Histamine Formation and Bacterial Spoilage of Albacore Harvested off the U.S. Northwest Coast

Iced and previously frozen albacore were monitored for histamine formation and bacterial growth during storage at 0–37°C. The optimum temperature for histamine formation in albacore tuna (Thunnus alalunga) was 25°C, and whole fish were more susceptible to histamine formation than dressed fish at that temperature. Storage at 25°C resulted in the highest histamine level, 60.4 mg/100g in whole fish stored for 7 days. When albacore were frozen prior to storage, reduced amount of histamine was found at 7.14 mg/100 g after 7 day storage at 25°C, only after decomposition became obvious. No histamine was found in any of the albacore samples stored in ice for 18 days.     

Mercury and Fatty Acids in Canned Tuna, Salmon, and Mackerel

ABSTRACT: Canned tuna ( n = 240), salmon ( n = 16), and mackerel ( n = 16) were analyzed for mercury and fatty acids. Average mercury levels were 188, 45, and 55 ppb, respectively, and below the FDA Action Level of 1000 ppb. "Light tuna in water" contained lower mercury (x = 54 ppb) compared with "white/albacore tuna in water," which contained higher eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) x= 711 mg/100 g wet tissue). Mercury residues in salmon (x = 45 ppb) and mackerel (x = 55 ppb) were lower than in tuna products, but the EPA/DHA levels were higher (salmon, ×= 1623 mg/100 g wet tissue; mackerel, ×= 851 mg/100 g wet tissue). Information from this study will help women of childbearing age to limit their intake of mercury while obtaining healthy fats from fish.     

An Automated Fluorimetric Method for the Determination of Histamine in Canned Fish Products

An automated extraction and fluorimetric detection procedure for the determination of histamine in fish products is described. Proteins are removed pr or to the automated procedure. Histamine, added at different concentration levels to a homogenized fish sample, is recovered quatitatively. The results from a study of histamine in samples of commercially canned mackerel, tuna, herring and sardines showed that ～79% of the investigated samples had histamine levels lower than 1 mg% while ～8% had a histamine content higher than 10 mg%.     

Histamine Formation in Albacore Muscle Analyzed by AOAC and Enzymatic Methods

Histamine formation in fresh albacore was studied. Whole albacore left on deck up to 1 d contained negligible levels of histamine (<0.4 mg/1 00g muscle). When they were abused at ambient temperatures for 1–4 days, 2 of 9 samples showed histamine levels >5 mg/100g. Histamine level was not affected by on-board handling techniques studied, i.e., bleeding and spiking. Enzymatic assay was compared to the AOAC fluorometric method for histamine analysis. Enzymatic results showed a good correlation with those of the AOAC method (r²=0.829). Although the enzymatic method tended to overestimate histamine at levels <1 mg/1 00g, it was rapid, simple, and suitable as a screening method for routine analysis.     

Determination of K-value and histamine of mackerel and tuna, by using the oxygen-sensor method

Determination of K-value (fish freshness index) and histamine (Hm) of mackerel and tuna during storage at various temperatures was done by using the oxygen-sensor method. Hm in mackerel increased even at low temperature (5 degrees C), and reached the Defect Action Level (DAL) of the U.S. FDA, 5 mg/100 g, before the K-value approached the inedible level. As the storage temperature was increased, the rate of Hm formation increased remarkably and the amount of Hm in fish meat passed through the DAL, and reached the real hazard level, AL (50 mg/100 g), in a short time. The initial Hm level of raw tuna was too low to determine by our oxygen-sensor method, and the final Hm level after 8 days' storage at under 5 degrees C was only 0.6 mg/100 g. But, when the storage temperature was elevated, the rate of Hm formation increased rapidly, as in mackerel, and the Hm level reached the DAL, then the AL, in a short time. Simultaneous determination of K-value and Hm is recommended for accurate and reliable quality inspection of fish and fish products.     

Effects of Frozen Storage on Survival of Staphylococcus aureus and Enterotoxin Production in Precooked Tuna Meat

This study investigated the survival of Staphylococcus aureus in precooked tuna meat for producing canned products during frozen storage (?20 ± 2 °C) as well as its growth and enterotoxin production at 35 to 37 °C after the storage. Samples (50 ± 5 g) of precooked albacore (loin, chunk, and flake) and skipjack (chunk and flake) tuna were inoculated with 5 enterotoxin‐producing strains of S. aureus at a level of approximately 3.5 log CFU/g and individually packed in a vacuum bag after 3 h incubation at 35 to 37 °C. Vacuum‐packed samples were stored in a freezer (?20 ± 2 °C) for 4 wk. The frozen samples were then thawed in 37 °C circulating water for 2 h and incubated at 35 to 37 °C for 22 h. Populations of S. aureus in all precooked tuna samples decreased slightly (<0.7 log CFU/g) after 4 wk of storage at ?20 ± 2 °C, but increased rapidly once the samples were thawed and held at 35 to 37 °C. Total S. aureus counts in albacore and skipjack samples increased by greater than 3 log CFU/g after 6 and 8 h of exposure to 35 to 37 °C, respectively. All samples became spoiled after 10 h of exposure to 35 to 37 °C, while no enterotoxin was detected in any samples. However, enterotoxins were detected in albacore loin and other samples after 12 and 24 h of incubation at 35 to 37 °C, respectively. Frozen precooked tuna meat should be used for producing canned tuna within 6 to 8 h of thawing to avoid product spoilage and potential enterotoxin production by S. aureus in contaminated precooked tuna meat.     

Occurrence of histamine and histamine-forming bacteria in kimchi products in Taiwan

Twenty kimchi products sold in supermarkets and 17 products sold in retail markets were purchased from southern Taiwan and tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH and salt content in all samples ranged from 3.6 to 5.1 and 1.5–16.0%, respectively. The supermarket kimchi products had 1–7.2 log CFU/g of APC and <3–600 MPN/g of total coliform (TC), and the retail market kimchi products had 4–8.03 log CFU/g of APC and <3 to >2400 MPN/g of TC. Only one of the retail market kimchi products contained 20 MPN/g Escherichia coli. Although, supermarket kimchi products had an average histamine content of 49.8 mg/100 g, 15 of them had histamine content greater than 5 mg/100 g, the allowable level set by the US Food and Drug Administration (FDA) for scombroid fish and/or product. In contrast, only eight retail market kimchi products had histamine levels greater than 5 mg/100 g. Among the supermarket samples, three contained histamine at 50.2, 273 and 535 mg/100 g, that are more than the 50 mg/100 g hazard action level. Four histamine-producing bacteria capable of producing 13.6–43.1 ppm of histamine in MRS broth supplemented with 0.25% l-histidine were identified as Lactobacillus para. paracasei (one strain), Lb. brevis (one strain), and Brevibacillus brevis (two strains). To our knowledge, this is the first report to demonstrate the occurrence of high contents of histamine and histamine-forming bacteria in kimchi products.     

Histamine formation by histamine-forming bacteria in douchi,a Chinese traditional fermented soybean product

Seven soybean and 19 black bean douchi products sold in the supermarkets in southern Taiwan were purchased and tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH, salt content, water content, yeast and mold, and aerobic plate count (APC) in all samples ranged from 4.7 to 5.9, 4.4% to 14.0%, 6.8% to 51.6%, 3.0 to 5.1 log CFU/g, and 5.2 to 9.2 log CFU/g, respectively. None of these samples contained total coliform and Escherichia coli. Although black bean douchi products had an average histamine content of 29.0 mg/100 g, 18 of them had histamine contents greater than 5 mg/100 g, the allowable level set by the US Food and Drug Administration (FDA) for scombroid fish and/or products. In contrast, only four soybean douchi products had histamine levels greater than 5 mg/100 g. Among the black bean samples, four contained histamine at 56.3, 62.1, 80.2 and 80.8 mg/100 g, that are above the 50 mg/100 g hazard action level. Eight histamine-forming bacterial strains, capable of producing 11.7–601 ppm of histamine in trypticase soy broth (TSB) supplemented with 1% l-histidine (TSBH), were identified as Bacillus subtilis (four strains) Staphylococcus pasteuri (one strain) and Staphylocuccus capitis (three strains) by 16S rDNA sequencing with PCR amplification. S. capitis, which was previously reported to be halotolerant, was a potent histamine-former capable of producing more than 500 ppm of histamine in TSBH in the presence of 0.5–10% NaCl.     

Histamine and Tyramine in Preserved and Semi-preserved Fish Products

Data were obtained on histamine and tyramine contents in 48 samples of preserved and semi-preserved Spanish fish products. Ranges of concentration for both amines were wide: from 1.35 to 219.20 mg/ kg for histamine, and from 0.5 to 66.40 mg/kg for tyramine. Higher concentrations were found in semi-preserved anchovies than in the rest of the samples studied: canned tuna, herring, mackerel and sardines. In semi-preserved anchovies stored at room temperature (18-22°C), histamine production was observed after 6 months. The increase in histamine was not observed in the samples stored under refrigeration (4-6°C). Tyramine did not increase at either temperature of storage.     

A Competitive Histamine Evaluation of Canned Tuna Fish Samples by Electrochemical and Immunochemical Methods for Post Market Surveillance

An enzyme-linked immunosorbent assay for histamine in canned tuna fish was compared with a fast Fourier transformation stripping cyclic voltammetry method. Histamine contents of 30 canned tuna fish products from several parts of Iran were analyzed by enzyme-linked immunosorbent assay and fast Fourier transformation stripping cyclic voltammetry methods. These analyses on commercial canned tuna fish products showed good agreement for histamine (r² = 0.992) level in the concentration range of 2–280 mg/kg. The results showed that 36.6% of samples had higher histamine contents than the FDA caution level. The present study also revealed that the histamine levels vary depending on production date and increased by the closing expiration date of samples. Detection limits and mean recoveries for enzyme-linked immunosorbent assay were 2 mg/kg and 97% and for fast Fourier transformation stripping cyclic voltammetry were 3.5?×?10^?7 mg/kg and 99.2%, respectively.     

Determination of histamine and histamine-forming bacteria in tuna dumpling implicated in a food-borne poisoning

An incident of food-borne poisoning causing illness in seven victims, due to ingestion of tuna dumpling, occurred in March 2006, in Chiayi Prefecture, southern Taiwan. The leftovers of the victims’ tuna dumpling and the five other tuna dumpling samples from five other retail stores were collected and tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH, salt content, aerobic plate count (APC), total volatile basic nitrogen (TVBN), total coliform (TC) and Escherichia coli in all samples ranged from 6.08 to 6.43, 0.46% to 0.81%, 5.90 to 8.95 log CFU/g, 6.38 to 21.29 mg/100 g, 750 to 8000 most probable number (MPN)/g, and <3 to 1000 MPN/g, respectively. The suspected tuna dumpling contained 160.8 mg/100 g of histamine greater than the hazard action level of 50 mg/100 g set by the US Food and Drug Administration (FDA) for tuna fish. Given the allergy-like symptoms of the victims and the high histamine content in the suspected tuna dumpling, this food-borne poisoning was strongly suspected to be due to histamine intoxication. In addition, although thirteen histamine-producing bacteria strains capable of producing 8.1–19.7 ppm of histamine in trypticase soy broth (TSB) supplemented with 1.0% l-histidine (TSBH), were identified as Enterobacter sp. (three strains), Pantoea agglomerans (two strains), Klebsiella variicola (four strains) and Serratia marcescens (four strains), by 16S rDNA sequencing with PCR amplification, they were not determined to be the main contributors to histamine accumulation in suspected tuna dumpling.     

市售东海鱼鲞生物胺及相关质量指标分析

为研究零售期东海鱼鲞的生物胺潜在风险及生物胺与品质指标的相关性,以浙江地区的4种鱼鲞（鳗鱼、大黄鱼、鲳鱼和马鲛鱼）为研究对象,对理化指标（水分含量、NaCl、pH、TVB-N和POV）、微生物指标（菌落总数）和8种生物胺进行测定分析。结果表明,4类鱼鲞的理化、微生物和生物胺指标各不相同。水分含量为25.6%～59.7%,NaCl含量为3.4%～24.1%,pH为6.08～6.97,TVB-N为7.7～56.4 mg/100 g,菌落总数为3.43～5.67 lg CFU/g,POV为0.04～1.76 g/100 g,其中50%样品超过水产干制品POV限值。鱼鲞样品的主要生物胺为亚精胺、组胺、尸胺和腐胺。15%的样品组胺含量>100 mg/kg,超过FDA和/或欧盟的限量标准,其中黄鱼鯗B4的组胺含量达到了1405.88 mg/kg。全部样品的酪胺含量均<100 mg/kg,符合FDA限量标准。生物胺总量在96.05～2164.64 mg/kg之间,其中15%的样品>1000 mg/kg,超过FDA限量标准。相关分析表明,部分生物胺指标与菌落总数和NaCl含量呈中度或高度相关（P<0.05）,相关系数r分别为0.727～0.975和?0.828～?0.970。综上,东海鱼鯗,包括以非高组胺鱼为原料的产品,可能存在生物胺超标风险及其他质量问题。本研究为鱼鲞类水产干制品的品质评价和安全控制提供了基础数据和参考依据。     

Histamine and other biogenic amines and histamine-forming bacteria in miso products

Twenty-seven miso products sold in supermarkets and 13 products sold in retail markets were purchased from southern Taiwan, and tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH, salt content, and aerobic plate count (APC) in all samples ranged from 5.1 to 5.8, 6.1% to 13.8%, and 2.1 to 9.1 log CFU/g, respectively. Only one of the supermarket miso products contained 100 MPN/g total coliform. None of these samples contained Escherichia coli. Although the average content for each of the nine biogenic amines in all samples was less than 5 mg/100 g, two supermarket samples (22.1 and 11.9 mg/100 g) and one retail market sample had histamine content (10.2 mg/100 g) greater than the 5.0 mg/100 g allowable limit suggested by the US Food and Drug Administration. Eight histamine-producing bacterial strains, capable of producing 10.4–39.4 ppm of histamine in trypticase soy broth (TSB) supplemented with 1.0% l-histidine (TSBH), were identified as Staphylococcus pasteuri (one strain), Bacillus sp. (one strain), B. amyloliquefaciens (two strains), B. subtilis (two strains) and B. megaterium (two strains), by 16S rDNA sequencing with PCR amplification.     

Total and methylmercury residues in tuna-fish from the Mediterranean sea

This study was carried out to determine the current levels of total mercury and methylmercury in the muscle tissue of albacore (Thunnus alalunga) and bluefin tuna (Thunnus thynnus) caught in the Mediterranean sea with the purpose of ascertaining whether the concentrations exceeded the maximum level fixed by the European Commission Decision. Total mercury concentrations ranged from 0.84 to 1.45 mg kg^-1 w.w. (av. 1.17 mg kg^-1 w.w.) and from 0.16 to 2.59 mg kg^-1 (av. 1.18 mg kg^-1 w.w.) in the muscle of albacore and bluefin tuna, respectively. In 78.6% of albacore and in 61.1% of bluefin tuna analysed, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg = 1 µg g^-1 wet wt). In the two species, mercury was present almost completely in the methylated form, with percentages between 77 and 100% (av. 91.3%) in albacore and between 75 and 100% (av. 91%) in bluefin-tuna. In order to assess the potential health impact, the estimated weekly intake was calculated. The estimated weekly intake was far above the established Provisional Tolerable Weekly Intake for both species.     

Histamine-related hygienic qualities and bacteria found in popular commercial scombroid fish fillets in Taiwan

To determine the histamine-related hygienic qualities and bacteria of scombroid fish fillets sold in traditional retail markets, 61 samples were collected from northern and southern Taiwan. It was found that the content of volatile base nitrogen in most samples was below 25 mg/100 g, which is the regulatory level in Taiwan. The ratio of unacceptable samples/total samples for aerobic plate count and Escherichia coli was 100% and 15% in northern samples and 100% and 20% in southern samples, respectively, compared with the requirements of hygienic standards. The average content of various biogenic amines in all samples were lower than 3 mg/100 g, except for histamine average content (4.6 mg/100 g) in southern samples. Among southern samples, four samples contained 12.8 to 28.8 mg/100 g histamine, which is more than 5 mg/100 g that is the allowable limit suggested by the U.S. Food and Drug Administration. Furthermore, 14 bacterial strains were isolated from sailfish fillets on a selective medium for histamine-forming bacteria. These presumptive histamine-forming strains, such as Proteus, Enterobacter, Klebsiella, Rahnella, and Acinetobacter, have been identified and found to produce 20 to 2,000 ppm histamine after incubating at 37 degrees C for 24 h.     

Histamine content and histamine-forming bacteria in dried milkfish (Chanos chanos) products

Thirty-two dried milkfish products sold in five retail markets in southern Taiwan were purchased and tested to determine the occurrence of histamine and histamine-forming bacteria. Except for histamine and cadaverine, the average content of various biogenic amines in tested samples was less than 8.5 mg/100 g. Most of the tested dried milkfish products (78.1%) had histamine levels greater than the FDA guideline of 5 mg/100 g for scombroid fish and/or product, while fourteen of them (43.7%) contained > 50 mg/100 g hazard action level. Thirty histamine-producing bacterial strains, capable of producing 5.4 ppm to 562 ppm of histamine in trypticase soy broth supplemented with 1.0% L-histidine (TSBH), were identified as Enterobacter aerogenes (seven strains), Citrobacter sp. (one strain), Staphylococcusxylosus (ten strains), S. sciuri (one strain), Bacillus thuringiensis (two strains), Citrobacter freundii (five strains), Klebsiella pneumoniae (one strain) and E. cloacae (three strains), by 16S rDNA sequencing with PCR amplification.     

Identification of bacteria crucial to histamine accumulation in pacific mackerel during storage

Bacterial growth and histamine formation in Pacific mackerel during storage at 0, 4, 15, and 25 degrees C were monitored. To identify bacterial species contributing to histamine formation, several groups of bacteria were isolated by using selective media under temperatures corresponding to the various storage conditions. Initially, low counts of bacteria were found in the gill, skin, and intestine of fresh fish, and only weak histamine formers were found in the gill. Histamine was found in the muscle when fish were stored above 4 degrees C, and aerobic plate counts reached 10(6) CFU/g. When fish became unsuitable for human consumption by abusive storage, toxicological levels of histamine were always found. The highest level of histamine formed was 283 mg/100 g in 2 days. The optimum temperature for supporting growth of prolific histamine formers was 25 degrees C. The most prolific and prevalent histamine former was Morganella morganii, followed by Proteus vulgaris, both of which were isolated on violet red bile glucose (VRBG) agar. At 15 degrees C, a significant level of histamine was still produced in fish muscle, although prolific histamine formers were less frequently detected than at 25 degrees C. The isolates on thiosulfate citrate bile salts sucrose (TCBS) agar were weak histamine formers and identified as Vibrio parahaemolyticus and Vibrio alginolyticus. At 4 degrees C, less than 57.4 mg/100 g of histamine was found in fish stored for 14 days. Most isolates were natural bacterial flora in the marine environment and identified as weak histamine formers. At 0 degrees C, neither histamine former nor histamine production was detected up to 14 days of storage.     

Survey of histamine content in seafood on the market

Food poisoning involving histamine has occurred almost every year for 20 years in Tokyo, and is usually due to ingestion of fish with lean meat, such as sardine, mackerel, horse mackerel and so on. Therefore, we were investigated the levels of histamine and 4 non-volatile amines (tyramine, putrescine, cadaverine, spermidine) in 637 samples on the market. The water activity of samples in which histamine was detected at 5 mg/100 g and over was examined. Histamine, tyramine, putrescine, cadaverine and spermidine were detected in 66, 43, 26, 64 and 5 samples, and the detection ranges were 5-340, 5-51, 5-42, 5-180 and 5-8 mg/100 g, respectively. Most of the samples in which histamine was detected were semi-dried round and split sardine. Water activity of 24 samples of semi-dried round and split sardine in which histamine was detected was in the range of 0.68-0.96.     

Chemical characterisation and histamine-forming bacteria in salted mullet roe products

Sixteen salted mullet roe products sold in the retail markets in Taiwan were purchased and tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH, salt content, water content, total volatile basic nitrogen (TVBN) and aerobic plate count (APC) in all samples ranged from 5.4 to 5.8, 5.1% to 7.2%, 15.4% to 27.3%, 32.0 to 69.6 mg/100 g and <1.0 to 7.1 log CFU/g, respectively. None of these samples contained total coliform and Escherichia coli. The average content of each of the nine biogenic amines in all samples was less than 4 mg/100 g, and only one mullet roe sample had the histamine content (8.18 mg/100 g) greater than the 5.0 mg/100 g allowable limit suggested by the US Food and Drug Administration. Two histamine-producing bacterial strains capable of producing 10.7 ppm and 9.6 ppm of histamine in trypticase soy broth (TSB) supplemented with 1.0% l-histidine (TSBH) were identified as Staphylococcus carnosus by 16S rDNA sequencing with PCR amplification, and they were isolated from the sample with higher histamine content (8.18 mg/100 g).     

Bacterial Growth and Histamine Production on Vacuum Packaged Tuna

Vacuum and nonvacuum packaged samples of tuna or tuna spiked with Klebsiella oxytoca T₂, Morganella morganii JM or Hafnia alvei T₈ were stored at 2°C and 10°C and examined for bacterial growth and histamine production on day 3, 6, 10 and 15. Unlike those stored at 2°C, tuna samples stored at 100°C showed significant bacterial growth over time and had high levels of histamine (>200 mg/100g tuna on day 15). Vacuum packaging did not show any beneficial effect in controlling bacterial growth and histamine production on tuna samples at these two temperatures. Low temperature storage was more effective than vacuum packaging in controlling histamine production by the bacteria tested.