Levels Of Tyramine Research Articles

Effects of black cumin (Nigella sativa) oil on ammonia and biogenic amine production in rainbow trout

In the present study, 0.00% (control), 0.10%, 0.40%, 0.70%, 1.00% and 1.30% black cumin oil was added to rainbow trout feed and the fish were fed for 120 days. Following the feeding period, the harvested fish were stored in the refrigerator at ±2 ºC, in Styrofoam boxes filled with ice, for 23 days. During the storage period, the effects of black cumin oil on ammonia and biogenic amine production in rainbow trout were examined. An increase was observed in the ammonia content during the storage period, with the most substantial increase observed in the control group and the least substantial increase observed in the 1.30% black cumin oil group. The biogenic amine level increased during the storage period. A significant increases was observed in the tyramine level during the storage period ( less than 3.08 mg/100 g), and significant differences were observed between the groups in terms of spermidine, spermine, histamine, and tyramine content (p less than 0.05). The results of the present study suggest that the addition of black cumin oil reduced ammonia and biogenic amine production in rainbow trout.

Pathogenesis of chronic cluster headache and bouts: role of tryptamine, arginine metabolism and α1-agonists.

The aim of this study was to explore the possible role of tryptamine in the pathogenesis of chronic cluster headache along with that of adrenaline and noradrenaline (α-agonists) together with arginine metabolism in the origin of cluster bouts. Plasma levels of tyramine, tryptamine, serotonin, 5-hydroxyindolacetic acid, noradrenalin, adrenalin and the markers of arginine metabolism such as arginine, homoarginine, citrulline, ADMA and NMMA, were measured in 23 chronic cluster headache patients (10 chronic cluster ab initio and 13 transformed from episodic cluster) and 28 control subjects. The plasma levels of tyramine, tryptamine, noradrenalin and adrenalin were found several times higher in chronic cluster headache patients compared to controls, whereas the plasma levels of arginine, homoarginine and citrulline were significantly lower. No differences were found in the plasma levels of serotonin, 5-hydroxyindolacetic, ADMA and NMMA between chronic cluster headache patients and control subjects. These results provide support for a role of tryptamine in the pathogenesis of chronic cluster headache and, in particular, in the duration of the cluster bouts. In addition, the low levels of the nitric oxide substrates together with the high levels of noradrenalin and adrenalin suggest an activation of endothelial TAAR1 receptors followed by the release of nitric oxide in the circulation that may constitute the final step of the physiopathology of cluster crisis.

Screening chemical hazards of dry fermented sausages from distinct origins: Biogenic amines, polycyclic aromatic hydrocarbons and heavy elements

This work aims to evaluate the presence of chemical hazards on commercially-available dry fermented sausages (DFS) from different origins and provide preventive recommendations to warrant products safety. Samples (n=20) were purchased at retail level in different markets of Lisbon (Portugal) and Novi Sad (Serbia). Biogenic amines (BAs), polycyclic aromatic hydrocarbons (PAHs) and heavy elements were determined. Portuguese and Serbian DFS showed low levels of cadaverine (0.6–202mg/kg and 1.6–291mg/kg, respectively), putrescine (3.5–401mg/kg and 1.4–291mg/kg, respectively) and tyramine (32.6–206mg/kg and 5.0–246mg/kg, respectively). Histamine never reached considerable levels in both DFS. Low molecular weight PAHs were the most abundant, comprising more than 90% of total PAHs. Serbian and the majority of Portuguese DFS well meet the EU legislation for the PAHs content. The most prevalent heavy element in DFS from both origins was lead (0.01–0.34mg/kg). Contents of heavy elements in DFS from Portuguese and Serbian markets indicated that these potential hazards were present but at low risk for consumers. Additional investigation still has to be done regarding selection of autochthonous starters not producers of BAs and smoking step optimization to minimize the contents of BAs and potential toxic PAHs in DFS.

Residual nitrite and biogenic amines of traditional northeast sauerkraut in China

ABSTRACTThe safety of northeast sauerkraut (NS) has always been a concern in China. In the present study, the nitrite and biogenic amine (BA) contents in 378 NS, collected or purchased from Chinese families and markets (including morning markets and local supermarkets), were measured. The results showed that the nitrite and BA contents of samples from Chinese families and some morning markets were higher than those from local supermarkets. The highest level of nitrites was 38.5 ± 5.2 mg/kg in unpackaged NS from Chinese families, and the lowest was 17.2 ± 2.1 mg/kg in packaged NS from local supermarkets. The highest levels of tyramine and tryptamine were 203 ± 3 and 28.1 ± 4 mg/kg in unpackaged NS from Chinese families, respectively. The highest levels of histamine, putrescine, and cadaverine were mainly found in Chinese families and morning markets, and the lowest level of BAs was from local supermarkets. The results suggest that improving the safety of NS by controlling environmental sanitation and strengthening standardised production is a top priority at present in China.

Abnormal tyrosine metabolism in chronic cluster headache.

Objective Episodic cluster headache is characterized by abnormalities in tyrosine metabolism (i.e. elevated levels of dopamine, tyramine, octopamine and synephrine and low levels of noradrenalin in plasma and platelets.) It is unknown, however, if such biochemical anomalies are present and/or constitute a predisposing factor in chronic cluster headache. To test this hypothesis, we measured the levels of dopamine and noradrenaline together with those of elusive amines, such as tyramine, octopamine and synephrine, in plasma of chronic cluster patients and control individuals. Methods Plasma levels of dopamine, noradrenaline and trace amines, including tyramine, octopamine and synephrine, were measured in a group of 23 chronic cluster headache patients (10 chronic cluster ab initio and 13 transformed from episodic cluster), and 16 control participants. Results The plasma levels of dopamine, noradrenaline and tyramine were several times higher in chronic cluster headache patients compared with controls. The levels of octopamine and synephrine were significantly lower in plasma of these patients with respect to control individuals. Conclusions These results suggest that anomalies in tyrosine metabolism play a role in the pathogenesis of chronic cluster headache and constitute a predisposing factor for the transformation of the episodic into a chronic form of this primary headache.

An analytical strategy to investigate Semen Strychni nephrotoxicity based on simultaneous HILIC-ESI-MS/MS detection of Semen Strychni alkaloids, tyrosine and tyramine in HEK 293t cell lysates.

A Previous metabolomics study has demonstrated that tyrosine metabolism might be disrupted by treating with Semen Strychni on the cell nephrotoxicity model. To investigate the relationship between Semen Strychni alkaloids (SAs) and endogenous tyrosine, tyramine under the nephrotoxicity condition, an HILIC-ESI-MS/MS based analytical strategy was applied in this study. Based on the established Semen Strychni nephrotoxicity cell model, strychnine and brucine were identified and screened as the main SAs by an HPLC-Q Exactive hybrid quadrupole Orbitrap mass system. Then, a sensitive HILIC-ESI-MS/MS method was developed to simultaneously monitor strychnine, brucine, tyrosine and tyramine in cell lysate. The analytes were separated by a Shiseido CAPCELL CORE PC (150mm×2.1mm, 2.7μm) HILIC column in an acetonitrile/0.1% formic acid gradient system. All the calibration curves were linear with regression coefficients above 0.9924. The absolute recoveries were more than 80.5% and the matrix effects were between 91.6%-107.0%. With the developed method, analytes were successfully determined in cell lysates. Decreased levels of tyrosine and tyramine were observed only in combination with increased levels of SAs, indicating that the disturbance of tyrosine metabolism might be induced by the accumulation of SAs in kidney cell after exposure of Semen Strychni. The HILIC-ESI-MS/MS based analytical strategy is a useful tool to reveal the relationships between the toxic herb components and the endogenous metabolite profiling in the toxicity investigation of herb medicines.

In vitro effects of sodium bicarbonate buffer on rumen fermentation, levels of lipopolysaccharide and biogenic amine, and composition of rumen microbiota.

Diets containing high levels of carbohydrates provoke a rapid decrease of rumen pH and high levels of biogenic amines and lipopolysaccharides (LPS), which severely impair the health and performance of ruminants. The goal of this study was to evaluate the effects of sodium bicarbonate (BC) buffer on rumen fermentation, levels of LPS and biogenic amine, and composition of rumen microbiota using in vitro rumen cultures. Sodium bicarbonate supplementation increased (P < 0.05) the final pH levels and concentrations of total volatile fatty acids and LPS, as well as the proportions of acetate, propionate, isobutyrate, isovalerate and valerate, and it decreased (P < 0.05) the proportion of butyrate and the levels of lactic acid, methylamine, tryptamine, tyramine, histamine and putrescine compared with the control. Pyrosequencing of the 16S rRNA gene showed that BC inclusion increased (P < 0.05) the bacterial diversity index compared with the control. Adding BC also decreased (P < 0.05) the relative abundance of Streptococcus and Butyrivibrio and increased (P < 0.05) the proportions of Ruminococcus, Succinivibrio and Prevotella. Sodium bicarbonate supplementation has beneficial effects in the reduction of bioamine levels and the increase in ruminal pH, and in modifying the microbial ecology of the rumen; however, it results in an accumulation of LPS under high-grain diet conditions. © 2016 Society of Chemical Industry.

Safety and technological characterization of coagulase-negative staphylococci isolates from traditional Korean fermented soybean foods for starter development

To select starters for the production of meju and doenjang, traditional Korean fermented soybean foods, we assessed the safety and technological properties of their predominant isolates, Staphylococcus saprophyticus, Staphylococcus succinus and Staphylococcus xylosus. Phenotypic antibiotic resistance, hemolysis and biofilm formation were strain-specific. None of the S. succinus isolates exhibited antibiotic resistance or hemolytic activities. Thirty-three selected strains, identified through safety assessments of 81 coagulase-negative staphylococci (CNS) isolates, produced cadaverine, putrescine, and tyramine, but not histamine in the laboratory setting. The production of these three biogenic amines may, however, be insignificant considering the high levels of tyramine produced by the control, Enterococcus faecalis. The 33 CNS strains could grow on tryptic soy agar containing 21% NaCl (w/v), exhibited acid producing activity at 15% NaCl, and expressed strain-specific protease and lipase activities. S. succinus 14BME1, the selected starter candidate, produced significant amounts of benzeneacetic acid, 2,3-butanediol, trimethylpyrazine, and tetramethylpyrazine through soybean fermentation.

Occurrence of biogenic amines in beers from Chilean market

The presence of tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine was determined for the first time in beers commercialized in Chilean market. Dansylated amines were separated on a Zorbax-XDB C18 column using a binary mobile phase composed of acetonitrile and 20 mmol L−1 ammonium formate, pH 5.5. Chromatographic conditions were optimized using an experimental design, and validation was carried out following ICH recommendations. Calibration data fitted a linear regression model with R2 > 0.996. Repeatability (n = 6) and intermediate precision (n = 3) in matrix showed RSD values lower than 5.00% and 5.21%, respectively. Recoveries at three different concentrations ranged from 75.50 to 96.48%. The proposed method was applied to determine the biogenic amines content in 101 beer samples produced by macro- (n = 65) and microbreweries (n = 36) using low (n = 63) and high fermentations (n = 38). Biogenic amines content in beer samples ranged from 0.53 to 85.04 mg L−1, from which beers produced by microbreweries (19.13 ± 16.92 mg L−1) showed a significant higher biogenic amines content (P = 0.0021) than beers produced by macrobreweries (9.65 ± 4.50 mg L−1). Putrescine was the principal biogenic amine found in all kind of beers regardless origin, and the type of fermentation and brewery. Only 2 samples presented relevant levels of histamine and tyramine, but both below the limits reported by the European Food Safety Authority (EFSA). Thus, it can be concluded that beers commercialized in Chile are not a serious toxicological risk (e.g. hypertensive crisis) regarding the type and content of biogenic amines.

Tyraminergic and Octopaminergic Modulation of Defensive Behavior in Termite Soldier.

In termites, i.e. a major group of eusocial insects, the soldier caste exhibits specific morphological characteristics and extremely high aggression against predators. Although the genomic background is identical to the other non-aggressive castes, they acquire the soldier-specific behavioral character during the course of caste differentiation. The high aggressiveness and defensive behavior is essential for colony survival, but the neurophysiological bases are completely unknown. In the present study, using the damp-wood termite Hodotermopsis sjostedti, we focused on two biogenic amines, octopamine (OA) and tyramine (TA), as candidate neuromodulators for the defensive behavior in soldiers. High-performance liquid chromatographic analysis revealed that TA levels in the brain and suboesophageal ganglion (SOG) and the OA level in brain were increased in soldiers than in pseudergates (worker caste). Immunohistochemical analysis revealed that TA/OA neurons that innervate specific areas, including the mandibular muscles, antennal nerve, central complex, suboesophageal ganglion, and thoracic and/or abdominal ganglia, were enlarged in a soldier-specific manner. Together with the results that pharmacological application of TA promoted the defensive behavior in pseudergates, these findings suggest that the increased TA/OA levels induce the higher aggressiveness and defensive behavior in termite soldiers. The projection targets of these soldier-specific enlarged TA/OA neurons may have important roles in the higher aggressiveness and defensive behavior of the termite soldiers, inducing the neuronal transition that accompanies external morphological changes.

Quality Indices of Cooked Southern King Crab (Lithodes santolla Molina, 1782) Meat During Storage at 0 and −20°C

ABSTRACTThe aim of this work was to determine the changes in quality of cooked southern king crab (Lithodes santolla) meat during storage at 0°C for 5 and 10 days and −20°C for 10, 30, 60, and 90 days. Chemical indices varied from the initial to the final storage time in refrigerated and frozen samples as follows: TVB-N, 15.8–29.2 and 15.8–23.2 mg/100 g; TMA, 0.0–8.3 and 0.0–1.2 mg/100 g; formaldehyde, 0.5–8.6 and 0.5–3.7 mg/kg; indole, 3.3–20.7 and 3.3–6.6 µg/100 g; lactic acid, 16.4–39.1 and 16.4–16.6 mg/100 g; and P ratio, 0–28.4 and 0–5.2%, respectively. The total nucleotide content rendered 6.77 µmol/g, with adenosine monophosphate (AMP) the main component. The nucleotide indices varied in refrigerated and frozen samples as follows: K, 7.37–27.5 and 7.37–10.3%; Ki, 58.3–86.5 and 58.3–82.7%; H, 30.2–54.9 and 30.2–38.0%; G, 19.4–57.8 and 19.4–15.8%; P, 17.2–42.3 and 17.2–14.7%; and Fr, 41.6–13.4 and 41.6–17.3%, respectively. Biogenic amines found at both storage temperatures were spermine, spermidine, tyramine, and agmatine. Spermine may be considered as a potential freshness index for refrigerated samples and spermidine for frozen storage. The tyramine level should be monitored. During the storage period tested, none of the chemical indices studied exceeded the legal limits.

SCREENING OF SOME FERMENTED MILK FOR DECARBOXYLASE AND BIOGENIC AMINES PRODUCING MICROORGANISMS AND THEIR PUBLIC HEALTH SIGNIFICANCE

The objectives of this study were based on screening for presence of decarboxylase producing microorganisms (Enterobacteriaceae, Enterococci and Lactobacilli) in sour milk, yoghurt and labenh, collected from supermarkets in Ismailia City. The isolated strains were tested for decarboxylase activity and the levels of histamine, tyramine, putrescine and cadaverine were determined in the examined samples. The results revealed that all the examined samples were contaminated with EnterobacteriaceaeandEnterococci at variable counts. All the isolated strains of Enterobacteriaceae, Enterococci and Lactobacillus spp. have the potential to release decarboxylase enzymes with biogenic amines formation. The examined samples were found to contain the estimated amines with variable levels, expect yoghurt that didn't contain tyramine. In conclusion, there was a positive correlation between the type of microorganisms present in fermented milk and the type of biogenic amines formed. The prevention of biogenic amines formation in fermented milks could be achieved by following good hygienic measures and careful screening of lactic acid bacteria for amino acid decarboxylase activity before selecting as starter or probiotic strains in dairy industry.

Changes in the levels of biogenic amines associated with aggressive behavior of queen in the social parasite ant Vollenhovia nipponica

Insect behavior is regulated by physiological and neurological systems. Biogenic amines play a role in motivating the behavior as neurotransmitters, neuromodulators, and neurohormones in the nervous systems. In ants, the change of brain amine levels is linked to various behavioral properties: reproduction, cooperation, and hostility. Aggressiveness is also manipulated by the neurological systems. The social structures in some ant species are established by aggressive interactions among queens. However, there are a few cases showing the putative role of biogenic amines for the queen aggression. Vollenhovia nipponica is a social parasite ant, which establishes functional monogyny that antagonistic interactions among multiple queens lead to dominance hierarchy. In this time, we examined changes in the levels of biogenic amines in heads of queens in V. nipponica, associated with the observation of aggressive behavior. In the colonies, dealate queens violently attacked toward each other by biting and pulling on body parts. Whereas, the aggressive behavior was never observed in alate queens. In the measurements in four biogenic amines, serotonin (5-HT), dopamine (DA), octopamine (OA), and tyramine (TA), the levels of 5-HT and DA in dealates were significantly higher than those in alates. The levels of OA and TA were not significantly different between them. Moreover, the similar changes were confirmed in the groups of young (10–30 days old) and old queens (more than 6-month old). In V. nipponica queens, 5-HT and DA could regulate motivation of aggression, irrespective of age. However, the changes of biogenic amines are possibly affected by other behavioral factors.

Pathogenesis of chronic migraine: the role of neuromodulators.

The pathogenesis of chronic migraine (CM) remains largely unknown. We hypothesized that anomalies of tyrosine metabolism, found in migraine without aura (MwoA) patients, play an important role in the transformation of MwoA into CM, since the increase in the number of MwoA attacks is the most predisposing factor for the occurrence of CM. To test our hypothesis we measured the plasma levels of dopamine (DA), noradrenaline (NE) and trace amines, including tyramine (TYR) and octopamine (OCT), in a group of 73 patients with CM, 13 patients with chronic tension-type headache (CTTH) and 37 controls followed in the Headache Centres of the Neurology Departments of Asti, Milan and Vicenza hospitals in Italy. The plasma levels of DA and NE were several-fold higher in CM patients compared with control subjects (p > 0.001). The plasma levels of TYR were also extremely elevated (p > 0.001); furthermore, these levels progressively increased with the duration of the CM. Our data support the hypothesis that altered tyrosine metabolism plays an important role in the pathogenesis of CM. The high plasma levels of TYR, a potent agonist of the trace amine associated receptors type 1 (TAAR1), may ultimately down-regulate this receptor because of loss of inhibitory presynaptic regulation, therein resulting in uncontrolled neurotransmitter release. This may produce functional metabolic consequences in the synaptic clefts of the painmatrix implicated in CM. Written informed consent to publication was obtained from the patient(s).

Biogenic amines residues in canned fish

One hundred random samples of local and imported canned Tuna and Mackerel fish (25 of each) wereanalyzed for detection and determination of biogenic amines residues (histamine, tyramine andputrescine) by High Performance Liquid Chromatography (HPLC). The obtained results revealed thatthe average concentration levels of histamine, tyramine, and putrescine (mg/kg) were 22.86±0.72,0.274±0.035 & 1.884±0.181, 19.48±0.64, 0.184±0.177& 1.72±0.076, 36.72±1.807, 0.393±0.048 &2.1±0.104, 29.04±1.46, 0.368±0.047 and 1.894±0.115 for local and imported tuna and mackerelsamples, respectively. All Samples of both canned tuna and mackerel were acceptable for histamine,tyramine and putrescine Except 8% of local canned mackerel A exceeded permissible limits forhistamine according to Egyptian Organization of Standardization (EOS, 2005).

Role of biogenic amines in the post-mortem migration of Anisakis pegreffii (Nematoda: Anisakidae Dujardin, 1845) larvae into fish fillets

Infective third-stage larvae (L3) of nematode Anisakis spp. have been recognized as one of the major food-borne threats in lightly processed fish products in Europe, particularly in the Mediterranean region. Therefore, the effect of different storage temperatures of fish on larval post-mortem migration from visceral cavity into fillets is an important parameter to take into account when evaluating the risk for consumer safety. The European anchovy (Engraulis encrasicolus) were caught during fishing season, a subsample of fillets was checked for the presence of Anisakis larvae at capture (mean abundance=0.07), and the rest was stored at four different temperatures (−18, 0, 4 and 22°C) in order to count migrating larvae and measure the production of biogenic amines over a period of time. Larvae were identified by morphological features and molecular tools. Post-mortem migration was observed in fillets stored at 0 and 4°C after three and five days, respectively, but not at 22 and −18°C. In case of storage at 22°C for two days, at the onset of putrefaction of the visceral organs, larvae migrated out of the visceral cavity towards the fish surface. Measured pH and biogenic amine profile during storage indicated that certain biochemical conditions trigger larval migration into fillets. Likewise, migration was observed at pH ~6.4 when sensory degradation of the fish was markedly visible. Although larval migration was delayed for approximately four days at a temperature of <4°C the correlation between pH and abundance of A. pegreffii larvae in the fillet was high and statistically significant at both 0 (r=0.998, p<0.01) and 4°C (r=0.946, p<0.05). Out of eight biogenic amines measured, cadaverine and putrescine levels correlated the most with the post-mortem migration at 4°C, while tyramine levels were significant at both temperatures.

Changes in the microbial communities of air-packaged and vacuum-packaged common carp (Cyprinus carpio) stored at 4 °C

The dominant microbiota of air-packaged (AP) and vacuum-packaged (VP) common carp fillets during storage were systematically identified. Culture-dependent methods were used for microbial enumeration and 16S rRNA genes of the isolated pure strains were sequenced and analyzed. Different packaging conditions affected the growth of microbiota and the shelf life of carp. Shelf-life of AP and VP fillets was 8 and 12 days, respectively. Vacuum packaging delayed the increase of biogenic amines levels compared to air packaging, especially for cadaverine and tyramine levels. In the present study, a total of 13 different genera comprised the microbial communities of fresh carp fillets and Acinetobacter dominated the indigenous flora of carp. However, variability in bacterial community composition was observed in these two packaging conditions. Pseudomonas were the only microbiota found in the spoiled AP carp, whereas Carnobacterium followed by Aeromonas were found mainly in VP samples. Other genera Shewanella, Lactococcus, and Pseudomonas were also found in low numbers at the end of the VP fillets’ shelf life. Additional microbial enumeration observed the highest Pseudomonas counts (8.77 log CFU/g on day 8) in AP samples and a relatively high level of lactic acid bacteria (7.74 log CFU/g on day 12) in VP samples.

Bioactive amines in fresh beef liver and influence of refrigerated storage and pan-roasting

The profile and levels of ten bioactive amines in fresh beef liver was determined and associated with physico-chemical parameters of quality. Furthermore, the influence of refrigerated storage at 0 ± 1 °C and 7 ± 1 °C and of pan-roasting on beef liver quality and safety was investigated. Fresh beef liver was characterized by pH of 6.71–6.92, TVB-N of 98.58–154.72 mg N/100 g and negative H2S. It contained high levels of spermine (up to 119 mg/kg), and low levels of spermidine, putrescine, tyramine and histamine. Therefore, beef liver constitutes one of the richest dietary source of spermine. During refrigerated storage, there were significant physico-chemical changes: the pH decreased, TVB-N increased, and hydrogen sulfide was moderate. The levels of most of the naturally occurring amines increased at rates which were faster at higher storage temperature. Two amines which were not initially detected, reached detectable levels – tryptamine and cadaverine. The proposed bioactive amines based indices of quality to access liver quality were not appropriate to follow gradual quality changes. A shelf life of up to 6 and 4 days during storage at 0 ± 1 °C and 7 ± 1 °C, respectively, is recommended. During pan-roasting at 180 °C for 10 min, the levels of the polyamines increased significantly.

Effect of NaCI Treatments on Tyramine Biosynthesis of Enterococcus faecalis

The effect of NaCl stress (0 to 8%, wt/vol) on the growth and tyramine production in two Enterococcus faecalis strains was examined during culture time. The growth of E. faecalis was inhibited by the increase in NaCl concentration, but tyramine production was unaffected. Tyramine accumulated rapidly during the logarithmic phase of the strains, and the final tyramine levels were approximately 800 μg/ml. Relative gene expression of four genes in the tyrosine decarboxylase locus, namely, tyrRS, tyrDC, tyrP, and nhaC, was evaluated at different incubation times. The results showed that NaCl stress could upregulate the expression of tyrDC and tyrP to improve the tyramine production of a single E. faecalis strain under certain conditions, and TyrS could act as a negative regulator on the genetic regulation of the tyramine cluster.

Biogenic amines in Zamorano cheese: factors involved in their accumulation.

Ripened cheese is among fermented food the most often associated with food poisoning from biogenic amines. The influence of ripening time, heat treatment of milk and the effect of using milk from a different ewe breed on the biogenic amine (BA) content of Zamorano cheese was studied by high-performance liquid chromatography. Physicochemical, proteolytic and microbiological parameters were also studied. BA content increased significantly during ripening and their final values were around 400 mg kg(-1). Cheeses elaborated with raw milk duplicated the concentration of BA relative to those elaborated with pasteurized milk (72 °C for 20 s). The average levels of putrescine, spermine and tyramine were higher in cheeses made with a greater proportion of milk from Churra breed. Significant differences in microbial counts and nitrogen soluble in 5% phosphotungstic acid were observed between the different batches. Ripening time and heat treatment applied to milk were the factors that exercised the greatest influence upon the concentration of BA in Zamorano cheese.