumigant antibacterial activity were conducted to evaluate the performance of the encapsulated samples. Tube-like morphology of the HNTs, and the location of cinnamaldehyde and polyelectrolytes were identified. The results showed that the stimuli-responsive layer formed by polyelectrolytes exhibited different release rate at different pH values. At higher pH, the polyelectrolytes layer restrained transportation of active molecules, while at lower pH, the coating assisted the release of cinnamaldehyde. Additionally, results of antimicrobial test in vitro illustrated significant fumigant antimicrobial activity of cinnamaldehyde/polyelectrolytes functionalized HNTs. To further learn the preservative effect of samples in food packaging, we conducted a pilot study of packed fresh wheat noodles with the designed nanocomposites, and tested total plate count, pH, color change and environmental-SEM of noodles. Results indicated that the nanocomposites with controlled pH-responsive cinnamaldehyde release is a promising packaging technology for extending the shelf-life of fresh wheat noodles.
查看更多>>摘要：Agar is a common adulterant of edible bird's nest (EBN) and is often added in preparation of EBN products. Currently, there is no method that can be used to assess agar content in products because it is difficult to analyze a macromolecule that does not absorb UV. Herein, we report an efficient qualitative and quantitative method for detecting agar in food products based on a daughter oligosaccharide-marker approach. There are three steps: 1) acid hydrolysis of parent agar to release daughter oligosaccharides, 2) p-aminobenzoic ethyl ester (ABEE) labeling, 3) Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (LC-QTOF-MS) analysis. Twenty-four daughter oligosaccharides found to be specific to agar were selected as qualitative authentication markers. One of them, which showed high signal abundance and satisfactory linearity with standard agar, was selected as the assay marker; and it was identified as neoagarotetraose by comparing with standard references. Based on this marker, a qualitative and quantitative analytical method was successfully developed and wellvalidated in terms of linearity, precision, repeatability, and accuracy. This method revealed that agar is being used as a minor adulterant (one out of 12) in EBN raw material. In this study, 60% of commercial "agar" was, in fact, starch and a significant number of EBN products labeled as having agar either did not contain agar or did not contain the amount listed on the label. It is proved that this oligomer approach can be used to improve quality control of all commercial products labeled as or containing agar. Furthermore, this oligomer approach is efficient and reliable in the quality analysis of other polymers like agar.
NSTL
Elsevier