Development and validation of a quantitative spectrophotometric method to detect the amount of carbon monoxide in treated tuna fish

In recent years carbon monoxide (CO) has been employed by the fishery industry to preserve the fresh appearance of fish products during frozen storage, particularly in vacuum packaged products. CO reacts with oxy-myoglobin to form a stable cherry coloured carboxy-myoglobin complex. We propose a method that allows the quantitative determination of CO in the meat drip of tuna fish by UV–Vis spectroscopy. It consists of: (i) preparations of CO secondary standard solutions titrated against horse heart Mb primary standard solutions; (ii) determination of calibration curves to measure CO concentration in treated and untreated samples. The accuracy of the spectrophotometric method has been evaluated in terms of trueness and precision by using fortified tuna fish samples. The spectroscopic results have been compared with those obtained using a head space gas chromatographic technique (HS-GC–MS). The CO levels measured in tuna fish samples by UV–Vis are substantially lower than those revealed by HS-GC–MS. The origin of this discrepancy is discussed.     

Development and validation of an HPLC-FLD method for rapid determination of histamine in skipjack tuna fish (Katsuwonus pelamis)

This study compared and validated two methods of high-performance liquid chromatography: fluorescence detection (HPLC-FLD) and UV–Vis detection. Recoveries greater than 55% at all spiking levels using UV–Vis detection could not be obtained. However, derivatization with pre-column o-phthalaldehyde (OPA) was found to efficiently enhance the method sensitivity. The analytical method was validated based on the following criteria: linearity, sensitivity, accuracy, precision, repeatability, and recovery. For fluorescence detection, excellent linear correlation with R² = 0.9977 was observed over the range of 5.0 to 100.0 mg/L. The minimum detection limit was calculated to be 1.5 mg/kg, while the limit of quantification (LOQ) value of the validated method was determined to be 4.5 mg/kg. Good recoveries (RSD% = 1.35) were obtained at all spiking levels ranging between 0 and 200 mg/kg. The proposed method was found to be suitable, selective, and rapid for the determination of histamine.     

Use of “filtered smoke” and carbon monoxide with fish

This review deals with the importance of flesh colour for quality assessment of muscle food and possibilities of influencing the colour via muscle colour pigments. Carbon monoxide as reagent to stabilise muscle colour and processes producing CO for this purpose are highlighted concentrating on those using filtered smoke (FS) to treat fish muscle. The scientific background is discussed and an overview is given on the situation concerning food law in this respect in different countries. Received: September 5, 2007     

Effect of modified atmosphere and active packaging on the shelf-life of fresh bluefin tuna fillets

The aim of this work was to study the influence of the combined use of MAP and antioxidant-based active packaging on the shelf-life of fresh bluefin tuna fillets stored at 3 °C. Active packaging films were produced by embedding α-tocopherol into an unstabilized low density polyethylene (LDPE) matrix at three concentrations (0.1%, 0.5%, 1%). α-Tocopherol release kinetics, in vitro antioxidant activity, oxygen permeability and crystallinity degree were determined to characterize the film. Preliminary shelf-life tests were performed to select critical quality indices, the best gas composition and the best α-tocopherol concentrations in the active film. Then, the effectiveness of the chosen active packaging film in combination with MAP was assessed by monitoring critical quality indices of fresh bluefin tuna fillet during storage at 3 °C for 18 days. Obtained results showed that (i) 100% N₂ atmosphere has a protective effect on haemoglobin and lipid oxidation processes monitored, (ii) active film is able to reduce fat oxidation, (iii) the combined effect of MAP and active packaging can be considered a valuable tool to increase the shelf-life of raw fish products.     

Effect of canned tuna fish processing steps on lead and cadmium contents of Iranian tuna fish

The contents of Pb and Cd in two species of Iranian tuna fish (yellowfin and skipjack), which were caught from the Persian Gulf and Oman Sea, and the effects of canning processing steps on their contents were assessed by electrothermal atomic absorption spectrometry. The results revealed that the levels of lead and cadmium throughout the processing steps in yellowfin were in range of 0.154 ± 0.019–0.441 ± 0.025 μg/g and 0.029 ± 0.002–0.084 ± 0.0005 μg/g, respectively. Pb and Cd concentrations from received fish to final product in skipjack were found to be in range of 0.072 ± 0.031–0.218 ± 0.031 μg/g and 0.016 ± 0.001–0.062 ± 0.002 μg/g, respectively. The limit of detection for lead and cadmium were 0.058 μg/g (11.6022 μg/l) and 0.0007 μg/g (0.1485 μg/l), respectively. Results from paired sample t-test analysis showed that defrosting, cooking, and sterilisation by autoclave would reduce the contents of lead and cadmium, considerably.     

鱼体新鲜度近红外光谱检测方法的比较研究

目的 建立针对淡水鱼整鱼鱼体新鲜度的快速无损检测方法. 方法 通过比较不同的光谱与相应挥发性盐基氮(TVB-N)值的建模结果, 以及对比分析竞争性自适应重加权算法(CARS)、遗传算法(GA)及连续投影算法(SPA)三种特征波长选择方法对模型的优化结果, 对鱼鳞及光谱采集部位等影响因素进行研究。结果 鱼体有鳞时的尾部为最佳新鲜度检测部位。CARS法较优且鱼体新鲜度检测的最优波段为800~1100 nm, 采用CARS特征波长选择方法选择出23个波长变量重新建立PLS模型, 模型预测集相关系数RP=0.957, 预测均方根误差RMSEP=0.589 mg/100 g。利用CARS方法选择的23个波长变量对淡水鱼进行新鲜度评价, 准确率达96.67%。结论 该方法为淡水鱼整鱼新鲜度快速无损检测提供了一种有效的方法。     

A rapid non‐destructive method for fish quality control by determination of smell intensity

The ‘Cosmos’ instrument (Japan) was applied to the evaluation of fish quality in six species of different origins, by determination of smell intensity. Pond‐raised fish (trout, carp, silver perch, tilapia, barramundi) were stored in ice for 4–5 weeks and frozen/thawed mackerel was kept at room temperature for 74 h. The fish quality was examined by organoleptic assessment, by determination of smell intensity and by tests of the chemical (total volatile basic nitrogen, hypoxanthine and histamine) and dielectric (Torrymeter) properties. Strong correlation was found between the organoleptic and ‘Cosmos’ results, whereas the data from the chemical and Torrymeter analyses were relatively poorly correlated with the sensory evaluation and ‘Cosmos’ data. Thus the application of the ‘Cosmos’ instrument for objective quantitative evaluation of fresh and chilled fish quality by determination of smell intensity seems practicable. The ‘Cosmos’ instrument is hand‐held and portable as well as being rapid and non‐destructive in operation; therefore it could be used for evaluation of fresh and chilled fish in the field and on board fishing vessels. Copyright © 2003 Society of Chemical Industry     

鱼肉制品中龙利鱼和巴沙鱼的鱼源性成分的双重实时荧光PCR快速检测法

目的 建立龙利鱼和巴沙鱼源性成分的双重实时荧光聚合酶链式反应(PCR)快速检测方法。方法 根据13种龙利鱼的线粒体16S rRNA序列,设计通用引物和探针,根据巴沙鱼的线粒体cytb基因序列设计引物和探针,通过优化扩增反应体系进行双重实时荧光PCR扩增,达到快速检测产物的目的。结果 本方法特异性良好,龙利鱼基因组DNA灵敏度可达到10^-3ng,在与鲤鱼粉混合的鱼肉制品中可检测,质量分数灵敏度达到1%。巴沙鱼基因组DNA灵敏度可达到10^-4ng,在与龙利鱼粉、大西洋鳕鱼粉混合的鱼肉制品中均可检测,质量分数灵敏度达到0.1%,在与米粉混合的鱼肉制品中可检测,质量分数灵敏度达到0.001%。结论 本方法检测特异性高、所需时间短、灵敏度高,可满足鱼肉制品中龙利鱼真伪鉴别和巴沙鱼掺假的检测要求。     

鱼肉制品中巴沙鱼源性成分的实时荧光聚合酶链式反应快速检测法

目的 建立巴沙鱼源性成分的实时荧光聚合酶链式反应(PCR)快速检测手段.方法 根据巴沙鱼的线粒体cytb基因序列设计引物,使用实时荧光PCR进行扩增,从而达到快速检测产物的目的.结果 此方法特异性良好,巴沙鱼基因组DNA灵敏度可达到10-4 ng,在与婴幼儿米粉、儿童副食芝麻粉、鸡肉粉和大西洋鳕鱼粉混合的鱼肉制品中均可...     

膜技术分离纯化淡水鱼内脏中复合酶的工艺研究

主要探讨了小型工业化水平的膜技术分离纯化复合酶的工艺,通过比较选取超滤膜I除杂及纳滤膜II浓缩,其酶比活力分别为6901.1U/mL和58659.4U/mL,表明复合酶产品具有较高的生物催化活性,纯化倍数分别达到了150.7倍和1280.8倍,通过SDS-PAGE测得其相对分子量为22.6~36.0ku。证明选用膜技术分离纯化复合酶是完全可行的。     

飞鱼籽生物酶法脱囊衣技术研究

以飞鱼籽为原料,鱼籽脱囊衣率为指标,从胰蛋白酶、胶原蛋白酶、碱性蛋白酶和木瓜蛋白酶4种酶中,筛选出胰蛋白酶为最佳使用酶,并采用L9(34)正交实验设计对胰蛋白酶脱除飞鱼籽囊衣工艺参数进行优化。结果表明,酶解液浓度0.8mg/mL、pH9、在20℃下酶解12min,飞鱼籽脱囊衣率可达83%以上。     

A novel method for the determination of sodium chloride in salted fish

A novel, simple and reliable spectrophotometric method to determine sodium chloride in salted fish was developed and validated. The method was based on the reaction of chloride with silver nitrate and the determination of turbidity of silver chloride formed. The absorbance was measured at 385 nm. The method was tested under various conditions, and we confirmed an optimal operation with 2 mL 1:4 (v/v) nitric acid, 2 mL 1.5 g L^?1 gelatin, 5 mL 0.5% silver nitrate in a total volume of 50 mL, mixed and heated at 60 °C for 10 min. The range of linearity and the detection limit were 0.4–24 mg L^?1 and 0.2 mg L^?1, respectively. The relative standard deviations and the recovery were 0.83% to 2.87% and 93.74% to 103.6%, respectively. The accuracy of this method was comparable with Volhard method, and it was cheap and successfully applied to determine sodium chloride in salted fish.     

Liquid chromatography-mass spectrometry method to detect Tetrodotoxin and Its analogues in the puffer fish Lagocephalus sceleratus (Gmelin, 1789) from European waters

The presence of tetrodotoxin (TTX) and its analogues, 4-epiTTX, 4,9-anhydroTTX, 5-deoxyTTX, 11-deoxyTTX, 5,6,11-trideoxyTTX, 11-norTTX-6(S)-ol, and 11-norTTX-6(R)-ol was investigated for the first time in five different tissues (liver, gonads, gastrointestinal tract, muscle, and skin) of six specimens of the marine puffer fish Lagocephalus sceleratus from European waters (Aegean Sea, Greece) by using liquid chromatography coupled to electrospray ionisation mass spectrometry operating in the conventional mode in addition to low-energy collision dissociation tandem mass spectrometry (CID-MS/MS).Two isomers of 5,6,11-trideoxyTTX were detected in all specimens as the major TTX analogues, followed by 11-deoxyTTX, 11-norTTX-6(S)-ol, and TTX. However, minor amounts of 4-epiTTX, 4,9-anhydroTTX, 5-deoxyTTX, and 11-norTTX-6(R)-ol were also found in most of the tested tissues. In all puffer fish specimens, gonads, gastrointestinal tract, and liver contained the highest toxin levels, whereas muscle and skin contained lower amounts. Toxin distribution within the tissues of the six L. sceleratus specimens was different depending on fish size, area, and season where fish were caught. The LC-ESI-CID-MS/MS analysis employed is proposed as a suitable technique for determination of TTX and its analogues with a low detection limit (0.08 μg/g).     

A micromethod for the differentiation of fresh from frozen fish muscle

A sensitive and rapid routine method was developed which allows a general, unambiguous and reliable differentiation between fresh and frozen-thawed fish muscle. The suggested procedure consists of (i) mild extraction of muscle in isotonic and buffered medium, (ii) rapid separation of the marker isozymes—those of the mitochondrial aspartate aminotransferase—by cellulose acetate electrophoresis, (iii) specific staining at neutral pH for enzyme activity by sandwich with an agarose-substrate-chromogen pad, and (iv) a clearing and drying process to make a permanent record.     

Color stability of frozen whole tilapia exposed to pre‐mortem treatment with carbon monoxide

BACKGROUND: Color of muscle foods plays a major role in consumer perception of meat quality. Carbon monoxide (CO) has been successfully used for improving color of packaged meat and fish products. In this study, we wanted to investigate pre‐mortem treatment of live tilapia using 100% CO for its ability to improve the color of frozen whole tilapia. We compared untreated and CO‐treated whole, gutted tilapia, frozen for 2 and 4 months at ? 20 °C. Frozen tilapia samples were thawed overnight at 4 °C, filleted and analyzed for their color, heme peak wavelength and CO concentration. RESULTS: Euthanasia using CO significantly increased redness (a* value) and lightness (L* value) of tilapia white and red muscle. Frozen storage significantly (P < 0.05) decreased redness of both CO‐treated and untreated tilapia. However, even after 4 months of frozen storage, a*‐value of CO‐treated tilapia was similar to fresh untreated tilapia fillets. Heme peak wavelengths of CO‐euthanized tilapia were higher than in untreated tilapia and there was no significant (P > 0.05) decrease in heme peak wavelengths of CO‐treated tilapia white and red muscle during frozen storage. The CO content of frozen euthanized tilapia fillets was significantly (P > 0.05) higher than in untreated fillets. In general, red muscle tissue of euthanized tilapia had a higher concentration of CO than white muscle. CONCLUSION: Color stability of tilapia fillets was significantly improved by pre‐mortem CO treatment. The color of CO‐treated fillets was retained during frozen storage compared to untreated fillets. Hence, pre‐mortem CO treatment could be used as a new method for improving color of tilapia. Copyright © 2008 Society of Chemical Industry     

一氧化碳在冷却猪肉保鲜中的应用

冷却肉的色泽是重要的感官指标,在贮存和销售过程中常常出现表面褪色现象,严重影响其外观及可接受性。在气调包装气体中添加低浓度CO,利用CO与肌红蛋白结合可形成羧基肌红蛋白,使鲜肉具有更吸引人的樱桃红色,提高冷却猪肉的感官效果。结果表明:1%的CO具有一定的抑菌作用,还可维持冷却猪肉鲜亮红色超过21d。     

Application of NMR to evaluate the oxidative deterioration of brown fish meal

Peroxide value (PV) and acid value (AV) are generally used as indices of deterioration in edible oil. However, they are not always useful for evaluation of oil deterioration in fish meal because the PV rises at the initial stage of oxidative deterioration, reaches a peak and then declines during long term storage of the meal; the AV hardly changes during long term storage. The use of NMR to evaluate oxidative deterioration of the oil in brown fish meal was examined. The ratio of olefinic protons to aliphatic protons (Ro) in brown fish meal oil determined by NMR decreased steadily with increasing storage time. By comparison with data from measurements of PV and AV, the Ro was considered to be useful as an index of oxidative deterioration in the oil in brown meal, especially in oil where the PV is peaking.     

Effect of heat treatment of fish meals,fines and the addition of lysine as related to gizzard erosion in chickens

The effect was studied of certain properties of fish meal on their tendency to predispose chickens to develop gizzard lesions when used in starter diets. These properties relate to the degree of heat treatment to which the meals had been subjected, the fineness of the meal, and the fish species involved. The effect on gizzard erosion of addition of dietary lysine was also considered. The results suggest that the use of meals heated to 130°C or higher, but not of meals stored at lower temperatures, is more likely to result in the development of gizzard lesions, while the fineness of the fish meal had no effect on this phenomenon. In some instances added dietary lysine reduced gizzard erosion incidence. No relationship was found between chicken liveweight gain during the experimental period and gizzard lesion scores. A 7-day biological test was used in these studies.