A tailored dual core-shell magnetic SERS substrate with precise shell-thickness control for trace organophosphorus pesticides residues detection.

For addressing the challenges of strong affinity SERS substrate to organophosphorus pesticides (OPs), herein, a rapid water-assisted layer-by-layer heteronuclear growth method was investigated to grow uniform UiO-66 shell with controllable thickness outside the magnetic core and provide abundant defect sites for OPs adsorption. By further assembling the tailored Au@Ag, a highly sensitive SERS substrate Fe3O4-COOH@UiO-66/Au@Ag (FCUAA) was synthesized with a SERS enhancement factor of 2.11 × 107. The substrate's suitability for the actual vegetable samples (cowpeas and peppers) was confirmed under both destructive and non-destructive detection conditions, showing a strong SERS response to fenthion and triazophos, with limits of detection of 1.21 × 10-5 and 2.96 × 10-3 mg/kg in the vegetables under destructive conditions, and 0.13 and 1.39 ng/cm2 for non-destructive detection, respectively. The FCUAA substrate had high SERS performance, effective adsorption capability for OPs, and demonstrated good applicability, thus exhibiting great potential for rapid detection of trace OPs residues in the food industry.

Preparation of Fe3O4@UiO-66(Zr)@Ag NPs core-shell-satellite structured SERS substrate for trace detection of organophosphorus pesticides residues.

Surface-enhanced Raman spectroscopy (SERS) technology has been revived and developed with the introduction of metal-organic frameworks (MOFs), while more valuable properties of MOFs for SERS substrates remain largely unexplored. This work constructed a new SERS substrate Fe3O4@UiO-66(Zr)@Ag nanoparticles (FUAs) with excellent SERS detection sensitivity, uniformity, reproducibility and stability, exhibiting a high Raman enhancement factor (5.62 × 106), low limit of detection (LOD, 2.11 × 10-11 M) and RSD (12.41 %) for 4-NBT, and maintaining 81 % SERS activity within 60 days. The FUAs took full advantage of the strong affinity of UiO-66(Zr) for organophosphorus pesticides (OPs) to realize trace OPs detection. The LODs of phoxim, triazophos and methyl parathion in apple juice were 0.041, 0.021 and 0.0031 mg/L, respectively, with good linearities ranging from 0.02 or 0.1-50 mg/L, meeting the requirements of the food control standards, indicating that the potentials and prospects of the FUAs SERS substrate for trace detecting OPs in foods.

Functional and bioactive properties of Larimichthys polyactis protein hydrolysates as influenced by plasma functionalized water-ultrasound hybrid treatments and enzyme types.

The effects of plasma functionalized water (PFW) and its combination with ultrasound (UPFW) on the functional and bioactive properties of small yellow croaker protein hydrolysates (SYPHs) produced from three enzymes were investigated. Fluorescence and UV-Vis spectroscopy indicated that SYPHs tended to unfold with increasing intensity and shift in wavelengths to more flexible conformations under PFW and UPFW treatments. Particle size distribution and microstructure analysis revealed that treatments could disrupt aggregation of protein molecules to increase the roughness, specific surface area, and decrease the particle size of peptides during hydrolysis. The partially denatured structure of SYPHs induced by treatments increased the susceptibility of the fish proteins to exogenous enzymes, thereby accelerating the hydrolytic process to yield peptides with improved solubility, decreased emulsifying and foaming properties, and improved enzyme-specific antioxidant properties. The results revealed that the functionality of SYPHs was influenced by the treatment method and the enzyme type employed.

Precision release systems of food bioactive compounds based on metal-organic frameworks: synthesis, mechanisms and recent applications.

Controlled release (CR) systems have become a powerful platform for accurate and effective delivery of bioactive compounds (BCs). Metal-organic frameworks (MOFs) are one of the best BCs-loaded carriers for CR systems. In the review, the principles and methods of the design and synthesis of MOFs-CR systems are summarized in detail, the encapsulation of BCs by MOFs and CR mechanisms are explored, and their biological toxicity and biocompatibility are highlighted and applications in the food industry are discussed. In addition, current challenges in this field and possible future development directions are also presented. MOFs have been proven to encapsulate BCs effectively, including gaseous and solid molecules, and control the release of BCs through spontaneous diffusion or stimulus-response. The solubility, stability and biocompatibility of BCs encapsulated by MOFs are greatly improved, which expands their applications in foods. The effective CR of BCs by MOFs-CR systems is beneficial to assist in maintaining or even improving the quality and safety of food, reduce the BCs usage while increasing the bioavailability. Low- or non-biotoxic MOFs, especially bio-MOFs, show greater application prospects in the food industry.

The effect of electron beam irradiation on IgG binding capacity and conformation of tropomyosin in shrimp.

To evaluate the effect of electron beam (EB) irradiation on IgG binding capacity and conformation of tropomyosin in shrimp (Solenocera melantho), shrimp meat was irradiated with different doses (0, 1, 3, 5, 7, 9 kGy) of EB. IgG binding capacity of TM from shrimp meat was detected by western blot and indirect enzyme-linked immunosorbent assay. The conformation of TM was analyzed with circular dichroism and Fourier transform infrared spectroscopy. Results showed that there was a significant decrease in IgG binding capacity of TM from shrimp meat treated with EB irradiation, with the most significant effect observed at 7 kGy. At this dose, the IgG binding capacity of TM decreased by 59% when compared to the control group. The structural changes were consistent with changes in IgG binding capacity of TM. It was concluded that EB irradiation can reduce the immunoreactivity of shrimp TM by altering its structure.

Effects of electron beam irradiation on the biochemical properties and structure of myofibrillar protein from Tegillarca granosa meat.

The effect of electron beam irradiation at doses of 0-9 kGy on the biochemical properties and structure of myofibrillar protein from Tegillarca granosa (T. granosa) was investigated. There was no effect of irradiation on the surface hydrophobicity of the myofibrillar protein, however total sulfhydryl content and Ca2+-ATPase activity both declined to varying extents with increasing irradiation dose. Irradiation also affected the composition of the myofibrillar protein; with increasing dose of irradiation, the actin, paramyosin and myosin heavy chain contents of the myofibrillar protein were partially degraded. Irradiation reduced the α-helix content and increased the ß-sheet content but these effects were less dependent on the dose of irradiation. The 'hardness', 'gumminess', 'chewiness' and 'resilience' of T. granosa meat were improved at irradiation doses of 3-5 kGy. Collectively, our results support an optimum irradiation dose of 3-5 kGy for the preservation of T. granosa meat.