Impact of the rearing environment on the metabolism of shrimps and tracing the origins and species of shrimps using specific metabolites.

Herein, the link between rearing environmental condition and metabolism was explored. Metabolite fingerprint datasets of black tiger shrimp (Penaeus monodon) from three production sites were collected and studied using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and HPLC-MS/MS. Two compounds, benzisothiazolinone and hippuric acid, were identified to be potentially related to pollution in the rearing environment and showed different abundances in the analysed shrimp samples with different origins. Furthermore, metabolomic analysis on three shrimp species, black tiger shrimp, kuruma shrimp (Penaeus japonicus) and sword shrimp (Parapenaeopsis hardwickii), under an identical rearing environment was also conducted. Two compounds, diethanolamine and benzisothiazolinone, potentially linked with pollution in the rearing environment were identified. The present protocol holds promise to be extended to the studies of exploring the relationship between rearing environmental conditions and metabolism. Furthermore, the analysis of single-blind samples was conducted. The results show that specific metabolites can be utilized as markers for tracing the origins of shrimp samples. The present protocol holds potential for application in tracing the origin and species of certain seafoods.

Quantum dots (QDs) attached magnetic beads (MBs) for on-chip efficient capture and detection of bacteria in ready-to-eat (RTE) foods.

In this study, we established a versatile and simple magnetic-assisted microfluidic method for fast bacterial detection. Quantum dots (QDs) were loaded onto magnetic beads (MBs) to construct performance enhanced on-chip capture of bacteria. Escherichia coli (E. coli), as a model bacterium was studied. CdSe QDs were deposited onto the surface of Fe3O4 MBs through layer-by-layer self-assembly to enhance the loading of antibodies (Abs). MBs functionalized with anti-E. coli antibody molecules in a micropillar-based microfluidic chip were utilized to capture E. coli, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used for characterization of captured bacteria. This method was found capable of specifically isolating E. coli within the range of 1.0 to 1.0 × 109 CFU/mL, having a detection limit (LOD) of 10 CFU/mL. The average similarity score among mass spectra for the bacterial capture obtained in independent experiments is calculated as 0.97 ± 0.01 (n = 3), which shows this work's excellent reproducibility for bacterial capture. Bacterial growth on ready-to-eat (RTE) foods during its time of storage was successfully monitored. The present protocol has promising potential for microbial control and pathogen detection in the food industry.

On-Chip Discovery of Allergens from the Exudate of Large Yellow Croaker (Larimichthys Crocea) Muscle Food by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.

It is extremely crucial to establish facile, accurate, and fast methods for testing allergenic proteins (allergens) in seafood. The current study focuses on the evaluation of fish muscle exudate proteins in an effort to discover potential allergens in fish exudate for allergy tests. Large yellow croaker (Larimichthys crocea) was studied as a seafood model. Magnetic beads (MBs) modified with an IgE antibody were utilized to isolate allergens existing in the exudate sample. Immunoglobulin E (IgE) in blood is a class of antibodies that is mainly associated with allergic reactions. Potential allergens in the muscle exudate were fished by IgE-biofunctional MBs in microfluidic channels. The protein-attached MBs were isolated under a magnetic field, eluted, and collected. The collected eluent was digested and analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to identify allergens. Eight allergens from large yellow croaker exudate were identified, i.e., parvalbumin beta, parvalbumin, protein S100, histone H4, cytochrome c, fatty acid binding protein 3 (FABP3), microsomal glutamate S-transfer 3 (MGST3), and C-C motif chemokine 21 (CCL21). The presently proposed microfluidic-magnetic-based allergen extraction protocol enables a facile and rapid test of potentials of seafood allergies, providing a solution to circumvent food safety issues, especially for allergic populations.

Microchip coupled with MALDI-TOF MS for the investigation of bacterial contamination of fish muscle products.

Bacterial contamination is a significant concern in food safety. Traditional methods, though being a gold standard for bacterial detection, are time-consuming. In this work, we managed to establish a simple and versatile magnetic-assisted microfluidic method for rapid bacterial detection of fish muscle products, by manipulating anti-human IgG functionalized magnetic beads in a zig-zag shaped microfluidic channel, increasing the probability for bacteria capture. The captured bacteria were characterized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). This method is capable of isolating Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae from 5 µL of sablefish sarcoplasmic protein sample, and detecting Escherichia coli in the range of 6.0 to 6.0×104 CFU/mL with a detection limit of 6 CFU/mL. Bacterial growth on salmon sashimi during its period of storage was successfully monitored. The current protocol holds great potential for pathogen detection and microbial control in the food industry.

MALDI-TOF MS and Magnetic Beads for Rapid Seafood Allergen Tests.

We developed a strategy using immunomagnetic separation (IMS) coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to test seafood allergens. The protocol employed commercial magnetic beads (MBs) functionalized with anti-human IgE antibodies to carry out the IMS of IgEs in blood samples, followed by capture of allergens from seafood protein extracts for allergy analysis. After elution, the captured allergens were identified by MALDI-TOF MS and HPLC-MS/MS. The non-specific adsorption of MBs to biomolecules, the reproducibility and sensitivity of the protocol were investigated. The method shows consistent results with enzyme-linked immunosorbent assay tests. The false positive rate of the present method for the allergy test is 0%. The protocol was applied to detect the allergens in greasy-back shrimp for checking the allergenicity of patients' serum. Cooking fish as soup may effectively decrease the allergenicity. The method can be potentially used to identify unknown allergens of seafood to ensure the safety of allergic patients.