Mercury in UK imported fish and shellfish and UK-farmed fish and their products

Total mercury concentrations were measured in fish and shellfish and their products imported into the UK and also in UK-produced farmed salmon and trout. Three hundred and thirty-six samples were collected using a two-stage sampling plan. The sample plan was weighted to reflect consumption, but with some bias towards fish that might accumulate higher levels of mercury, such as large predatory fish at the top of the food chain. The highest levels of total mercury were found in billfish (swordfish and marlin) and shark. Mercury concentrations in the five samples of fresh/frozen shark ranged from 1.006 to 2.200 mg kg -1 , all above the European Commission limit for the species, and concentrations in 20 samples of fresh/frozen billfish ranged from 0.153 to 2.706 mg kg -1 with 13 samples above the 1.0 mg kg -1 limit for the species. One sample of Antarctic ice fish was collected and had a mercury concentration of 0.664 mg kg -1 . The limit for this species was 0.5 mg kg -1 . One sample of fresh/frozen tuna out of the 20 collected had a mercury concentration above the limit of 1.0 mg kg -1 (1.5 mg kg -1 ), but all other fresh tuna samples were well within the regulatory limit (average 0.4 mg kg -1 ). Mercury concentrations in canned tuna were lower with concentrations on average half that measured in fresh/frozen tuna. Mercury concentrations in UK-farmed salmon and trout were relatively low. The maximum concentration found in 46 samples of fresh/frozen or smoked trout and salmon was 0.103 mg kg -1 .     

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.     

牛磺酸影响胆固醇代谢的研究进展

牛磺酸是小分子含硫氨基酸,为常见食物成分之一,富含于海产品中。动物实验证实牛磺酸可显著降低饮食性高胆固醇血症动物的胆固醇水平,临床试验也显示牛磺酸能降低血清总胆固醇及动脉粥样硬化指数,表明牛磺酸具有良好的抗动脉粥样硬化作用,因此被认为是心血管细胞保护剂。本文从体内和体外两方面的研究情况介绍了牛磺酸对胆固醇代谢的影响,并主要从胆固醇/胆汁酸稳态的角度,总结归纳了牛磺酸对血液循环中胆固醇的清除、对胆固醇向胆汁酸的生物转化、以及对胆汁酸排出等多条作用途径的影响,为牛磺酸降胆固醇作用机制的深入研究、也为牛磺酸在功能食品领域的进一步开发利用提供参考。     

牛磺酸影响脂肪代谢的研究概况

牛磺酸是一种广泛存在于哺乳动物组织中的小分子含硫氨基酸,结构简单且不参与蛋白质合成,牛磺酸可由甲硫氨酸和半胱氨酸合成,也可以由饮食提供,富含于鱼贝类等海产品中,具有多种生理功能。动物实验和临床实验表明牛磺酸可显著改善肥胖,降低血清甘油三酯水平,减少肝脏脂肪蓄积。本文从动物实验、细胞实验、临床实验和流行病学调查四个方面总结了牛磺酸对脂肪代谢的影响,并主要从促进脂肪分解代谢、抑制脂肪合成、减少炎症反应和氧化应激、提高脂联素水平、与胆汁酸结合等方面归纳了牛磺酸影响脂肪代谢的作用机理,为进一步研究牛磺酸促进脂肪代谢的作用机制提供参考,也为开发以牛磺酸为功能因子、具有减肥、改善血脂及脂肪肝功能的保健品提供理论依据。     

Sterol Content of Fish,Crustacea and Mollusc: Effects of Cooking Methods

Sterol contents (desmosterol, cholesterol, stigmasterol, and sitosterol) of 36 fresh and cooked seafood and four freshwater fish species were investigated by high performance liquid chromatography (HPLC) method. Cholesterol and sitosterol were main sterols in seafood and freshwater fish species. Raw shellfish and molluscs contained cholesterol above 18.92 mg/100 g fish muscle, while the cholesterol content of marine fish ranged from 6.5 to 78.40 mg/100 g fish muscle. The cooking process resulted in significant effects on the sterol contents of seafood and freshwater species (p < 0.05). A remarkable increase in sitosterol (more than 3–4 fold compared to raw fish) was recorded for some fish species cooked in the oven. The highest desmosterol content was observed for fried fish, whereas the frying process resulted in a significant loss in cholesterol and sitosterol contents of marine fish (p < 0.05). The impacts of cooking methods on sterol content of seafood and their form varied depending on fish species and the cooking method used.     

Taurine: A Regulator of Cellular Redox Homeostasis and Skeletal Muscle Function

Taurine is a nonproteinogenic ß‐aminosulfonic acid. Important dietary sources of taurine are fish and seafood. Taurine interacts with ion channels, stabilizes membranes, and regulates the cell volume. These actions confirm its high concentrations in excitable tissues like retina, neurons, and muscles. Retinal degeneration, cardiomyopathy, as well as skeletal muscle malfunction are evident in taurine‐deficient phenotypes. There is evidence that taurine counteracts lipid peroxidation and increases cellular antioxidant defense in response to inflammation. In activated neutrophils, taurine reacts with hypochloric acid to form taurine chloramine, which triggers the Kelch‐like ECH‐associated protein 1–nuclear factor E2‐related factor 1 (Keap1–Nrf2) pathway. Consequently, Nrf2 target genes, such as heme oxygenase‐1 and catalase, are induced. Furthermore, taurine may prevent an overload of reactive oxygen species (ROS) directly by an inhibition of ROS generation within the respiratory chain. Taurine affects mitochondrial bioenergetics and taurine‐deficient mice exhibit an impaired exercise performance. Moreover, some studies demonstrate that taurine enhances the glycogen repletion in the postexercise recovery phase. In the case of taurine deficiency, many studies observed a phenotype known in muscle senescence and skeletal muscle disorders. Overall, taurine plays an important role in cellular redox homeostasis and skeletal muscle function.     

Incidence of Listeria monocytogenes in raw seafood products in Japanese retail stores

The incidence of Listeria monocytogenes in raw fish, shellfish, and fish roe was investigated in seafood products collected from randomly selected retail stores in and around Tokyo, Japan. Of the 10 samples of 208 examined found positive for L. monocytogenes by mini-VIDAS LMO, seven were fish roe (cod, salmon) and three were minced tuna. Three serotypes (1/2a, 1/2b, 3b) were detected among the isolated strains; serotype 1/2a was predominant (8 of 10).     

Copper content of commonly consumed food in Brazil

Little is known of copper content of Brazilian food. In this paper, copper contents of several typical Brazilian foods were determined. The samples were bought in retail stores in cities of the southeast region of Brazil. Atomic absorption spectrophotometry with wet oxidation of the organic material was employed. The highest copper content was found in beef liver (6.06 mg/100 g of fresh product). Lowest copper content was found in milk and in fish fillet, with values below 0.01 mg/100 g of fresh product. Crude beans, Nescau^TM and whole wheat had copper contents from 0.44 to 1.04 mg/100 g of fresh food. Other foods, such as fruits, vegetables, grain products, baked products, roots and meat products had copper contents varying from 0.02 to 0.41 mg/100 g.     

A SURVEY OF HISTAMINE LEVELS IN COMMERCIALLY PROCESSED SCOMBROID FISH PRODUCTS12

Analysis of 100 samples of each of 3 types of commercially processed scombroid fish products obtained at the retail level showed mean histamine concentrations (mg/100 g) of 3.58 for chunk light tuna, 1.50 for albacore tuna, and 2.56 for mackerel. Only 2 samples of chunk light tuna and 2 of mackerel contained greater than 10 mg% histamine. The highest level of histamine found in albacore tuna was 5.35 mg/100 g, while 99% ofthe samples had less than 5 mg% histamine. Chunk light tuna samples contained up to 28.0 mg/100 g, and mackerel samples contained up to 31.5 mg/100 g; 92% of the chunk light tuna and 95% of the mackerel had less than 5% histamine. The histamine levels found in these products were far below any level associated with food poisoning incidents.     

Total Phenolics,Carotenoids, Ascorbic Acid,and Antioxidant Properties of Fresh‐cut Mango (Mangifera indica L., cv. Tommy Atkin) as Affected by Infrared Heat Treatment

Abstract: Mango (Mangifera indica L.) is a major tropical fruit that has not been exploited for fresh‐cut or minimally processed products on a scale similar to apples, pineapples, or melons. The objective of this study was to investigate the effect of infrared (IR) treatment on total phenolics, carotenoids, ascorbic acid, and antioxidant properties of fresh‐cut cubes from ‘Tommy Atkin’ mangoes. Mango cubes were IR treated (5, 10, 15 min) and evaluated at 4‐d intervals during 16‐d storage at 4 ± 1 °C. Total phenolics, carotenoids, and ascorbic acid content in fresh‐cut control mango cubes were 43.33, 1.37, and 15.97 mg/100 g FW, respectively. IR treatments increased total phenolics (59.23 to 71.16 mg/100 g FW) and decreased ascorbic acid (12.14 to 15.38 mg/100 g, FW). Total carotenoids showed a mixed trend (1.13 to 1.66 mg/100 g, FW). The IR treatment showed a significant positive impact on antioxidant properties (μM TE/100 g, FW) of mango cubes, as assayed by ABTS (261.5 compared with 338.0 to 416.4), DPPH (270.5 compared with 289.4 to 360.5), and ORAC (6686 compared with 8450 to 12230). Total phenolics, carotenoids, ascorbic acid, and antioxidant capacity decreased over 16‐d storage. However, IR treated samples had consistently higher ABTS, DPPH, and total phenolics during storage. It was demonstrated that IR treatment can be effectively used in improving antioxidant properties of fresh‐cut mangoes with minimal effect on the visual appearance. Practical Application: Various methods/treatments are in use for extending the quality of fresh‐cut fruits, including mild heat treatment. This study explored the application of infrared (IR) heat for processing fresh‐cut mango cubes and evaluated its effect on vitamin C and antioxidant capacity during 16‐d storage. This is the first study reporting on the use of IR heat in fresh‐cut fruits. IR treatment was shown to be effective in retaining antioxidant properties of fresh‐cut mango cubes with minimal effect on the visual appearance.     

Polycyclic aromatic hydrocarbons,polychlorinated biphenyls,chlorinated pesticides (DDTs), hexachlorocyclohexane,and hexachlorobenzene residues in smoked seafood

Smoked seafoods were screened for the presence of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and other organochlorine compounds. Total PAH concentrations ranged from 46.5 ng/g (wet weight) for smoked swordfish to 124.0 ng/g (wet weight) for smoked herring. Among the carcinogenic PAHs, benzo(a)pyrene ranged from undetectable levels for several smoked fish to 0.7 ng/g for Scottish salmon, dibenzo(ah)anthracene was not present in any of the samples analyzed, and benzo(a)anthracene was found in all samples and at particularly high levels in salmon (23.2 ng/g). Benzo(a)pyrene concentrations were below the tolerance limit for all samples. PCB concentrations for the different samples ranged from 2 to 30 ng/g. Chlorinated pesticides (DDTs: p,p'-DDE, p,p'-DDT, o,p'-DDT, p,p'-DDD, and o,p'-DDD) were detected at levels ranging from 0.2 ng/g (wet weight) in bluefin tuna to 17.5 ng/g (wet weight) in salmon. Hexachlorocyclohexane isomers (alphaHCH + betaHCH + gammaHCH) were present in higher amounts in eels (6.5 ng/g) than in the other smoked fish. For 40% of the samples, PCB concentrations exceeded the limit fixed by the European Union, while pesticide levels were below the maximum acceptable limit proposed by the Food and Agriculture Organization.     

Detection of fish DNA in ruminant feed by PCR amplification

The Japanese Government has prohibited the use of seafood protein, as well as mammalian protein, in ruminant feed. There is an official method to detect meat and bone meal, but no method is yet available to detect fishmeal in ruminant feed. We tried to develop a suitable method to detect fishmeal in ruminant feed, similar to the official method "PCR detection of animal-derived DNA in feed". Our previously reported primers (fishcon5 and fishcon3-1) showed low sensitivity, so we designed new primers based on a DNA sequence from yellowfin tuna mitchondrial DNA. Among the primers, FM5 and FM3 specifically detected fish DNA (sardine, yellowfin tuna, skipjack tuna, chub mackerel, Pacific saury, salmon, rainbow trout, Japanese anchovy, codfish and Japanese horse mackerel) from fish meat, and did not amplify DNA from animals and plants. The sensitivity for detection of the presence of fishmeal in ruminant feed was 0.01-0.001%.     

牛磺酸降血压作用研究概况

牛磺酸是一种含硫的非蛋白氨基酸,具有多种生理功能。本文概述了牛磺酸对不同类型高血压的影响,并归纳了其主要通过抑制RAAS系统、抑制交感神经的兴奋性、刺激KKS系统、舒张血管而发挥降压作用,为牛磺酸降血压作用机制的深入研究、也为牛磺酸在营养保健食品领域的进一步开发利用提供参考。      

Mercury and cadmium concentrations in farmed bluefin tuna (Thunnus orientalis) and the suitability of using the caudal peduncle muscle tissue as a monitoring tool

Three regions (cephalic, central, and caudal) of the dorsal and ventral muscle tissue (R1 through R6) and the caudal peduncle muscle tissue (CPMT) of 20 farmed bluefin tuna (Thunnus orientalis) were analyzed for mercury (Hg) and cadmium (Cd) concentrations. Region 1 (cephalic-ventral) had significantly lower concentrations of Hg but significantly higher concentrations of Cd than did the other regions. However, average metal concentrations of all regions (R1 through R6) were only 6% lower for Hg and were not significantly different for Cd from those in the CPMT. Therefore, the CPMT was used to monitor the concentrations of these two metals in more than 100 farmed tuna collected from July 2004 to January 2009 under the assumption that the Cd concentrations in the CPMT would be representative of the Cd concentration in the whole body and that the Hg concentrations would be, in the worst case, overestimated by approximately 6%. The Hg and Cd concentrations in these tuna were inversely related to the condition index, i.e., the tuna in better condition had the lowest concentrations of these metals. The mean concentrations in the CPMT of all fish analyzed were 0.31 ± 0.17 μg/g wet weight for Hg and 0.007 ± 0.006 μg/g wet weight for Cd. These concentrations were below the limits established by Mexican regulations for seafood (1.0 and 0.5 μg/g for Hg and Cd, respectively) and Japan (0.4 μg/g for Hg).     

Levels of specific polychlorinated biphenyl congeners in fatty foods from five Canadian cities between 1986 and 1988.

A total of 155 fatty food composites from five major Canadian cities were analysed for 36 selected polychlorinated biphenyl (PCB) congeners. Total PCB congener levels of more than 1 ng/g (wet weight) were found in fresh water fish, canned fish, butter, marine fish and cheese, with fresh water fish (18.7 ng/g) containing 5 to 10 times more total PCBs than the other four food commodities. Milk (2%), cooking oils/salads and canned meat soup contained less than 0.1 ng/g (wet weight). The observed total PCB residue levels in fatty foods were well within the Canadian guidelines for fish, dairy products, poultry, eggs and beef. The most predominant congeners found in fish, butter, cheese, meat and poultry were the 2,2',4,4',5-, 2,3',4,4', 5-pentachloro-, 2,2',3,4,4',5'-, 2,2',4,4',5,5'-hexachloro- and 2,2',3,4,4',5,5'-heptachlorobiphenyls. The predominant congener pattern was not always evident in other dairy products (e.g. ice cream) and processed foods (e.g. canned meat soup). An attempt was made to relate the intake of PCB congeners from fatty foods with congener levels found in adipose tissue of Canadians. The estimated daily intake of some specific PCB congeners from fatty foods, in most cases accounted for more than half the total deposit of these congeners in adipose tissue of Canadians.     

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.     

固相微萃取-气质联用分析方法评价 水产品鲜度研究进展

鲜度是影响水产品品质的重要因素。鲜度评价对水产品加工、储运及安全都具有重要意义。固相微萃取-气质联用方法是一种快速方便检测食品挥发性物质的方法。此方法已经被应用于一些水产品如鳕鱼、鲅鱼、金枪鱼、鲈鱼等挥发性物质检测及鲜度评价中。该方法具有客观、快速、方便的特点。本文就目前该分析方法在水产品鲜度评价中的原理、应用及前景作一简要综述。     

Prevalence and contamination levels of Listeria monocytogenes in retail foods in Japan

Retail foods in Japan were surveyed for the presence and contamination levels of L. monocytogenes. It was isolated from 12.2, 20.6, 37.0 and 25.0% of 41 minced beef, 34 minced pork, 46 minced chicken and 16 minced pork-beef mixture samples, respectively. MPN values were higher than 100/g in five (10.9%) minced chicken samples, but lower than 100/g in all minced beef, pork and pork-beef mixture samples. The organism was also isolated from 5.4% of the 92 smoked salmon samples at MPN values lower than 10/g, and from 3.3% of 213 ready-to-eat raw seafood samples at MPN values from lower than 0.3 to higher than 100/g. None of the 285 vegetable samples were contaminated with L. monocytogenes. These findings indicate that ready-to-eat raw seafoods are relatively high risk among the foods surveyed in this study.     

Histamine levels in seventeen species of fresh and processed South African seafood

Histamine levels were determined in fresh and processed seafood from a representative range of 10 outlets after several incidents of scombroid seafood poisoning occurred. Species included seventeen fresh and processed scombroid- and non-scombroid fish, marine mollusks and crustaceans. Histamine levels in fresh seafood were generally low (0–9 ppm) with the exception of one sample of snoek (scombroid fish; >50 ppm) and one sample of yellowtail (non-scombroid fish; >50 ppm). Both species are rich in free histidine (1.5–5.3 ppb), a precursor of histamine. Processed seafood had, in general, low histamine concentrations (0–3 ppm) with the exception of fish meal (76 ppm), salted herring (47 ppm), one sample of smoked snoek (>50 ppm) and dried tuna (8000 ppm). In total, 5 of 80 examined samples (6%) contained histamine concentrations above the legal limit of 50 ppm. Experimental formation of histamine was demonstrated to be strongly temperature- and time-dependent. Samples were not contaminated with Vibrio spp., Pseudomonas spp., Klebsiellas spp. or Enterobacteria.     

Rapid Detection of Fish Major Allergen Parvalbumin by Surface Plasmon Resonance Biosensor

ABSTRACT: Seafood allergy is a common and major cause of food allergy in adults. In recent years, seafood allergy has become a serious problem with the increase of seafood consumption. To develop a rapid allergen detection method based on the affinity of antigen‐antibody interaction, fish major allergen, parvalbumin, was used for kinetic analysis by a surface plasmon resonance (SPR) biosensor. Anti‐parvalbumin murine monoclonal antibody (MAb) EG8 was immobilized onto a carboxymethyl dextran (CMD) surface. By the injection of various concentrations of purified carp parvalbumin (CPa), a standard curve and the affinity constants (K_D and k_*) for the MAb EG8‐CPa model system were determined. In addition, kinetic data were also obtained by the injection of serial dilutions of extracts from seafood products: sardine fish cake (tsumire) and dried skipjack tuna (katsuonut). Sardine tsumire and katsuonut contained 0.11 mg/kg and 0.39 mg/kg parvalbumins, respectively, where affinity constants K_D and k_* were almost similar among paralbumins from different sources. In the SPR system, the allergen can be detected only for 5 min according to the allergen‐MAb binding interaction. Consequently, by the use of a SPR biosensor, kinetic analysis based on the allergen specific MAb would be a rapid and powerful tool for allergen detection and quantification.