Biogenic amines in Chinese soy sauce

The biogenic amine contents in 40 samples of Chinese soy sauce from different manufactures were determined using HPLC after pre-column derivatization with dansyl chloride. Also, the amino nitrogen levels and pH values of these samples were analyzed. Of the five biogenic amines under study, tyramine was the most prevailing amine and was detected in 97.5% of the samples, followed by spermidine (95%), histamine (92.5%), cadaverine (82.5%) and spermine (80%). The total content for the five biogenic amines in these samples was 497 mg/l with a range from 41.7 to 1357 mg/l. The pH and amino nitrogen levels in soy sauce samples were between 3.86 and 4.98 and between 0.25 and 1.26 mg/100 g, respectively. In general, total content for the five biogenic amines was high in samples that had high amino nitrogen levels.     

Monitoring the contents of biogenic amines in sufu by HPLC with SPE and pre-column derivatization

Sufu is a nutritious fermented food whose consumption is currently increasing in many countries. The purpose of this study was to develop an HPLC method with SPE and pre-column derivatization for monitoring the content of biogenic amine in sufu and to understand the differences in the contents of biogenic amines with different processing technologies. Biogenic amines in sufu were extracted with 6% trichloroacetic acid, derivatized with 4-chloro-3,5-dinitrobenzotrifluoride, purified with Waters Oasis MCX cartridge, separated by HPLC using gradient elution, and detected by spectrophotometric UV at 254 nm. The method linearity, calculated for each biogenic amine, has a correlation coefficient higher than 0.9915. Detection limits of the biogenic amines were ranged from 0.016 mg/kg for putrescine to 0.067 mg/kg for spermine. Spiking experiments showed that the overall recoveries ranged between 83.6% and 103.5% with relative standard deviations of 1.26–5.24%. Of the seven biogenic amines under study, at least four biogenic amines were detectable in different kinds of sufu. Tryptamine, putrescine, histamine, and tyramine were the most prevailing biogenic amines in all sufu samples. The mean values of histamine, tryptamine, phenylethylamine, tyramine, putrescine, spermidine and spermine determined in samples were found to be 18.2 mg/kg, 39.0 mg/kg, 1.1 mg/kg, 21.7 mg/kg, 34.6 mg/kg, 11.1 mg/kg, and 8.7 mg/kg, respectively. The total contents of biogenic amines in bacteria fermented sufu samples (129.0 mg/kg) were slightly lower than those in enzymatically ripened sufu samples (137.7 mg/kg). The concentrations of biogenic amines detected in sufu samples were below the maximum permissible limits.     

Biogenic amines in commercial fish and fish products sold in southern China

Eight biogenic amines (histamine, tryptamine, putrescine, 2-phenylethylamine, cadaverine, tyramine, spermidine and spermine) were determined in 13 species of fish and 49 fish products commonly consumed in southern China. The biogenic amines were analyzed by reverse phase HPLC with a fluorescence detector following pre-column derivation with dansyl chloride. In the fish samples, the total level of biogenic amine (BA) ranged from 5.03 mg/kg to 156.17 mg/kg, with a mean value of 44.17 mg/kg. Histamine levels were less than 21.85 mg/kg. The BA levels detected were not high enough to indicate fish decomposition. Low BA levels were also found in most fish product samples. However, several samples of fermented fish products and packaged fish products showed higher levels (484.42 mg/kg of BA in lightly cured horse mackerel and 166.45 mg/kg of BA in packaged eel). Specifically, lightly cured horse mackerel, which is a traditional fish product in southern China, exhibited relatively high levels of 2-phenylethylamine (57.61 mg/kg), cadaverine (244.41 mg/kg) and tyramine (62.85 mg/kg). Such samples with relatively high BA content require careful monitoring to ensure their safety for human consumption.     

A rapid screening of histamine concentration in fish fillet by direct analysis in real time mass spectrometry (DART-MS)

Histamine is a biogenic amine causing scombroid foodborne poisoning. A rapid determination of the amine is effective in preventing the distribution of histamine-accumulated foods to market. Conventional methods for the determination of histamine concentration in foods include analyses by high performance liquid chromatography (HPLC). The present study tried to utilize a direct analysis in real-time ionization coupled to mass spectrometer (DART-MS) to estimate the histamine concentration in fish filets as an alternative to HPLC. The DART-MS responses to histamine and 1,8-diaminooctane as an internal standard were highly dependent on heater temperature; the highest responses were obtained at 400 °C. Histamine was spiked from 16.3 mg/kg to 407.0 mg/kg in tuna and yellowtail filets to obtain contaminated samples. The contaminated samples were homogenized with 0.1 mM EDTA containing 1,8-diaminooctane. The filtrates of the suspension were analyzed by DART-MS, and peak areas corresponding to the histamine and internal standard were obtained. The ratios of the histamine peaks to the internal standard peaks increased with higher histamine concentrations in the fish filets. The high linearity between the histamine concentrations and peak area ratios and the determination coefficient was more than 0.95. The results suggested that DART-MS is an attractive tool as a rapid screening method for determining histamine concentrations in fish filets.     

Monitoring the contents of biogenic amines in fish and fish products consumed in Korea

In order to obtain the level of biogenic amines in fish and fish products, a reversed phase high performance liquid chromatographic method was used for the quantitation of 12 biogenic amines in 300 fish and 80 fish products in Korea. Biogenic amines were extracted with hydrochloric acid, derivatized with dansyl chloride, separated using gradient elution, and detected by photodiode array and all detected biogenic amines were identified by UPLC/MS/MS. The detection levels of biogenic amines in the sample ranged from ND (not detected) to 30.6 mg/kg for agmatine, from ND to 390.0 mg/kg for cadaverine, from ND to 19.8 mg/kg for dopamine, from ND to 70.1 mg/kg for histamine, from ND to 17.8 mg/kg for noradrenaline, from ND to 29.7 mg/kg for 2-phenylethylamine, from ND to 43.0 mg/kg for putrescine, from ND to 11.9 mg/kg for serotonin, from ND to 9.5 mg/kg for spermidine, from ND to 13.5 mg/kg for spermine, from ND to 12.8 mg/kg for tryptamine, and from ND to 67.7 mg/kg for tyramine. Anchovy samples showed the high levels of histamine from 15.2 to 70.1 mg/kg, putrescine from 9.1 to 43.0 mg/kg, cadaverine from 152.2 to 90.0 mg/kg, and tyramine from 27.1 to 67.7 mg/kg. Agmatine was found at 30.6 mg/kg in cuttlefish. In the others fish samples agmatine detection levels were in the range from ND to 27.2 mg/kg. Spermidine and dopamine were detected about more than 85% samples in the range from ND to 19.3 mg/kg. Most of fish product samples showed less than 20 mg/kg of each biogenic amine. The maximum histamine and tyramine detection levels were respectively less than those of the regulation and recommendation.     

Chemical characterisation, biogenic amines contents, and identification of fish species in cod and escolar steaks, and salted escolar roe products

Forty-one cod steaks, fifteen escolar steaks, and fifteen salted escolar roe products sold in Taiwan market were purchased and tested to determine the biogenic amine, histamine-forming bacteria, and identification of fish species. The levels of pH value, salt content, Aw, TVBN and APC in all samples ranged from 5.3 to 7.0, 0.7 to 5.6%, 0.80 to 0.99, 0.8 to 59.9 mg/100 g and 2.5 to 7.3 log CFU/g, respectively. None of these samples contained coliform bacteria and Escherichia coli. The average content of histamine in all samples was less than 5 mg/100 g US Food and Drug Administration guideline value. Nine histamine-forming bacterial strains isolated from cod, escolar, and salted escolar roe samples produced 2.0-62.3 ppm of histamine in trypticase soy broth (TSB) supplemented with 1.0% l-histidine (TSBH). Assay of DNA direct sequence and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) revealed that mislabeling rate of 41 cod steaks was 31.6% (13/41). Among them, 7 samples (17%) and 6 samples (14.6%) were identified as Ruvettus pretiosus (oilfish) and Reinhardtius hippoglossoides (Greenland halibut), respectively. In addition, most of escolar steaks and salted escolar roe products were identified as Lepidocybium flavobrunneum (escolar), while other samples were identified as R. pretiosus.     

Histamine content and histamine-forming bacteria in mahi-mahi (Coryphaena hippurus) fillets and dried products

Forty-two mahi-mahi fillets and 17 dried products sold in retail markets in Taiwan were tested for histamine and histamine-forming bacteria. The levels of pH, salt content, water content, Aw, TVBN, APC, TC and Escherichia coli in mahi-mahi fillet samples ranged from 5.6 to 6.5, 0.05 to 2.44%, 70.9 to 82.8%, 0.95 to 0.99, 5.9 to 23.5 mg/100 g, 3.1 to 7.0 log CFU/g, <3 to 1650 MPN/g and <3 to 45 MPN/g, respectively. The levels of pH, salt content, water content, Aw, TVBN, APC, TC and E. coli in dried mahi-mahi samples ranged from 5.7 to 6.4, 0.63 to 20.13%, 7.1 to 42.9%, 0.51 to 0.85, 21.4 to 133.9 mg/100 g, 3.6 to 8.7 log CFU/g, <3 to 5900 MPN/g and <3 to 2500 MPN/g, respectively. The average content of various biogenic amines in fillets samples was less than 0.3 mg/100 g. Four of the 17 dried samples (23.4%) had histamine levels greater than the FDA guideline of 5 mg/100 g for scombroid fish and/or product with one of them containing 68.15 mg/100 g of histamine, which is greater than the 50 mg/100 g hazard action level. Eight histamine-producing bacterial isolates, capable of producing 12.6 ppm–562 ppm of histamine in trypticase soy broth supplemented with 1.0% l-histidine (TSBH), were identified as Raoultella ornithinolytica (three isolates), Pantoea agglomerans (two isolates), Proteus vulgaris (two isolates) and Enterobacter amnigenus (one isolate), by 16S rDNA sequencing with PCR amplification.     

Microbiological quality of raw-fermented sausages with Lactobacillus casei LOCK 0900 probiotic strain

The objective of this study was to evaluate the microbiological quality, defined as health safety, microbiological stability, sensory acceptability and dietary value, of raw-fermented sausages with Lactobacillus casei LOCK 0900 probiotic strain. The study assessed the impact of the number of probiotic starter culture suspension (Lc1 ≈ 6 log cfu/g; Lc2 ≈ 7.3 log cfu/g) on the microbiological quality of sausages after the fermentation and following 6 months' storage. The number of used probiotic in the examined raw-fermented sausages was approx. 9 log cfu/g after the fermentation and following 6 months' storage. The number of lactic acid bacteria in the Lc1 and Lc2 samples after the fermentation was similar, however, the smaller number of Staphylococcus aureus, Escherichia coli and Enterobacteriaceae in the Lc2 sample shows that a greater addition of the starter culture suspension is more beneficial. The sensory evaluation results showed that the overall quality was positively correlated with the aroma of cured meat, the taste of dried meat and muscle tissue fragmentation following the fermentation. Negative evaluation of the product was based on such parameters as bitter or other taste, acrid odour, fatty taste. The environment of raw-fermented sausages is suitable for the growth and survival of probiotic.     

Determination of histamine and biogenic amines in fish cubes (Tetrapturus angustirostris) implicated in a food-borne poisoning

An incident of food-borne poisoning causing illness in 347 victims due to ingestion of fried fish cubes occurred in June, 2007, in Kaohsiung city, southern Taiwan. A high-performance liquid chromatography (HPLC) was developed for determining nine biogenic amines in two suspected fish samples by dansylation with dansyl chloride. One sample has histamine content (52.3 mg/100 g) greater than the hazard action level of 50 mg/100 g. Given the allergy-like symptoms of the victims and the high histamine content in the suspected fried fish samples, this food-borne poisoning was strongly suspected to be due to histamine intoxication. In addition, two weak histamine-producing isolates were identified as Acinetobacter baumannii, by 16S rDNA sequencing with PCR amplification.     

Biogenic amines content in traditional dry fermented sausage Petrovská klobása as possible indicator of good manufacturing practice

The aim of this study was to determine the content of nine biogenic amines (tryptamine, phenylethylamine, putrescine, cadaverine, histamine, serotonin, tyramin, spermidine and spermine) and total biogenic amines in traditional dry fermented sausage Petrovská klobása at the end of drying period, as possible indicators of good manufacturing practice (GMP).Chromatographic separation of dansyl chloride derivatizated amines was completed in 8 min. Analyses were performed by HPLC-DAD on Eclipse XDB-C18 column. Tryptamine and spermine were determined in all analyzed samples, while histamine, serotonin and spermidine were not detected in any samples. Average content of individual biogenic amine ranged from 5.54 mg/kg (putrescin) to 75.1 mg/kg (tryptamine) and total content of biogenic amines varied from 77.8 mg/kg to 174 mg/kg.The results obtained in this study provided no evidence for deviations from good manufacturing practice in Petrovská klobása production.