Application Of High Pressure Processing Research Articles

Stability of sous-vide cooked salmon loins processed by high pressure

Abstract Sous-vide cooking has become a popular procedure in restaurants. To assure optimal texture and flavours of salmon loins, restaurant chefs recommend using a maximal core temperature around 40 °C, which implies immediate consumption to avoid potential microbiological growth. High pressure processing (HPP) is a well known technology to decontaminate prepared food. This study proposes to evaluate the application of HPP to improve shelf life of such delicate products. Sous-vide cooked salmon loins were processed at 3 different pressures (210, 310 and 400 MPa) for 5 min at 10 °C. The microbiological stability (total viable counts and Enterobacteriaceae) of the products was checked during a storage period of 13 days at 4 °C. Texture, colour, pH and a hedonic sensorial analysis were conducted during this storage period. Results have shown that pressure above 310 MPa enables to extend shelf life up to 6 days. After that time, lipid oxidation and microbiological spoilage lead to product degradation. Industrial Relevance Sous-vide cooking is a common procedure in the catering industry where core temperatures are above 90 °C for most applications. In restaurants core temperature tends to be between 40 and 60 °C for fish and sea food implying that the product cannot be kept for more than 2 h in a refrigerated temperature before serving to avoid microbiological growth. HPP is proposed to pasteurize delicate sous-vide cooked products and use them as ready to eat meals.

High Pressure Processing of Meat, Meat Products and Seafood

High pressure processing (HPP) allows the decontamination of foods with minimal impact on their nutritional and sensory features. The use of HPP to reduce microbial loads has shown great potential in the meat, poultry and seafood industry. HPP has proven to be a promising technology, and industrial HPP applications have grown rapidly, especially in the stabilization of ready-to-eat meats and cured products, satisfying the demands of regulatory agencies such as the United States Department of Agriculture-Food Safety and Inspection Services (USDA-FSIS). HPP has been investigated for a wide range of operations including non-thermal decontamination of acid foods, combined pressure–heating treatments to inactivate pathogenic bacteria, pressure-supported freezing and -thawing, texturization and the removal of meat from shellfish and crustaceans. Research has also been conducted on the impact of the technology on quality features. Processing-dependent changes in muscle foods include changes in colour, texture and water-holding capacity, with endogenous enzymes playing a major role in the phenomena. This review summarizes the current approaches to the use of high hydrostatic pressure processing, focusing mainly on meat, meat products and seafood. Recent findings on the microbiological, chemical and molecular aspects of HPP technology, along with commercial and research applications, are also described.

Application of high pressure processing to reduce verotoxigenic E. coli in two types of dry-fermented sausage

The effect of high pressure processing (HPP) on the survival of verotoxigenic Escherichia coli (VTEC) in two types of Norwegian type dry-fermented sausages was studied. Two different types of recipes for each sausage type were produced. The sausage batter was inoculated with 6.8 log(10) CFU/g of VTEC O103:H25. After fermentation, drying and maturation, slices of finished sausages were vacuum packed and subjected to two treatment regimes of HPP. One group was treated at 600 MPa for 10 min and another at three cycles of 600 MPa for 200 s per cycle. A generalized linear model split by recipe type showed that these two HPP treatments on standard recipe sausages reduced E. coli by 2.9 log(10) CFU/g and 3.3 log(10) CFU/g, respectively. In the recipe with higher levels of dextrose, sodium chloride and sodium nitrite E. coli reduction was 2.7 log(10) CFU/g in both treatments. The data show that HPP has a potential to make the sausages safer and also that the effect depends somewhat on recipe.

Dimethylamine, Trimethylamine, and Biogenic Amine Formation in High‐Pressure Processed Semidried Squid (Todarodes pacificius) during Refrigerated Storage

The quality properties of semidried squid treated with high-pressure processing (HPP) were investigated during refrigerated storage. The vacuum-packed semidried squid samples were subjected to 500 MPa for 0 min (HPP-0), 5 min (HPP-5), and 10 min (HPP-10) by using a custom-made high-pressure processor and stored at a refrigerated temperature for 28 d. The populations of indigenous psychrotrophic and mesophilic bacteria were effectively reduced by approximately 1 and 2 log CFU/g at the HPP-10 treatment, respectively. Compared to the control, the bacterial counts in HPP-treated semidried squid samples were maintained at low levels throughout the storage period. The increase in the amounts of dimethylamine (DMA) and trimethylamine (TMA) was more pronounced at the unpressurized control than at the HPP treatments. The production of biogenic amines (BAs) varied with HPP treatment during refrigerated storage. Therefore, the application of HPP may provide a significant improvement in the safety and quality of semidried squid.

Application of high pressure processing for extending the shelf-life of sliced raw squid

This study was designed to evaluate the effect of high pressure processing (HPP) on the microbiological safety and quality of sliced raw squid during refrigerated storage. The sliced and vacuum-packed raw squid samples were treated at 200, 300, and 400 MPa for 20 min by using a custom-made high pressure processor. The numbers of psychrotrophic bacteria in the sliced raw squids treated at 200, 300, and 400 MPa were reduced by 0.5, 2.5, and >4.7 log CFU/g, respectively. The amounts of trimethylamine (TMA) produced in the sliced raw squids were reduced by 20, 33, and 51% at 200, 300, and 400 MPa, respectively, as compared to the control. The amount of total biogenic amines (BAs) in the control significantly increased up to 1.70 mg/g after 10 days of refrigerated storage, while that in the 400 MPa-treated squid sample gradually increased up to 1.33 mg/g. The autolytic activity values in the control, 200, 300, and 400 MPa-treated squid samples were 4.70, 2.28, 2.18, and 1.55 nkat/g, respectively, after 20 days of refrigerated storage. The HPP effectively retarded the microbial growth, TMA formation, autolytic activity in the sliced raw squids. Therefore, the HPP could be used as an effective processing tool for improving microbiological safety and quality of seafood.

Sensory perception and quality attributes of high pressure processed carrots in comparison to raw, sous-vide and cooked carrots

Abstract The application of high pressure processing (HPP) has shown its potential to reduce quality losses of many fruit and vegetable products in comparison to other traditional technologies such as cooking. To identify further opportunities of the application of high pressures in vegetable pieces, the sensory perception and correlation to quality parameters were investigated on carrot sticks (used as model product) submitted to high pressure treatments (600 MPa, 2 min) and compared to other traditional treatments such as sous-vide (90 °C, 5 min), cooked (100 °C, 20 min) and unprocessed (raw). The results indicated that HPP carrots were not different from sous-vide carrots in many parameters such as: sweetness, green flavour and crunchy texture. Furthermore, high pressure carrots showed significantly higher intensity perception of orange colour and fibrousnesses to the rest of the treatments, while similar brightness to cooked carrots and green odour to raw. Throughout 14 days of storage at 4 °C, there was clear evidence that HPP samples could be preserved better in comparison to the rest of the treatments by not presenting any production of acetic acid (used as quality deterioration reference). Overall, sensory evaluation showed correlations to many quality measurements in this study, indicating similarities in hardness versus crunchiness perception and juiciness versus moisture perception between HPP and sous-vide samples. GC/MS and GC/MS-O results were also in agreement in most cases when identifying carrot volatile changes between the different treatments and the identification of the development of new compounds formed. Finally, the tissue structure observed by using Cryo-SEM microscopy, supported the similarities (between HPP and sous-vide) and differences (between treatments) of the quality parameters analysed in this research. Industrial Relevance Previous reports on HPP for food applications indicated that this technology will only be commercially successful if added value is achieved or if the product characteristic can be retained at a higher level as compared to thermally/traditionally processed foods. This work provides information on textural and chemical (volatile) changes as well as the sensorial perception of carrots which have undergone high pressure processing, as well as how those changes compare to the quality of both raw and thermally processed carrots. These results may be generally applicable to what could be expected to happen to other ‘hard’ tissue vegetable products produced by high pressure processing, over a refrigerated storage time of 14 days.

Application of High Pressure Processing To Kill Escherichia coli O157 in Ready-to-Eat Meats

Uncooked ready-to-eat (RTE) meats have previously been identified as vehicles for the transmission of the foodborne pathogen Escherichia coli O157. In this study, the potential for high pressure processing (HPP) to kill E. coli O157 in two RTE meats (Hungarian salami and All Beef salami) was investigated. The RTE meats were inoculated with a five-strain cocktail of E. coli O157, vacuum packed, and then pressure treated at 600 MPa with a hold time of 3 min. Samples were stored at 15°C for 28 days. HPP initially reduced E. coli numbers on both RTE meats by greater than 4 log CFU/g. However, with enrichment and immunomagnetic separation we were able to recover E. coli O157 from the samples. During storage, the numbers of E. coli O157 increased on the All Beef samples but remained static on the Hungarian salami, which had a restrictive pH and water activity. Increasing the hold time to 6 or 9 min did not result in additional reduction of E. coli O157. The sensory appeal of the two products was not significantly changed by HPP as determined by a sensory panel (n = 50). Analysis of the reflected light parameters of luminance, green-red, and blue-yellow revealed no significant changes. The results of these experiments indicate that HPP has potential as a lethal treatment for E. coli O157 on RTE meats with minimal changes in consumer appeal.

Pressure assisted thermal sterilization

High pressure processing (HPP) can inactivate various types of microorganisms in their vegetative form. However, spores can be resistant to pressures as high as 1000 MPa, which in the absence of heat limits the application of HPP to pasteurization only. A new technology has been recently developed to generate mild pressure by heating the treated liquid food in enclosure. This technology was examined for its ability to inactivate spore forming bacteria ( Bacillus cereus and Geobacillus stearothermophilus) to produce a sterile product which retained its original organoleptic characteristics. Results shows that this pressure assisted thermal sterilization process could decrease the decimal reduction time ( D-value) and hence, reduce the sterilization temperature significantly. The mild pressure generated assisted spores to germinate allowing the heat to inactivate the germinated spores. Vegetative microorganisms ( Saccharomyces cerevisiae and Escherichia coli) were also tested using the technology. However, the effect of this mild pressure on the inactivation was found insignificant.

Baroprotective effect of increased solute concentrations on yeast and moulds during high pressure processing

The baroprotective effect of increasing solute concentrations on yeast cells and fungal conidia subjected to high pressure processing (HPP) was studied. Suspensions of yeast cells (Saccharomyces cerevisiae, Pichia anomala and Hanseniaspora uvarum) or fungal spores (Penicillium expansum, Fusarium oxysporum and Rhizopus stolonifer) in citrate phosphate buffer formulated with sucrose at 40, 50 and 60 °Brix, or with glycerol and NaCl at equivalent water activity (aw) values (0.925, 0.903 and 0.866 aw) were subjected to 600 MPa pressure for varying times, and then were enumerated by spread plate technique to assess survival. There was an increasing resistance to inactivation by high pressure with an increase in solute concentration. The two moulds with easily wetted spores, R. stolonifer and F. oxysporum, showed strongest resistance to HPP at 0.866 aw. Differing responses to the three solutes were observed among the fungal species tested, indicating that the chemical nature of the solute may also be important in protecting yeasts and moulds during and after pressure treatment. Sucrose had a stronger baroprotective effect for S. cerevisiae than the other solutes, at two of the three investigated aws. For P. expansum at 0.903 aw, NaCl gave the best protective effect. Scanning electron microscopy of HPP treated cells showed the protective effects of increased sucrose concentration. The results reported here have practical implications for the food industry in the application of HPP for production of fruit preparations or syrups, and should be taken in account in establishing efficient process design. As high concentrations of sugar, salt and glycerol provide protection for yeasts and moulds during high pressure processing, foods containing high levels of solutes may need longer processing times or higher pressures to achieve inactivation of these fungi.

Application of high-pressure processing for preservation of germinated legumes

High-pressure processing on germinated legume seeds (pea, chickpea, lentil, green gram) was studied. Total microflora was decreased: in three days germinated pea seeds decreased from 2.4 × 106 CFU/g to less than 10; in two days germinated chickpea seeds decreased from 1.6 × 105 CFU/g to less than 10; in three days geminated lentil seeds decreased from 3.4 × 107 CFU/g to less than 10; and in three days germinated green gram decreased from 1.4 × 109 to 1.8 × 102 after treatment of high pressure 500 MPa for 10 min. High pressure treated germinated seeds were stored in tap water (pea) and in citric acid pickle pH=2.5 (chickpea) or pH=2.0 (lentil, green gram) at 4–8 °C. The total microflora increased during 21 days storage in pressurized germinated pea seeds to 7.5 × 104 CFU/g and in green gram to 3.5 × 105. The contents of microorganisms in pressurized germinated chickpea and lentil seeds were under detection limits of methods used.

High pressure processing of fruits and vegetables

Purpose of review: Hi gh pressure processing (HPP) is one of the many novel techniques for processing food materials. This revi ew details potential applications of the HPP technique for fruit and vegetable processing. Recent findings: HPP employs high pressures (400–1200 MPa) to kill microorganisms and inactivate the enzymes that cause un desirable changes in fruits and vegetables, which reduces their shelf-life. This technique can be applied with minimal increase in product temperature. HPP is gaining in popularity because of its potential to achieve desirable effects with minimum changes i n sensory and nutritional attributes, and reliable food safety. Directions for future research: Fu ture research should: evaluate synergistic effects among pressure, temperature and other v ariables, investigate the influence of pressure on reduction/eli mination of pathogenic and spoilage microbial populations, invest igate the inactivation of enzymes in fruits and vegetables using a proper experimental design so that kinetic parameters are q uantified, identify and evaluate the critical pr ocess factors for the survival of pathogens or surrogates in a statistical manner, and de velop Hazard Analysis and Critical Control Point plans for the application of HPP for the processing fruits and vegetabl es.

Effect of high-pressure processing on the mechanical and barrier properties of selected packagings

This investigation focuses on the effect of high-pressure processing (HPP) on possible changes of the mechanical properties and of the water vapour permeability of seven selected packaging materials. NOD 259 (PA-PE), BB4L (Cryovac-Grace packaging), PET/BOA/PE, PET/PVDC/PE, PA/SY, LDPE and EVA/PE were investigated (PET, polyester; PE, polyethylene; SY, surlyn; LDPE, low-density polyethylene; EVA, polyethylene–vinyl acetate co-polymer; BOA, biaxially oriented polyamide). These packaging materials were selected because of their interest to the food industry. All had an internal film of PE for food use. High-pressure tests were realized at 10°C for 10 min at pressures of 200, 400 and 600 MPa, with water as a food-simulating fluid. The depressurization rate was either rapid (pressure drop in <10s) or slow (20 MPa/min). Permeability to water vapour was realized using the NFF H 00 030–ASTM E96-90 standard. Mechanical tests were carried out with a tensile testing machine (Lloyd LR5K), according to the NF 54-102 standard. Maximal stress, rupture stress and strain at rupture were evaluated with non-treated and treated samples. Obtained results showed that HPP minimally affects the mechanical strength of packaging material. The depressurization rate did not have any significant influence in our conditions. The barrier properties to water vapour were not significantly affected and were even slightly enhanced for LDPE, which is a packaging material commonly used for HPP applications and at least as a food contact material. Copyright © 2006 John Wiley & Sons, Ltd.

Evaluation of High Pressure Processing as an Additional Hurdle to Control Listeria monocytogenes and Salmonella enterica in Low‐Acid Fermented Sausages

ABSTRACTLow‐acid fermented sausages (fuet and chorizo) were manufactured to evaluate the combined effect of high pressure processing (HPP) and ripening on foodborne pathogens. Raw sausages inoculated with a three‐strain cocktail of Salmonella ser. Derby, London, and Schwarzengrund, and a three‐strain cocktail of L. monocytogenes ser. 1/2 c and 4b were pressurized at 300 MPa for 10 min at 17 °C. Afterwards, sausages were ripened at 12 °C and 80% RH for 27 d. Salmonella counts decreased in all studied sausages during ripening. However, the application of HPP as an additional hurdle to the ripening process produced a greater decrease in the Salmonella population, showing lower counts (3 MPN/g) in ripened sausages. By contrast, lower values of L. monocytogenes counts were obtained in non‐treated (NT) than in pressurized sausages due to the delay of pH drop caused by HPP inactivation of endogenous lactic acid bacteria. After pressurization of raw sausages at 300 MPa, a discoloration of sausages was observed, coinciding with an increase in L* values.

APLICACIONES DEL PROCESADO DE ALIMENTOS POR ALTA PRESIÓNHIGH PRESSURE FOOD PROCESSING APPLICATIONSAPLICACIÓNS DO PROCESADO DE ALIMENTOS POR ALTA PRESIÓN

The high pressure processing (HPP) of foods can achieve the inactivation of microbial pathogens with minimal losses in food quality. The scale-up of food preservation processes based on the application of HPP is relatively simple; this is the factor that explains best why HPP is the only new alternative technology for food preservation that has reached consumers with a variety of new products. In this article, the essential components of the HPP units are described and key differences between high and low commercial-cost applications are also outlined. Examples of numerous specific competitive commercial opportunities to implement this novel technology are then presented. © 2005 Altaga. All rights reserved. Resumen El procesado de un alimento por alta presión (HPP, por sus siglas en inglés) inactiva los microorganismos perjudiciales produciendo perdidas mínimas en la calidad del alimento. El escalado industrial de los procesos de HPP a temperatura ambiente es relativamente simple, constituyendo una razón importante por lo que esta tecnología alternativa de conservación es la única que ha llegado ya al consumidor con una gran variedad de nuevos productos. En este artículo se describen los componentes esenciales de las unidades de HPP y se mencionan las diferencias principales entre las aplicaciones de bajo y alto coste comercial de esta tecnología. Se presentan numerosas oportunidades que se han comercializado y muchas otras que representan nuevas oportunidades para que la industria de alimentos implemente esta tecnología innovadora. © 2005 Altaga. Todos los derechos reservados. Palabras clave: Procesado de alimentos, Alta presión, HPP, inactivación microbiana, conservación Resumo O procesado dun alimento por alta presión (HPP, polas súas siglas en inglés) inactiva os microorganismos perxudiciais producindo perdas mínimas na calidade do alimento. O escalado industrial dos procesos de HPP a temperatura ambiente é relativamente simple, constituíndo unha razón importante polo que esta tecnoloxía alternativa de conservación é a única que chegou xa ó consumidor cunha grande variedade de novos productos. Neste artículo descríbense os compoñentes esenciais das unidades de HPP e menciónanse as diferencias principais entre as aplicacións de baixo e alto custe comercial desta tecnoloxía. Preséntanse numerosas oportunidades que se comercializaron e moitas outras que representan novas oportunidades para que a industria de alimentos implemente esta tecnoloxía innovadora. © 2005 Altaga. Tódolos dereitos reservados. Palabras chave: Procesado de alimentos, Alta presión, HPP, inactivación microbiana, conservación

Potential applications of high pressure for improvement in salmon quality

Cold-smoked salmon is an important value added, ready-to-eat food. Quality issues associated with cold-smoked salmon are examined. Effects of smoking, drying, enzymatic spoilage, feed usage, textural and biochemical changes during frozen storage of cold-smoked salmon are described. Important pathogens associated with cold-smoked salmon, such as Listeria monocytogenes and other spoilage organisms are also described and potential areas for further research are identified. Recent advances in the application of high pressure processing to seafood safety and quality improvement are discussed and the potential of this technology to improve the quality of cold-smoked fish from farmed Atlantic salmon is outlined.

Application of high-pressure processing and nisin to mechanically recovered poultry meat for microbial decontamination

The combined effect of high-pressure, nisin and acidification on the mesophilic and psychrotrophic microbiota of mechanically recovered poultry meat (MRPM) was evaluated. Nisin (0, 12.5, 100 and 200 ppm) and 1% of glucono-delta-lactone were added to MRPM. Samples were treated by combinations of pressure (350 and 450 MPa), time (5 and 15 min) and temperature (−20 and 20 °C). Both alone or in combination with nisin, pressurization at 20 °C was more lethal than that at −20 °C. The significantly highest decreases in counts occurred in samples with 200 ppm of nisin treated at 450 MPa: 5.3 log CFU/g for mesophiles and above 7.5 log CFU/g (nondetected growth) for psychrotrophs. So, this combined treatment can improve the safety and shelf-life of MRPM.

Muscle protein gelation by combined use of high pressure/temperature

One of the various applications of high pressure processing (HPP) in food treatment is to affect myofibrillar proteins and their gel-forming properties, which suggests interesting possibilities for the development of processed muscle-based food. In light of the thermolabile nature of protein meat systems and the variation in the rates at which pressure (P) and temperature (T) changes take place in the product, this article provides an overview of the conditions in which pressure-assisted gelation is achieved in myosystems depending on the sequence in which pressure/temperature combinations are applied. It also analyses other relevant circumstances affecting the conditions in which muscle foods are pressurized, which could place limitations on the interpretation of the results.

Dairy research in the Food Science Division, Belfast

This paper describes dairy related research currently underway in the Food Science Division in Belfast. Topics include the heat resistance of Mycobacterium paratuberculosis, which has been implicated as the causative agent of Crohn's disease of humans, incidence of enterovirulent Escherichia coli in raw milk, shelf‐life of pasteurized milk, dietary manipulation of milk fat composition and the application of high pressure processing to dairy products.