Analysis of biogenic amines in northern and southern European sausages and role of flora in amine production

Histamine contents in raw long-ripening meat products commercially available in Poland

Introduction

Many consumers seek long-ripening meat products. The availability of these highly distinctive cured pork varieties is continuously expanding and their safety should be subject to monitoring. One of potentially harmful substances in these products is histamine. The presence of this toxic amine is reported in many countries, even in high concentrations. However, the EU has not regulated the permissible histamine content in meat, in a situation at odds with that of regulated fish and fish products. This study established the usefulness of biogenic amine testing in long-ripening pork and furnished indicative concentrations potential useful as a background for future research in preparation for EU regulative intervention.

Material and Methods

A total of 97 samples of long-ripening meat products untreated by heat were bought from various shops in the Puławy and Lublin regions of Poland and tested for the presence of histamine using high-performance liquid chromatography with diode array.

Results

The histamine concentration ranged from below limit of detection to 346.64 mg/kg, where 3.47 mg/kg was the lowest in a positive sample. Histamine was detected in 48 samples (49.5%). The maximum amount of histamine was identified in dry ham and the minimum in traditional salami.

Conclusion

The results of this study suggest that testing meat products for biogenic amines should be a very good indicator of the food safety of long-ripening meats. In half of the tested products, levels of biogenic amines potentially toxic to consumers were determined.

Microbial community changes induced by Pediococcus pentosaceus improve the physicochemical properties and safety in fermented tilapia sausage

Amine-negative lactic acid bacteria can prevent excess biogenic amines from accumulating in sausage. In this study, the amine-negative Pediococcus pentosaceus 30-7 and 30-15 with good fermentation properties and biogenic amine removal ability were isolated for tilapia sausage production. P. pentosaceus 30-7 improved the physical characteristics such as gel strength and hardness in tilapia sausage, while P. pentosaceus 30-15 significantly enhanced the contents of umami and sweet free amino acids. The microbial metabolic network revealed that the dominant microbial community in the fermentation process including Pediococcus and Lactococcus contributed to the physicochemical formation of sausage. The significant decrease of biogenic amine contents after addition of P. pentosaceus strains mainly resulted from their ability to remove biogenic amines and to inhibit the growth of amine-producing Enterobacter, Citrobacter, and Streptococcus. This study provides an effective method for directionally improving the physicochemical properties and safety in fermented tilapia sausage.

Food-derived coagulase-negative Staphylococcus as starter cultures for fermented foods

Food safety is of significant concern to consumers and is a major issue for the food industry. As such, the industry is aware of the importance of safety assessments of starters used in the production of fermented foods. Coagulase-negative staphylococci (CNS) are the predominant bacteria found in fermented foods worldwide. Because of this, food-derived CNS are used as starters for cheese and meat fermentation, and have been investigated for use as starters in soybean fermentation. Although food-derived CNS are generally considered non-pathogenic, their safety remains uncertain following the isolation of CNS from skin infections in humans and animals, and because they belong to the same genus as the highly pathogenic species Staphylococcus aureus. This review explores what is known about the safety of food-derived CNS, focusing on antibiotic resistance, enterotoxin genes, and biogenic amine production, to aid in the selection of starter candidates.

Biogenic amines in selected foods of animal origin obtained from the Croatian retail market

This study aimed to investigate the presence of eight biogenic amines (BAs): tryptamine (TRP), phenylethylamine (PHE), putrescine (PUT), cadaverine (CAD), histamine (HIS), tyramine (TYR), spermidine (SPD) and spermine (SPM) in cheese, fish & fishery products and meat & meat products obtained from the Croatian retail market. A selective and robust method of high-performance liquid chromatography (HPLC) with diode array detection (DAD) was applied for the determination of BAs in a total of 91 samples in accordance with the performance criteria outlined in the European legislation. A high inter- and intra-food group variability of the amounts of BAs was observed. In the analysed samples, the most represented amines were TYR, HIS, CAD and PUT. Based on the highest content of the most toxic BAs (HIS and TYR) and consequential food safety concerns, the studied food groups can be ranked in the following order: cheese (HIS up to 106.4 mg/kg; TYR up to 206.6 mg/kg), fish &fishery products (HIS up to 98.8 mg/kg; TYR up to 47.9 mg/kg), and meat & meat products (HIS up to 20.0 mg/kg; TYR up to 117.5 mg/kg). The total BA content was significantly higher (p < .05) in fermented in comparison with other food. The study aimed to contribute to the knowledge on BA toxicity and food quality, as well as to support the indispensable future studies of consumption data and exposure assessment, to the end of defining allowable BA concentrations in food.

SadA-Expressing Staphylococci in the Human Gut Show Increased Cell Adherence and Internalization

A subgroup of biogenic amines, the so-called trace amines (TAs), are produced by mammals and bacteria and can act as neuromodulators. In the genus Staphylococcus, certain species are capable of producing TAs through the activity of staphylococcal aromatic amino acid decarboxylase (SadA). SadA decarboxylates aromatic amino acids to produce TAs, as well as dihydroxy phenylalanine and 5-hydroxytryptophan to thus produce the neurotransmitters dopamine and serotonin. SadA-expressing staphylococci were prevalent in the gut of most probands, where they are part of the human intestinal microflora. Furthermore, sadA-expressing staphylococci showed increased adherence to HT-29 cells and 2- to 3-fold increased internalization. Internalization and adherence was also increased in a sadA mutant in the presence of tryptamine. The α2-adrenergic receptor is required for enhanced adherence and internalization. Thus, staphylococci in the gut might contribute to gut activity and intestinal colonization.

Nonconventional starter cultures of coagulase-negative staphylococci to produce animal-derived fermented foods, a SWOT analysis

Coagulase-negative staphylococci (CNS) are ubiquitous micro-organisms that are commonly present on animal skin and animal-derived foods. They are members of the beneficial microbial consortia of several fermented food products where they contribute to quality. Currently, only a few CNS species are included in commercial starter cultures, although many other ones with promising properties have been isolated from diverse food ecosystems. In the present study, a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis of the potential use of unconventional CNS starter cultures for the fermentation of animal-derived foods is carried out. An overview of both their desirable and worrisome metabolic traits is given. In general, the application of innovative CNS-based starter cultures offers opportunities to modulate flavour, improve the safety and health aspects and develop novel colour development strategies for clean label products. Yet, their implementation is often not straightforward as nontrivial obstacles or threats are encountered, which relate to technological, food safety and legal concerns. As most of the desirable and undesirable characteristics of CNS species are strain dependent, a case-by-case evaluation is needed when evaluating specific strains for their potential use as novel starter cultures.

A possible approach to assess acidification of meat starter cultures: a case study from some wild strains of Lactobacillus plantarum

BACKGROUND

The performances of four autochthonous isolates of Lactobacillus plantarum were assessed to study the most important variables acting on acidification and to propose a possible step-by-step approach for the validation at laboratory scale. This main topic was addressed through three intermediate steps: (1) evaluation of acidification in liquid and solid media, as a function of salt, nitrites, nitrates, lactose, pepper and temperature; (2) assessing acidification in a pork-meat preparation; and (3) designing a protocol to improve the performances at sub-optimal temperatures. The concentration of the ingredients and the temperature were combined through a 3^k-p Fractional Factorial Design. Acidification and viable count were assessed and modelled through a multi-factorial ANOVA.

RESULTS

In model systems acidification was affected by lactose and was maximum (ΔpH of ca. 2.8-3.0) in the combinations containing 0.4% lactose, 250 mg kg^-1 nitrates or 150 mg kg^-1 nitrites, 5% salt, and at 30 °C. Solid media caused a higher acidification. In the pork meat preparation, the effect of salt and nitrites was significant. At 10 °C the strains could not reduce pH, but this ability could be induced using an adaptation step.

CONCLUSION

Acidification was affected by lactose in the model system, whereas in meat preparation the other variables were significant. In addition, a protocol to improve acidification at 10 °C was optimised. © 2016 Society of Chemical Industry.

Effects of Temperature, Humidity and Additives on the Formation of Biogenic Amines in Sucuk during Ripening and Storage Periods

The effects of temperature (20, 30 and 40 C), humidity (50, 65 and 80% RH) and additives on the formation of biogenic amines (tryptamine, -phenyl ethylamine, putrescine, cadaverine, histamine, 1,7-diamino heptane, serotonin, tyramine, spermidine and spermine) in sucuk (Turkish dry-fermented sausage) were studied during ripening and storage periods. Cadaverine was not detected in any sausage. Tryptamine, -phenyl ethylamine, 1,7-diamino heptane, serotonin, spermidine and spermine were the minor biogenic amines found in sucuk. The formation of tryptamine, -phenyl ethylamine, histamine, 1,7-diamino heptane and spermidine were affected significantly (P<0.05) by temperature and% RH during the storage. Preservatives had also a significant effect (P<0.05) on the formation of biogenic amines. The lowest putrescine formation was observed in sucuk type containing the highest amount of additives after 60 days of storage, whereas the highest putrescine formation was obtained in the control sucuk made without additives. Histamine concentration ranged from 0.0 to 242.2 mg/kg and 0.0 to 135.8 mg/kg during ripening and storage periods, respectively. In general, tryptamine formation increased during ripening and decreased during the storage periods. Temperature and% RH of the storage might be used as hurdle factors to control the formation of biogenic amines in sucuk.

Amino acid conversions by coagulase-negative staphylococci in a rich medium: Assessment of inter- and intraspecies heterogeneity

The ability of coagulase-negative staphylococci (CNS) to convert amino acids into volatile compounds and biogenic amines was investigated after 24h and 48 h of incubation in a rich medium (brain heart infusion). Volatile compounds were measured with static-headspace gas chromatography and mass spectrometry (SH-GC-MS); biogenic amine measurements were carried out with a newly developed method based on ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). In total, 56 CNS strains from five different species were used, namely Staphylococcus carnosus, Staphylococcus epidermidis, Staphylococcus equorum, Staphylococcus saprophyticus, and Staphylococcus xylosus. With respect to the production of volatile compounds, the leucine-derived 3-methyl butanol was produced over time by most CNS strains, up to 52 μM for S. xylosus W1-1 after 48 h of incubation. The average production by strains of S. xylosus was significantly higher than for strains of S. carnosus, whereas strains of S. epidermidis turned out to be poor producers. Yet, differences between species were blurred to a large degree because of the high strain variability. A few strains also produced 3-methyl butanal on top of the amount that was already present in the medium background, although most CNS led to a decrease of this compound. Concerning biogenic amines, the average total concentrations per species remained below 100 μM after 48 h of incubation. The most abundant variant was 2-phenylethylamine (PEA), especially within S. carnosus (average of 65 μM after 48 h of incubation). Yet, some individual strains were able to produce higher concentrations, as found for the PEA production of 295 μM by S. epidermidis ATCC 12228 after 48 h of incubation. The insights obtained during this study indicate heterogeneity and are of importance in view of both starter culture development and the evaluation of a spontaneously established CNS microbiota in artisan-type meat fermentations.

Evolution of amino acids and biogenic amines throughout storage in sausages made of horse, beef and turkey meats

The changes in concentration of free amino acids and biogenic amines, along 28 d of storage at 4°C, were monitored in a wide range of European ripened sausages manufactured from horse, beef and turkey meats. Generally speaking, both chemical families became more concentrated with elapsing time--but rather distinct patterns were followed in each meat type: total free amino acids increased by 13-fold in the case of horse sausages, and 5-fold in the case of beef sausages, but decreased to one third in the case of turkey sausages; and total biogenic amines attained 730 mg/kg in turkey sausages, 500 mg/kg in beef sausages and 130 mg/kg in horse sausages by 28 d of refrigerated storage. For putrescine, maximum levels of 285 mg/kg were attained in turkey and 278 mg/kg in beef sausages; for cadaverine, maximum levels of 6 mg/kg in turkey and 9 mg/kg in beef; and for histamine, maximum levels of 263 mg/kg in turkey and 26 mg/kg in beef. Hence, public safety concerns may be raised in the case of turkey sausages.

Influence of various cooking methods on the concentrations of volatile N-nitrosamines and biogenic amines in dry-cured sausages

N-nitrosamines, biogenic amines, and residual nitrites are harmful substances and are often present in cured meats. The effects of different cooking methods (boiling, pan-frying, deep-frying, and microwave) were investigated on their contents in dry-cured sausage. The various N-nitrosamines were isolated by a steam distillation method and analyzed by gas chromatography mass spectrometry (GC-MS). The biogenic amines were determined after extraction with perchloric acid as dansyl derivatives by high-performance liquid chromatography (HPLC) method. The results showed that initial dry-cured raw sausage contained 5.31 μg/kg of total N-nitrosamines. Cooking by deep-frying or pan-frying resulted in products having the highest (P < 0.05) contents, compared with boiling or microwave treatments, which were not different from the raw. Although frying increased the content of N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), and N-nitrosopyrrolidine (NPYR), it decreased the contents of histamine and cadaverine. Boiling and microwave treatments decreased the total biogenic amines significantly (P < 0.05). Residual nitrite was significantly reduced by cooking treatments. The results suggest that boiling and microwave treatments were more suitable methods for cured meat.

Changes in biogenic amine levels during storage of Mexican-style soft and Spanish-style dry-ripened sausages with different a(w) values under modified atmosphere

Two raw sausages were prepared: a soft and a dry-ripened one, both by local traditional and industrial manufacturing practices. Sausages were packaged under a CO2/N2 atmosphere at different targeted activity water (aw) values: 0.96 and 0.92 (soft sausages) and 0.88 and 0.82 (dry-ripened sausages). Sausages were then stored at 5 °C for 42 days or at 12 °C for 240 days (soft and a dry-ripened sausages, respectively). The time-related changes in dominant microbiota, pH and biogenic amine contents during storage were determined. Tyramine was the most abundant biogenic amine in all the sausages. Biogenic amine levels were higher in dry-ripened sausages than in soft sausages at packaging. However, during refrigerated storage soft sausages were fermented and the levels of biogenic amines increased (P<0.05). At the end of storage, traditional soft sausages with 0.96 aw presented comparable levels of biogenic amines to traditional dry-ripened sausages.

Lactobacillus sakei CRL1862 improves safety and protein hydrolysis in meat systems

AIMS

The capacity of Lactobacillus sakei CRL1862 to prevent the growth of pathogens and its ability to degrade sarcoplasmic and myofibrillar proteins in pork meat systems was evaluated. In addition, basic safety aspects of Lact. sakei CRL1862 such as production of biogenic amines and antibiotic susceptibility were addressed.

METHODS AND RESULTS

The bacteriocin-producing Lact. sakei CRL1862 showed respectively bactericide and bacteriostatic effect against Listeria monocytogenes and Staphylococcus aureus in beaker sausage assay during 9 days of storage at 22 °C. The hydrolytic effect of Lact. sakei CRL1862 on protein extracts was evaluated by SDS-PAGE and reverse phase HPLC. A more pronounced proteolysis was evidenced in inoculated sarcoplasmic proteins compared with myofibrillar extracts with the generation of predominantly hydrophilic peptides and increase of total free amino acids concentration. Lactobacillus sakei CRL1862 produced neither histamine nor tyrosine and exhibited no resistance to the antibiotics assayed.

CONCLUSIONS

Lactobacillus sakei CRL1862 effectively controlled the growth of L. monocytogenes and Staph. aureus; moreover, it was able to hydrolyse pork meat extracts generating peptides and amino acids, which may improve hygienic and sensorial attributes of fermented meat products.

SIGNIFICANCE AND IMPACT OF THE STUDY

The use of an integrated approach to evaluate the major traits of Lact. sakei CRL1862 showed it can be applied as an autochthonous functional starter in meat fermentation.

Use of autochthonous Pediococcus acidilactici and Staphylococcus vitulus starter cultures in the production of "chorizo" in 2 different traditional industries

The present study determined how the different ripening conditions affected the growth and development of 3 autochthonous starter cultures, and the physico-chemical and sensory characteristics of chorizo. Each of 3 strains of Pediococcus acidilactici (MC184, MS198, and MS200) and one of Staphylococcus vitulus (RS34) were associated to prepare the starter cultures, P184S34, P198S34, and P200S34. Then, chorizo was prepared following 2 manufacturing procedures. The autochthonous starter cultures were able to compete and colonize the sausages in both ripening procedures. The use of the starter cultures showed evident differences by the texture analysis, with the control batches being generally tougher than the starter culture batches. Also, the highest biogenic amine (BA) levels were found in control batches and the lowest in P200S34 batches. While the use of these starter cultures does not change the sensory characteristics of these traditional fermented sausages, it improves their homogeneity and safety, except for P184S34 batch in which more BAs are detected in industry 2.

PRACTICAL APPLICATION

The 3 autochthonous starter cultures selected could be used in traditional industries because they are able to compete well and colonize the dry fermented sausages "chorizo." The use of these starter cultures improves the texture and homogeneity of traditional fermented sausages. Biogenic amines decreased in the starter cultures batches improving the safety.

Post-mortem volatiles of vertebrate tissue

Volatile emission during vertebrate decay is a complex process that is understood incompletely. It depends on many factors. The main factor is the metabolism of the microbial species present inside and on the vertebrate. In this review, we combine the results from studies on volatile organic compounds (VOCs) detected during this decay process and those on the biochemical formation of VOCs in order to improve our understanding of the decay process. Micro-organisms are the main producers of VOCs, which are by- or end-products of microbial metabolism. Many microbes are already present inside and on a vertebrate, and these can initiate microbial decay. In addition, micro-organisms from the environment colonize the cadaver. The composition of microbial communities is complex, and communities of different species interact with each other in succession. In comparison to the complexity of the decay process, the resulting volatile pattern does show some consistency. Therefore, the possibility of an existence of a time-dependent core volatile pattern, which could be used for applications in areas such as forensics or food science, is discussed. Possible microbial interactions that might alter the process of decay are highlighted.

Biogenic amine formation in Nham, a Thai fermented sausage, and the reduction by commercial starter culture, Lactobacillus plantarum BCC 9546

Biogenic amines are of concern for sausage due to their toxicological effects on nervous, blood pressure, gastric and intestinal systems. In this study, the influence of raw pork meat quality and starter culture inoculation on biogenic amines accumulation in Nham, a Thai traditional fermented pork, were studied. Before Nham processing, pork meat was stored at 30°C for 6h, and at 4 and -20°C for 2days. Formation of biogenic amines (cadaverine, putrescine, histamine and tyramine) was significantly higher in Nham processed from stored meat. Accumulation of these biogenic amines in Nham reduced significantly by the addition of Lactobacillus plantarum BCC 9546, a commercial Nham starter culture. The results highlight the importance of using fresh meat products and the inclusion of an appropriate starter culture to minimise the formation of biogenic amines during the process of Nham fermentation.

Diversity and safety hazards of bacteria involved in meat fermentations

Food safety is a major concern for consumers and a major issue for industry which has become aware of the importance of the starter safety assessment. In the European Union, the Food Safety Authority has introduced the Qualified Presumption of Safety (QPS) approach for safety assessment of microorganisms throughout the food chain. This assessment relies on: taxonomy, familiarity, pathogenicity and end use. Productions of toxins as well as biogenic amines by food isolates are both of major concern as they can lead to food poisoning. The other important criterion is the presence of transmissible antibiotic resistance markers. This review underlined that the main hazard of bacteria involved in food fermentations concerns antibiotic resistance and particularly the presence of transferable genetic determinants that may present a risk for public health. Selection of starter strains should consider this hazard. Following the QPS approach, a list of bacteria has been acknowledged acceptable for consumption.

Application of Lactobacillus fermentum HL57 and Pediococcus acidilactici SP979 as potential probiotics in the manufacture of traditional Iberian dry-fermented sausages

The purpose of this study was to investigate the potential of implanting the probiotics Lactobacillus fermentum HL57 and P. acidilactici SP979 during manufacture of Iberian dry-fermented sausages, and their effect on the sensory properties of these meat products. Microbial counts were studied in sausages inoculated with these strains and compared with a control batch. To detect the presence of probiotic strains at high counts (>7 log CFU/g) in the inoculated sausages, specific PCR and (RAPD)-PCR techniques were carried out. Changes due to probiotic inoculations on parameters and compounds related to fermentation, and nitrogen and lipid fractions were determined, and the impact on sensory quality evaluated by descriptive and hedonic tests. Iberian dry-fermented sausages inoculated with L. fermentum HL57 and P. acidilactici SP979 may be considered as functional products according to the counts of these strains found at the end of processing. However, inoculation with L. fermentum HL57 increased the amount of acetic acid and lipid degradation products such as malonaldehyde in Iberian dry-fermented sausages, resulting in a negative impact on relevant sensory parameters related to colour and taste. On the contrary, P. acidilactici SP979 did not notably modify the physicochemical parameters or the sensory quality of Iberian dry-fermented sausages when compared to the autochthonous microbial population present in the control batch.

DNA microarray based detection of genes involved in safety and technologically relevant properties of food associated coagulase-negative staphylococci

Aim of the work was to design a polynucleotide based DNA microarray as screening tool to detect genes in food associated coagulase-negative staphylococci (CNS). A focus was laid on genes with potential health concern and technological relevance. The microarray contained 220 probes for genes encoding antibiotic resistances, hemolysins, toxins, amino acid decarboxylases (e.g. biogenic amine formation), binding proteins to extracellular matrix (ECM), lipases, proteases, stress response factors, or nitrate dissimilation. Hybridization of genomic DNA isolated from 32 phenotypically characterized CNS permitted to detect numerous genes, corresponding with the phenotype. However, numerous hybridization signals were obtained for genes without any detectable phenotype. The antibiotic resistance genes blaZ, lnuA, and tetK involved in ß-lactam, lincomycin and tetracycline resistance, respectively, were rarely identified in CNS, however, all species contained some strains with such resistance genes. Decarboxylase genes involved in biogenic amine formation were detected regularly in Staphylococcus carnosus, S. condimenti, S. piscifermentans and S. equorum, but was rarely correlated with the phenotype. The same applied for the fibrinogen (clf) and fibronectin (fbp) binding protein genes, whose phenotype (binding assay) was only correlated in S. equorum and Staphylococcus succinus. Although some CNS showed hemolytic activity and enterotoxin production (Immunoblot) the corresponding genes could not be verified. Technological relevant genes such as proteases or lipases revealed good hybridization signals. In addition, genes involved in nitrate dissimilation (nre, nar, nir), catalase (kat), or superoxide dismutase (sod) were well detected. Interestingly, genes involved in dissimilatory nitrate reduction were more prevalent in strains of S. carnosus, S. condimenti and S. piscifermentans than of S. equorum, S. succinus and S. xylosus.

Distribution of aminogenic activity among potential autochthonous starter cultures for dry fermented sausages

Any bacterial strain to be used as starter culture should have suitable characteristics, including a lack of amino acid decarboxylase activity. In this study, the decarboxylase activity of 76 bacterial strains, including lactic acid bacteria and gram-positive, catalase-positive cocci, was investigated. These strains were previously isolated from European traditional fermented sausages to develop autochthonous starter cultures. Of all the strains tested, 48% of the lactic acid bacteria strains and 13% of gram-positive, catalase-positive cocci decarboxylated one or more amino acids. Aminogenic potential was strain dependent, although some species had a higher proportion of aminogenic strains than did others. Thus, all Lactobacillus curvatus strains and 70% of Lactobacillus brevis strains had the capacity to produce tyramine and beta-phenylethylamine. Some strains also produced other aromatic amines, such as tryptamine and the diamines putrescine and cadaverine. All the enterococcal strains tested were decarboxylase positive, producing high amounts of tyramine and considerable amounts of beta-phenylethylamine. None of the staphylococcal strains had tyrosine-decarboxylase activity, but some produced other amines. From the aminogenic point of view, Lactobacillus plantarum, Lactobacillus sakei, and Staphylococcus xylosus strains would be the most suitable for use as autochthonous starter cultures for traditional fermented sausages.

Development of biogenic amines during the ripening of Italian dry sausages

The effect of modification of different chemical and microbiological parameters and the production of biogenic amines (histamine, cadaverine, putrescine, and tyramine) was examined during ripening of various types of typical Italian dry sausages (salami). Water activity decreased from 0.97 to 0.87, and pH reached the lowest value between the 13th and the 20th day of the ripening period, and then increased. Putrescine (up to 122.7 mg/kg) and tyramine (up to 105.9 mg/kg) mean levels showed dominance in comparison with cadaverine (up to 26.1 mg/kg) and histamine (up to 6.2 mg/kg) mean values in all sausage types. The highest putrescine and tyramine concentrations were observed in salami with the largest diameters. This comparative study suggests a good correlation between microbial behavior and amine evolution, particularly tyramine and putrescine, in dry sausage production.

Combined use of starter cultures and preservatives to control production of biogenic amines and improve sensorial profile in low-acid salami

The combined effect of starter culture, nitrites, and nitrates has been studied in low-acidity salamis, typical products of northern Italy. Nine batches have been prepared, combining three different inoculations of starter cultures (control, Lactobacillus plantarum , and Lactobacillus plantarum together with Kocuria varians ) with three different preservatives (control, sodium nitrate, and sodium nitrite). All of the batches showed a good fermentation process with a proper pH decrease, which was quicker in batches inoculated with L. plantarum. The use of starter cultures and in particular the use of nitrites allowed the control of the proliferation of Enterobacteriaceae and enterococci. The accumulation of biogenic amines, especially putrescine, cadaverine, tryptamine, and tyramine, in salami ready for consumption (60 days of ripening) was strongly affected by the presence of Enterobacteriaceae and enterococci. Results obtained showed that the combined use of adequate preservatives and starter cultures allows the production of safer products with improved sensorial profile.