DNA‐Based Methods for the Identification of Commercial Fish and Seafood Species

ABSTRACT: The detection of species substitution has become an important topic within the food industry and there is a growing need for rapid, reliable, and reproducible tests to verify species in commercial fish and seafood products. Increases in international trade and global seafood consumption, along with fluctuations in the supply and demand of different fish and seafood species, have resulted in intentional product mislabeling. The effects of species substitution are far‐reaching and include economic fraud, health hazards, and illegal trade of protected species. To improve detection of commercial seafood fraud, a variety of DNA‐based techniques have been developed, including Multiplex PCR, FINS, PCR‐RFLP, PCR‐RAPD, PCR‐AFLP, and PCR‐SSCP, which are all based on polymorphisms in the genetic codes of different species. These techniques have been applied in the differentiation of many types of fish and seafood species, such as gadoids, salmonids, scombroids, and bivalves. Some emerging technologies in this field include the use of real‐time PCR, lab‐on‐a‐chip, and DNA microarray chips. In this review article, the major DNA‐based methods currently employed in the authentication of commercial fish and seafood species are discussed and future trends are highlighted. Examples of commercial applications and the use of online database resources are also considered.     

Application of DNA‐Based Methods to Identify Fish and Seafood Substitution on the Commercial Market

ABSTRACT: Fish and seafood substitution has become an important concern in domestic and international marketplaces, in part due to increased international trade, per capita seafood consumption, and production of processed foods. In many cases, seafood substitution is a form of economic deception, where highly prized species are substituted with those of lesser value. To prevent illegal species substitution, a number of DNA‐based methods have been developed to detect fish and seafood species in commercial products. These methods, along with common gene targets, have been reviewed previously in this journal. The current article is meant to build upon earlier discussions by providing a comprehensive review of the application of these DNA‐based methods to the discovery of fish and seafood substitution on the commercial market. Popular food uses, potential substitution cases, and peer‐reviewed research articles published to date are discussed for all major species groups of concern, including flatfish, gadoids, scombroids, salmonids, percoids, sturgeons, sharks, eels, and bivalves. The use of DNA‐based methods to monitor commercial whale meat products is also reviewed.     

The use of molecular markers in the verification of fish and seafood authenticity and the detection of adulteration

The verification of authenticity and detection of food mislabeling are elements that have been of high importance for centuries. During the last few decades there has been an increasing consumer demand for the verification of food identity and the implementation of stricter controls around these matters. Fish and seafood are among the most easily adulterated foodstuffs mainly due to the significant alterations of the species' morphological characteristics that occur during the different types of processing, which render the visual identification of the animals impossible. Even simple processes, such as filleting remove very important morphological elements and suffice to prevent the visual identification of species in marketed products. Novel techniques have therefore been developed that allow identification of species, the differentiation between species and also the differentiation of individuals that belong to the same species but grow in different populations and regions. Molecular markers have been used during the last few decades to fulfill this purpose and several improvements have been implemented rendering their use applicable to a commercial scale. The reliability, accuracy, reproducibility, and time-and cost-effectiveness of these techniques allowed them to be established as routine methods in the industry and research institutes. This review article aims at presenting the most important molecular markers used for the authentication of fish and seafood. The most important techniques are described, and the results of numerous studies are outlined and discussed, allowing interested parties to easily access and compare information about several techniques and fish/seafood species.     

鱼产品掺假鉴别技术研究进展

由于水产品种类多、消费量大,近缘关系之间的物种品质和价格差距悬殊,导致水产品掺假以及错贴标签等欺诈现象层出不穷,损害了消费者的利益甚至健康。传统的感官识别方法具有一定的局限性,因此需要建立快速、准确的水产品鉴别方法。本文总结了常见的几类易掺假的鱼肉及鱼产品,并综述了水产品掺假鉴别技术。掺假鉴别技术主要分为无损检测技术、蛋白质分析技术和核酸分析技术三大类,包括光谱、质谱、酶联免疫吸附测定和聚合酶链式反应等。本文概括了水产品掺假鉴别技术的应用与特点,深入探讨了其发展趋势,期望为水产品掺假鉴别提供技术参考。     

Hatchery Flounder Going Wild: Authenticity,Aesthetics, and Fetishism of Fish in Japan

This article—based on ethnographic research on fish stocking and discourses surrounding authenticity, aesthetics, and taste of wild fish in Japan—examines the cultural production of the “wilderness.” While Japan's seafood culture has long historical roots, this fetishism of wild fish is a product of the recent advancement of fisheries technology, namely aquaculture and fish stocking. The expansion of aquaculture has shaped not only the notion of the “cultivated” but also that of the “wild.” Simultaneously, the development of fish stocking—the national project to enhance wild fish stocks by releasing hatchery-bred juveniles into the ocean—has also contributed to the reimagining of the authenticity of “wild” fish while complicating it. By looking at flounder, one of the most popular species for fish stocking, this article reveals that tasting “wilderness” is a multisensory experience that reflects not only gustatory but also visual dimensions.     

Quality evaluation of fish and other seafood by traditional and nondestructive instrumental methods: Advantages and limitations

Although being one of the most vulnerable and perishable products, fish and other seafoods provide a wide range of health-promoting compounds. Recently, the growing interest of consumers in food quality and safety issues has contributed to the increasing demand for sensitive and rapid analytical technologies. Several traditional physicochemical, textural, sensory, and electrical methods have been used to evaluate freshness and authentication of fish and other seafood products. Despite the importance of these standard methods, they are expensive and time-consuming, and often susceptible to large sources of variation. Recently, spectroscopic methods and other emerging techniques have shown great potential due to speed of analysis, minimal sample preparation, high repeatability, low cost, and, most of all, the fact that these techniques are noninvasive and nondestructive and, therefore, could be applied to any online monitoring system. This review describes firstly and briefly the basic principles of multivariate data analysis, followed by the most commonly traditional methods used for the determination of the freshness and authenticity of fish and other seafood products. A special focus is put on the use of rapid and nondestructive techniques (spectroscopic techniques and instrumental sensors) to address several issues related to the quality of these products. Moreover, the advantages and limitations of each technique are reviewed and some perspectives are also given.     

Methicillin‐Resistant Staphylococcus aureus in Seafood: Prevalence,Laboratory Detection,Clonal Nature,and Control in Seafood Chain

Methicillin‐resistant Staphylococcus aureus (MRSA), a versatile pathogen bearing multiple virulence determinants, is increasingly being detected in various food‐producing animals, including fish. In addition, it is a potential food poisoning agent. MRSA is not an inherent microbiota of fish; its presence is attributed to pre‐ or postharvest contamination through fish handlers, water, ice, and processing equipment. Several reviews have been written on MRSA in clinical as well as the food animal‐producing sector, but information specific to MRSA in seafood is scant. This review puts forth insights on MRSA detection in seafood, antibiotic resistance, diversity of clones in seafood, and possible control measures in seafood production chain. Emphasis has been given on assessing the variations in the protocols employed for isolation and identification in different food matrices and lay the foundation for researchers to develop optimized procedure.     

Risk‐Benefit Analysis of Seafood Consumption: A Review

Abstract: Seafood, defined here as marine and freshwater fish and shellfish, is recognized as a healthy food choice because it is a low‐fat protein source that provides long‐chain omega‐3 fatty acids important for early development along with eye and heart health. However, seafood is also known to contain certain contaminants, such as methylmercury and persistent organic pollutants, which can have harmful effects on human health and development. In order to limit exposure to contaminants while maximizing the benefits of seafood consumption, a number of quantitative and qualitative risk‐benefit analyses have been conducted for seafood consumption. This review paper provides a brief background on risk‐benefit analysis of foods, followed by a discussion of the risks and benefits associated with fish consumption. Next, risk‐benefit analyses are reviewed in an historical context. While risk‐benefit analysis consists of three main elements (that is, assessment, management, and communication), this review will primarily focus on risk‐benefit assessments. Overall, most studies have found that the benefits far outweigh the risks among the general population, especially when a variety of fish is consumed at least twice per week. However, for certain populations (for example, pregnant women and young children) a more targeted approach is warranted in order to ensure that these groups consume fish that are low in contaminants but high in omega‐3 fatty acids. The potentially harmful unintended consequences of risk‐benefit communication on the general population and certain groups are also discussed.     

基于HACCP的海产品供应链冷链物流 质量安全控制

目的针对海产品供应链冷链物流质量安全控制难点,应用HACCP体系,以鱼贝类海产品为例,制定HACCP危害分析表和实施计划表。方法从养殖及捕捞、清洗整理、海产品冷却、冷冻储存及运输、加工、搬运和装卸等各个环节进行全过程控制。从生物性污染、化学性污染和物理性污染3个方面确定出鱼贝类供应链冷链物流中的关键控制点和关键限值,主要监控致病菌、重金属、化学药物残留等因素。结果从监控对象、方法、频率、人员方面建立具体监控措施、纠偏措施及验证方法,并制定鱼贝类海产品较详细的危害分析表和实施计划表。结论本研究为其他水产品的供应链冷链物流HACCP质量控制体系的建立提供案例,确保海产品冷链物流中的质量安全,为阳江市海产品企业在冷链物流中的质量安全体系控制提供参考。     

Implementation of chemometrics in quality evaluation of food and beverages

Conventional methods for food quality evaluation based on chemical or microbiological analysis followed by traditional univariate statistics such as ANOVA are considered insufficient for some purposes. More sophisticated instrumental methods including spectroscopy and chromatography, in combination with multivariate analysis—chemometrics, can be used to determine food authenticity, identify adulterations or mislabeling and determine food safety. The purpose of this review is to present the current state of knowledge on the use of chemometric tools for evaluating quality of food products of animal and plant origin and beverages. The article describes applications of several multivariate techniques in food and beverages research, showing their role in adulteration detection, authentication, quality control, differentiation of samples and comparing their classification and prediction ability.     

L‐Carnitine Contents in Seafoods Commonly Eaten in Middle Eastern Countries

Beta‐hydroxy‐gamma‐trimethyl amino butyric acid (L‐carnitine) content of raw and cooked seafood was determined using high‐performance liquid chromatography method. Thirty‐one different fish species and nine different crustaceans were used to compare L‐carnitine content of raw and cooked seafood. Significant differences in L‐carnitine content were found in some species, regardless of the raw or cooked seafood (P < 0.05). There were also significant differences between some of the raw and cooked species (P < 0.05). The levels of L‐carnitine in raw fish samples ranged from 17.98 mg/kg for big‐scale sand smelt to 73.07 mg/kg for European conger (Conger conger). Squid (Loligo vulgaris) and green tiger prawn (Penaeus semisulcatus) were found as the best sources of L‐carnitine among the tested seafood. Microwave cooking also significantly reduced the L‐carnitine content of some seafoods (P < 0.05). The study showed that seafoods are an important origin of L‐carnitine for covering the daily requirements of humans.     

An Updated Review of Meat Authenticity Methods and Applications

Adulteration of foods is a serious economic problem concerning most foodstuffs, and in particular meat products. Since high-priced meat demand premium prices, producers of meat-based products might be tempted to blend these products with lower cost meat. Moreover, the labeled meat contents may not be met. Both types of adulteration are difficult to detect and lead to deterioration of product quality. For the consumer, it is of outmost importance to guarantee both authenticity and compliance with product labeling. The purpose of this article is to review the state of the art of meat authenticity with analytical and immunochemical methods with the focus on the issue of geographic origin and sensory characteristics. This review is also intended to provide an overview of the various currently applied statistical analyses (multivariate analysis (MAV), such as principal component analysis, discriminant analysis, cluster analysis, etc.) and their effectiveness for meat authenticity.     

DNA barcoding for the species identification of commercially important fishery products in Indonesian markets

The DNA barcoding approach was used for the species identification of 44 Indonesian commercial fishery products. Additionally, the intronless nuclear rhodopsin gene fragment (RH1) was added to the analysis to enable the identification of species not yet barcoded and possible hybrids. The 655‐bp cytochrome C oxidase subunit I (COI) gene fragment marker was successfully amplified and used to identify 86% of the total fish samples at the species level using the BOLD and BLAST public databases. Moreover, the RH1 marker was used to complete COI analysis. For a number of fish species, the COI sequences (six species) and RH1 sequences (eight species) were the first entries submitted to GenBank. This study demonstrated that COI barcoding is a promising tool for Indonesian fishery products and confirmed that it could be adopted in the future for regular seafood control as part of the Indonesian integrated food traceability system.     

Analytical methods combined with multivariate analysis for authentication of animal and vegetable food products with high fat content

BackgroundFood fraud is described as a violation of food law, which is intentionally committed to get an economic or financial gain through the consumer's swindle resulting in multi-million business and posing a public health threat. The main fraudulent practices are mislabelling of composition, certificates of origin, health claims, and artificial increases in weight or volume caused by replacement, dilution, addition or removal of some ingredients. Hardly 68% of the food fraud violations are produced in animal and vegetable products with high fat content (27% meat, 13% fish, 11% oils, 10% dairy products, 4% nuts and seeds and 3% animal by-products) becoming a crucial issue for food processing industries.Scope and approachThe present review focuses on the main authentication techniques and methods employed to clarify the authenticity of both animal and vegetable fat food products emphasizing the importance of the use of robust and reliable analytical techniques combined with multivariate analyses.Key findings and conclusionsTargeted approaches, such as chromatography and DNA-based methods, combined with multivariate analysis have shown high accuracy, sensitivity and selectivity, allowing the simultaneous evaluation of multiple analytes. In addition, non-target methods, such as those based on spectroscopic techniques, have been used to establish the geographic origin of food products with quick response, low cost, non-destructive character and also offering the possibility to be miniaturized.     

Modern analytical methods for the detection of food fraud and adulteration by food category

This review provides current information on the analytical methods used to identify food adulteration in the six most adulterated food categories: animal origin and seafood, oils and fats, beverages, spices and sweet foods (e.g. honey), grain‐based food, and others (organic food and dietary supplements). The analytical techniques (both conventional and emerging) used to identify adulteration in these six food categories involve sensory, physicochemical, DNA‐based, chromatographic and spectroscopic methods, and have been combined with chemometrics, making these techniques more convenient and effective for the analysis of a broad variety of food products. Despite recent advances, the need remains for suitably sensitive and widely applicable methodologies that encompass all the various aspects of food adulteration. © 2017 Society of Chemical Industry     

Potato: a comparative study of the effect of cultivars and cultivation conditions and genetic modification on the physico-chemical properties of potato tubers in conjunction with multivariate analysis towards authenticity

Potato (Solanum tuberosum L.) is a highly nutritious, mild flavored, easy to blend food that has many possibilities for "building in" desired nutrients. Varietal and environmental differences are known to exist in the shape, size, and nutritional content of potatoes. Different populations opt for varying sensory properties in relation to their diets. Potatoes are a low energy food in comparison to cereals and legumes. The aim of this review was to present an update of the currently conducted studies both on the characterization of several potato varieties (physical, chemical, and sensory analysis) and by means of genetic modification. Towards this target, five comprehensive tables were compiled where all recent data (physicochemical properties) and GM varieties were presented in conjunction with multivariate analysis (chemometrics). The latter was shown to be effectively used towards authenticity purposes (identification of geographical origin, variety, GM).     

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.     

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.     

Effects of specific egg yolk antibody (IgY) on the quality and shelf life of refrigerated Paralichthys olivaceus

BACKGROUND: The spoilage of fishery food has been attributed to limited types of microorganisms called specific spoilage organisms (SSO). Unlike traditional food‐preserving techniques which usually exploit broad‐spectrum antimicrobial agents, here, based on the specific antimicrobial activity of egg yolk antibodies (IgY) against two SSO in refrigerated fish (Shewanella putrefaciens and Pseudomonas fluorescens), a novel strategy for fish preservation was suggested and evaluated. RESULTS: During storage of Paralichthys olivaceus fillets at 4 ± 1 °C, the bacteria growth (including total microorganisms and the two SSO) in test groups was significantly inhibited in comparison to that of controls (P < 0.05). This antibacterial activity of the specific IgY was also confirmed by chemical analysis (pH, total volatile base nitrogen and 2‐thiobarbituric acid value) and sensory evaluation, and the shelf life of samples was extended approximately from 9 days to 12–15 days in the presence of the specific IgY. CONCLUSION: These results indicated a significant antimicrobial activity of the anti‐SSO IgY for refrigerated fish products, which allowed us to suggest its potential as a bio‐preservative for seafood. Copyright © 2011 Society of Chemical Industry     

Development of an indirect α-actinin-based immunoassay for the evaluation of protein breakdown and quality loss in fish species subjected to different chilling methods

α‐Actinin release from the myofibrillar protein fraction to the sarcoplasm can be considered as an accurate proteolysis index in seafood muscle. The main objective of the present study was to develop a specific enzyme‐linked immunosorbent assay (ELISA), based on the use of a monoclonal antibody against α‐actinin to evaluate the degree of proteolysis in two different chilled fish species – European hake (Merluccius merluccius) and turbot (Psetta maxima) – kept under two different storage systems: flake ice and slurry ice. Comparison with sensory assessment, K‐value and sarcoplasmic protein profiles was carried out. A different degree of proteolysis could be observed in both fish species; thus, the immunoassay was shown to be useful in monitoring the protein degradation events in hake muscle especially under flake ice storage. In the case of turbot, as very low proteolysis development could be obtained, the assay was not suitable for assessing quality changes. A different break point of immunoassay values for each fish species is suggested.