Biogenic Amine Content Research Articles

Use of two autochthonous bacteriocinogenic strains as starter cultures in the production of salchichónes, a type of Spanish fermented sausages

In this work, two autochthonous LAB strains (Lactiplantibacillus paraplantarum BPF2 and Pediococcus acidilactici ST6), isolated from spontaneously fermented sausages produced in Spain, were tested to produce Spanish fermented sausages (salchichón) in pilot plants, due to their promising technological and anti-listerial activity. These products were compared with a sample obtained with a commercial starter (RAP) and a spontaneously fermented control sample. Physico-chemical parameters, microbial counts, metagenomic analysis, biogenic amines content and organoleptic profile of the obtained samples were studied to assess the performances of the native starters. In fact, traditional and artisanal products obtained through spontaneous fermentations can represent an important biodiversity reservoir of strains to be exploited as new potential starter cultures, to improve the safety, quality and local differentiation of traditional products. The data underlined that ST6 strain resulted in a final lower percentage if compared with the other LAB used as starter cultures. The use of starters reduced the BA concentration observed in the sausages obtained with spontaneous fermentation and the BPF2 and ST6 strains were able to decrease the level of products rancidity.Moreover, a challenge test against L. monocytogenes were performed. The data confirmed the effectiveness in the inhibition of L. monocytogenes by the two bacteriocinogenic strains tested, with respect to RAP and control samples, highlighting their ability to produce bacteriocins in real food systems. This work demonstrated the promising application in meat industry of these autochthonous strains as starter cultures to improve sensory differentiation and recognizability of typical fermented sausages.

Simple analytical method for total biogenic amines content determination in wine using a smartphone.

A simple, fast, and green smartphone-based procedure for total biogenic amines content determination in wine was developed and validated. Sample preparation and analysis were simplified to make the method suitable for routine analyses even in resource-scarce settings. The commercially available S0378 dye and smartphone-based detection were used for this purpose. The developed method has satisfactory figures of merit for putrescine equivalent determination with R2 of 0.9981. The method's greenness was also assessed using the Analytical Greenness Calculator. Samples of Polish wine were analysed to demonstrate the applicability of the developed method. Finally, results obtained with the developed procedure were compared with those previously obtained with GC-MS in order to evaluate the equivalence of the methods.

Increasing amino acids and biogenic amines content of white and rosé wines during ageing on lees

The presence of biogenic amines in wine is more and more important both to consumers and producers alike, due to the potential threats of toxicity of humans and consequent trade implications. Biogenic amines are formed from amino acids by decarboxylation carried out by various enzymes located in yeasts and bacteria. During ageing of wines on lees, the release of different compounds, especially proteins, peptides, amino acids, breakdown products of yeasts, can impact on the quality of wine. The aim of this study is to describe the evolution of twenty-two amino acids, precursors of seven biogenic amines during ageing on lees for 12 months, respectively 18 months, using 12 commercial maturation products. The number of experimental samples is 26 (V1SB-V13SB, V1BB-V13BB), produced in Iasi vineyard, vintage 2020, from Sauvignon Blanc and Busuioaca de Bohotin grapes variety. Data indicated a major impact of the variables (commercial maturation products, autolysis process and grape variety) on wine’s characteristics. Considerable amounts of some essential amino acids, such as L-alanine, L-leucine, L-lysine, L-valine and L-glutamic acid were found in samples treated with commercial products, which contained significant amounts of mannoproteins, amino acids and vitamins (samples V6SB, V4SB, V5SB, V5BB, V4BB and V6BB). Vitamins and nitrogenous compounds released by autolysis are used as a support in the decarboxylation process, thus forming biogenic amines.

Quality assessment of fermented soybeans: physicochemical, bioactive compounds and biogenic amines

In this research, a total of 47 samples from five types of fermented soybeans were selected. The physicochemical parameters, biogenic amines (BAs) and bioactive compounds such as isoflavones, total phenolic (TPC) and γ-aminobutyric acid (GABA) were investigated. The results showed that the contents of isoflavones ranged from 598.06 mg/kg to 2725.03 mg/kg in all samples and it varied from 598.96 mg/kg to 2241.67 mg/kg in Semen Sojae Preparatum (SSP) which was higher than other types of fermented soybeans. The maximum variation of GABA content was found in Aspergillus-type douchi (AD) samples. The maximum value of TPC in SSP was 4.53 g/kg. For BAs, the indicator of spoilage, 4.26% of fermented soybeans samples may lead to histamine poisoning and 42.55% of samples with total BAs contents exceeding 100 mg/kg may be harmful to human body. It indicated that different types of fermented soybeans had various bioactive compounds and BAs, so different fermented soybeans could be selected according to bioactive substances. This finding could provide comprehensive information of health beneficial compounds and BAs risks of fermented soybeans. It could guide consumers to select healthy, nutritious and safety fermented soybeans.

Influence of Brewing Process on the Profile of Biogenic Amines in Craft Beers

The evaluation of the biogenic amines (BAs) profile of different types of craft beers is herein presented. A previously developed and validated analytical method based on ion-pair chromatography coupled with potentiometric detection was used to determine the presence of 10 BAs. Good analytical features were obtained for all amines regarding linearity (R2 values from 0.9873 ± 0.0015 to 0.9973 ± 0.0015), intra- and inter-day precision (RSD lower than 6.9% and 9.7% for beer samples, respectively), and accuracy (recovery between 83.2-108.9%). Detection and quantification limits range from 9.3 to 60.5 and from 31.1 to 202.3 µg L-1, respectively. The validated method was applied to the analysis of four ale beers and one lager craft beer. Ethylamine, spermidine, spermine, and tyramine were detected in all analyzed samples while methylamine and phenylethylamine were not detected. Overall, pale ale beers had a significantly higher total content of BAs than those found in wheat pale and dark samples. A general least square regression model showed a good correlation between the total content of BAs and the brewing process, especially for Plato degree, mashing, and fermentation temperatures. Knowledge about the type of ingredients and manufacturing processes that contribute to higher concentrations of these compounds is crucial to ensuring consumer safety.

The role of neurotransmitters and indicators of oxidative stress in the formation of disorders of central conductive structures in patients who came into contact with metallic mercury

Introduction. Studies of toxic lesions due to exposure to metallic mercury compounds do not allow us to identify the features of the violation of central afferent conducting structures in the long-term period of chronic mercury intoxication (CHMI). The contribution of various systems to the development of pathology is not sufficiently disclosed. The study aims to identify the role of neurotransmitters in pathological changes in central hemodynamics, the value of lipid peroxidation products and the activity of antioxidant protection in the demyelination of central afferent conductive structures in workers exposed to metallic mercury in the workplace. Materials and methods. The authors examined 47 people (group one) - trained chemical production workers exposed to metallic mercury, and group two (51 people) - patients in the long-term period of CHMI. The control group (CG) consisted of 30 people who had no contact with toxicants. We have determined concentration of neurotransmitters, lipid peroxidation products (LPP), superoxide dismutase (SOD) and reduced glutathione (RG), nitric oxide. Results. Experts observed statistically significant changes in indicators in subgroups with and without changes in cerebral hemodynamics and in group two when compared with group one. Comparison of persons with CHMI without changes in blood circulation with the presence of disorders revealed an increase in normetanephrine in the latter, a decrease in NT-3. Correlation analysis showed: in group jne, there was a statistically significant difference between the vasomotor reactivity index (VRI) and serotonin. In group two - between CHMI and serotonin, adrenaline and dopamine. Changes in afferent pathways are interrelated with indicators of oxidative stress. Violations are accompanied by the formation of a pathological system, are signs of dysregulatory pathology. Limitations. The disadvantage of the study is the fact that scientists determined the content of neurotransmitters and products of lipid peroxidation and antioxidant protection in the blood of the subjects, and not in the structures of the brain. Conclusion. The increased content of biogenic amines leads to a change in peripheral blood circulation and regulation of cerebral blood flow by pressor action on the regulation of the vascular bed, leading to vasoconstriction, changes in the bioelectric activity of the structures of the reticular formation of the midbrain, hypothalamus, thalamocortical structures, most pronounced in the long-term period of chronic mercury intoxication. We found that the formation of demyelination in patients with chronic mercury intoxication was accompanied by a decrease in the concentration of NT-3. It was natural to reduce the level of reduced glutathione and superoxide dismutase in neurodegenerative processes in trained workers exposed to metallic mercury at work, and in patients with a long period of chronic mercury intoxication. Ethics. The study was conducted in compliance with the principles of the Helsinki Declaration of the World Association "Ethical principles of conducting Scientific medical research with human participation" (as amended in 2008), "Rules of Clinical Practice in the Russian Federation" (approved by the Order of the Ministry of Health of the Russian Federation dated 06/19/2003 No. 266).

The relationship between reaction to a moving object with concentrations of biogenic amines and kynematic-dynamic parameters of complex coordination movement in elite alpine skiers

Aim of the study: to identify mutual interaction between the reaction to a moving object with functional state of the central nervous system and kinematic-dynamic parameters of complex coordination movement.Materials and methods: 9 elite alpine skiers were participated in this study. Visual-motor coordination variables were assessed by computer complex for psychophysiological testing NS-Psychotest (Neurosoft, Russia). Dynamic parameters of complex coordination movement during counter movement jump were registered on the MuscleLab Force Plate (Ergotest Innovation A.S., Norway). Quantitation of hormones — adrenaline and noradrenaline as well as neurotransmitters — dopamine and serotonin in blood samples was performed using ultra-high performance liquid chromatograph combined with triple quadrupole mass analyzer LCMS-8060 (Shimadzu, Japan).Results: a significant negative relationship between the maximum output of motor efforts during counter movement jump, mean reaction time and the number of negative reactions recorded within visual-motor coordination testing was documented. A reliable positive relationship between excitation processes, jump power and jump time was established. Increases in noradrenaline and serotonin concentrations are positively associated with the number of accurate reactions, whereas dopamine level was positively correlated with jump altitude.Conclusion: the predominance of excitation over inhibition processes in the central nervous system had a positive effect on reducing the time spent on counter moving and increasing the maximum power of movement. As applied to alpine skiers we registered the following relationship: the higher the speeds of signal perception and muscle activation when solving a visual-motor task, the higher the power of working efforts, the shorter the time of the eccentric phase and total time spent on performing counter movement jump.

Chemical Safety and Quality Attributes of Dried Sausage Snacks Stored in Modified Atmosphere.

A sausage snack was produced by air blast drying of cottage sausage, and its safety and quality were investigated during 10-week storage period in a modified atmosphere (20% CO2/80% N2) at 4 ± 1°C and 20 ± 1°C. The results of a sensory and instrumental evaluation of colour and texture showed that significantly greater changes in these parameters were caused by drying the sausage rather than during subsequent storage of the produced snacks. Although total viable count increased and reached a maximum value of 6.5 log CFU g-1 after 70 days of storage at 20 ± 1°C, Enterobacteriaceae were not detected. The histamine level was approx. 18 mg kg-1, while the average content of the other biogenic amines after 70 days of storage ranged from 4.4 mg kg-1 (cadaverine) to 32.1 mg kg-1 (tyramine). The biogenic amine index was small and varied from 34.5 mg kg-1 (in the sausage before drying) to 73.4 mg kg-1 (at the end of the snack storage at 20 ± 1°C). The lipid hydrolysis and oxidation proceeded slowly and did not pose a threat to the product quality. The combination of drying and modified atmosphere packaging maintains good quality and safety of sausage snack during 70 days at refrigerated storage and/or 4 weeks at room temperature.

Effect of stress factors on the production of biogenic amines by lactic acid bacteria isolated from fermented Mexican foods (cheese and beer)

The growth of lactic acid bacteria (LAB) in fermented foods, especially in ripened foods, could be associated with the production of biogenic amines (BAs). BAs are small, nitrogen-containing, thermostable, non-volatile organic compounds, which can induce toxic effects in food consumers. This work aimed to determine potential BAs-producer LAB strains isolated from ripened cheese and beer and to evaluate stress factors that induce the production of these metabolites. Determination of BAs-related genes in eighteen strains of LAB was done by polymerase chain reaction (PCR). The effect of pH, NaCl concentration and ethanol concentration on the LAB growth and BAs production was evaluated. The concentration of BAs (histamine, tyrosine, putrescine and cadaverine) was determined by high performance liquid chromatography (HPLC). Additionally, survival of selected LAB strains during beer making process was evaluated. All LAB strains could tolerate concentrations of 4 and 6 mL/100 mL of ethanol. More than one strain showed the ability to produce all the BAs studied and all beer strains were able to produce Tyramine. The pH level was the most influent factor in BAs production; pH 4 was optimal for the production of histamine (cheese and beer strains) and pH 5 for tyramine (beer strains). LAB population showed a 2-log reduction along the two initial days of fermentation. At the end of the beer making process 1.6 log of LAB were recovered. BAs production has been considered a mechanism that increases bacterial survival against acidic environment. Some LAB strains in fermented products may represent a health risk for consumers. Sanitary practices during food production and raw material quality should be complement measurements to a good control of fermentation process to minimize BAs presence in foods.

Bioactive Amines in Wines. The Assessment of Quality Descriptors by Flow Injection Analysis with Tandem Mass Spectrometry.

Biogenic amines (BAs) occur in a wide variety of foodstuffs, mainly from the decomposition of proteins by the action of microorganisms. They are involved in several cellular functions but may become toxic when ingested in high amounts through the diet. In the case of oenological products, BAs are already present in low concentrations in must, and their levels rise dramatically during the fermentation processes. This paper proposes a rapid method for the determination of BAs in wines and related samples based on precolumn derivatization with dansyl chloride and further detection by flow injection analysis with tandem mass spectrometry. Some remarkable analytes such as putrescine, ethanolamine, histamine, and tyramine have been quantified in the samples. Concentrations obtained have shown interesting patterns, pointing out the role of BAs as quality descriptors. Furthermore, it has been found that the BA content also depends on the vinification practices, with malolactic fermentation being a significant step in the formation of BAs. From the point of view of health, concentrations found in the samples are, in general, below 10 mg L-1, so the consumption of these products does not represent any special concern. In conclusion, the proposed method results in a suitable approach for a fast screening of this family of bioactive compounds in wines to evaluate quality and health issues.

Changes in the physicochemical parameters and microbial community of a new cultivar blue wheat cereal wholemeal during sourdough production.

Changes in the characteristics of a new cultivar (DS8472-5) of blue wheat during wholemeal fermentation with Pediococcus acidilactici (LUHS29), Liquorilactobacillus uvarum (LUHS245), and Lactiplantibacillus plantarum (LUHS122), including acidity, microbiological and chromaticity parameters, free amino acid (FAA), gamma-aminobutyric acid (GABA), and biogenic amine (BA) contents, macro- and micro-element concentrations and fatty acid (FA) and volatile compounds (VC), were evaluated. In addition, a metagenomic analysis was performed. The lactic acid bacteria (LAB) strains used for fermentation was a significant factor in wholemeal fermentation sample pH, redness (a*) and LAB counts (p ≤ 0.05). In most of the samples, fermentation increased the FAA content in wheat wholemeal, and the highest concentration of GABA was found in DS8472-5 LUHS122 samples. Phenylethylamine (PHE) was found in all wheat wholemeal samples; however, spermidine was only detected in fermented samples and cadaverine only in DS8472-5 LUHS122. Fermented samples showed higher omega-3 and omega-6 contents and a higher number and variety of VC. Analysis of the microbial profile showed that LAB as part of the natural microbiota present in cereal grains also actively participates in fermentation processes induced by industrial bacterial cultures. Finally, all the tested LAB were suitable for DS8472-5 wheat wholemeal fermentation, and the DS8472-5 LUHS122 samples showed the lowest pH and the highest LAB viable counts (3.94, 5.80°N, and 8.92 log10 CFU/g, respectively).

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.

숙성 장소에 따른 전통된장의 품질 특성 및 미생물군집 비교

We investigated the quality characteristics and microbial community found in traditional outdoor-type doenjang fermented at different temperatures. The quality characteristics that were highly correlated with fermentation temperature were analyzed. The average temperature of doenjang in the summer was highest in the order of fermentation by field in Damyang (JDF), fermentation by smart management facility in Damyang (JDS), and fermentation by field in Pyeongchang (JDFP), and in winter was the highest in the order JDS, JDF, and JDFP. The b* value and the degree of browning were highest in the order of JDF, JDS, and JDFP. Among the quality characteristics that affect the degree of fermentation and taste, samples with high summer temperature showed high ammonia nitrogen content, α-amylase activity, sugar content, organic acid content, and acidity and samples with high winter temperature showed high protease activity, amino nitrogen content, biogenic amine content, and alcohol content. Regarding the microbial community, the level of the Enterococcus genus was high in the samples with low winter temperatures, while the level of the Bacillus genus was high in the samples with high winter temperatures. Additionally, the genus Wickerhamiella and Zygosaccharomyces were highest in the samples with the lowest temperatures in summer and winter. Furthermore, acidity, biogenic amine content, glucose content, and lactic acid content were analyzed as major factors influencing the quality characteristics of doenjang according to the ripening region and location.

Reduced formation of biogenic amines in low-salt Zhacai via fermentation under CO2-modified atmosphere

Reducing sodium salt content in traditional fermented vegetables and developing low-salt fermented products have attracted increasing attention.However, low-salt fermented vegetables are prone to accumulate toxic biogenic amines (BAs) caused by the undesirable metabolism of spoilage microorganisms. This study aimed to investigate the impact of a CO2-modified atmosphere (MA) approach to the fermentation of low-salt Zhacai and the accumulation of BAs. The results show CO2-MA effectively suppressed the production of excessive BAs in low-salt Zhacai, as evidenced by a decrease in the total BA content from 63.66 to 161.41 mg/ kg under natural air conditions to 1.88–24.76 mg/ kg under CO2-MA. Overall, the mechanism of hindering BA formation was closely related to the change in the microbial community and the downregulation of BA-producing enzymes. Lactic acid bacteria, including Lactiplantibacillus plantarum, Weissella spp., and Pediococcus spp., were enriched under CO2-MA, whereas amine-producing microorganisms (e.g., Halomonas spp., Psychrobacter spp., Corynebacterium spp., and Levilactobacillus brevis) were greatly inhibited. Moreover, metagenomic analysis revealed that genes encoding amino acid decarboxylase, amine deiminase, and amine synthase were downregulated, which could be the fundamental reason for BA reduction. This study provides an alternative method for reducing BA production in fermented food.

Bacterial species diversity of traditionally ripened sheep legs from the Faroe Islands (skerpikjøt)

Skerpikjøt is a traditionally ripened sheep leg product from the Faroe Islands, constituting a relatively underexplored microbial ecosystem. The objective of this study is to achieve a deeper understanding of the microbial composition of this artisanal product. Nine ripened hind legs, obtained from three different producers, were assessed regarding their bacterial communities and contents of biogenic amines, including both surface and core samples. Biogenic amine concentrations were generally low, although one sample had a somewhat elevated concentration of cadaverine. Bacterial diversity was investigated by culture-dependent and culture-independent techniques. Gram-positive catalase-positive cocci (GCC) constituted the most abundant group. Within this group, Staphylococcus equorum was the most prevailing species, followed by Kocuria sp., Mammaliicoccus vitulinus, and Staphylococcus saprophyticus. Lactic acid bacteria prevailed in only one sample and were mainly represented by Latilactobacillus curvatus. Enterobacterial communities were characterised by the prevalence of Serratia proteamaculans. Despite the majority of GCC, Clostridium putrefaciens was the most abundant bacterial species in some core samples. Taken together, the culture-dependent and culture-independent identification methods gave complementary results.

Combined Thermomechanical-Biological Treatment for Corn By-Product Valorization into Added-Value Food (Feed) Material.

The aim of this study was to apply the combined thermomechanical-biological treatment for corn processing by-product (CPBP) valorization to added-value food and feed material. The mechanical-thermal pre-treatment was performed by applying the extrusion technique. Extruded CPBPs (14, 16, and 18% moisture) were further biodegraded with Lactiplantibacillus plantarum-LUHS122 (Lpl), Liquorilactobacillus uvarum-LUHS245 (Lu), Lacticaseibacillus casei-LUHS210 (Lc), and Lacticaseibacillus paracasei-LUHS244 (Lpa). Acidity parameters, microbial characteristics, sugars concentration, amino and fatty acids profile, biogenic amines (BA), and antibacterial and antifungal properties of CPBP were analyzed. Fermented CPBP had a reduced count of mould/yeast. A significantly lower (p ≤ 0.05) count of total enterobacteria was found in most of the extruded-fermented CPBP. Fermentation of extruded CPBP (moisture of 16 and 18%) increased valine and methionine content. Cadaverine and spermidine were not found after treatment of CPBP, and the lowest content of BA was found in the extruded-fermented (Lpa, moisture 18%) CPBP. Applied treatment had a significant effect on most of the fatty acids. CPBP fermented with Lpl, Lu, and Lpa displayed inhibition properties against 3 of the 10 tested pathogenic/opportunistic bacterial strains. Extruded-fermented (Lu, Lc, and Lpa moisture of 14 and 18%) CPBP showed antifungal activity against Rhizopus. Extruded-fermented (14% moisture, Lpl) CPBP inhibited Rhizopus and Aspergillus fumigatus. In conclusion, combined treatment can improve certain parameters and properties of CPBP in order to produce safer and more nutritious ingredients for food and feed industries.

Зміна окремих показників еритроцитів крові щурів за впливу гістаміну і кверцетину

Зміна окремих показників еритроцитів крові щурів за впливу гістаміну і кверцетину

Survey of the biogenic amines in craft beer from the Chinese market and the analysis of the formation regularity during beer fermentation

This study evaluated the levels of eight biogenic amines in 59 craft beers of five styles and monitored the changes during beer fermentation, showing that putrescine and tryptamine were the most abundant at maximum values of 46.14 mg/L and 89.97 mg/L, respectively. This research indicated for the first time that dark beer, such as Stout/Porter, displayed the highest total biogenic amine content due to considerable tryptamine accumulation, with a maximum value of 116.95 mg/L. The total biogenic amine level increased gradually during the segmental saccharification and main fermentation stages, representing the two critical control points for their formation during beer fermentation. This study provides a theoretical basis and technical guidance for the safe and standardized production of craft beer and the formulation of biogenic amines limit standards, which is highly significant for protecting the health of consumers.

Exploration of the roles of microbiota on biogenic amines formation during traditional fermentation of Scomber japonicus.

The influence of microbiota composition and metabolisms on the safety and quality of fermented fish products is attracting increasing attention. In this study, the total viable count (TVC), pH, total volatile base nitrogen (TVB-N) as well as biogenic amines (BAs) of traditional fermented Scomber japonicus (zaoyu) were quantitatively determined. To comprehend microbial community variation and predict their functions during fermentation, 16S rRNA-based high-throughput sequencing (HTS) and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) were employed, respectively. The fresh samples stored without fermentation were used as controls. TVC and TVB-N values increased rapidly, and the content of BAs exceeded the permissible limit on day 2 in the controls, indicating serious spoilage of the fish. In contrast, a slower increase in TVC and TVB-N was observed and the content of BAs was within the acceptable limit throughout the fermentation of zaoyu. Significant differences in microbiota composition were observed between zaoyu and the controls. The bacterial community composition of zaoyu was relatively simple and Lactobacillus was identified as the dominant microbial group. The accumulation of histamine was inhibited in zaoyu, which was positively correlated with the relative abundance of Vibrio, Enterobacter, Macrococcus, Weissella, et al. based on Redundancy analysis (RDA), while Lactobacillus showed a positive correlation with tyramine, cadaverine, and putrescine. Functional predictions, based on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis, revealed that the relative abundance of metabolic function exhibited a decreasing trend with prolonged fermentation time and the abundance of metabolism-related genes was relatively stable in the later stage of fermentation. Those metabolisms related to the formation of BAs like histidine metabolism and arginine metabolism were inhibited in zaoyu. This study has accompanied microbiota analysis and functional metabolism with the accumulation of BAs to trace their correspondences, clarifying the roles of microorganisms in the inhibition of BAs during fermentation of Scomber japonicus.

Grape Pomace in Ewes Diet Affects Metagenomic Profile, Volatile Compounds and Biogenic Amines Contents of Ripened Cheese

The main objective of this research was to evaluate the development of volatile organic compounds (VOCs) and the accumulation of biogenic amines (BAs) in relation to the dynamic of microbial population composition in fresh and ripened cheese produced from raw milk of ewes fed a diet containing grape pomace (GP+) and fed a standard diet (Ctrl). Genomic DNA was extracted from the cheeses at 2 (T2), 60 (T60), 90 (T90) and 120 (T120) days of ripening and prepared for 16S rRNA-gene sequencing to characterize the cheese microbiota; furthermore, VOCs were determined via solid-phase microextraction combined with gas chromatography-mass spectrometry and biogenic amines by HPLC analyses. Diet did not affect the relative abundance of the main phyla identified, Proteobacteria characterized T2 samples, but the scenario changed during the ripening. At genus level, Pseudomonas, Chryseobacterium and Acinetobacter were the dominant taxa, however, a lower percentage of Pseudomonas was detected in GP+ cheeses. Enterococcus became dominant in ripened cheeses followed in Ctrl cheeses by Lactobacillus and in GP+ cheeses by Lactococcus. The diet affected the development of carboxylic acids and ketones but not of aldehydes. Low levels of esters were identified in all the samples. In total, four biogenic amines were determined in cheeses samples and their levels differed between the two groups and during ripening time. In 60, T90 and T120 GP+ cheeses, a lower amount of 2-phenylethylamine was found compared to Ctrl. Putrescine was detected only in GP+ samples and reached the highest level at 120 days. Conversely, the amount of cadaverine in GP+ samples was invariable during the ripening. The concentration of tyramine in GP+ samples was compared to Ctrl during the ripening. Overall, significant positive correlations between some families of bacteria and the formation of VOCs and BAs were found.