Effects of high pressure processing on protein fractions of blue crab (Callinectes sapidus) meat

The studies about the effect of high pressure processing (HPP) on the myofibrillar proteins of crab meat are scarce in the literature. The aim of this study is to evaluate the effect of high pressure processing (HPP) at 100, 300 and 600 MPa (10 °C/5 min) on the muscular protein fractions of blue crab meat (Callinectes sapidus) and compares the effect of high pressure treatments and the thermal cooking process on the yielding of crab meat. Differential scanning calorimetry analysis of raw crab meat showed two peaks at 48.18 and 76.76 °C corresponding to myosin and actin denaturation. The increasing in the pressure level resulted in a decrease in denaturation enthalpy of both proteins. Data from Fourier transform infrared spectroscopy indicated changes in the secondary protein structures in which a reduction in α-helix and an increase in β-turn were observed as a result of denaturation induced by HPP. Electrophoresis analysis (SDS-PAGE) showed myofibrillar protein denaturation as the pressure level increased. The HPP at 100 and 300 MPa resulted in a significant increase in the yielding of meat extracted when compared to the thermal treatment (90 °C/20 min). Higher sensory scores were obtained in 300 and 600 MPa suggesting higher acceptance. Results suggest the feasibility of applying HPP as an alternative to the thermal treatment to process crab meat.Industrial relevanceHigh pressure processing (HPP) technology has been successfully applied to several seafood products. However, it is important to study the effect of HPP on the food components, mainly proteins in the crab meat to optimize the processing parameters to get high-quality products. In the present study, the benefit of using HPP as an alternative to the commercial thermal processing for extraction of crab meat has been confirmed. Applying 600 MPa (10 °C/5 min) to the whole blue crab resulted in a higher yield of extracted crab meat compared with the other treatments. However, using a range of 100–300 MPa (10 °C/5 min) also increases the yielding of extracted crab meat when compared to the thermal process, and moreover, the extraction procedure is faster. The quality and the functional properties of the crab meat with fresh appearance is preserved after the treatment at 100 MPa. These results could promote subsequent applications of pressurized crab meat in the crab industry, especially with the HPP treatments in a range between 100 and 300 MPa.     

Effect of high pressure processing on the gel properties of salt-soluble meat protein containing CaCl2 and κ-carrageenan

The effects of high pressure processing (HPP) on the water-binding capacity and texture profile (TPA) of salt-soluble meat protein (SSMP) containing 0.2% CaCl₂ and 0.6% κ-carrageenan (SSMP-CK) gels were investigated. The results showed that 300–400 MPa improved water-binding capacity and decreased TPA parameters of SSMP-CK gels (P < 0.05), while 100 MPa could increase hardness and chewiness of the gels. The thermal transition temperature peak for the myosin head (T_peak1) of SSMP disappeared on addition of CaCl₂ and κ-carrageenan. 300 MPa produced a new peak, and caused a shift of the NH-stretching left peak and amide I and the disappearance of NH-stretching right peak. The destruction of network structure and the weakening of molecular interaction within the pressurized gels could result in the decrease of TPA parameters. Thus gelling properties could be modified by HPP, κ-carrageenan and Ca^2 +. It is of interest to develop low-fat and sodium-reduced meat products.     

Effects of High-Pressure Processing on the Cooking Loss and Gel Strength of Chicken Breast Actomyosin Containing Sodium Alginate

The effects of high-pressure processing (HPP) (0–400 MPa for 10 min) on the cooking loss (CL), gel strength, and thermal gelling mechanism of chicken breast actomyosin solution containing 0.5 % (w/v) sodium alginate (AS-SA) were investigated. The results showed that HPP could significantly increase (P?相似文献   

Effect of high‐pressure treatments on mechanical and functional properties of restructured products from arrowtooth flounder (Atheresthes stomias)

Restructured fish products from arrowtooth flounder (Atheresthes stomias), an abundant and subutilized species from the Gulf of Alaska, were obtained by hydrostatic pressure processing (HPP) at 400 and 600 MPa with 0–5 min pressure‐holding time. Minced fish meat was massaged with 20 g kg^?1 salt at 10 °C during 5 min, stuffed in commercial sausage case and HPP‐treated. Raw and cooked (90 °C for 15 min) pressure‐treated gels were characterized by changes in mechanical properties (texture profile analysis and punch test), protein solubility, electrophoretic profile, expressible water and color. The mechanical properties of raw fish gels increased with pressure level and pressure‐holding time while solubility decreased. Myosin aggregation shown by SDS‐PAGE was associated with changes in mechanical and functional properties. The values for mechanical properties of heat‐induced gels were higher in cooked pressure‐treated samples than in the heat‐only control. Copyright © 2004 Society of Chemical Industry     

High pressure processing pretreatment of Chinese mitten crab (Eriocheir sinensis) for quality attributes assessment

The present study evaluated high pressure processing (HPP) pretreatment effects on the quality attributes of Chinese mitten crab (Eriocheir sinensis). Process parameters were optimized (300 MPa for 5 min) and the effects of HPP pretreatment on the total edible part of Eriocheir sinensis were investigated. The results showed that steamed loss has no significant difference and water holding capacity of inner meat was increased by approximately 51.33% with HPP pretreatment. HPP pretreatment can also decrease hardness value of crab carapace and preserve texture properties of crab leg meat. Compared with raw inner meat, results of DSC analysis of inner meat with HPP pretreatment has revealed that the denaturation temperature and the enthalpy of protein were decreased remarkably. The results of water distribution indicated that HPP pretreatment reduced the loss of entrapped water in inner meat. Finally, compare with the conventional steamed crabs, it has been detected that the aroma of the edible viscera of crabs has a significant difference with HPP pretreatment. Above findings indicated that HPP pretreatment retains quality attributes of Eriocheir sinensis well, in the meantime improves the processing efficiency since steaming time can be reduced by applying HPP pretreatment.Industrial relevanceHPP is a novel non-thermal technique widely used in the field of food production. Compared with conventional thermal processing, it is important for assessing the impact of HPP pretreatment on the quality attributes of crab in order to obtain high-quality products. According to recent studies, HPP pretreatment has been confirmed to be able to improve the quality of hot processed crabs. By applying 300 MPa for 5 min on Eriocheir sinensis, the total edible part was improved, and the water holding capacity of crab inner flesh was increased. Moreover, HPP pretreatment can also decrease hardness value of crab carapace and preserve sensorial properties of crab leg meat. These results indicated HPP pretreatment retains high quality characteristics of Eriocheir sinensis and reduces steaming time by which means the processing efficiency can be improved. This work provided further support for the use of HPP in Eriocheir sinensis.     

Restructured products from arrowtooth flounder (<Emphasis Type="Italic">Atheresthes stomias</Emphasis>) using high-pressure treatments

The texture of arrowtooth flounder, an underutilized fish species abundant in Alaska, degrades during cooking, a phenomenon that has been associated with proteolysis. Interest in safer fish products by high-pressure processing (HPP) is increasing. The objective of this study was to evaluate the effect of HPP treatments at 400 and 600 MPa for 1 and 5 min on the mechanical and functional properties of heat-induced fish gels obtained from arrowtooth flounder fish paste. Three thermal treatments of pressure-treated and control samples were evaluated: 90 °C for 15 min (kamaboko); 40 °C for 30 min plus 90 °C for 15 min (setting); 60 °C for 30 min plus 90 °C for 15 min (modori). Changes in texture profile analysis parameters, water holding capacity, sodium dodecyl sulfate polyacrylamide gel electrophoretic pattern and color parameters were determined. HPP improved the mechanical properties of heat-induced gels. Proteolysis of fish gels when they were incubated at 60 °C was not inhibited by HPP. The results obtained suggest distinct mechanisms of protein aggregation for pressure- and heat-induced fish gels.     

Effect of high pressure treatment on the quality of rainbow trout (Oncorhynchus mykiss) and mahi mahi (Coryphaena hippurus)

ABSTRACT:  High pressure processing (HPP) is becoming a promising seafood preservation method. The objective was to investigate the effect of HPP on quality of rainbow trout and mahi mahi during cold storage. Skinless fillets treated with different pressures (150, 300, 450, and 600 MPa for 15 min) and stored at 4 °C were analyzed at 1, 3, and 6 d storage. Red muscle was analyzed for lipid oxidation products by measuring thiobarbituric reactive substances (TBARS) and whole muscle was analyzed for total aerobic count, texture profile analysis, and color. A pressure of 300 MPa effectively inactivated the initial microbial population in rainbow trout (6-log reduction). However, inactivation of the initial population on mahi mahi was only about 4-log reduction at the same pressure. Microbial growth was significantly retarded after HPP. Color results showed that redness ( a * value) of rainbow trout at 300 MPa and above was significantly ( P < 0.05) lower compared to mahi mahi. TBARS values for rainbow trout increased with increased pressure, whereas the same trend was not seen for mahi mahi where maximum oxidation was found at 300 MPa and then declined. This study demonstrates the usefulness of HPP in seafood processing and the influence of species variation on processing parameters. The optimum HPP conditions for influencing lipid oxidation, microbial load, and color changes were found to be 300 MPa for rainbow trout and 450 MPa for mahi mahi.     

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.     

Variations of polyphenols,sugars, carotenoids,and volatile constituents in pumpkin (Cucurbita moschata) during high pressure processing: A kinetic study

High pressure processing (HPP) is an attractive technology for the preservation of vegetables with health promoting properties such as pumpkins. In this study pumpkin cubes were treated at six different pressures (100 to 600 MPa) at 20 °C for 3 min. Polyphenols (extracted both with solvent and by squeezing the residual material), carotenoids, sugars, and volatiles were evaluated. HPP at medium pressures (200–400 MPa) resulted in higher number of extractable polyphenols. Total sugars in HPP-treated samples were overall declining with increasing pressure. The total amount of carotenoids was higher in samples treated at lower pressures (100–300 MPa) and in the one at 600 MPa compared to untreated ones. Regarding volatile compounds, significant changes were observed for some aldehydes that increase after HPP application. This study revealed that treatment with intermediate pressure could ensure a higher amount of “availability” of polyphenols, carotenoids, volatiles, and total sugars in pumpkin samples.     

Effects of Rigor Status during High‐Pressure Processing on the Physical Qualities of Farm‐Raised Abalone (Haliotis rufescens)

High‐pressure processing (HPP) is used to increase meat safety and shelf‐life, with conflicting quality effects depending on rigor status during HPP. In the seafood industry, HPP is used to shuck and pasteurize oysters, but its use on abalones has only been minimally evaluated and the effect of rigor status during HPP on abalone quality has not been reported. Farm‐raised abalones (Haliotis rufescens) were divided into 12 HPP treatments and 1 unprocessed control treatment. Treatments were processed pre‐rigor or post‐rigor at 2 pressures (100 and 300 MPa) and 3 processing times (1, 3, and 5 min). The control was analyzed post‐rigor. Uniform plugs were cut from adductor and foot meat for texture profile analysis, shear force, and color analysis. Subsamples were used for scanning electron microscopy of muscle ultrastructure. Texture profile analysis revealed that post‐rigor processed abalone was significantly (P < 0.05) less firm and chewy than pre‐rigor processed irrespective of muscle type, processing time, or pressure. L values increased with pressure to 68.9 at 300 MPa for pre‐rigor processed foot, 73.8 for post‐rigor processed foot, 90.9 for pre‐rigor processed adductor, and 89.0 for post‐rigor processed adductor. Scanning electron microscopy images showed fraying of collagen fibers in processed adductor, but did not show pressure‐induced compaction of the foot myofibrils. Post‐rigor processed abalone meat was more tender than pre‐rigor processed meat, and post‐rigor processed foot meat was lighter in color than pre‐rigor processed foot meat, suggesting that waiting for rigor to resolve prior to processing abalones may improve consumer perceptions of quality and market value.     

超高压处理对山楂黄酒品质的影响

文中研究了山楂黄酒经100MPa～600MPa处理15min后其理化性质、香气成分及感官品质的变化.研究结果表明,山楂黄酒经200MPa处理后,总酸显著增加(p＜0.05),而经300MPa～600MPa处理后则显著降低(p＜0.05);高压处理后其稳定性、可溶性固形物并无显著变化(p＞0.05),总糖、氨基酸态氮、pH值显著增加(p＜0.05),酒精度、电导率显著降低(p＜0.05).GC-MS结果表明:经200MPa、400MPa和600MPa处理15min后,1-丁醇、2,3-丁二醇、苯乙醇等醇类和乙酸乙酯、乳酸乙酯、丁二酸二乙酯、苯乙酸乙酯等酯类含量明显增加,乙醛含量明显降低,400MPa处理的酒样香气变化最显著.感官评定结果表明,高压处理后的山楂黄酒澄清透明,果香味突出,酒体醇厚,口感协调、饱满.     

High pressure-induced tapioca starch gels: physico-chemical characterization and stability

Gelatinization of tapioca starch (25% dry basis) was induced by high hydrostatic pressure processing (HPP) at 600 MPa under different time and temperature regimes (30 °C for 10, 20 and 30 min; 50 °C for 10 min; 80 °C for 10 min). Textural, thermal and structural properties of the gels were studied and their stability was evaluated after 28 days of refrigerated (4 °C) and frozen (−18 °C) storage. Thermally induced gels (90 ± 1 °C, 20 min, gel-T) were used as controls. HPP resulted in the formation of harder gels than thermal processing (more significantly at lower processing temperatures) partially preserving the granular structure of the native starch. Longer HPP treatments caused only a slight decrease in hardness that was significant only at longer processing times (30 min). DSC thermograms of high pressure-induced samples showed a more asymmetrical ice-melting peak than that of thermally induced gels. Asymmetry of the peak of HP treated samples was more pronounced in samples processed at lower than at higher temperature. A different starch–water and/or starch/starch interaction may be hypothesized. During storage, all samples became stiffer and the amylopectin recrystallization increased, more extensively in thermally induced than in HPP samples where a stronger starch–starch and/or starch/water interactions may have hindered the recrystallization process.     

High-pressure processing (HPP) of raw and dry-cured ham from experimentally infected pigs as a potential tool for the risk control of Toxoplasma gondii

Raw and dry-cured meats have been identified as a potential source of Toxoplasma gondii infection for humans. The present study evaluated the efficacy of an alternative non-thermal food-processing treatment, high hydrostatic pressure, on the viability of T. gondii bradyzoites in raw and dry-cured ham. Meat of pigs experimentally exposed to 4000 oocysts of T. gondii VEG strain was vacuum-packaged and subjected to high pressure processing (HPP). Tap water (6 °C ± 1 °C) was used as the pressure-transmitting fluid, and its temperature during HPP increased 2.7 °C per 100 MPa. The effect was evaluated by bioassay in mice followed by qPCR. In raw ham, 100–400 MPa/1 min did not inactivate T. gondii, whereas 600 MPa/20 min was effective. In dry-cured ham, 600 MPa for 3 or 10 min were not effective and a 20-min treatment was required to render the bradyzoites non-infectious for mice. Our results point toward the potential use of HPP as a tool for risk control of T. gondii and as a food safety guarantee.Industrial relevance textUnder real production conditions, the usual HPP treatments applied by the food industry to control L. monocytogenes and other pathogenic bacteria are 600 MPa of pressure and holding times of 3–10 min. Our study demonstrated, however, that longer treatment times are required to inactivate the parasite and, thus, to guarantee the safety of raw and dry-cured meats in order to reduce the public health risk of toxoplasmosis. Further research is needed to evaluate other HPP conditions, including pulsed cycles, for the inactivation of T. gondii in foods of animal origin.     

低场核磁共振研究高压处理对乳化肠特性的影响

以低温乳化肠为材料,对0.1 ～ 400 MPa 压力处理组肉糜进行扫描电镜观察和低场核磁共振检测,评估加热后的感官特性,并进行相关性分析,从显微结构和水分子弛豫特性变化角度揭示高压处理对乳化肠感官特性改善的原因。结果表明：与对照组相比,压力从100 MPa 增大到200 MPa,感官特性得分增加,而200 MPa 到400 MPa得分减小（P ＜ 0.05）;扫描电镜结果显示各组肉糜显微结构存在明显差异;T2 弛豫结果显示,实验组T21 峰面积大于对照组而T22 峰面积小于对照组（P ＜ 0.05）,T21 弛豫时间在压力从100 MPa 增大到200 MPa 过程中升高,而在200 MPa 到400 MPa 降低（P ＜ 0.05）;相关性分析表明,感官特性各指标与T21 弛豫时间及其峰面积正相关,与T22 峰面积负相关（P ＜ 0.05）。因此,高压处理使自由水部分转化为不易流动水,并影响不易流动水与肉糜蛋白的结合程度,而转化比例和结合程度的强弱又会显著影响肉糜微结构及其加热后的感官特性。     

高压预处理及加热方式对混合蛋白凝胶特性的影响

将鸡肉肌原纤维蛋白(MPI)和大豆分离蛋白(SPI)按体积比1∶1混合,经过100、200、400、600MPa高压预处理20min,在40、55、70、85℃水浴加热20min制成凝胶,研究了凝胶的质构特性、保水性及微观结构。结果表明,55℃加热制备的凝胶明显优于传统线性升温制备的凝胶,硬度、弹性、保水性分别提高了35.50%、27.71%、47.29%。微观观察发现,混合蛋白高压处理后,形成的凝胶结构均匀致密,然而过高的压力预处理对混合蛋白凝胶会产生破坏作用。     

Frozen storage of high-pressure- and heat-induced gels of blue whiting (Micromesistius poutassou) muscle: rheological, chemical and ultrastructure studies

This paper examines the influence of frozen storage over 34 weeks on the rheological properties as well as the chemical and microstructural characteristics of gels made from muscle of blue whiting (Micromesistius poutassou) subjected to different gelling treatments entailing three combinations of pressure, temperature and time: 200 MPa, <10°C, 10 min (lot L), 375 MPa, 38°C, 20 min (lot H) and atmospheric pressure, 37°C, 30 min and then 90°C, 50 min (lot T). Freezing at –40°C caused certain changes in rheological parameters. In heat-induced gels, breaking deformation, elasticity and cohesiveness increased. Of the high-pressure-induced gels, breaking force increased and cohesiveness decreased in the gel formed at lower pressures, while the only change in the gel formed at higher pressure was some loss of elasticity. There was a general fall in water holding capacity (WHC) values. Lightness remained stable. In terms of protein solubility, there was an increase in covalent bonds in lot L. As for the ultrastructure, all gels matrixes were more disorganized as a result of freezing. In the course of frozen storage, the greatest changes in rheological parameters generally took place during the first 8 weeks, and in all the gels there was a decrease in WHC. In the heat-induced gel the changes were less marked over the storage period compared with those in the high-pressure-induced gels, but the heat-induced gel was more brittle and did not maintain maximum folding test scores. Covalent bonds increased and hydrophobic interactions decreased in all lots. The general appearance of the structure of gel T remained more homogeneous, while the pressurized gels exhibited more and larger cavities.     

High-Pressure Pretreatment to Improve the Water Retention of Sodium-Reduced Frozen Chicken Breast Gels with Two Organic Anion Types of Potassium Salts

The effect of high-pressure pretreatment (HPP, 100–300 MPa) before heating on the water holding capacity (WHC) and cooking loss (CL) of sodium-reduced (1.35% NaCl) frozen chicken breast gels with the organic anion types potassium lactate (KL-gel) and potassium citrate (KC-gel) was investigated. The results showed that 100–300 MPa could significantly decrease the CL of both gels, and 200 MPa increased the WHC of the KC-gel (P?<?0.05). HPP could decrease the storage modulus (G′) of meat batters, increase the thermal stability of their proteins, facilitate gelation with a dense and uniform microstructure, and immobilize free water, thus improving the gel’s water retention. The water retention of the pressurized sodium-reduced gel varied with the organic anion types of salts. The water retention was better with pressurized KC-gel than with KL-gel, resulting from higher pH and thermal stability of the batters. These results indicate that proper HPP could improve the water retention of sodium-reduced meat gels with organic potassium salts, thus increasing the economic benefit and properties of sodium-reduced products from frozen meat.     

Effect of high hydrostatic pressure processing on freely suspended and bivalve-associated T7 bacteriophage

The effectiveness of hydrostatic pressure processing (HPP) for inactivating viruses has been evaluated in only a limited number of studies, and most of the work has been performed with viruses freely suspended in distilled water. In this work, HPP inactivation of freely suspended and shellfish-associated bacteriophage T7 was studied. T7 was selected in hopes that it could serve as a model for animal virus behavior. Clams (Mercenaria mercenaria) and oysters (Crassostrea virginica) were homogeneously blended separately and inoculated with bacteriophage T7. The inoculated bivalve meat and the freely suspended virus samples were subjected to HPP under the following conditions: 2, 4, and 6 min at 241.3, 275.8, and 344.7 MPa pressure and temperatures of 29.4 to 35, 37.8 to 43.3, and 46.1 to 51.7 degrees C. Reductions of 7.8 log PFU (100% inactivation) were achieved for freely suspended T7 at 344.7 MPa for 2 min at 37.8 to 43.3 degrees C. At 46.1 to 51.7 degrees C, T7 associated with either clams or oysters was inactivated at nearly 100% (>4 log PFU) at all pressure levels and durations tested. These results indicate that T7 is readily inactivated by HPP under the proper conditions, may be made more susceptible to HPP by mixing with shellfish meat, and may serve as a viable model for the response of several animal viruses to HPP.     

High pressure thermal processing for the inactivation of Clostridium perfringens spores in beef slurry

The spores of Clostridium perfringens can survive and grow in cooked/pasteurized meat, especially during the cooling of large portions. In this study, 600 MPa high pressure thermal processing (HPTP) at 75 °C for the inactivation of C. perfringens spores was compared with 75 °C thermal processing alone. The HPTP enhanced the inactivation of C. perfringens spores in beef slurry, resulting in 2.2 log reductions for HPTP vs. no reductions for thermal processing after 20 min. Then, the HPTP resistance of two C. perfringens spore strains in beef slurry at 600 MPa was compared and modeled, and the effect of temperature investigated. The NZRM 898 and NZRM 2621 exhibited similar resistance, and Weibull modeled well the log spore survivor curves. The spore inactivation increased when HPTP temperature was raised from 38 to 75 °C. The results confirm the advantage of high pressure technology to increase the thermal inactivation of C. perfringens spores in beef slurry.Industrial relevanceC. perfringens spores may cause food/meat poisoning as a result of improperly handled and prepared foods in industrial kitchens. Thermal processes at 100 °C or higher are generally carried out to ensure the elimination of these pathogenic spores. High pressure processing (HPP) is a food pasteurization technique which would help to maintain the sensorial and nutritional properties of food. Preservation of foods with HPP in conjunction with mild heat (HPTP) would enhance the spore inactivation compared to thermal processing alone at the same temperature, due to a known germination–inactivation mechanism. This technology, together with the application of Good Manufacturing Practices, including rapid cooling, is a good alternative to the traditional methods for producing safe processed meat and poultry products with enhanced sensory and nutritional quality.     

Inactivation of hepatitis A virus and a calicivirus by high hydrostatic pressure

Potential application of high hydrostatic pressure processing (HPP) as a method for virus inactivation was evaluated. A 7-log10 PFU/ml hepatitis A virus (HAV) stock, in tissue culture medium, was reduced to nondetectable levels after exposure to more than 450 MPa of pressure for 5 min. Titers of HAV were reduced in a time- and pressure-dependent manner between 300 and 450 MPa. In contrast, poliovirus titer was unaffected by a 5-min treatment at 600 MPa. Dilution of HAV in seawater increased the pressure resistance of HAV, suggesting a protective effect of salts on virus inactivation. RNase protection experiments indicated that viral capsids may remain intact during pressure treatment, suggesting that inactivation was due to subtle alterations of viral capsid proteins. A 7-log10 tissue culture infectious dose for 50% of the cultures per ml of feline calicivirus, a Norwalk virus surrogate, was completely inactivated after 5-min treatments with 275 MPa or more. These data show that HAV and a Norwalk virus surrogate can be inactivated by HPP and suggest that HPP may be capable of rendering potentially contaminated raw shellfish free of infectious viruses.