Occurrence and reduction of biogenic amines in traditional Asian fermented soybean foods: A review

Insights into Genomic Characteristics and Biogenic Amine Degradation Potential and Mechanisms: A Strain of Pediococcus acidilactici Sourced from Doubanjiang

The control of excess biogenic amines (BAs) is crucial for the sustainable development of fermented foods. This study aimed to screen endogenous functional strains in Doubanjiang with the capacity to degrade BAs and to elucidate their application potential. Pediococcus acidilactici L-9 (PA), which was confirmed as a safe strain by phenotypic and genotypic analyses, exhibited an efficient degradation ability on BAs, particularly regarding tyramine. Notably, the degradation of tyramine was maintained at 24.03-50.60% at different temperatures (20-40 °C), pH values (4.0-9.0), and NaCl concentrations (3-18%, w/v). Additionally, genomic data revealed the presence of the laccase-coding gene, which was demonstrated to play a pivotal role in BA degradation by heterologous expression. Further, molecular docking results indicated that the degradation of BA by laccase is closely linked to the electron transfer pathway formed by the substrate and key amino acid residues. Finally, the degradation of tyramine by PA remained within the range of 8.19-64.19% under the simulated system with 6-12% salinity. This study provided valuable insights into the safety of PA and its potential degradation capacity on BAs, particularly in mitigating tyramine accumulation, which could improve the quality of Doubanjiang and other fermented foods.

Fermentation Parameters, Amino Acids Profile, Biogenic Amines Formation, and Bacterial Community of Ensiled Stylo Treated with Formic Acid or Sugar

Substantial proteolysis occurs and free amino acids can be degraded to biogenic amines by decarboxylation during stylo (Stylosanthes guianensis) ensiling. High biogenic amine concentrations in silage are harmful to the health of ruminant animals. The purposes of this work were to (1) analyze the biogenic amines and amino acids concentrations, bacterial composition, and fermentation profile of spontaneously fermented stylo silage, (2) explore the effect of formic acid or sugar additive on these silage parameters, and (3) further reveal the correlations between silage amines and fermentation parameters, amino acids, and bacteria. Freshly chopped stylo was treated with distilled water (control), formic acid (4 mL/kg), and sugar (20 g/kg) and fermented for 28 days. The results indicated that putrescine (321 mg/kg dry matter), cadaverine (384 mg/kg dry matter), and tyramine (127 mg/kg dry matter) rapidly increased in concentration and become predominant in the control silage after 28 days of fermentation. Applying formic acid and sugar at ensiling, especially the acidifier, significantly decreased putrescine, cadaverine, tyramine, and total biogenic amine concentrations compared with the control treatment (p < 0.0001). Clostridium pabulibutyricum, Weissella cibaria and W. paramesenteroides were the predominant bacteria in the control silage, and the application of both additives remarkably lowered their relative abundance in comparison with the control treatment (p < 0.001). Correlation analysis showed that putrescine, cadaverine, and tyramine were positively related to pH, butyric acid, non-protein nitrogen, and ammonia nitrogen (p < 0.01). These amines also had significant correlations with C. pabulibutyricum, W. cibaria and W. paramesenteroides (p < 0.001). Putrescine, cadaverine, and tyramine were the main biogenic amines and C. pabulibutyricum was the predominant undesirable bacterium in naturally fermented stylo silage. C. pabulibutyricum, W. cibaria and W. paramesenteroides were positively related to putrescine, cadaverine, and tyramine formation. The application of formic acid or sugar significantly reduced the undesirable bacterial population and improved the fermentation and hygienic quality of the stylo silage. These findings lay the foundation for further elucidating the microbial mechanism underlying the main biogenic amine formation during fermentation of stylo silage.

Targeted inhibition of biogenic amine-producing strains by spice extracts and control of biogenic amine accumulation in reduced-salt dry sausages

This study aimed to screen spice extracts that can target the inhibition of biogenic amine (BA)-producing bacteria and reduce the BA accumulation in reduced-salt dry sausages. A total of 59 bacterial strains were isolated from reduced-salt dry sausages; among them, three isolates, namely, Staphylococcus epidermidis S1, S. saprophyticus S2, and S. edaphicus S3, had the strongest ability to produce BA. Eight spice extracts, i.e. Angelica dahurica, cinnamon, ginger, clove, fennel, Amomum, nutmeg, and orange peel, were extracted. The inhibition zone diameter and minimum inhibitory concentration indicated that A. dahurica, Amomum, and clove elicited the strongest inhibitory effect on BA-producing strains. Growth kinetics showed the strongest inhibitory effect of clove extracts, followed by Amomum and A. dahurica. In the medium system, clove extract was the most effective in controlling the total BA content by inhibiting of BA-producing strains S. epidermidis S1, S. saprophyticus S2, and S. edaphicus S3; their contents were reduced by 23.74%, 31.05% and 21.37%, respectively. In the dry sausage system, the control of BA accumulation by clove was quite prominent, and the total BA content was reduced from 373.70 mg/kg to 259.05 mg/kg on day 12.

A comprehensive review on novel synthetic foods: Potential risk factors, detection strategies, and processing technologies

Nowadays, the food industry is facing challenges due to the simultaneous rise in global warming, population, and food consumption. As the integration of synthetic biology and food science, novel synthetic foods have obtained high attention to address these issues. However, these novel foods may cause potential risks related to human health. Four types of novel synthetic foods, including plant-based foods, cultured meat, fermented foods, and microalgae-based foods, were reviewed in the study. The original food sources, consumer acceptance, advantages and disadvantages of these foods were discussed. Furthermore, potential risk factors, such as nutritional, biological, and chemical risk factors, associated with these foods were described and analyzed. Additionally, the current detection methods (e.g., enzyme-linked immunosorbent assay, biosensors, chromatography, polymerase chain reaction, isothermal amplification, and microfluidic technology) and processing technologies (e.g., microwave treatment, ohmic heating, steam explosion, high hydrostatic pressure, ultrasound, cold plasma, and supercritical carbon dioxide) were reviewed and discussed critically. Nonetheless, it is crucial to continue innovating and developing new detection and processing technologies to effectively evaluate these novel synthetic foods and ensure their safety. Finally, approaches to enhance the quality of these foods were briefly presented. It will provide insights into the development and management of novel synthetic foods for food industry.

Halophilic lactic acid bacteria - Play a vital role in the fermented food industry

Halophilic lactic acid bacteria have been widely found in various high-salt fermented foods. The distribution of these species in salt-fermented foods contributes significantly to the development of the product's flavor. Besides, these bacteria also have the ability to biosynthesize bioactive components which potentially apply to different areas. In this review, insights into the metabolic properties, salt stress responses, and potential applications of these bacteria have been have been elucidated. The purpose of this review highlights the important role of halophilic lactic acid bacteria in improving the quality and safety of salt-fermented products and explores the potential application of these bacteria.

Acid tolerance response of Salmonella during the squid storage and its amine production capacity analysis

Salmonella exhibits a strong inducible acid tolerance response (ATR) under weak acid conditions, and can also induce high-risk strains that are highly toxic, acid resistant, and osmotic pressure resistant to aquatic products. However, the induction mechanism is not yet clear. Therefore, this study aims to simulate the slightly acidic, low-temperature, and high-protein environment during squid processing and storage. Through λRed gene knockout, exploring the effects of low-acid induction, long-term low-temperature storage, and two-component regulation on Salmonella ATR. In this study, we found the two-component system, PhoP/PhoQ and PmrA/PmrB in Salmonella regulates the amino acid metabolism system and improves bacterial acid tolerance by controlling arginine and lysine. Compared with the two indicators of total biogenic amine and diamine content, biogenic amine index and quality index were more suitable for evaluating the quality of aquatic products. The result showed that low-temperature treatment could inhibit Salmonella-induced ATR, which further explained the ATR mechanism from the amino acid metabolism.

A review of biogenic amines in fermented foods: Occurrence and health effects

Biogenic amines (BAs) are low-molecular decarboxylation products of amino acids formed during microbial fermentation. Several fermented foods may contain BAs such as histamine, tyramine, and/or phenylethylamine, at levels above documented toxic doses. Dietary exposure to foods containing high levels of BAs is associated with many adverse health effects, such as migraines, elevated blood pressure, and tachycardia. BA-mediated toxicity may occur at levels a hundred times below regulatory and suggested toxic doses, depending on an individual's sensitivity and factors such as alcohol consumption and certain medications. Although BAs occur in a wide variety of fermented foods, food safety and public health professionals are not well informed about the potential health risks and control strategies in these foods. In this review, we highlight the health risks and symptoms linked to BA exposures, the BA levels found in different fermented foods, regulatory and suggested toxic doses, and risk mitigation strategies to inform food industry and public health professionals' practice.

Effect of enzyme-assisted fermentation on quality, safety, and microbial community of black soldier fly larvae (Hermetia illucens L.) as a novel protein source

Considering the significance and scarcity of quality protein, this study aims to obtain a novel safe protein source through fermenting the black soldier fly larvae (BSFL). Lactobacillus crispatus M1027 and Pichia kudriavzevii DHX19 were added as starters together with neutral protease for enzymolysis during fermentation. The results showed that the low pH value (from 6.60 to 3.99), generated by lactic acid accumulation, created an environment where the pathogen could hardly grow. During fermentation, the flavor compound ethyl acetate content reached up to 406.55 mg/L, and the melanization was effectively inhibited by the starters. The increase of trichloroacetic acid-soluble protein content (from 8.73 % to 17.96 %) contributed to improving the absorbability of product by animals after feeding. Notably, the contents of detrimental substances, including total volatile basic nitrogen and histamine, were both below specified limits after fermentation. Simultaneously, the malonic dialdehyde content remained stable during fermentation. Relative abundance of Lactobacillus and Pichia gradually increased and finally dominated in the culture during fermentation, accompanied by pathogens decline below detection limit (1.0 Log cfu/g). Moreover, there was a close relationship between the dynamics of physicochemical indices and microbial succession. Overall, our studies explored a new process to ferment the BSFL paste which would improve the quality and safety of fermented BSFL paste. This research provided theoretical support for fermented insect as a novel protein source.

Safety Analysis of Korean Cottage Industries' Doenjang, a Traditional Fermented Soybean Product: A Special Reference to Biogenic Amines

The typical Korean diet contains a significant quantity of doenjang owing to its unique taste and health benefits. However, the presence of anti-nutritional and toxic substances, such as biogenic amines and microbial pathogens, in doenjang has resulted in a loss of revenue and poor consumer health. The present study focused on the identification and quantification of different biogenic amines, pathogenic Bacillus cereus, and yeast counts in 36 doenjang products (designated as De-1 to De-36, 500 g each) procured from the different cottage industries situated in different parts of the Republic of Korea. The results indicated, only three samples were contaminated with B. cereus, exceeding the recommended limit (4 log CFU/g) suggested by the national standards of Korea. A total of six distinct yeasts were identified in different doenjang samples, whose comprehensive enzymatic profiling suggested the absence of harmful enzymes such as N-acetyl-β-glucosaminidase, α-chymotrypsin, and β-glucuronidase. The biogenic amines were detected in the range of 67.68 mg/kg to 2556.68 mg/kg and classified into six major groups based on hierarchical cluster analysis. All doenjang samples contained tryptamine, putrescine, cadaverine, histamine, and tyramine, while 94.44% were positive for spermidine and spermine. The results documented the analysis of traditional cottage industry doenjang and suggest the need for constant monitoring to ensure the safety of food for the consumer.

The latest advances on soy sauce research in the past decade: Emphasis on the advances in China

As an indispensable soybean-fermented condiment, soy sauce is extensively utilized in catering, daily cooking and food industry in East Asia and Southeast Asia and is becoming popular in the whole world. In the past decade, researchers began to pay great importance to the scientific research of soy sauce, which remarkably promoted the advances on fermentation strains, quality, safety, function and other aspects of soy sauce. Of them, the screening and reconstruction of Aspergillus oryzae with high-yield of salt and acid-tolerant proteases, mechanism of soy sauce flavor formation, improvement of soy sauce quality through the combination of novel physical processing technique and microbial/enzyme, separation and identification of soy sauce functional components are attracting more attention of researchers, and related achievements have been reported continually. Meanwhile, we pointed out the drawbacks of the above research and the future research directions based on published literature and our knowledge. We believe that this review can provide an insightful reference for international related researchers to understand the advances on soy sauce research.

Mitigation of microbial nitrogen-derived metabolic hazards as a driver for safer alcoholic beverage choices: An evidence-based review and future perspectives

Alcoholic beverages have been enjoyed worldwide as hedonistic commodities for thousands of years. The unique quality and flavor are attributed to the rich microbiota and nutritional materials involved in fermentation. However, the metabolism of these microbiota can also introduce toxic compounds into foods. Nitrogen-derived metabolic hazards (NMH) are toxic metabolic hazards produced by microorganisms metabolizing nitrogen sources that can contaminate alcoholic beverages during fermentation and processing. NMH contamination poses a risk to dietary safety and human health without effective preventive strategies. Existing literature has primarily focused on investigating the causes of NMH formation, detection methods, and abatement techniques for NMH in fermentation end-products. Devising effective process regulation strategies represents a major challenge for the alcoholic beverage industry considering our current lack of understanding regarding the processes whereby NMH are generated, real-time and online detection, and the high degradation rate after NMH formation. This review summarizes the types and mechanisms of nitrogenous hazard contamination, the potential risk points, and the analytical techniques to detect NMH contamination. We discussed the changing patterns of NMH contamination and effective strategies to prevent contamination at different stages in the production of alcoholic beverages. Moreover, we also discussed the advanced technologies and methods to control NMH contamination in alcoholic beverages based on intelligent monitoring, synthetic ecology, and computational assistance. Overall, this review highlights the risks of NMH contamination during alcoholic beverage production and proposes promising strategies that could be adopted to eliminate the risk of NMH contamination.

Metagenomic Insights into the Regulatory Effects of Microbial Community on the Formation of Biogenic Amines and Volatile Flavor Components during the Brewing of Hongqu Rice Wine

As one of the typical representatives of Chinese rice wine (Huangjiu), Hongqu rice wine is produced with glutinous rice as the main raw material and Hongqu as the fermentation starter. The complex microbial flora in the brewing process may have a great influence on the formation of the flavor quality and drinking safety of Hongqu rice wine. Previous studies have shown that high biogenic amine (BA) content in rice wine has potential physiological toxicity and has become a bottleneck problem restricting the development of the rice wine industry. This study aimed to evaluate the regulatory effects of the microbial community on the formation of BAs and volatile flavor components during the brewing of Hongqu rice wine. The results demonstrated that histamine, putrescine, cadaverine, tyramine, tryptamine, spermine, and spermidine were the main BAs in Hongqu rice wine. The contents of putrescine, cadaverine, histamine, tyramine, and spermidine in Hongqu rice wine of HBAs (with higher BAs content) were significantly higher than those in LBAs (with lower BAs content). GC-MS testing results showed that there were significant differences in the composition of volatile organic compounds (VOCs) between HBAs and LBAs. Among them, VOCs such as 2-methoxy-4-vinylphenol, ethyl caprate, phenethyl acetate, ethyl lactate, ethyl myristate, ethyl palmitate, ethyl n-octadecanoate, ethyl oleate, and ethyl linoleate were identified as the characteristic volatile components with significant differences between HBAs and LBAs. Microbiome analysis based on metagenomic sequencing revealed that unclassified_g_Pantoea, Klebsiella pneumoniae, Panobacter disperse, unclassified_f_Enterobacteriaceae, Leuconostoc mesenteroides, and Saccharomyces cerevisiae were the dominant microbial species in the HBA brewing process, while Weissella confuse, Pediococcus acidilactici, Saccharomyces cerevisiae, and Aspergillus niger were the dominant microbial species in the LBA brewing process. Furthermore, correlation heatmap analysis demonstrated that BAs were positively related to Lactobacillus curvatus, Lactococcus lactis, and Leuconostoc mesenteroides. Bioinformatical analysis based on the KEGG database revealed that the microbial genes encoding enzymes involved in BAs' synthesis were more abundant in HBAs, and the abundances of microbial genes encoding enzymes related to BAs' degradation and the metabolism of characteristic volatile components were higher in LBAs. Overall, this work provides important scientific data for enhancing the flavor quality of Hongqu rice wine and lays a solid foundation for the healthy development of the Hongqu rice wine industry.

Effects of a Novel Starter Culture on Quality Improvement and Putrescine, Cadaverine, and Histamine Inhibition of Fermented Shrimp Paste

Fermented shrimp paste is a popular food in Asian countries. However, biogenic amines (BAs) are a typically associated hazard commonly found during the fermentation of shrimp paste and pose a food-safety danger. In this work, an autochthonic salt-tolerant Tetragenococcus muriaticus TS (T. muriaticus TS) strain was used as a starter culture for grasshopper sub shrimp paste fermentation. It was found that with the starter culture, putrescine, cadaverine, and histamine concentrations were significantly lower (p < 0.05) with a maximal reduction of 19.20%, 14.01%, and 28.62%, respectively. According to high-throughput sequencing data, T. muriaticus TS could change the interactions between species and reduce the abundance of bacterial genera positively associated with BAs, therefore inhibiting the BA accumulation during shrimp paste fermentation. Moreover, the volatile compounds during the fermentation process were also assessed by HS-SPME-GC-MS. With the starter added, the content of pyrazines increased, while the off-odor amines decreased. The odor of the shrimp paste was successfully improved. These results indicate that T. muriaticus TS can be used as an appropriate starter culture for improving the safety and quality of grasshopper sub shrimp paste.

Determination of Biogenic Amines in Wine from Chinese Markets Using Ion Chromatography-Tandem Mass Spectrometry

A method for the determination of nine biogenic amines (BAs) in wine was established using ion chromatography-tandem mass spectrometry (IC-MS/MS) without derivatization. BAs were separated by a cation exchange column (IonPac CG17, 50 mm × 4 mm, 7 µm) with a gradient aqueous formic acid elution. Good linearity was obtained for nine BAs with coefficients of determination (R²) > 0.9972 within the range of 0.01-50 mg/L. The limits of detection and quantification were within the ranges of 0.6-40 µg/L and 2.0-135 µg/L, respectively, with the exception of spermine (SPM). The recoveries were demonstrated within the range of 82.6-103.0%, with relative standard deviations (RSDs) of less than 4.2%. This simple method featuring excellent sensitivity and selectivity was suitable for the quantification of BAs in wines. The occurrence of BAs in 236 wine samples that are commercially available in China was determined. The BA levels in wines of different geographical origins varied significantly. The acute dietary exposure assessment of BAs was carried out by calculating the estimated short-term intake (ESTI) and comparing the acute reference dose (ARfD) specified by the European Food Safety Authority (EFSA). Results showed that the exposure to histamine (HIS) and tyramine (TYR) via the consumption of wines was much lower than the recommended ARfD level for healthy individuals. However, exposure could lead to symptoms in susceptible individuals. These results provided basic data regarding the occurrence and risk of BAs in wines for wine production, health guidance and consumer safety.

Effects of selected Bacillus strains on the biogenic amines, bioactive ingredients and antioxidant capacity of shuidouchi

The control of biogenic amines (BAs) is crucial to guarantee the safety of fermented soybean products. In this study, the BAs composition of eleven shuidouchi samples was analyzed, and the BAs degradation strains were selected from shuidouchi samples with a low BAs content. Then the influences of screened BAs degradation strains on BAs, total phenolics (TP), total flavonoids (TF), isoflavones and the antioxidant ability of fermented shuidouchi were evaluated. Results showed that the total BAs content of all shuidouchi samples was within the safe range, while the GZXQ, GZQY and GZMX samples had higher levels of tyramine. Meanwhile, 109 strains were isolated from the YNLJ, GZLG, GZMZ, GZDY, and YNHY sample. Bacillus tropicus A11, Bacillus siamensis D11, Bacillus subtilis T2, and B. subtilis U2 with higher BAs degradation capacity and lower BAs production ability were selected to ferment shuidouchi. These four Bacillus strains could effectively control the BAs concentration of fermented shuidouchi, especially B. tropicus A11 and B. siamensis D11. Furthermore, compared to naturally fermented shuidouchi, higher levels of antioxidant ability, TP, TF, daidzein, glyciein, and genistein were found in the shuidouchi fermented with selected strains. These findings demonstrated that these screened strains could be applied as potential candidates for the production of high quality shuidouchi.

Electrospun nanofibrous poly(ether-block-amide) membrane for removing biogenic amines in acidic wastewater from the yellow rice wine factory

Compared with other techniques for wastewater treatment, adsorption offers an effective, economical and ecofriendly way to reduce the content of biogenic amines. Herein, the poly(ether-block-amide) (PEBA 2533) membranes were employed as the adsorbent to remove histamine, putrescine, cadaverine and tyramine in the synthetic and real wastewater from a local yellow rice wine factory. Electrospun PEBA membranes consisting of fine nanofibers were successfully obtained without the addition of surfactant for the first time. Characteristics of the prepared membranes were evaluated by their morphology, wetting behaviors and mechanical properties. Adsorption performance of the nanofibrous membrane was investigated in comparison to the dense membrane prepared by conventional casting. The fibrous membrane exhibited much higher adsorption rate over 10 times to the dense membrane along with 1.5 times more adsorption capacity towards the amines. In addition, the as-prepared membrane showed a promising reusability in the real wastewater treatment. The good balance of its chemical stability, adsorption capacity, selectivity, removal efficiency and reusability endows the electrospun membrane with an outstanding potential to be applied in the acidic wastewater treatment for the yellow rice wine industry.

Patterns of biogenic amine during broad bean paste fermentation: microbial diversity and functionality via Bacillus bioaugmentation

BACKGROUND

Broad bean paste is a high nitrogen and high salt traditional Chinese condiment, which triggers biosynthesis of nitrogen hazards like biogenic amines (BAs). Mechanisms of association and applied research of functional safety and community assembly within multiple-microbial fermentation are currently lacking. Here, bioaugmentation was performed based on the profiles of BAs accumulation and microbial succession to evaluate the functional variation within broad bean paste fermentation.

RESULTS

Putrescine, spermine, and spermidine were the main BAs during traditional broad bean paste fermentation. Staphylococcus, Streptococcus, Lactococcus, Lactobacillus, Leuconostoc, and Bacillus were the predominant bacteria, whereas Aspergillus and Zygosaccharomyces dominated in fungal species, and community structure shifted upon salt exposure. PICRUSt software uncovered that Bacillus contributed significantly (>1%) to the amine oxidase gene family. Bacillus amyloliquefaciens 1-G6 and Bacillus licheniformis 2-B3 were screened to perform the bioaugmentation of broad bean paste, which achieved a 29% and 16% BA decrease respectively. Interaction network analysis showed that Cronobacter and Lactobacillus were significantly negatively correlated with Bacillus (ρ = -0.829 and ρ = -0.714, respectively, P < 0.05) in the B. amyloliquefaciens 1-G6 group, and Staphylococcus and Buttiauxella were inhibited by Bacillus (ρ = -0.657 and ρ = -0.543, respectively, P < 0.05) in the B. licheniformis 2-B3 group.

CONCLUSION

The synergism of amine oxidase activity and microbial interactions led to the decline of BAs. Thus, this study improves our understanding of the underlying mechanisms of microbial succession and functional variation to further facilitate the optimization of the fermented food industry.

Recent advances in development of electrochemical biosensors for the detection of biogenic amines

Biogenic amines (BAs) are widely found in food as a consequence of diverse factors including free amino acid availability, microbial production of decarboxylases, and variations in processing and storage conditions. Hence, BAs are considered as an important marker for determining the freshness and quality of food. Owing to the documentation of BAs in different dietary products, their numerous negative impacts on human health have reported to be a serious concern in past few decades. Therefore, the quantification of these chemical species in food becomes crucial as it can immensely contributes toward control of new episodes on food intoxication in humans. In this line, various chromatographic and colorimetric methods have been developed to detect BAs. However, these methods are in use from a longer time, still are limited by high cost, lengthy procedures, huge infrastructure and skilled personnel requirements that hinder their on-field application. In pursuit of a reliable method offering accurate detection of BAs, this review presents the state-of-the-art of electrochemical strategies for BAs sensing in food. The core of the review discusses about the widely employed electrochemical transducers, such as amperometric, potentiometric, impedimetric and conductometric-based BAs biosensors with significant findings of research work conducted previously. The application of electrochemical sensors to analyze BAs in different fields including food systems (fermented and non-fermented types) and smart packaging systems has been reviewed. Moreover, existing challenges and further available prospects for the development of rapid, facile, and sensitive electrochemical strategies for on-site determination of BAs have also been discussed.

Reduction of biogenic amines formation by foodborne pathogens using postbiotics in lysine-decarboxylase broth

Postbiotics is a novel term proposed to describe as a set of bioactive compounds obtained from beneficial microorganisms. In this work, postbiotics from four lactic acid bacteria (LAB) including Leuconostoc mesenteroides subsp. cremoris, Pediococcus acidilactici, Lactococcus lactis subsp. lactis and Streptococcus thermophilus were prepared in MRS broth. The antimicrobial properties and organic acids content of postbiotics were also investigated. Postbiotics were used to tentatively reduce the production of biogenic amines by foodborne pathogens (i.e., Salmonella paratyphi A and Escherichia coli) on lysine decarboxylase broth (LDB). Experimental data showed that acetic, propionic, and butyric acids were in the range of 387.51-709.21 mg/L, 0.00-1.28 mg/L, and 0.00-20.98 mg/L, respectively. The inhibition zone of postbiotics on E. coli and S. paratyphi A were 11.67, and 12.33 mm, respectively. Two different levels of postbiotics (25%, and 50%) were used in LDB to measure the diamines (cadaverine and putrescine), polyamines (agmatine, spermidine, and spermine, ammonia), and other biogenic amine formation by pathogens. E. coli produced cadaverine and putrescine with concentrations of 1072.21 and 1114.18 mg/L, respectively. The postbiotics reduced cadaverine formation by 67% in E. coli, and cadaverine production was mostly suppressed by postbiotics from P. acidilactici in E. coli (97%) and L. lactis subsp. lactis in S. paratyphi A (90%). Putrescine production by E. coli was reduced by 94% with postbiotics of P. acidilactici at a concentration of 25%, whereas putrescine production by S. paratyphi A has been decreased by 61% in the presence of postbiotics from L. lactis subsp. Lactis with a 25% concentration. The results revealed that an increase in postbiotics concentration (from 25% to 50%) in LDB may lead to synergistic effects, resulting from the production of biogenic amines by microbial pathogens. It was importantly concluded that postbiotics of LAB may degrade biogenic amines or prevent their formation by foodborne pathogens.

Fermented Soy Products and Their Potential Health Benefits: A Review

In the growing search for therapeutic strategies, there is an interest in foods containing natural antioxidants and other bioactive compounds capable of preventing or reversing pathogenic processes associated with metabolic disease. Fermentation has been used as a potent way of improving the properties of soybean and their components. Microbial metabolism is responsible for producing the β-glucosidase enzyme that converts glycosidic isoflavones into aglycones with higher biological activity in fermented soy products, in addition to several end-metabolites associated with human health development, including peptides, phenolic acids, fatty acids, vitamins, flavonoids, minerals, and organic acids. Thus, several products have emerged from soybean fermentation by fungi, bacteria, or a combination of both. This review covers the key biological characteristics of soy and fermented soy products, including natto, miso, tofu, douchi, sufu, cheonggukjang, doenjang, kanjang, meju, tempeh, thua-nao, kinema, hawaijar, and tungrymbai. The inclusion of these foods in the diet has been associated with the reduction of chronic diseases, with potential anticancer, anti-obesity, antidiabetic, anticholesterol, anti-inflammatory, and neuroprotective effects. These biological activities and the recently studied potential of fermented soybean molecules against SARS-CoV-2 are discussed. Finally, a patent landscape is presented to provide the state-of-the-art of the transfer of knowledge from the scientific sphere to the industrial application.

Development of a High-Coverage Quantitative Metabolome Analysis Method Using Four-Channel Chemical Isotope Labeling LC-MS for Analyzing High-Salt Fermented Food

Metabolome analysis of high-salt fermented food can be an analytical challenge, as the salts can interfere with the sample processing and analysis. In this work, we describe a four-channel chemical isotope labeling (CIL) LC-MS approach for a comprehensive metabolome analysis of high-salt fermented food. The workflow includes metabolite extraction, chemical labeling of metabolites using dansyl chloride, dansylhydrazine, or p-dimethylaminophenacyl bromide reagents to enhance separation and ionization, LC-UV measurement of the total concentration of dansyl-labeled metabolites in each sample for sample normalization, mixing of ¹³C- and ¹²C-reagent-labeled samples, high-resolution LC-MS analysis, and data processing. Metabolome analysis of fermented foods, including fermented red pepper (FRP) sauce, soy sauce, and sufu (a fermented soybean food), showed unprecedented high metabolic coverage. Metabolome comparison of FRP, soy sauce, and sufu, as well as soy sauce and sufu, indicated great diversity of metabolite types and abundances in these foods. In addition, we analyzed two groups of samples of the same type, FRP with 10% (w/w) and 15% (w/w) salt contents, and detected large variations in multiple categories of metabolites belonging to a number of different metabolic pathways. We envisage that this CIL LC-MS approach can be generally used for metabolomic studies of high-salt fermented food. CIL LC-MS allows high-coverage identification and quantification that could not be done using other methods.

Untargeted Metabolomics reveals Doenjang metabolites affected by manufacturing process and microorganisms

Doenjang is a traditional Korean fermented soybean-based food that is now produced industrially as traditional Doenjang and modernized Doenjang, depending on the conditions of the manufacturing process. In this study, the effect of the production process on Doenjang metabolites was analyzed using untargeted capillary electrophoresis time-of-flight mass spectrometry (CE-TOF/MS). Of the 247 metabolites detected in 19 traditional and three modernized Doenjang samples, the level of 55 metabolites were significantly different between the two production groups. The S-plot of the orthogonal projection to latent structures-discriminant analysis (OPLS-DA) revealed that nine compounds (tryptamine, 2-phenylethylamine, citrulline, gamma-aminobutyric acid, putrescine, tyramine, 2-aminoisobutyric acid, stachydrine, and N5-ethylglutamine) were highly distributed in the traditional group, and six compounds (arginine, citric acid, choline, cytidine, hypoxanthine, and glucaric acid) were considered distinguishable metabolites of the modernized group. Microbial community analysis indicated that the levels of these metabolites were significantly altered by the presence of Bacillus spp., Enterococcus faecium, Tetragenococcus halophilus, Aspergillus oryzae, Penicillium spp., and Saccharomyces cerevisiae. These findings will give better understanding of the influence of the manufacturing process on Doenjang production in terms of both microbial activity and metabolite profiles.

Bioinformatics analysis of amino acid decarboxylases related to four major biogenic amines in pickles

Microbial amino acid decarboxylases (AADs) produce biogenic amines (BAs) in fermented food. However, a systematic comparison of the AADs' properties from different microorganisms in pickle fermentation remains unexplored. Here, we bioinformatically analyzed the amino acid sequences of AADs corresponding to four major BAs for common microorganisms in pickle fermentation. We showed that their sequences, besides tyrosine decarboxylase, differed among microorganisms. Overall, the AAD sequences varied lesser among bacterial species than between bacteria and fungi, with those in Lactobacillus sharing occasionally high similarity with other bacteria. Most AADs were predicted as stable cytosolic endoenzymes. Molecular docking showed that most commonly used spice components in pickle production, especially pepper, chili, and ginger, strongly bind to the AAD active sites, thus may inhibit the enzymes and reduce the BA accumulation. This study provides insights for deeply understanding the different microbial AAD properties in pickle fermentation and reducing BAs by appropriately using spices.

Metagenomics Reveals the Microbial Community Responsible for Producing Biogenic Amines During Mustard [Brassica juncea (L.)] Fermentation

Biogenic amines (BAs) are considered potential hazards produced during fermented food processing, and the production of BAs is closely related to microbial metabolism. In this work, the changes of BA content were analyzed during mustard fermentation, and microbes and gene abundance responsible for producing BAs were revealed by metagenomic analyses. The results showed that cadaverine, putrescine, tyramine, and histamine were generated during mustard fermentation, which mainly accumulate in the first 6 days of fermentation. According to the metagenome sequencing, the predominant genus was Bacillus (64.78%), followed by Lactobacillus (11.67%), Weissella (8.88%), and Leuconostoc (1.71%) in the initial fermentation stage (second day), while Lactobacillus (76.03%) became the most dominant genus in the late stage. In addition, the gene abundance of BA production enzymes was the highest in the second day and decreased continuously as fermentation progressed. By tracking the source of the enzyme in the KEGG database, both Bacillus and Delftia closely correlated to the generation of putrescine. Besides, Bacillus also correlated to the generation of tyramine and spermidine, and Delftia also correlated to the generation of cadaverine and spermine. In the processes of fermentation, the pH of fermented mustard showed slower decrease compared with other similar fermented vegetables, which may allow Bacillus to grow at high levels before the pH &lt;4. This study reveals the change of BA content and microbes involved in BA formation during mustard fermentation.

Simultaneous derivatization and liquid-solid phase transition microextraction of six biogenic amines in foods followed by narrowbore liquid chromatography-ultraviolet detection

Biogenic amines are quality control criteria for foods that are potentially toxic to humans. In this study, amidation derivatization for biogenic amines and liquid-solid phase transition microextraction were carried out simultaneously for food sample pretreatment. The derivatization reaction was executed in one pot with coumarin-3-carboxylic acid as the derivatizing reagent and (1-cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylamino-morpholino-carbenium hexafluorophosphate as the coupling agent. Liquid-solid phase transition microextraction was achieved by the salting-out effect, using a phase change salt (1 M disodium hydrogen phosphate) solution. The combined derivatization and microextraction process was completed within 3 min at 30 °C, and the liquid top phase was easily obtained by placing the tube in an ice bath. Finally, a narrowbore liquid chromatograph coupled with a UV detector was used to determine the levels of six biogenic amines. The coupling agent-assisted derivatization and liquid-solid phase transition microextraction parameters were also investigated. The quantitative linear ranges were 3-400 μM for histamine, putrescine, spermidine, cadaverine, and tyramine and 5-400 μM for spermine, and the detection limit was 1 μM. The relative standard deviations of the intra- and inter-batches were <5.3% and 8.4%, respectively, while the relative error was <4.5% for both. We successfully applied this simultaneous derivatization-microextraction method to determine the biogenic amines in fermented foods.

Occurrence of Polyamines in Foods and the Influence of Cooking Processes

Dietary polyamines are involved in different aspects of human health and play an important role in the prevention of certain chronic conditions such as cardiovascular diseases and diabetes. Different polyamines can be found in all foods in variable amounts. Moreover, several culinary practices have been reported to modify the content and profile of these bioactive compounds in food although experimental data are still scarce and even contradictory. Therefore, the aim of this study was to evaluate the occurrence of polyamines in a large range of foods and to assess the effect of different cooking processes on the polyamine content of a few of them. The highest level of polyamines was found in wheat germ (440.6 mg/kg). Among foods of a plant origin, high levels of total polyamines over 90 mg/kg were determined in mushrooms, green peppers, peas, citrus fruit, broad beans and tempeh with spermidine being predominant (ranging from 54 to 109 mg/kg). In foods of an animal origin, the highest levels of polyamines, above all putrescine (42-130 mg/kg), were found in raw milk, hard and blue cheeses and in dry-fermented sausages. Regarding the influence of different domestic cooking processes, polyamine levels in food were reduced by up to 64% by boiling and grilling but remained practically unmodified by microwave and sous-vide cooking.

Biogenic amines: formation, action and toxicity - a review

Biogenic amines (BA) are organic compounds commonly found in food, plants and animals, as well as microorganisms that are attributed with the production of BAs. They are formed as an effect of a chemical process: the decarboxylation of amino acids. Factors determining the formation of BAs include the availability of free amino acids and the presence of microorganisms that show activity with respect to carrying out the decarboxylation process. On the one hand, BAs are compounds that are crucial for maintaining cell viability, as well as the proper course of the organism's metabolic processes, such as protein synthesis, hormone synthesis and DNA replication. On the other hand, despite their positive effects on the functioning of the organism, an excessive content of BAs proves to be toxic (diarrhea, food poisoning, vomiting, sweating or tachycardia). Moreover, they can accelerate carcinogenesis. Amines are a natural component of plant and animal raw materials. As a result of the proven negative effects of amines on living organisms, the reduction of these compounds should be the subject of scientific research. The present review aims to synthesize and summarize the information currently available on BAs, as well as discuss the interpretation of the results. © 2020 Society of Chemical Industry.

Fabrication of Carbon Disulfide Added Colloidal Gold Colorimetric Sensor for the Rapid and On-Site Detection of Biogenic Amines

Meat is often wasted due to the perceived concerns of its shelf life and preservation. Specifically, in meat formation, biogenic amines (BAs) are the major agents to spoil them. Herein, we have developed a carbon disulfide (CS2) added colloidal gold nanoparticles-based colorimetric sensor for the rapid and on-site detection of biogenic amines. Transmission electron microscopy is used to observe the morphological changes in colloidal gold nanoparticles and aggregation behavior of CS2 added to the colloidal gold nanoparticles' solution. Raman spectroscopic analysis is further used to characterize the peaks of CS2, Cad and CS2-Cad molecules. Absorption spectroscopy is used to estimate the colorimetric differences and diffuse reflectance spectra of the samples. The sensing analysis is performed systematically in the presence and absence of CS2. CS2 added colloidal gold nanoparticles colorimetric sensor detected the BAs with a limit of detection (LOD) value of 50.00 µM. Furthermore, the developed sensor has shown an LOD of 50.00 µM for the detection of multiple BAs at a single time. The observed differences in the colorimetric and absorption signals indicate that the structure of BAs is converted to the dithiocarbamate (DTC)-BA molecule, due to the chemical reactions between the amine groups of BAs and CS2. Significantly, the developed colorimetric sensor offers distinct features such as facile fabrication approach, on-site sensing strategy, rapid analysis, visual detection, cost-effective, possibility of mass production, availability to detect multiple BAs at a single time and appreciable sensitivity. The developed sensor can be effectively used as a promising and alternative on-site tool for the estimation of BAs.

Assessment of the Distribution and Safety of Tetragenococcus muriaticus for Potential Application in the Preparation of Chinese Grasshopper Sub Shrimp Paste

The bacterial profiles of 63 grasshopper sub shrimp paste samples collected from seven typical regions around the Bohai Sea were investigated by high-throughput sequencing. Tetragenococcus muriaticus was found to be the prevailing species present in all the samples, and the presence of T. muriaticus also weakly correlated with the histamine content in the samples. Six T. muriaticus strains with low biogenic amine (BA)-producing ability and deficient in histamine production were identified and subjected to safety assessment. All six strains displayed weak resistance to fifteen known antibiotics as based on the Enterococcus breakpoint values. None of the strains exhibited hemolytic activity or biofilm formation. All strains exhibited were able to grow on MRS agar containing 21% NaCl and expressed amine oxidase and strain-specific proteases and lipases. Most of the strains exhibited acid production at 18% NaCl. Moreover, three of the strains (designated as SG, TS, and QH) with histamine degradation ability were inoculated into separate shrimp paste samples to determine their effect on BA accumulation. The results indicated that the addition of T. muriaticus to shrimp pastes not only led to a significant reduction of BA content in the pastes but also improved the flavor of the pastes. Consequently, these strains may be used as potential candidates for controlling the content of histamine in fermented foods.

Traditional fermented soybean products: processing, flavor formation, nutritional and biological activities

Traditional fermented soybean food has emerged as an important part of people's dietary structure because of the unique flavors and improved health benefit. During fermentation, the nutrients in soybean undergo a series of biochemical reactions catalyzed naturally by microorganism secreted enzymes. Thereafter, many functional and bioactive substances such as bioactive peptides, unsaturated fatty acids, free soy isoflavones, vitamins and minerals are produced, making fermented soy products more advantageous in nutrition and health. This review comprehensively discusses the historical evolution, distribution, traditional fermentation processing, main sources and characteristics of fermented strains, flavor components, nutritional properties, and biological activities of four traditional fermented soybean foods including douchi, sufu, dajiang, and soy sauce. In the end, we introduce four major challenges encountered by traditional fermented soybean foods including high salt content, formation of biogenic amine, the presence of pathogenic microorganisms and mycotoxins, and quality inconsistency. We conclude that the establishment of scientific quality standard and innovated fermentation processing is the potential solutions to combat the issues and improve the safety of traditional fermented soybean products.

Integrated metabonomic-proteomic analysis reveals the effect of glucose stress on metabolic adaptation of Lactococcus lactis ssp. lactis CICC23200

A combined proteomic and metabonomic approach was used to investigate the metabolism of Lactococcus lactis ssp. lactis subjected to glucose stress treatment. A proteomic method was used to determine 1,427 altered proteins, including 278 proteins with increased expression and 255 proteins with decreased expression. A metabonomic approach was adopted to identify 98 altered metabolites, including 62 metabolites with increased expression and 26 metabolites with decreased expression. The integrated analysis indicated that the RNA and DNA mismatch repair process and energy metabolism were enhanced in response to high-glucose stress in L. lactis. Lactococcus lactis responded to glucose stress by up-regulating oxidoreductase activity, which acted on glycosyl bonds, hydrolase activity, and organic acid transmembrane transporter activity. This led to an improvement in the metabolic flux from glucose to pyruvate, lactate, acetate, and maltose. Down-regulation of amino acid transmembrane transporter, aminoacyl-transfer RNA ligase, hydroxymethyl-, formyl-, and related transferase activities resulted in a decrease in the nitrogen metabolism-associated metabolic pathway, which might be related to inhibition of the production of biogenic amines. Overall, we highlight the response of metabolism to glucose stress and provide potential possibilities for the reduced formation of biogenic amines in improved level of sugar in the dairy fermentation industry. Moreover, according to the demand for industrial production, sugar concentration in fermented foods should be higher, or lower, than a set value that is dependent on bacterial strain and biogenic amine yield.