Modified Enzymatic Assays for the Determination of Histamine in Fermented Foods

Multifunctional Lactiplantibacillus plantarum SQ1 from Baijiu Daqu: Application of histamine degradation and probiotic potential in yogurt production

Yogurt in this study is a milk drink with probiotics added during the fermentation process and has a variety of ingredients. To identify microorganisms capable of efficiently degrading histamine, thereby enhancing yogurt's quality and safety. This study focused on screening Lactiplantibacillus plantarum (L. plantarum) from Baijiu Daqu (saccharification starter for Baijiu brewing), which exhibits histamine-reducing properties through biological characterization and molecular biology techniques. The results indicated that the strain has an optimal growth temperature of 37 °C, can survive within a pH range of 3 to 9, and demonstrates tolerance levels for sugar (4 % to 12 %) and salt (1 % to 7 %). Additionally, it possesses notable surface hydrophobicity and self-aggregation capabilities, along with robust survival rates in gastrointestinal fluids and bile salts. This strain also produces more than 40 flavor compounds, including trimethylpyrazine, pyrrole, and phenylglyoxal; its metabolites inhibit certain pathogenic bacteria, such as Escherichia coli (E. coli) and Pseudomonas putida (P. putida). Following co-fermentation with this bacterium in yogurt, there was a significant reduction in histamine levels-achieving a degradation rate of (41.74 ± 1.86)%. In the study, genes related to histamine degradation, such as the multicopper oxidase gene (cueO, EC: 1.16.3.4) and glyceraldehyde-3-phosphate dehydrogenase (gapA, EC: 1.2.1.12), were found to be present L. plantarum SQ1 by whole genome sequencing. This research provides technical support for reducing histamine concentrations in the manufacturing process of high-histamine fermented foods such as yogurt or aged vinegar, thereby reducing the risk of adverse reactions to consumers and laying the theoretical foundation for safer and healthier dairy production.

Au@Ag Core-Shell Nanoparticles for Colorimetric and Surface-Enhanced Raman-Scattering-Based Multiplex Competitive Lateral Flow Immunoassay for the Simultaneous Detection of Histamine and Parvalbumin in Fish

Foodborne allergies and illnesses represent a major global health concern. In particular, fish can trigger life-threatening food allergic reactions and poisoning effects, mainly caused by the ingestion of parvalbumin toxin. Additionally, preformed histamine in less-than-fresh fish serves as a toxicological alert. Consequently, the analytical assessment of parvalbumin and histamine levels in fish becomes a critical public health safety measure. The multiplex detection of both analytes has emerged as an important issue. The analytical detection of parvalbumin and histamine requires different assays; while the determination of parvalbumin is commonly carried out by enzyme-linked immunosorbent assay, histamine is analyzed by high-performance liquid chromatography. In this study, we present an approach for multiplexing detection and quantification of trace amounts of parvalbumin and histamine in canned fish. This is achieved through a colorimetric and surface-enhanced Raman-scattering-based competitive lateral flow assay (SERS-LFIA) employing plasmonic nanoparticles. Two distinct SERS nanotags tailored for histamine or β-parvalbumin detection were synthesized. Initially, spherical 50 nm Au@Ag core-shell nanoparticles (Au@Ag NPs) were encoded with either rhodamine B isothiocyanate (RBITC) or malachite green isothiocyanate (MGITC). Subsequently, these nanoparticles were bioconjugated with anti-β-parvalbumin and antihistamine, forming the basis for our detection and quantification methodology. Additionally, our approach demonstrates the use of SERS-LFIA for the sensitive and multiplexed detection of parvalbumin and histamine on a single test line, paving the way for on-site detection employing portable Raman instruments.

Modulating Substrate Specificity of Rhizobium sp. Histamine Dehydrogenase through Protein Engineering for Food Quality Applications

Histamine is a biogenic amine found in fish-derived and fermented food products with physiological relevance since its concentration is proportional to food spoilage and health risk for sensitive consumers. There are various analytical methods for histamine quantification from food samples; however, a simple and quick enzymatic detection and quantification method is highly desirable. Histamine dehydrogenase (HDH) is a candidate for enzymatic histamine detection; however, other biogenic amines can change its activity or produce false positive results with an observed substrate inhibition at higher concentrations. In this work, we studied the effect of site saturation mutagenesis in Rhizobium sp. Histamine Dehydrogenase (Rsp HDH) in nine amino acid positions selected through structural alignment analysis, substrate docking, and proximity to the proposed histamine-binding site. The resulting libraries were screened for histamine and agmatine activity. Variants from two libraries (positions 72 and 110) showed improved histamine/agmatine activity ratio, decreased substrate inhibition, and maintained thermal resistance. In addition, activity characterization of the identified Phe72Thr and Asn110Val HDH variants showed a clear substrate inhibition curve for histamine and modified kinetic parameters. The observed maximum velocity (V_max) increased for variant Phe72Thr at the cost of an increased value for the Michaelis-Menten constant (K_m) for histamine. The increased K_m value, decreased substrate inhibition, and biogenic amine interference observed for variant Phe72Thr support a tradeoff between substrate affinity and substrate inhibition in the catalytic mechanism of HDHs. Considering this tradeoff for future enzyme engineering of HDH could lead to breakthroughs in performance increases and understanding of this enzyme class.

In vitro evaluation of antibacterial nanomaterial-induced anaphylactoid reaction for indwelling catheters

Background

To prevent tunnel infection of indwelling catheters, impregnation with antiseptics or antibiotics is effective. However, 13 patients using chlorhexidine–silver sulfadiazine-impregnated catheters experienced serious anaphylactic shock in Japan. Thus, it is necessary to select a suitable evaluation method for allergic reactions and develop a novel antibacterial coating material that does not cause anaphylactic reaction.

Methods

Two types of highly dispersible and antibacterial nanoparticles—fluorine (F)-doped hydroxyapatite (HAp) and zinc (Zn)-doped HAp—were tested using of the system and compared with compound 48/80 (c48/80) as a histamine releaser and chlorhexidine gluconate (CHG) as an anaphylactic inducer.

Results

The histamine concentrations secreted from HMC-1 cells remained mostly the same even with the addition of F-HAp and Zn-HAp. On the contrary, the levels of the chemical mediators from the cells by the addition of F-HAp and Zn-HAp were significantly lower than those of only c48/80 and CHG without the addition of HAp.

Conclusions

The assay was a well-evaluated method for quantifying histamine concentrations released from HMC-1 cells. Our study induced HMC-1 cells accompanied with and without the nanomaterials; the potential of F-HAp and Zn-HAp to induce allergic reactions was found to be quite low. Therefore, the antibacterial nanomaterials are expected to hardly induce anaphylactoid reactions.

Formation, Analytical Methods, Change Tendency, and Control Strategies of Biogenic Amines in Canned Aquatic Products: A Systematic Review

ABSTRACT

Biogenic amines (BAs) are organic compounds with low molecular weight and can be used as indicators of the quality and safety of canned aquatic products during processing and storage. However, excess of these amines can cause foodborne poisoning. Therefore, the determination, analysis, and prevention of BAs are of great importance. This article focuses on the sources, formation, and pretreatment methods, as well as analytical techniques, change tendency, and control techniques of BAs, with the aim of promoting more appropriate analysis of canned aquatic products to provide a reference for the food industries.

HIGHLIGHTS