辐照对蛋白质及过敏原的影响研究进展

我国辐照食品技术发展迅速,是世界上辐照食品产量最大的国家。辐照技术具有处理效率高、处理时间短、处理量大、非热加工、易于产业化生产等优点,被广泛用于水果、蔬菜、海产品等的保鲜过程中,随着研究深入也被用于食品有害物质的降解、品质改善等过程中。尽管国际卫生组织(World Health Organization,WHO)强调低剂量辐照(小于10 kGy)对食品加工具有安全性,可以大量推广应用,但由于消费者对辐照食品的加工过程及其作用机制缺乏了解,普遍对其比较谨慎,往往担心产生辐射残留、生成新的危害物、破坏营养组分等。为了揭示辐照对食品组分及其营养安全性的影响,近年来国内外学者开展了大量研究,本文结合课题组前期研究成果及国内外相关研究进展,就辐照对食品组分中蛋白质及过敏原的影响研究进行简要综述。     

基于间酪氨酸和邻酪氨酸鉴定辐照海产品

利用超高效液相色谱-三重四极杆/线性离子阱质谱（ultra performance liquid chromatography-quadrupole linear ion trap tadem mass spectrometry,QTRAP-UPLC-MS/MS）技术测定海产品中与辐照相关的多种氨基酸及同分异构体,研究辐照剂量（0.5～20?kGy）与不同海产品中辐照标识性产物间酪氨酸和邻酪氨酸的产生和含量的关系。不同贮藏条件和加工方式对间酪氨酸和邻酪氨酸特异性和稳定性,以及对辐照海产品测定的影响。结果表明：辐照可诱导苯丙氨酸产生对酪氨酸、间酪氨酸和邻酪氨酸,无需其他酶和微生物的作用,且含量与辐照剂量呈线性关系;辐照剂量和样品含水量与辐照标识物的产生量密切相关;在－20?℃,间酪氨酸和邻酪氨酸具有良好的稳定性;不同贮藏条件和加工方式对辐照海产品中间酪氨酸和邻酪氨酸含量具有一定影响,但是仍能提取到足够量的间酪氨酸和邻酪氨酸用于辐照海产品的鉴定;利用QTRAP-UPLC-MS/MS对海产品中邻酪氨酸和间酪氨酸作为辐照标识物的测定,最低可检测到经0.5?kGy辐照的样品,可准确地对辐照海产品是否经过辐照进行判定,为辐照海产品的检测提供依据。     

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.     

Rapid Detection of Chemical Hazards (Toxins,Dioxins, and PCBs) in Seafood

Among the various hazards occurring in fish and seafood chemical hazards and in particular toxins (ciguatera, scombroid fish poisoning, paralytic shellfish poisoning, neurotoxic (brevetoxic) shellfish poisoning, puffer fish poisoning, diarrhetic shellfish poisoning) have an important place in food poisoning cases. On the other hand, some of the chemical hazards are often due to the pollution of the environment (heavy metals, dioxins, polychlorinated biphenyls, and halogenated aromatic hydrocarbons) and their detection is neither rapid nor facile. As a result there was a great need for developing new rapid and effective methods toward the chemical hazards determination mainly because of their high toxicity. The aim of this review is to provide the information about the new up-to-date detection techniques (Immunological, Chemical and Biochemical, and Molecular assays) in conjunction with detection limits. The latter is made possible by means of inclusion of seven comprehensive and, in most case cases, very extended tables. A reference is also made on the risk characterization of toxins as regards their importance to food contamination or poisoning.     

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.     

Brazilian consumer views on food irradiation

This study investigated the consumer attitude to food irradiation in São Paulo, Brazil, through a qualitative research perspective. Three focus groups were conducted with 30 consumers, responsible for food choices and purchases. Both irradiated and nonirradiated food samples were served in the sessions to motivate the discussion and elicit the participants´ knowledge, opinions, feelings and concerns towards the irradiation process. Reactions were similar among the groups and differences between the irradiated and the nonirradiated samples were hardly perceived. When provided with positive information about irradiation and its benefits to foods and human health, many people still remained suspicious about the safety of the technology. Risk perception seemed to be related to unease and lack of knowledge about nuclear power and its non-defense use. Participants claimed for more transparency in communication about risks and benefits of irradiated foods to the human health, especially with respect to the continued consumption.Industrial relevanceIrradiation is an emerging food processing technology, which has been gaining interest by food technologists, producers and manufacturers all over the world in the last decades. Irradiation is suitable for disinfestation, microorganism load reduction or sterilization, assuring the safety, as well as having benefits in the shelf-life of foodstuffs.Food irradiation is approved in many countries and its use in food processing is endorsed by several reputed authorities, such as FAO and USDA. Despite the approval and recommendation, this technology still remains underutilized not only in Brazil, but also in other countries. The main reason appears to be the consumer concerns and doubts about the use of radiations in food processing. To develop communication strategies in promotion of irradiated foods it is necessary to investigate consumer attitudes, knowledge, opinions, as well as fears, with respect to the use of radiation in food processing.It is well-known that consumer views on technology may vary from a culture to another. So, findings from consumer research in a country may certainly not reflect the consumer views in other countries. In this sense, Brazilian studies focused on consumer views on food irradiation are necessary to gain understanding on how the local market accepts the technology. Brazil is one of the most important food producers in the world and an emerging consumer market with a population of about 184 million people. Food irradiation is regulated in Brazil since 1973, but to date only a few food ingredients are subjected to irradiation. The wide use of irradiation in food processing would favor Brazilian producers in the quality and safety assurance of food products, both for the local market and for exports.     

POTENTIAL FUTURE CHALLENGES TO THE APPLICATION OF GAMMA IRRADIATION TO SEAFOOD IN TUNISIA

There is an increasing consumer demand for high quality, minimally processed, additive-free and microbiologically safe foods. The future application of irradiation to the seafood industry is developing. In order to investigate the feasibility of using gamma irradiation in the fish and seafood industry, questionnaires were distributed to the managers of 25 fish exporting companies. The cost of irradiation and the additional transport services were discussed and mostly accepted. This survey showed that essential conditions are to be found in Tunisia to introduce irradiation technology into the exporting seafood industry. However, the legal status of seafood irradiation varies in some importing countries (mainly European Union [EU]). Regulators within the EU have taken different approaches to allowing processors to use this technology. Such inconsistency is related to the objection of misinformed consumers. Consequently, commercial trade of irradiated seafood could be impeded.

PRACTICAL APPLICATIONS

This article provides evidence of the importance of industry managers' role in the food chain when testing the feasibility of a new process. Fish shelf-life extension using gamma irradiation is an emerging technology that presents many advantages to all food chain components and allows international trade requirements to be met. The seafood export industry in Tunisia shows the technological need for such a process. Furthermore, this study demonstrated that the economic cost of irradiation in Tunisia is acceptable and that it could enhance fish export capacity. However, the legal status of fish irradiation in the import countries, mainly the European Union, should be modernized in order to assure the feasibility of irradiated fish export from Tunisia.     

Effect of x-ray irradiation on reducing the risk of listeriosis in ready-to-eat vacuum-packaged smoked mullet

Listeria monocytogenes can pose a serious threat in several areas of the nation's food supply including ready-to-eat seafood products. Use of irradiation processing can potentially reduce the risk of listeriosis caused by consumption of ready-to-eat seafood products. This study measured the effect of X-ray irradiation on reducing the population of L. monocytogenes on ready-to-eat, vacuum-packaged smoked mullet. Smoked mullet were inoculated with a five-strain mixture of L. monocytogenes (10(4) CFU/g), vacuum packaged, and irradiated (0, 0.5, 1.0, 1.5, and 2.0 kGy). The packaged fish were then stored at 3 and 10 degrees C for 90 and 17 days, respectively. Radiation doses of 0.5, 1.0, and 1.5 kGy reduced the initial population of L. monocytogenes by 1.1, 1.6, and 2.1 log CFU/g, respectively. The 2.0-kGy dose reduced L. monocytogenes to undetectable levels with no recovery growth at either temperature. Compared to the control, irradiation at 1.5 kGy demonstrated 1.0 and 1.7 log CFU/g less growth at 3 degrees C after 60 days and 10 degrees C after 17 days, respectively. Sensory flavor analysis was conducted to determine if a difference existed between irradiated samples. Panelists indicated that there were no differences among treated and untreated samples. An X-ray dose of 2 kGy effectively eliminated 10(4) CFU/g L. monocytogenes on smoked mullet without changing sensory quality.     

辐照对四川泡生姜的影响

为了保证品质并减少食品添加剂的使用,采用60Co-γ射线对四川泡生姜进行辐照灭菌处理,研究辐照对泡生姜中微生物数量、乳酸含量、亚硝酸盐含量及感官评价等因素的影响。结果表明,在0-5kGy辐照剂量范围内,细菌总数及乳酸菌数随着辐照吸收剂量的增加而逐渐减少,当初始含菌量在105-106CFU/g范围内,5 kGy的辐照可将细菌总数及乳酸菌数降至100 CFU/g;泡生姜中的乳酸含量受辐照影响不大;亚硝酸盐含量随辐照吸收剂量的增加略有上升,但在0-5 kGy范围内始终远低于四川泡菜地方标准及食品安全国家标准;在实验剂量范围内,辐照对泡生姜感官无明显影响。说明60Co-γ射线辐照处理对泡生姜的总体质量没有明显影响,并可减少化学防腐剂的使用,增加食品安全,同时有效杀灭微生物,延长货架期。     

Recent advancements in the application of non-thermal plasma technology for the seafood industry

Abstract

Non-thermal plasma (NTP) is one of the most promising minimal processing methods for the food industry. However up until recently there are limited studies which would report the application and effect of NTP on processed seafood. The objective of this review is to highlight the recent findings and advancements in the application of NTP within the fish and other seafood industry, including direct application of fresh and dried fish and seafood with as well as indirect application of plasma activated water and seafood industry wastewater purification. The article also summarizes the effect of plasma treatment on microbiological quality, physicochemical and sensory properties and oxidation rate of treated fish and seafood. NTP has high potential to be used within various fields of seafood industry. It is especially effective in treatment of dried seafood products, but the use of plasma activated water during various processing steps such as seafood washing could be also beneficial. Moreover NTP could also be used as a cost effective and environmentally friendly method for seafood wastewater purification.     

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.     

Implementation of quality control methods (physico-chemical, microbiological and sensory) in conjunction with multivariate analysis towards fish authenticity

Nowadays authenticity of foods and fish in particular has become of crucial importance because of high number of adulteration cases. Authenticity control has gained ground thanks to the development of several rapid physico‐chemical and microbiological methods aiming at distinguishing one species from another based on solid scientific evidence. It has been proven that despite the precision and accuracy of robust analytical and protein and DNA‐based techniques, detection of authenticity could not be claimed without resorting to multivariate analysis. This review summarizes both the most advanced and state of the art used techniques for detecting fish and seafood authenticity (both in terms of species and geographical origin). Another issue reported in this review is the preservation of fish and seafood through the implementation of old and novel techniques (ice, modified atmosphere packaging). Several informative tables were included in this paper referring to the employed quality control and sensory analysis methods and multivariate analysis for fish and seafood.     

Sensory and Microbial Quality of Irradiated Crab Meat Products

Low dose gamma irradiation has proved effective in reducing pathogenic and spoilage microorganisms in a variety of seafood products. However, little information is available on the effect of irradiation on the sensory quality and consumer acceptance of such products. We compared microbial and sensory quality of irradiated (2 kGy or less) crab products (white lump, claw, and fingers) through 14-days of ice-storage. Irradiation effectively reduced spoilage bacteria extending shelf-life by more than 3 days beyond control samples. During storage, fresh crab odor and flavor were similar for treated and control samples, while off-flavors and odors developed more rapidly in controls. Overall acceptability scores for irradiated crab samples were higher than for control samples throughout 14-days ice storage.     

Influence of refrigerated storage time on efficacy of irradiation to reduce Salmonella on sliced Roma tomatoes

Contamination of tomatoes with Salmonella is a recurring food safety concern. Irradiation is a nonthermal intervention that can inactivate pathogens on fresh and minimally processed produce. However, the influence of tomato processing protocols, including time in refrigerated storage and time between slicing and irradiation, has not been determined. Roma tomatoes were sliced and inoculated with a cocktail of Salmonella outbreak strains. The inoculated tomatoes were held in refrigerated storage for various times after inoculation to simulate the potential time delay between packaging and irradiation. Tomatoes were irradiated immediately (0 h) or after 24, 48, or 72 h in storage. The surviving populations were recovered and enumerated. Irradiation effectively reduced Salmonella at all times. The D(10)-values (the dose necessary for a 1-log reduction of the pathogen) were not significantly different at each storage time and ranged from 0.382 to 0.473 kGy. These results suggest that the time required for holding of processed Roma tomatoes or shipment to an off-site irradiation service provider will not alter the efficacy of irradiation in a commercial environment.     

Applications of ozone, bacteriocins and irradiation in food processing: a review

An article is presented describing the background information on the use of ozone, bacteriocins and irradiation for destroying pathogens in food products. Their effectiveness on some pathogens of importance in food processing systems and issues of concern are highlighted. It could be concluded that although each one has the potential for use as an alternative preservation technology in specific food processing applications, no single method, except irradiation, is likely to be effective against all food spoilage and food poisoning microorganisms in all food matrices. However, the synergistic effect of one of these methods and other 'hurdles' or modes of food preservations could be used to ensure the microbial safety and prevention of the development of undesirable sensory and chemical changes in some food products. Bacteriocins may contribute an additional barrier in the 'hurdle concept' of food safety.     

Impact of irradiation on the safety and quality of poultry and meat products: a review

For more than 100 years research on food irradiation has demonstrated that radiation will make food safer and improve the shelf life of irradiated foods. Using the current food safety technology, we may have reached the point of diminishing returns even though recent figures from the CDC show a significant drop in the number of foodborne illnesses. However, too many people continue to get sick and die from eating contaminated food. New and under utilized technologies such as food irradiation need to be re-examined to achieve new levels of safety for the food supply. Effects of irradiation on the safety and quality of meat and poultry are discussed. Irradiation control of the principle microbial pathogens including viruses, the differences among at-risk sub-populations, factors affecting the diminished rate of improvement in food safety and published D values for irradiating raw meat and poultry are presented. Currently permitted levels of irradiation are probably not sufficient to control pathogenic viruses. Typical gram-negative spoilage organisms are very sensitive to irradiation. Their destruction leads to a significant increase in the acceptable shelf life. In addition, the destruction of these normal spoilage organisms did not provide a competitive growth advantage for irradiation injured food pathogens. Another of the main focuses of this review is a detailed compilation of the effects of most of the food additives that have been proposed to minimize the negative quality effect of irradiation. Most of the antimicrobials and antioxidants used singly or in combination produced an increased lethality of irradiation and a decrease in oxidation by-products. Combinations of dosage, temperature, dietary and direct additives, storage temperature and packaging atmosphere can produce meats that the average consumer will find indistinguishable from non-irradiated meats. A discussion of the production of unique radiological by-products is also included.     

Effectiveness of irradiation treatments in inactivating Listeria monocytogenes on fresh vegetables at refrigeration temperature

Ionizing radiation can be effective in controlling the growth of food spoilage and foodborne pathogenic bacteria. This study reports on an investigation of the effectiveness of irradiation treatment to eliminate Listeria monocytogenes on laboratory-inoculated broccoli, cabbage, tomatoes, and mung bean sprouts. Irradiation of broccoli and mung bean sprouts at 1.0 kGy resulted in reductions of approximately 4.88 and 4.57 log CFU/g, respectively, of a five-strain cocktail of L. monocytogenes. Reductions of approximately 5.25 and 4.14 log CFU/g were found with cabbage and tomato, respectively, at a similar dose. The appearance, color, texture, taste, and overall acceptability did not undergo significant changes after 7 days of postirradiation storage at 4 degrees C, in comparison with control samples. Therefore, low-dose ionizing radiation treatment could be an effective method for eliminating L. monocytogenes on fresh and fresh-cut produce.