Inactivation of a calicivirus and enterovirus in shellfish by high pressure

This study demonstrates the potential of high pressure (HP) processing to reduce viral contamination in shellfish. Bovine enterovirus, which is structurally similar to hepatitis A virus, was more pressure-resistant than feline calicivirus, a surrogate for norovirus. Both viruses were more pressure-resistant when treated in “naturally” contaminated mussels and oysters, compared to seawater and culture medium, suggesting that the medium can have a significant protective effect against HP treatment. Treatment at pressures of 250 MPa showed only a limited inactivation of either virus in shellfish, suggesting that relatively mild HP treatments (approximately 260 MPa) currently used for the commercial processing of oysters, principally to assist the shucking process, may be insufficient to ensure the safety of shellfish for human consumption, particularly in relation to human pathogenic viruses.Industrial relevanceHigh pressure (HP) processing is increasingly being used in the commercial processing of oysters, principally to assist the opening or shucking of oysters. Little is known about the effect of HP treatment on pathogens in shellfish, particularly human enteric viruses, which are the predominant cause of shellfish-borne disease. This article demonstrates the inactivation of surrogate animal viruses, as potential models for noroviruses and hepatitis A virus, by HP processing and compares the efficacy of inactivation when viruses are treated in culture medium, seawater and shellfish. The potential of HP processing to reduce viral contamination in shellfish is discussed in light of these findings.     

High pressure-induced inactivation of Qbeta coliphage and c2 phage in oysters and in culture media

High pressure (HP) treatment inactivates bacteria in shellfish, but its effects on viruses in shellfish have not yet been determined, although viral illness is frequently associated with shellfish consumption. The aim of this study was to investigate the baroresistance of two bacteriophage viruses, Qbeta coliphage and c2 phage, in oysters and in culture media. High numbers (>or=10(7) ml(-1) or g(-1)) of both phages were obtained in culture media and in oysters. Samples were HP treated at 200-800 MPa at 20 degrees C for up to 30 min. Little or no inactivation of either phage was observed in oysters or in culture media after treatment at 相似文献   

Effect of different high pressure treatments on shucking,biochemical, physical and sensory characteristics of oysters to elaborate a traditional Taiwanese oyster omelette

BACKGROUND: Whole oysters (Crassostrea gigas) were processed using high‐pressure (HP) treatment (150–300 MPa) to determine their shucking and biochemical properties. Subsequently, HP‐treated oysters were cooked at 160 °C for 90 s, as when preparing the oyster omelette dish, to evaluate their physical and sensory characteristics as compared to raw oysters. RESULTS: The treatments of 250 and 300 MPa for 2 min and 0 min, respectively, resulted in 100% release. The pH of HP‐treated oysters increased slightly from 6.50 to 6.82, and the moisture contents of the HP‐treated oysters with or without further cooking were all higher than those of the control. The brightness, yellowness and cutting strength of HP‐treated oysters with further cooking changed insignificantly, while the redness decreased compared to the control. Sensory evaluation showed that oysters treated at 250 and 300 MPa oysters after cooking received higher quality scores than the control. CONCLUSIONS: HP processing at 250 and 300 MPa proved to be a good method for oyster shucking. The HP‐treated oysters cooked in the oyster omelette are acceptable to consumers. Overall, the application of HP as a processing method to improve the quality and acceptability of oysters and their related products would be possible. Copyright © 2009 Society of Chemical Industry     

牡蛎超高压脱壳效果的研究

以脱壳效果和得肉率为评价指标研究了牡蛎超高压脱壳工艺参数,并以牡蛎肉的持水率、pH、质构特性、感官特性、菌落总数和大肠杆菌数为指标评价了超高压脱壳对牡蛎肉品质的影响。结果表明,牡蛎超高压脱壳的最佳条件为压力300MPa、保压时间1min。与手工脱壳、热烫脱壳相比,超高压脱壳处理能改善牡蛎肉的持水性,而对pH、感官品质无显著影响。此外,超高压脱壳同时能部分杀灭微生物,使牡蛎肉达到生食水产品卫生标准。牡蛎超高压脱壳总体效果优于手工脱壳和热烫脱壳,是一种较为理想的脱壳技术。      

高压对牛乳理化性质和成分的影响

高压食品加工是一种非热杀菌技术,是指在室温或低温下用100-800MPa高压处理食品。与传统的热杀菌比较,它具有很多优点,不仅能杀死微生物钝化酶类,而对食品的营养成分和感官品质改变较小。本文综述了高压处理对牛奶物理化学性质和成分的影响。     

贝类开壳技术与装备研究现状及发展趋势

开壳是贝类加工中必不可少的一项重要工序,其效果直接影响着后续加工产品的品质。为了解目前国内外 贝类开壳技术及装备的现状和存在的问题,本文对人工开壳、热力开壳、超高压开壳和微波开壳等贝类开壳技术与 装备的研究进展和应用现状进行分析,对不同开壳方法的优缺点进行对比,对存在的主要问题进行归纳总结,并提 出了解决方案,同时对贝类开壳技术与装备的发展趋势进行了展望,以期丰富贝类开壳加工理论基础,为贝类开壳 技术创新和设备研发提供一定的参考和借鉴。     

Effects of high-pressure treatment on the microflora of oysters (Crassostrea gigas) during chilled storage

The microbiological quality of oysters high-pressure (HP)-treated in-shell at 260 MPa for 3 min, or 500 or 800 MPa for 5 min and then stored at 2 °C, were investigated. Microbial counts after HP treatment showed that the bacterial load was reduced after treatment at all pressures to levels below the detection limit. Randomly-selected isolates from the total aerobic viable counts of untreated and HP-treated oysters after 14 days of storage were identified by the API identification system. Bacteria isolated from oysters HP-treated at 260 MPa were Shewanella putrifaciens and Pseudomonas fluorescens. For oysters HP-treated at 500 or 800 MPa, the main bacteria isolated were Pseudomonas spp. Vibrio spp. comprised 44% of the microflora in untreated oysters after storage for 14 days at 2 °C, but no Vibrio were detected in HP-treated oysters. This study confirmed that HP processing can inactivate microorganisms and delay microbial growth in chilled stored oysters.

Industrial relevance

High-pressure (HP) treatment is being increasingly employed for commercial processing of oysters but no studies of the microflora of HP-treated in-shell oysters have been reported. HP treatment significantly changed the microflora of oysters and apparently has good potential for inactivation of Vibrio spp as HP treatment, in combination with adequate chilled storage, can improve the microbiological shelf-life and safety of oysters.     

超高压技术在贝类脱壳加工中的应用

贝类是现代备受青睐的海产品,由于其营养丰富而受到消费者的喜爱,贝类的脱壳问题是加工过程的关键。超高压脱壳是一种新兴的食品加工技术,它既可以完成脱壳过程,又可以减少贝肉中的有害微生物,是现代比较热门和常用的脱壳技术。通过对目前脱壳技术的应用状况进行研究和分析,发现利用超高压技术对贝类进行脱壳处理,不仅可以获得较高的脱壳率,还可以获得完整的贝肉,并保持产品的感官品质和营养价值,延长产品的货架期,是一种比较适合于贝类脱壳的加工技术。      

超高压处理在毛蚶脱壳和减菌化中的作用研究

目的明确超高压处理对毛蚶脱壳效果、感官品质以及细菌总数的影响,建立超高压技术在毛蚶加工中的工艺参数。方法以鲜活毛蚶为对照,在250~500 MPa的压力范围内设置6个超高压处理组,根据闭壳肌是否脱离以及壳的完整情况记录毛蚶脱壳效果,通过感官评定、电子鼻气味分析,以及p H、TVB-N、细菌总数等指标的测定评价不同压力处理对毛蚶品质和微生物的影响。结果 300 MPa及以下的处理压力对毛蚶闭壳肌作用小,脱壳效果较差,而450 MPa及以上的压力处理会造成毛蚶壳的破损。毛蚶经超高压处理后,感官评分略有下降,其中350 MPa及以下压力的处理组与对照组之间无显著性差异(P0.05),而400 MPa及以上压力处理组由于气味的变化,对应的感官评分显著降低(P0.05)。超高压处理对毛蚶TVB-N无显著影响(P0.05),300 MPa及以上压力处理组的p H显著升高(P0.05)。毛蚶细菌总数随处理压力的增大显著下降。结论综合考虑脱壳效果、感官品质以及减菌化效果,350~400 MPa的区间范围比较适宜作为毛蚶的超高压处理工艺。     

Inactivation of foodborne viruses of significance by high pressure and other processes

The overall safety of a food product is an important component in the mix of considerations for processing, distribution, and sale. With constant commercial demand for superior food products to sustain consumer interest, nonthermal processing technologies have drawn considerable attention for their ability to assist development of new products with improved quality attributes for the marketplace. This review focuses primarily on the nonthermal processing technology high-pressure processing (HPP) and examines current status of its use in the control and elimination of pathogenic human viruses in food products. There is particular emphasis on noroviruses and hepatitis A virus with regard to the consumption of raw oysters, because noroviruses and hepatitis A virus are the two predominant types of viruses that cause foodborne illness. Also, application of HPP to whole-shell oysters carries multiple benefits that increase the popularity of HPP usage for these foods. Viruses have demonstrated a wide range of sensitivities in response to high hydrostatic pressure. Viral inactivation by pressure has not always been predictable based on nomenclature and morphology of the virus. Studies have been complicated in part from the inherent difficulties of working with human infectious viruses. Consequently, continued study of viral inactivation by HPP is warranted.     

High-pressure processing of fish and shellfish products: Safety,quality, and research prospects

Seafood products have been one of the main drivers behind the popularity of high-pressure processing (HPP) in the food industry owing to a high demand for fresh ready-to-eat seafood products and food safety. This review provides an overview of the advanced knowledge available on the use of HPP for production of wholesome and highly nutritive clean label fish and shellfish products. Out of 653 explored items, 65 articles published during 2016–2021 were used. Analysis of the literature showed that most of the earlier work evaluated the HPP effect on physicochemical and sensorial properties, and limited information is available on nutritional aspects. HPP has several applications in the seafood industry. Application of HPP (400–600 MPa) eliminates common seafood pathogens, such as Vibrio and Listeria spp., and slows the growth of spoilage microorganisms. Use of cold water as a pressure medium induces minimal changes in sensory and nutritional properties and helps in the development of clean label seafood products. This technology (200–350 MPa) is also useful to shuck oysters, lobsters, crabs, mussels, clams, and scallops to increase recovery of the edible meat. High-pressure helps to preserve organoleptic and functional properties for an extended time during refrigerated storage. Overall, HPP helps seafood manufacturers to maintain a balance between safety, quality, processing efficiency, and regulatory compliance. Further research is required to understand the mechanisms of pressure-induced modifications and clean label strategies to minimize these modifications.     

Essential Elements in Oysters (Caassostrea virginica) as Affected By Processing Method

The purpose of this work was to evaluate the effect of three processing methods currently used in the commercial processing of oysters on the concentration of 15 essential elements in oysters. The processing methods evaluated were: traditional hand shucking, steam tunnel, and retorting. Significant differences were observed in the retention of some of the essential elements as the result of processing.     

Greater high-pressure resistance of bacteria in oysters than in buffer

High-pressure (HP) treatment is currently being investigated as a process for extending the shelf life of oysters through microbial inactivation. The aim of this study was to compare baroresistance in oysters and phosphate-buffered saline (PBS) of the Gram-negative bacteria, Vibrio mimicus 9583 and Escherichia coli O157:H45, and the Gram-positive bacteria, Listeria innocua MP2418 and Listeria monocytogenes LO28. A novel injection method was developed to allow reproducible, high numbers (10⁶–10⁸) of bacteria to be obtained in oysters. At a pressure >400 MPa, inactivation of all bacteria studied was considerably less in oysters than in PBS. This difference in the level of HP-induced inactivation of bacteria between oysters and PBS increased with treatment pressure, culminating in a 5-log difference at 480–600 MPa for all bacteria studied. E. coli and L. innocua were the most baroresistant of the species studied, with only a ∼3-log inactivation of both bacteria observed in oysters after treatment at 700 MPa. The influence of salt content, one of the main differences between oysters and PBS, on baroresistance of bacteria in tryptone soya yeast extract broth (TSBYE) containing 3.5% salt and 0.5% salt was subsequently investigated; all bacteria were considerably more resistant at higher salt concentrations.Industrial relevanceConsumption of oysters is often associated with bacterial and viral illnesses. HP treatment is employed commercially in the USA to increase safety of oysters, but further research into the effects of this technology on the microflora and biochemical characteristics of oysters is ongoing to maximise the benefits of this treatment. In this study, the effects of HP on bacteria associated with illness in oysters and the influence of a high-salt environment on inactivation were investigated. The higher baroresistance of all bacteria in oysters than in buffer is particularly important, indicating that studies of HP-induced bacterial inactivation in buffer systems may not predict inactivation in foods.     

Food processing by high hydrostatic pressure

The use of high hydrostatic pressures (HHP) for food processing is finding increased application within the food industry. One of the advantages of this technology is that because it does not use heat, sensory, and nutritional attributes of the product remain virtually unaffected, thus yielding products with better quality than those processed traditional methods. HHP have the ability to inactivate microorganisms as well as enzymes responsible for shortening the life of a product. In addition to lengthening the shelf-life of food products, HHP can modify functional properties of components such as proteins, which in turn can lead to the development of new products. Equipment for large-scale production of HHP processed products are commercially available nowadays. Guacamole, sliced ham, oysters, and fruit juices are some of the products currently available on the market. HHP technology is one of the most promising nonthermal processes.     

Pulsed Electric Field Processing of Orange Juice: A Review on Microbial,Enzymatic, Nutritional,and Sensory Quality and Stability

During the last decades pulsed electric field (PEF) processing received considerable attention due to its potential to enhance food products or create alternatives to conventional methods in food processing. It is generally acknowledged that PEF processing can deliver safe and chill‐stable fruit juices with fresh‐like sensory and nutritional properties. Relatively low‐processing temperature and short residence times can achieve highly effective inactivation of microorganisms while retaining product quality. A first commercial application of PEF for preservation of fruit juices was launched in 2006 in the United States. Since then, industrial‐scale processing equipment for liquid and solid products were developed and, in Europe in 2009, an industrial juice preservation line was installed using 20 kV/cm pulses at 40 to 50 °C to extend the chill‐stability of fruit juices, including citrus juices and smoothies, from 6 to 21 d. The related PEF processing costs are in the range of US $0.02 to 0.03 per liter and are justified due to access to new markets and reduced return of spoiled product. However, despite its commercial success there are still many unknown factors associated with PEF processing of fruit and citrus juices and many conflicting reports in the literature. This literature review, therefore, aims to provide a comprehensive overview of the current scientific knowledge of PEF effects on microbial, enzymatic, nutritional, and sensory quality and stability of orange juices.     

五种开壳方式对牡蛎开壳效率和品质的影响

为了探明不同开壳方式对牡蛎开壳效率和品质的影响,采用水煮、蒸煮、微波、超高压和电击5种开壳方式对牡蛎进行开壳,以开壳率、张壳大小作为开壳效率的评价指标,以生鲜度、汁液流失率、闭壳肌蛋白质变性程度作为品质评价指标,综合对比几种开壳方法的开壳效率和品质,并分析其应用于牡蛎开壳的可行性.研究结果显示:微波开壳的效率最快,30...     

Depuration and Relaying: A Review on Potential Removal of Norovirus from Oysters

Pollution of coastal waters can result in contamination of bivalve shellfish with human enteric viruses, including norovirus (NoV), and oysters are commonly implicated in outbreaks. Depuration is a postharvest treatment involving placement of shellfish in tanks of clean seawater to reduce contaminant levels; this review focuses on the efficacy of depuration in reducing NoV in oysters. There have been many NoV outbreaks from depurated oysters containing around 10³ genome copies/g oyster tissue, far exceeding the median infectious dose (ID50). Half of the published NoV reduction experiments showed no decrease in NoV during depuration, and in the remaining studies it took between 9 and 45.5 d for a 1‐log reduction—significantly longer than commercial depuration time frames. Surrogate viruses are more rapidly depurated than NoV; the mean number of days to reduce NoV by 1 log is 19, and 7.5 d for surrogates. Thus, surrogates do not appear to be suitable for assessing virological safety of depurated oysters; data on reduction of NoV infectivity during depuration would assist evaluations on surrogate viruses and the impact of methods used. The longer persistence of NoV highlights its special relationship with oysters, which involves the binding of NoV to histo‐blood group‐like ligands in various tissues. Given the persistence of NoV and on‐going outbreaks, depuration as currently performed appears ineffective in guaranteeing virologically safe oysters. Conversely, relaying oysters for 4 wk is more successful, with low NoV concentrations and no illnesses associated with products. The ineffectiveness of depuration emphasizes the need for coastal water quality to be improved to ensure oysters are safe to eat.     

Principles and recent applications of novel non-thermal processing technologies for the fish industry—a review

Thermal treatment is a traditional method for food processing, which can kill microorganisms but also lead to physicochemical and sensory quality damage, especially to temperature-sensitive foods. Nowadays consumers’ increasing interest in microbial safety products with premium appearance, flavor, great nutritional value and extended shelf-life has promoted the development of emerging non-thermal food processing technologies as alternative or substitution to traditional thermal methods. Fish is an important and world-favored food but has a short shelf-life due to its extremely perishable characteristic, and the microbial spoilage and oxidative process happen rapidly just from the moment of capture, making it dependent heavily on post-harvest preservation. The applications of novel non-thermal food processing technologies, including high pressure processing (HPP), ultrasound (US), pulsed electric fields (PEF), pulsed light (PL), cold plasma (CP) and ozone can extend the shelf-life by microbial inactivation and also keep good sensory quality attributes of fish, which is of high interest for the fish industry. This review presents the principles, developments of emerging non-thermal food processing technologies, and also their applications in fish industry, with the main focus on microbial inactivation and sensory quality. The promising results showed great potential to keep microbial safety while maintaining organoleptic attributes of fish products. What’s more, the strengths and weaknesses of these technologies are also discussed. The combination of different food processing technologies or with advanced packaging methods can improve antimicrobial efficacy while not significantly affect other quality properties under optimized treatment.     

Effects of high-pressure and heat treatments on physical and biochemical characteristics of oysters (Crassostrea gigas)

Physical and biochemical changes in oysters following high-pressure (HP) treatment at 260 MPa for 3 min or heat treatment (cool pasteurisation (CP) at 50 °C for 10 min or traditional pasteurisation (TP) at 75 °C for 8 min) were investigated and compared to changes in untreated oysters. HP or TP oysters had higher (P < 0.05) pH values (6.49–6.58) than untreated or CP oysters (6.45–6.46). HP and heat treatment both modified the gross composition of oyster tissue. The protein content of HP-treated oysters (6.9%) was significantly (P < 0.05) lower compared to control or heat-treated oysters (7.9–9.1%). The moisture content of HP-treated whole oyster tissue (86.5%) was higher than that of heat-treated or untreated oysters (83.5–84.7%), but HP or CP treatments did not affect the salt content or water activity of oysters. However, all treatments increased Hunter L- (66.3–68.9) while decreasing a- (− 1.6 to − 2.4) and b- (15.8–14.5) values of oyster tissue; overall, HP treatment had less negative effects on tissue colour of oysters than thermal treatments. HP-treated, CP and TP oysters had higher shucking yields (15.5%, 12.5% and 2.6%, respectively) than untreated oysters. One significant advantage of HP treatment over heat treatment of oysters was that the former process opened the oyster and separated the muscle of the oyster from the shell.     

Nonthermal pasteurization of liquid foods using high‐intensity pulsed electric fields

Processing foods with high‐intensity pulsed electric fields (PEF) is a new technology to inactivate microorganisms and enzymes with only a small increase in food temperature. The appearance and quality of fresh foods are not altered by the application of PEF, while microbial inactivation is caused by irreversible pore formation and destruction of the semipermeable barrier of the cell membrane. High‐intensity PEF provides an excellent alternative to conventional thermal methods, where the inactivation of the microorganisms implies the loss of valuable nutrients and sensory attributes. This article presents recent advances in the PEF technology, including microbial and enzyme inactivation, generation of pulsed high voltage, processing chambers, and batch and continuous systems, as well as the theory and its application to food pasteurization. PEF technology has the potential to improve economical and efficient use of energy, as well as provide consumers with minimally processed, microbiologically safe, nutritious and freshlike food products.