Discrimination of three commercial tuna species through species-specific peptides: From high-resolution mass spectrometry discovery to MRM validation.

The risk of tuna adulteration is high driven by economic benefits. The authenticity of tuna is required to protect both consumers and tuna stocks. Given this, the study is designed to identify species-specific peptides for distinguishing three commercial tropical tuna species. The peptides derived from trypsin digestion were separated and detected using ultrahigh-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) in data-dependent acquisition (DDA) mode. Venn analysis showed that there were differences in peptide composition among the three tested tuna species. The biological specificity screening through the National Center for Biotechnology Information's Basic Local Alignment Search Tool (NCBI BLAST) revealed that 93 peptides could serve as potential species-specific peptides. Finally, the detection specificity of species-specific peptides of raw meats and processed products was carried out by multiple reaction monitoring (MRM) mode based on a Q-Trap mass spectrometer. The results showed that three, one and two peptides of Katsuwonus pelamis, Thunnus obesus and Thunnus albacores, respectively could serve as species-specific peptides.

Differentiation of three commercial tuna species through GC-Q-TOF and UPLC-Q/Orbitrap mass spectrometry-based metabolomics and chemometrics.

Food fraud is common in the tuna industry because of the economic benefits involved. Ensuring the authenticity of tuna species is crucial for protecting both consumers and tuna stocks. In this study, GC-Q-TOF and UPLC-Q/Orbitrap mass spectrometry-based metabolomics were used to investigate the metabolite profiles of three commercial tuna species (skipjack tuna, bigeye tuna and yellowfin tuna). A total of 22 and 77 metabolites were identified with high confidence using GC-Q-TOF and UPLC-Q/Orbitrap mass spectrometry, respectively. Further screening via chemometrics revealed that 38 metabolites could potentially serve as potential biomarkers. Hierarchical cluster analysis showed that the screened metabolite biomarkers successfully distinguished the three tested tuna species. Furthermore, a total of 27 metabolic pathways were identified through enrichment analysis based on the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways.

Differentiation of three commercial tuna species through Q-Exactive Orbitrap mass spectrometry based lipidomics and chemometrics.

Mislabeling and adulteration of tuna are common due to the diminishing of morphological characteristics during processing. The tuna authenticity is now being focused in the seafood supply chain. In this study, the lipid profiles of 3 commercial tuna species (skipjack tuna, bigeye tuna and yellowfin tuna) were investigated via ultra-high performance liquid chromatography coupled with Q-Exactive Orbitrap mass spectrometry (UPLC-Q-Exactive Orbitrap MS). A total of 439 lipid species were identified and semi-quantitated by MS-DIAL. Further biomarkers discovery was carried out by chemometrics, leading to 27 lipids being identified as potential lipid biomarkers. Comparisons to reference standards revealed that lipid biomarkers were effective for discrimination of different tuna species. Interestingly, the proposed lipid biomarkers were all glycerophospholipids, implying that they might be the focus of future study.

Identification of novel antioxidant peptide from porcine plasma hydrolysate and its effect in in vitro digestion/HepG2 cells model.

A novel antioxidant peptide EDEQKFWGK from porcine plasma hydrolysate (PPH) was separated by chromatography, HPLC, and identified by LC-MS/MS. Results showed that EDEQKFWGK had better antioxidant ability (Hydroxyl RAS 32.19%, ABTS RAS 92.93% and DPPH RAS 26.76%) compared with glutathione (30.11%, 82.01%, 26.44%) due to the presence of hydrophobic, aromatic acids (F, W) and acidic amino acids (E, D), decreasing ROS by providing hydrogen atom and chelating metal ions. Furthermore, the antioxidant properties of synthetic EDEQKFWGK still significant despite in vitro digestion because of the production of smaller active peptide. Additionally, it could increase SOD, CAT, GSH-Px to resist oxidative damage in HepG2 cells by inhibiting ROS (O2- , OH·), forming complexes to prevent OH· from destroying DNA and binding to ARE to promote antioxidase expression. Thereby, the novel peptide EDEQKFWGK from porcine plasma had much stable antioxidant properties and hade great potential in formulating functional foods. PRACTICAL APPLICATIONS: This research isolated a novel antioxidant peptide. Moreover, the antioxidant effects of peptide were confirmed under the in vitro digestion model and oxidative damage HepG2 cells model. The results showed the antioxidant peptide could play better effect after digestion and protect the cells from oxidative damage. These data could expand the sequence data of antioxidant peptides and promote the high-value utilization of PPH.

Chitosan-based films with antioxidant of bamboo leaves and ZnO nanoparticles for application in active food packaging.

The function of chitosan film was reinforced by ZnO nanoparticles and antioxidant of bamboo leaves (AOB) for food packaging application. The results of structural characterization indicated the good compatibility among chitosan, ZnO nanoparticles and AOB. The chitosan film had the best mechanical strength and the highest light transmittance. The addition of AOB remarkably reduced the UV light transmittance and significantly enhanced the antioxidant activity of the films. Meanwhile, AOB and ZnO nanoparticles synergistically enhanced the antibacterial activity against E. coli and S. aureus. Our results suggested that the chitosan/ZnO/AOB films could be applied as potential active packaging materials in food industry to extend the shelf-life of packaged food.

pH-sensitive and antibacterial films developed by incorporating anthocyanins extracted from purple potato or roselle into chitosan/polyvinyl alcohol/nano-ZnO matrix: Comparative study.

pH-sensitive and antibacterial films based on chitosan/polyvinyl alcohol/nano-ZnO (CPZ) containing anthocyanins extracted from purple potato (PPE) or roselle (RE) were developed. When incorporated with PPE or RE, the moisture contents and flexibility of film significantly reduced (P < 0.05), while mechanical resistance of film was significantly enhanced (P < 0.05). Water vapor permeability (WVP) of film was slightly influenced by the addition of PPE or RE (P > 0.05). CPZ-RE film exhibited darker color and lower light transmittance than CPZ-PPE film at the same incorporation level. CPZ-PPE and CPZ-RE films exhibited distinguishable color changes in different pH buffer solutions. CPZ-PPE films exhibited higher antibacterial activity against Escherichia coli and Staphylococcus aureus than CPZ-RE films. Moreover, film could effectively monitor spoilage degree of shrimp when film changed from purple to light-green. Our results suggested CPZ-PPE and CPZ-RE films have promising potential as active and smart packaging materials for applications in food industry.

Uncovering proteome variations of differently heat-treated sea cucumber (Apostichopus japonicus) by label-free mass spectrometry.

The effects of heat treatment on the proteome of Apostichopus japonicus have been evaluated using label-free quantitative proteomics by ultrahigh performance liquid chromatography-quadrupole/time of flight (UHPLC-Q/TOF) mass spectrometry with sequential window acquisition of all the theoretical fragment ion (SWATH) acquisition mode. Chemometric tools are integrated to reveal proteomic changes by mining the protein quantitation data from fresh and differently heat-treated samples. SWATH allows the quantitation of 548 proteins, of which 24 proteins are significantly sensitive to heat treatment and 13 proteins vary significantly responding to different heat procedures (boiling, steaming, and microwave heating), and 5 of them are sharing proteins. Gene ontology (GO) annotation of the differentiating proteins highlights most of them are relevant to molecular functions. The results can be favorable to evaluate the effects of heat treatment on the nutrition and function of processed sea cucumbers and facilitate the selection of an optimal thermal treatment.

Discrimination of dried sea cucumber (Apostichopus japonicus) products from different geographical origins by sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH-MS)-based proteomic analysis and chemometrics.

The article reports on discrimination of dried sea cucumber Apostichopus japonicus (A. japonicus) products from different geographical regions in China (Xiapu, Jiaonan, Weihai, Yantai, Dalian). For this purpose, sequential window acquisition of all theoretical fragment ion mass spectra (SWATH-MS)-based proteomic analysis combined with chemometrics was evaluated. Proteome variations of A. japonicus samples determined by SWATH-MS using ultra-high performance liquid chromatography coupled to quadrupole time of flight mass spectrometer were mined by chemometric tools to clarify the correlation between protein quantitation data and geographical origin. A differentiating OPLS-DA model was constructed with 55 SWATH-MS quantified proteins. A. japonicus samples from five locations were clearly classified by the developed OPLS-DA model and 100% prediction accuracy was achieved in validation testing as well as real-life sample analysis. Seventeen proteins were identified as discriminatory biomarkers allowing geographical provenance. The proposed method might be applied in origin authentication of commercially dried A. japonicus products.

Identification of Peptide Biomarkers for Discrimination of Shrimp Species through SWATH-MS-Based Proteomics and Chemometrics.

Incorrect labeling and adulteration of shrimp occurs due to interspecies similarities and carapace removal during processing. This study attempted to identify three related commercial shrimp species of the order Decapoda: Marsupenaeus japonicus, Fenneropenaeus chinensis, and Litopenaeus vannamei. All measurable trypsin-digested peptides in the individual shrimp were detected using ultrahigh-performance liquid chromatography quadrupole time-of-flight (UPLC-Q-TOF) mass spectrometry with sequential window acquisition of all theoretical fragment ion spectra (SWATH) data-independent acquisition. Further analysis of peptide biomarkers was carried out with an orthogonal partial least-squares discriminant analysis (OPLS-DA) model. BLAST was used for species-specific analysis. Subsequently, multiple reaction monitoring (MRM) methods were developed for sensitivity and selectivity screening of the selected peptides, and 27 were identified as biomarkers allowing rapid and accurate discrimination of shrimp species without high-resolution mass spectrometry or statistical model building. These strategies could be applied in authentication of other products containing highly homologous proteomes.

[Correlation of clinical features with pathology in chronic viral hepatitis].

BACKGROUND: To investigate the correlation of clinical features with pathology in chronic viral hepatitis (CH). METHODS: Analyses of single factor and multiple factors of serum biochemical indices, imaging examination results, symptoms and signs with degree of pathological lesion of hepatic tissue in 973 cases of CH were conducted. Meanwhile, the hepatic functional index (AAPEA index) was used to investigate the role of serum biochemical indices in diagnosis of CH. RESULTS: In these patients with CH,the severity of hepatic lesion was closely correlated to symptoms and signs, biochemical indices such as PTA, ALT, TBIL, ALB, A/G, gamma-globulin (gamma-G) by electrophoresis, AST and cholinesterase (CHE) as well as splenic thickness. AST was superior to ALT in reflecting degree of hepatic inflammatory activity. The total mistaken judgment rate of multiple factor analysis was 28.1%. The correlation coefficient of AAPEA index to degrees of hepatic inflammatory activity, fibrosis and pathological grading was 0.559, 0.545 and 0.529, respectively (P<0.000 1) CONCLUSIONS: The biochemical indices such as PTA, ALT, TBIL, ALB, A/G, gammaG, AST, CHE and the determination of splenic thickness by ultrasonography B could reflect hepatic pathological changes to certain extent. AST was superior to ALT in reflecting degree of hepatic inflammatory activity. Incorrect judgment rate was high in determination of moderate and severe CH by multiple factor analysis. Conformity rate between AAPEA index and pathological diagnosis was better than any of them alone in diagnosing CH.