Authentication and traceability of fish maw products from the market using DNA sequencing

Fish maws (dried swimbladders of fishes) are regarded as traditional luxurious delicacies, medicine and tonics, which have been recommended and consumed in Asia over many centuries. At the commercial level, they are ranked as different values based on species. However, fish maw species and the trade are still unknown and undocumented. The processing treatments make them difficult for species identification based on morphological characterization. In the present study, the genetic identification of the main commercialized species of fish maws has been carried out, based on the amplification of a fragment of mitochondrial 16S rRNA gene and subsequent BLAST analysis. The applicability of all kinds of processed products was verified, including dried, water soaked, salt fried and salt fried plus water soaked forms. The result indicated this method was applicable to all of them, showed that 53.3% of the products were incorrectly labeled and 58.3% of “croaker” products were substituted with catfish or perch species. Moreover, results indicated that besides traditional trade in Asia, the fish maw trade has been globally expanded to meet the growing demand of market. Therefore, this method can be useful in normative control of processed products, particularly in the authenticity of imported species, verifying the correct traceability in commercial trade, the correct labeling, and also for fisheries control of endangered species to conserve stocks biodiversity.     

Microbiological safety and sensory characteristics of salmon slices processed by the sous vide method

The aim of this work is to evaluated the microbiological quality and the sensory characteristics of salmon slices processed by the sous vide method under different conditions of time–temperature when stored at 2 and 10 °C.Three different combinations of time–temperature were studied (5 min/65 °C, 10 min/90 °C and 15 min/90 °C). The product stored at 2 or 10 °C was evaluated periodically to study its sensory quality, microbiological condition and proximate composition. Batches stored at 2 °C had lower growth rates of mesophiles and psychrotrophs. Staphylococcus aureus, Bacillus cereus, Clostridium perfringens and Listeria monocytogenes were not found in any of the samples. Neither aerobic nor anaerobic sporeforming bacteria were detected in the salmon processed at 90 °C for 15 min and stored at 2 °C after 45 days. The heat treatment of 90 °C for 15 min was the most effective for extending the shelf life of fish (>45 days). However, under these conditions the sensory characteristics were not optimal.It can be conclude that the treatment at 90 °C for 15 min was the most effective one to ensure the safety and to extend the shelf life of sous vide salmon. However, under these conditions the sensory characteristics were not optimal immediately after processing.This study emphasizes the importance of heat treatment and storage temperature in order to ensure the safety particularly in a fat fish, since fat can acts as a protecting agent in the heat resistance of microorganisms.     

DNA barcode identification of fish products in Taiwan: Government-commissioned authentication cases

Mislabeling of fish products not only impacts consumer finances, but can also be deleterious to public health. Fish products may be mislabeled for reasons including ambiguity of common fish names, challenging morphological identification, or willful intention to deceive. We reveal a high rate of mislabeling (70%) in 34 samples from 17 cases entrusted to us by three different Customs offices and one Coastal Patrol Office in Taiwan using DNA barcoding based on a partial segment of the mitochondrial cytochrome c oxidase subunit I gene (COI). In order to reduce the mislabeling of imported fish products, the authorities should take some actions into consideration, such as institutionalizating molecular authentication of fish products, standardizing the usage of common fish names, and legislating for penalties.     

Development of a sous-vide packaging process for Korean seasoned beef

From an analysis of the conventional process for cooking Korean seasoned beef, a sous-vide processing method was developed that offers convenience and storage stability. The new process consists of boiling, simmering and slicing the meat slab, evaporative concentration of boiled beef brine and soy sauce, filling a gas-barrier film pouch with the beef slices and concentrated brine with spice ingredients, and pasteurising the sealed package. The sous-vide packaging resulted in better sensory quality and storage stability compared with the conventional method. The shelf life based on the sensory quality change was around 12 days when stored at 3 and 10 °C for the products processed by the sous-vide method, whereas it was 7 and 3 days, respectively, for the conventionally processed products. The sous-vide packaging was effective in protecting the product from microbial, physical, and sensory quality degradation.     

Sensory analysis to assess the freshness of Mediterranean anchovies (Engraulis encrasicholus) stored in ice

A quality index method and a sensory scheme were developed to assess raw and cooked Mediterranean anchovies (Engraulis encrasicholus), respectively. Fresh anchovies were stored in ice for 7 days in three trials. The changes in sensory punctuations showed satisfactory correlations with time of storage. Enterobacteria were the first microorganisms that exceeded the maximum allowable limit for marketable fish according to the Spanish regulations, reaching more than 10³ colony former units/g after 5 days of storage. Receiver operating characteristic curves of the sensory scores of raw and cooked anchovy against Enterobacteria counts were used to corroborate the suitability of the schemes. Areas under the curves were satisfactory and the estimated rejection values ranged from 0.43 to 0.51 and from 6.6 to 7.1 for raw and cooked anchovies, respectively.     

高强度封堵技术

针对沈84-安12块及曙光古潜山油藏高含水开发中后期形成的大孔道及裂缝,研究了粉煤灰及橡胶粉填充的聚丙烯酰胺一三聚氰胺冻胶堵剂及不饱和聚酯树脂堵剂封堵大孔道技术.该技术现场应用10井次,取得了明显增油降水效果,对提高油藏水驱波及程度,改善开发效果发挥了重要作用.     

Nucleotide degradation and quality changes in mullet (Liza corsula) and pearlspot (Etroplus suratensis) in ice and at ambient temperatures

Quality changes in Mullet (Liza corsula) and Pearlspot (Etroplus suratensis) stored at ambient temperature and in ice were studied by sensory, nucleotide and volatile base nitrogen analysis. The K-value increased linearly with storage time and appeared to be a good index of freshness for the two brackish water fish. Inosine monophosphate bears a significant positive correlation with (P ≤ 0.001) flavour score. Hypoxanthine increased exponentially with time and volatile base nitrogen showed a slow increase during the early periods of iced storage.     

加工含硫原油设备腐蚀状况及有关对策

随着外油加工量的增加,中国石化股份有限公司广州分公司的生产装置和储运系统的硫腐蚀问题日益突出。文章对该公司低温部位、高温部位以及油罐和输油管线的几种突出腐蚀情况及有关对策进行了介绍。经过完善“一脱三注”工艺、合理选材和对储油罐来取涂料-电化学联合保护等措施后,使腐蚀问题得到了缓解。     

Identification of ochratoxin A in Chinese spices using HPLC fluorescent detectors with immunoaffinity column cleanup

Spices can be heavily contaminated with Penicillium verrucosum and Aspergillus ochraceus, which develop during cultivation and after harvest if relative humidity is not controlled during storage. The present study was undertaken with the aim to provide an analytical method to detect OTA in spices commercialized in China, specifically to develop a simple and rapid method for the determination of Ochratoxin A content in spices via immunoaffinity column and high performance liquid chromatography with fluorescence detection (HPLC-FLD). The recovery (75.0–102.0%) and repeatability (RSD < 12) are acceptable according to the requirements of the Commission Regulation (EC) No. 401/2006. The method is accurate, sensitive and rapid. A total of 480 spice products were analyzed with the amended analytical methods used in our study, which involved the extraction of OTA, immunoaffinity cleanup and high performance liquid chromatography determination with fluorescence detection. This report is the first describing the OTA presence in retail spices (pepper, chili, prickly ash, cinnamon, aniseed, fennel, curry powder and cumin) in China. The percentage of OTA contamination in spice product is 9.6%, and two chili products were above the levels permitted by the EU for safe consumption. Surveillance of a large number of suspected spice products should be continuous and widespread.     

DNA barcoding reveals a high level of mislabeling in Egyptian fish fillets

Accurate identification of seafood species in the markets is a growing concern due to the high incidence of species substitution at international level. It is a prime priority for governments to be able to identify the already processed fish products (fish fillets). In this context, DNA barcoding was applied to ascertaining species in fish fillets (tilapia, Nile perch and panga) purchased from Egyptian markets. Ninety commercial samples were analyzed. Sequencing of a short fragment of mitochondrial cytochrome oxidase I (COI) gene revealed 33.3% species substitution in the fish fillets analyzed, 50% Nile perch (Lates niloticus) and 50% basa fish (Pangasius bocourti) being replaced by imported Vietnamese tra fish (Pangasianodon hypophthalmus). These results demonstrate that DNA barcoding is a reliable tool for detecting fish products adulteration in Egypt. We recommend its use for control and law enforcement of seafood quality.     

轴流泵机械密封国产化

轴流泵P201是大庆炼化公司30×10^4t／a聚丙烯装置的进口关键设备,其机械密封存在价格高、检修成本高及进货周期长的问题。国产化改造后效果良好,其经验可为同类产品提供借鉴。     

储氢材料及其在含能材料中的应用

详细介绍了储氢材料品种，其中包括苯和甲苯有机液体氢化物，氢化硼和氢化铝络合物，超级活性炭，碳纳米纤维和碳纳米管的纳米碳材料，镧（稀土）系列、钛铁系列、镁系列等金属及合金氢化物，多孔聚合物等；并简单介绍了这些储氢材料的制备方法、在含能材料中应用时存在的问题及改进方向。重点介绍了多孔聚合物储氢材料的特点及合成方法，提出金属氢化物和多孔聚合物应作为储氢材料在含能材料中应用的重点研究对象。     

Effect of packaging and storage conditions on quality of shelled walnuts

The present study investigated the effect of packaging and storage conditions on quality of raw shelled walnuts. Walnut kernels were packaged in: (a) low density polyethylene (LDPE), 55 μm in thickness in air, (b) polyethylene terephthalate||polyethylene (PET||PE), 70 μm in thickness under N₂, and (c) PET-SiO_x||PE pouches, 62 μm in thickness under N₂. Samples were stored either under fluorescent light or in the dark at 4 or 20 °C for a period of 12 months. Quality parameters monitored were peroxide value (PV), hexanal, 2-thiobarbituric acid (TBA), odor, and taste of product. PV ranged between 0.3 for fresh walnut kernels and 31.4 meq O₂/kg oil for walnuts packaged in PE pouches exposed to light after 12 months of storage. Respective values for hexanal were <28.5 μg/kg and 36.0 mg/kg and for TBA ca. 0.2 and 11 mg MDA/kg. Values for odor ranged between 0.2 for fresh walnut kernels and 5.7 for walnut kernels packaged in PE exposed to light after 12 months of storage at 20 °C. Respective values for taste were 0.7 and 6.8. Taste proved to be a more sensitive attribute than odor. Based on shelf life (taste) values and PV data it is proposed that the upper limit value for PV is close to 10.0 meq O₂/kg walnut oil. Respective limit values for hexanal are 1–2 mg hexanal/kg walnut and for TBA is 1–2 mg malondialdehyde/kg walnut. Walnuts retained acceptable quality for ca. 2 months in PE-air, 4–5 months in PET||PE-N₂ and at least 12 months in PET-SiO_x||PE-N₂ pouches at 20 °C, with samples stored in the dark retaining slightly higher quality than those exposed to light. The effect of parameters investigated followed the sequence: temperature > degree of O₂ barrier > lighting conditions.     

An evaluation of the effect of storage and processing temperatures on the microbiological status of sous vide extended shelf-life products

The microbiological and organoleptic quality of selected sous vide products was monitored over a storage period of up to five weeks at 3°C and 8°C, respectively. Sous vide products stored at the recommended temperature of 3°C showed negligible microbial growth and were found to be organoleptically acceptable throughout the storage period. Total plate counts at the end of the fourth week of storage were in the range <10–7×10³ CFU/g for all 19 products under study. Listeria monocytogenes, Salmonella, Clostridium perfringens, Bacillus cereus and Enterobacteriaceae were not detected in any of the processed samples. At 8°C, under temperature abuse conditions, while some products had acceptable microbial levels of 10²–10⁴ CFU/g after three weeks, others such as chicken chasseur had counts above 10⁶ CFU/g by the second week of storage. Lactic acid bacteria and Pseudomonas species were dominant in the microbial flora of spoilt samples and B. cereus (>3×10⁴ CFU/g) was isolated from spoilt chicken chasseur samples in the fourth week of storage at 8°C. Critical factors affecting sous vide product safety are discussed.     

Evaluation of carbonyl species in fish oil: An improved LC–MS/MS method

Fish oil, a common source of omega-3 fatty acids, can be easily oxidized to generate carbonyl species, thus, the measurement of these compounds in fish oil are significant for food safety. Here, a comprehensive and sensitive method to quantify forty-four carbonyl species including toxic substances such as acrolein, glyoxal, methylglyoxal and trans-4-hydroxy-2-hexenal in fish oil has been developed and validated. The samples were derivatized with 2,4-dinitrophenylhydrazine, cleaned using C18 solid phase extraction, and analyzed by liquid chromatography coupled with tandem mass spectrometry. The calibration curves represented satisfactory linearity (r² > 0.998) and the quality control samples showed favorable precisions within an acceptable range (RSD < 10%). The accuracies ranged from 96 to 109%. The detection and quantification limits ranged from 1.5 to 30 ng/mL and 5–90 ng/mL, respectively. The method was successfully applied to determine carbonyl species in ten fish oil products. The proposed method is suitable for high throughput analysis of carbonyl species in fish oil.     

Determination of heavy metals in selected black sea fish species

Heavy metals can be accumulated by marine organisms thought a variety of pathways, including respiration, adsorption and ingestion. The levels of heavy metals are known to increase drastically in marine environment through mainly anthropogenic activities. Fish are good indicators for the long term monitoring of metal accumulation in the marine environment. The aim of this study was to determine the levels of Cd, As, Hg, Pb, Zn and Cu in edible part and gill of seven most consumed Bulgarian fish species collected from north-east coast of Black Sea. These fish species are sprat (Sprattus sprattus sulinus), Mediterranean horse mackerel (Trachurus mediterraneus ponticus), Black sea gobies (Neogobius melanostromus), shad (Alosa pontica), Atlantic bonito (Sarda sarda), bluefish (Pomatomus saltatrix) and grey mullet (Mugil cephalus). The fish samples were collected during 2010. The analytical determination of As, Cd, Pb, Zn and Cu were performed by using flame and graphite furnace atomic absorption spectrometry after microwave digestion procedure. The total mercury determination was determined using a direct mercury analyzer (DMA-80). The metal concentration of analyzed elements was highest in the gill for all fish species. The maximum metal concentration was measured for Cu (1.40 mg kg⁻¹ w.w), Zn (11 mg kg⁻¹ w.w) and Pb (0.08 mg kg⁻¹ w.w) in muscle tissues of shad and sprat. The edible part of horse mackerel has the maximum value for Hg (0.12 mg kg⁻¹ w.w) while Atlantic bonito predominantly accumulates As (1.10 mg kg⁻¹ w.w). The analytical results obtained from this study were compared within acceptable limits for human consumption set by various health institutions.     

催化剂CS-1-G用于生产1102K型聚丙烯树脂的工业试验

介绍了15万t/a Novolen气相法聚丙烯(PP)装置采用国产催化剂CS-1-G生产1102 K型PP树脂的工业试验情况,并与装置原用进口催化剂进行了对比。结果表明,在原料、助剂性质及生产工艺条件基本接近的情况下,催化剂CS-1-G的活性达到56.86 kg/g,比进口催化剂高出7.75%;装置运行稳定,所产PP产品的细粉含量少,其主要性能指标达到进口催化剂生产产品的水平。     

Effect of Anisakis simplex (sl) larvae on the spoilage rate and shelf-life of fish mince products under laboratory conditions

Wild caught marine fish are commonly infected with anisakid nematodes lodging in the intestinal linings or in the fish muscle. One of the most commonly found nematode parasites in marine fish is Anisakis simplex. During production of mince from the muscle of wild caught Anisakis-infected fish, the larvae would be disrupted during mince production. Any bacteria within or on the surface of such larvae are during the mincing process evenly distributed throughout the mince, and could thus possibly affect the spoilage rate of the final products. To explore if or how any bacteria associated with muscle-invading Anisakis larvae may affect the spoilage rate of fish mince, a controlled storage trial was conducted. Fillets of farmed Atlantic cod (Gadus morhua), exclusively fed on dried and heat-treated compound feed and hence expectably free from Anisakis larvae, were aseptically collected and homogenised. Fish mince aliquots were added different volumes of Anisakis homogenate based on larvae which were freshly sampled from the visceral cavity of NE Atlantic blue whiting (Micromesistius poutassou). The volumes of added parasite homogenate (parasite(+)-samples) reflected different infection intensities from 15 (low) to 50 (high) larvae per 100 g fish fillet, representing an actual Anisakis intensity range in the flesh of blue whiting. The samples were kept at 4 °C for 15 days and subjected to microbiological, sensory and chemical evaluation at 3 days intervals. Upon visual examination and plate count measurements (PC) on Iron Agar Lyngby (IAL), the samples without any parasite additives (no[parasite]) spoiled differently and more rapidly than any of the parasite(+)-samples. However, H₂S-producing bacteria were only recorded in the latter samples, which were also the only ones that showed increased levels of the spoilage indicator substance trimethylamine (TMA). Moreover, the parasite(+)-samples changed their sensory characteristics at a later stage compared to the no[parasite]-samples. Although some cultures of H₂S-producing bacteria were found on IAL, molecular identification by PCR-DGGE of the actual bacteria was not conclusive. Psychrobacter sp. which has no or only little spoilage activity, was identified in all samples until trial day 9, but was probably outgrown by the stronger spoilers Pseudomonas fluorescence/fragi and Photobacterium phosphoreum. Thus, and somewhat unexpected, our findings indicate that – under the present trial conditions – fish mince contaminated with bacteria which originate from Anisakis larvae, spoiled less rapidly than samples without any parasite-related bacteria present. Moreover, the shelf-life of fish mince was apparently not reduced by the presence of bacteria transferred to the mince by Anisakis larvae.     

A survey of the incidence and level of aflatoxin contamination in a range of locally and imported processed foods on Malawian retail market

Samples of locally (Malawian) processed and imported maize- and groundnut-based food products (peanut butters, roasted groundnuts, peanut based therapeutic foods, instant baby cereals, maize puffs and de-hulled maize flour) were collected from popular markets of Lilongwe City, Malawi. The samples were analysed in order to determine the frequency and extent of aflatoxin contamination, using immuno-affinity column and reversed-phase liquid chromatography with post-column photochemical derivatization and fluorescence detection. No aflatoxins were detected in all samples of imported baby cereal and locally processed de-hulled maize flour. However, all locally processed maize based baby foods had aflatoxins above EU maximum tolerable level of 0.1 μg/kg. In 75% of locally processed maize puffs, aflatoxins were detected at levels of up to 2 μg/kg. Peanut based therapeutic foods had aflatoxin level between 1.6 and 2.9 μg/kg, exceeding the EU tolerable maximum level (0.1 μg/kg) set for food for health purposes. Locally processed peanut butters had aflatoxins levels in the range of 34.2–115.6 μg/kg, which was significantly higher than their imported counterparts (<0.2–4.3 μg/kg). Samples of locally processed skinned and de-skinned roasted groundnuts had aflatoxins in range of 0.5–2.5 μg/kg and 0.6–36.9 μg/kg, respectively. These results highlight the need for rigorous monitoring of aflatoxins in commercially available processed products in order to reduce likely health risks associated with dietary aflatoxin intake.     

Combined effect of electrolyzed oxidizing water and chitosan on the microbiological,physicochemical, and sensory attributes of American shad (Alosa sapidissima) during refrigerated storage

This study evaluated the combined effect of electrolyzed oxidizing water (EOW) and chitosan (CH) on the quality and shelf-life of American shad (Alosa sapidissima) stored at 4 °C for 25 days. A CH solution (2% w/v; pH 3.7) was used to coat the fish flesh after washing with EOW (pH 2.4; oxidation-reduction potential, 1185 mV; free chlorine level, 70–80 ppm). Control and treated fish samples were analyzed for microbiological (total viable count), physicochemical (pH, total volatile basic nitrogen, thiobarbituric acid, texture, and color), and sensory characteristics. The results revealed that EOW + CH was more effective than either treatment alone (EOW or CH) in inhibiting microbial growth, protein decomposition, and lipid oxidation. Furthermore, EOW + CH maintained better texture, color, and sensory characteristics of fish. This treatment extended the shelf-life of American shad fillets by 9–10 days during refrigerated storage.