Effect Of High Pressure Treatment Research Articles

Effects of High Pressure Treatment on the Microbiological and Chemical Properties of Milk

Effects of High Pressure Treatment on the Microbiological and Chemical Properties of Milk

Effects of High Pressure Treatment on the Hardness and Electrical Resistivity of CuW Alloy

Effects of High Pressure Treatment on the Hardness and Electrical Resistivity of CuW Alloy

Monte Carlo analysis of the product handling and high-pressure treatment effects on the Vibrio vulnificus risk to raw oysters consumers

A Monte Carlo procedure considering the variability in oyster handling from harvest to raw consumption estimated reductions in the number of Vibrio vulnificus induced septicemia cases achieved by high-pressure processing (HPP). The calculations yielded pathogen load distributions in raw oysters from harvest to consumption. In the warm season, 2–6min treatments at 250MPa and 1°C would lower the predicted number of septicemia cases associated with raw oyster consumption from 4932 to less than four per 100 million consumption events (95% confidence). This study highlighted that HPP conditions should be selected according to the seasonal pathogen load and environment temperature. Finally, the procedure emphasized that the variability in the V. vulnificus population at harvest, before and after HPP treatments, reflecting in part the microbiological quantification methods used, significantly affected the estimated number of septicemia cases. Therefore, improving microbiological quantification should provide better predictions of the number of septicemia cases.

Assessment of Salmonella and Listeria monocytogenes level in ready-to-cook poultry meat: Effect of various high pressure treatments and potassium lactate concentrations

The objective of this study was to develop a probabilistic model in order to determine the contamination level of Salmonella and Listeria monocytogenes in ready-to-cook poultry meat, after a high pressure (HP) treatment. The model included four steps: i) Reception of raw meat materials, mincing and mixing meat, ii) Partitioning and packaging into 200-g modified atmosphere packs, iii) High pressure treatment of the meat, and iv) Storage in chilled conditions until the end of the shelf-life. The model excluded the cooking step and consumption at consumer's home as cooking practices and heating times are highly variable. The initial contamination level of Salmonella and L. monocytogenes was determined using data collected in meat primary processing plants. The effect of HP treatment and potassium lactate on microbial reduction was assessed in minced meat, using a full factorial design with three high pressure treatments (200, 350 and 500MPa), three holding times (2, 8 and 14min) and two potassium lactate concentrations (0 or 1.8% w/w). The inactivation curves fitted with a Weibull model highlighted that the inactivation rate was significantly dependent on the HP treatment. From the literature, it was established that Salmonella was not able to grow in the presence of lactate, under modified atmosphere and chilled conditions whereas the growth of L. monocytogenes was determined using an existing model validated in poultry (available in Seafood Spoilage and Safety Predictor software, V. 3.1).Once implemented in the Excel add-in @Risk, the model was run using Monte Carlo simulation. The probability distribution of contamination levels was determined for various scenarios. For an average scenario such as an HP treatment of 350MPa for 8min, of 200g minced meat containing 1.8% lactate (pH6.1; aw 0.96), conditioned under 50% CO2, the prevalence rate of Salmonella and L. monocytogenes, after a 20-day storage at 6°C was estimated to be 4.1% and 7.1%, respectively. The contamination level was low considering that the product is going to be cooked by the consumer afterwards: the 99th percentile of the distribution was equal to −2.3logcfu/g for Salmonella and 0.5logcfu/g for L. monocytogenes. More generally, the model developed here from raw material reception up to the end of the shelf-life enables to recommend combinations of HP treatment and lactate formulation to guarantee an acceptable microbial concentration before cooking.

Effect of High pressure processing of food characteristics: a review of quality aspect

To achieve the balance between food quality and safety, there is a need to optimize conventional processing techniques currently applied in food industries and to develop novel processing techniques such as highpressure (HP) processing. HP processing is a unique technology compared to other food processing technologies as pressure can result in enhancement or retardation of chemical and biochemical reactions as well as in both desired and undesired modification of biopolymers (e.g. enzyme (in)activation, gel formation).This paper focuses specifically on the effects of HP treatment on colour, flavour and texture of foods and tries to elucidate the mechanisms behind the observed changes in quality attributes.

Microstructure evolution and thermal physical properties of CuCr alloy after high pressure treatment

The thermal diffusion coefficient, thermal conductivity, and thermal expansion coefficient of CuCr alloy prepared by infiltration were measured by thermal constant tester and dilatometer before and after high pressure heat treatment, at the same time, the effect of high pressure treatment on the thermal physical properties of CuCr alloy was discussed by the analysis of its microstructure. The experimental results show that high pressure heat treatment can increase the thermal diffusion coefficient and thermal conductivity of CuCr alloy, but it changes slightly in the pressure range of 1–6 GPa. As for thermal expansion coefficient, when the temperature is higher than 130 °C, it is obviously higher than that of the alloy without high pressure treatment after 1 GPa pressure treatment, and the higher the temperature is, the larger their differences are.

Effects of high pressure processing on immunoreactivity and microbiological safety of crushed peanuts

Abstract Peanuts are a common economical food source consumed worldwide but exist health concern of food allergy and are particularly susceptible to infection by the mold fungus Aspergillus flavus during storage, accumulating highly toxic substance aflatoxin. In this study, the effect of high pressure treatments on peanut immunoreactivity, peanut amino acid composition, A. flavus growth and aflatoxin contents on crushed peanuts was evaluated. Results showed that immunoreactivity of peanuts treated with 600 MPa and 800 MPa for 10 min was significantly lower (P

Effects of High Pressure Treatments on Polymeric Films for Flexible Food Packaging

Effects of high pressure (HP) treatments on functional and morphological properties of commercial packaging films have been investigated, to assess their suitability for use in these processes. Experimental analyses have been performed on packaging films, used to make pouches containing four different types of food simulants, after HP pasteurization and sterilization treatments at 200, 500 and 700 MPa. The investigated polymeric flexible packaging structures were single layer as well as bilayer films. Effects of treatments on structural/morphological properties (i.e. crystallinity and density) and on thermodynamic and barrier properties were addressed. Quite all the investigated films were found to be suitable for HP pasteurization, which only determined a negligible effect on the glass transition temperatures and on density of the amorphous regions of some polymeric materials, without a significant effect on functional properties of the packaging. Only bilayer structures including metalized polyethyleneterephthalate were not able to withstand processing conditions because of an extensive delamination accompanied by loss of metallization layer. Conversely, in the case of HP sterilization, combined effects of HP and relatively high temperature caused significant modifications in some of the packaging materials, even those not including a metalized film. In particular, localized delamination occurred in the case of bilayer structures made by laminating polyethyleneterephtalate with linear low density polyethylene or with polypropylene. Films obtained by laminating cast polyamide and bioriented polyamide with polypropylene displayed no evidence of delamination. In the case of films not displaying delamination, only limited changes in gas and vapour barrier properties were detected. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of High Pressure Treatment on Nanoindentation Creep Property of Al-Zn-Mg-Cu Alloy

Al-Zn-Mg-Cu alloy was 3GPa pressure treated, and the effect of high pressure treatment on nanoindentation creep property of Al-Zn-Mg-Cu alloy was investigated by using nanoindentation. The results show that indentation creep in Al-Zn-Mg-Cu alloy before and after 3GPa pressure treatment can occur at room temperature, 3GPa pressure treatment can reduce creep deformation of Al-Zn-Mg-Cu alloy at room temperature at different pressure and time, and leads to the creep resistance of Al-Zn-Mg-Cu alloy rises.

Influence of high-pressure treatment on charge carrier transport in PbS colloidal quantum dot solids

We investigated the effects of high-pressure treatment on charge carrier transport in PbS colloidal quantum dot (CQD) solids. We applied high pressure to PbS CQD solids using nitrogen gas to reduce the inter-dot distance. Using this simple process, we obtained conductive PbS CQD solids. Terahertz time-domain spectroscopy was used to study charge carrier transport as a function of pressure. We found that the minimum pressure needed to increase the dielectric constant, conductivity, and carrier mobility was 4 MPa. All properties dramatically improved at 5 MPa; for example, the mobility increased from 0.13 cm(2) V(-1) s(-1) at 0.1 MPa to 0.91 cm(2) V(-1) s(-1) at 5 MPa. We propose this simple process as a nondestructive approach for making conductive PbS CQD solids that are free of chemical and physical defects.

High pressure processing of garlic paste: effect on the quality attributes

SummaryThe effect of high pressure treatment and conventional thermal processing on the various quality attributes of garlic paste was evaluated in terms of physicochemical, enzymatic, sensory and microbiological parameters. Thermal treatment inactivated the polyphenol oxidase and peroxidase enzymes, whereas an enhanced activity was noted at 200 MPa which reduced significantly (P < 0.05) when treated with 400 and 600 MPa. Total phenolics, flavonoids and antioxidant activities showed an increasing trend with increase in pressure, whereas thermal processing was found to significantly (P < 0.05) decrease these phytocompounds. The CIE (L*, a*, b*) values were found to be better retained in high pressure‐processed pastes compared with thermally treated one. The microbial counts in terms of total plate count, yeast and mould count as well as total coliform counts were reduced significantly (P < 0.05) in both the treatments. Sensory attributes were found to be better in the case of high pressure‐processed samples as compared to the thermally treated one.

Effect of high pressure treatment on the survival of Shiga toxin-producing Escherichia coli in strawberry puree

Most fresh produce, such as strawberries, receives minimal processing and is often eaten raw. Contamination of produce with pathogenic bacteria may occur during growth, harvest, processing, transportation, and storage (abuse temperature) and presents a serious public health risk. Strawberries have been implicated in an outbreak of Escherichia coli O157:H7 infection that sickened 15 people, including one death. Strawberries may also be contaminated by other serogroups of non-O157 Shiga toxin-producing E. coli (STEC), including O26, O45, O103, O111, O121 and O145, which have become known as the “Big Six” or “Top Six” non-O157 STECs. The objective of this research was to explore the potential application of high pressure processing (HPP) treatment to reduce or eliminate STECs in fresh strawberry puree (FSP). FSP, inoculated with a six-strain cocktail of the “Big Six” non-O157 STEC strains or a five-strain cocktail of E. coli O157:H7 in vacuum-sealed packages, were pressure-treated at 150, 250, 350, 450, 550, and 650 MPa (1 MPa = 106 N/m2) for 5, 15, and 30 min. HPP treatment, at 350 MPa for ≥5 min, significantly reduced STECs in FSP by about 6-log CFU/g from the initial cell population of ca. 8-log CFU/g. Cell rupture, observed by scanning electron microscopy (SEM), demonstrated that the HPP treatments can be potentially used to control both non-O157 and O157:H7 STECs in heat sensitive products.

Effects of high-pressure processing on the quality of chopped raw octopus

This study evaluated the effects of high-pressure treatment on microbial growth and production of off-flavor compounds in raw octopus during 16 days of refrigerated storage. Chopped raw octopus samples were treated at 150, 300, 450, and 600 MPa for 6 min using high-pressure laboratory food processing equipment. The number of psychrotrophic bacteria on day 16 was reduced by 0.1, 0.5, 1.3, and 2.8 CFU/g after pressure treatment at 150, 300, 450, and 600 MPa, respectively, as compared with control group. The amounts of trimethylamine (TMA) and dimethylamine (DMA) produced in the chopped raw octopus treated at 600 MPa was significantly reduced by 42.5% and 62.2%, respectively, as compared to the levels in the control. The production of biogenic amines (BAs) increased up to 1.82 mg/g in the control after 12 days of refrigerated storage, while the BA levels in the 450 MPa- and 600 MPa-treated octopus were 1.40 and 1.35 mg/g, respectively. Thus, high-pressure treatment effectively inhibited microbial growth and suppressed the formation of off-flavor compounds in raw octopus. High-pressure treatment is a promising alternative technology for extending the shelf life of raw octopus.

Application of time–intensity method to assess the sensory properties of Iberian dry-cured ham: effect of fat content and high-pressure treatment

This paper describes the effect of high-pressure treatment (HHP) (600 MPa) on the oxidative stability (hexanal) and the sensory properties of sliced and vacuum-packaged Iberian dry-cured ham varying in intramuscular fat (IMF) content (low fat—flank, high fat—hip) after refrigerated storage (120 days, +2 °C). Both static and dynamic time–intensity sensory techniques were applied. Samples subjected to HHP treatment and HF samples showed the highest hexanal content. HF samples displayed higher scores for colour intensity, marbling and brightness of lean. IMF content contributed to a more intense temporal perception of hardness and fibrousness and to a more intense and longer rancid flavour perception. External fat from pressurized samples showed a higher colour intensity and hardness probably due to the extent of lipid oxidation and the development of fat crystallization. Results of temporal analysis indicated that pressurized samples turned out harder, juicier, more fibrousness, saltier and displayed a more intense overall and rancid flavour.

Effects of High Pressure Treatments on the Ripening of Hard Cheeses

The effects of high-pressure (HP) treatments (200, 300, 400 and 500MPa for 10 min, 2P to 5P) applied on day 1 to accelerate the ripening of hard cheeses. The proteolysis, lipolysis, texture and sensory properties were studied in 90 days at 10°C. HP treatments increased proteolysis and sensory properties at all stages of ripening in all treated cheeses, furthermore, higher hydrolysis and sensory properties were found in 3P cheeses. However, HP treatments had no positive effects on cheeses lipolysis development, especially, in 5P cheeses.

초고압처리 및 결착제 첨가가 재구성 돈육의 품질특성에 미치는 효과

본 연구에서는 식육의 재구성에 첨가되는 식염의 함량을 줄인 저염 재구성육 제품을 제조하기 위하여 다양한 결착제의 활용, GdL 첨가 및 초고압처리 수준에 따른 재구성돈육의 품질 특성을 조사하였다. 본 연구에서 첨가된 0.5% GdL 수준은 제품의 pH를 유의적으로 감소시키며, GdL 자체 혹은 초고압처리에 의한 식육단백질의 젤 형성에 기인하여 효과적으로 pH 저하에 따른 보수력 감소를 억제할 수 있었다. 또한 첨가된 결착제에 의한 부가적인 보수력 및 조직감 향상을 얻을 수 있었다. 따라서 본 연구결과 초고압 처리 및 GdL을 조합 사용함으로써 식육 재구성에 요구되는 식염의 함량을 0.5%까지 저감시킬 수 있었으며, 다양한 식물성 단백질을 활용한 식육 재구성이 가능할 것으로 기대되었다. The objective of this study was to investigate the effect of high pressure treatment and type of binding agents on the quality characteristics of restructured pork. For binding agents, 2% (w/w) isolated soy protein (SP), 0.5% (w/w) wheat flour (WF) and 0.5% (w/w) <TEX>${\kappa}$</TEX>-carrageenan (KC) were incorporated into meat batter with or without 0.5% (w/w) glucono-<TEX>${\delta}$</TEX>-lactone (GdL). The restructured pork was pressurized at varying pressure levels (0.1-450 MPa) for 3 min under ambient temperature and thermal treated at <TEX>$75^{\circ}C$</TEX> for 30 min. As quality parameters of restructured pork, pH, water binding properties, instrumental color and texture profile analysis were determined and compared with control (C, no binder). For type of binders, SP exhibited the best water binding properties, however, the impact on textural properties were lesser than KC and WF. The addition of GdL decreased the pH of restructured pork down to 0.4 unit, while high pressure processing prevented the moisture loss caused from pH decrease by GdL. In particular, meat restructuring efficiency of SP as a binder improved under the presence of GdL. Therefore, the present study demonstrated the potential advantages of low amount of GdL (0.5%, w/w) combined with protein based binder (SP) and high pressure processing in restructuring meat particles.

The effect of high pressure treatment and cryotexturization on odorant mixture binding by corn, sorghum and amaranth starch

The binding extent of odorant mixtures from aqueous suspensions by native, high pressure-treated starches and starch cryotexturizates was studied using capillary gas chromatography. The materials were corn, sorghum and amaranth starches. The native and high pressure-treated (650 MPa/9 min) starches were mixed with odorants and incubated (24 h) at room temperature. To obtain the cryotexturizate-odorant product, starch gels were frozen with odorants (−24 °C), stored (48 h) and thawed. Terpene hydrocarbons were strongly bound from the mixture by all the starches analyzed. The nonpolar molecules of terpene hydrocarbons modified the nature of hydrophobic binding sites in starch which in turn affected binding affinity of alcohols, ketones and phenols to the preparations. The competition effect between odorants for the binding sites was found. The varied ability of starch preparations to bind odorants was also related to the granule morphology and alteration in their structure upon treatment used.

Spectroscopic studies on the effect of high pressure treatment on the soluble protein fraction of porcine longissimus dorsi

The effect of high pressure (HP) treatment (400MPa, 10min) of porcine longissimus dorsi was investigated using reflectance spectroscopy and by UV–vis and circular dichroism spectroscopy for the soluble protein fraction. The soluble protein content was expectedly lowered significantly by HP treatment, whereas the solid state fraction of the meat responded to HP by exhibition of characteristic spectral changes in the visible reflectance data with a temporal evolution over the course of 2days. However, the soluble protein fraction did not exhibit the same altered spectral characteristics in the visible region as seen in the solid state following HP, and there were no indications of altered folding of the proteins that remain in solution.

Changes after high-pressure processing on physicochemical parameters, bioactive compounds, and polyphenol oxidase activity of red flesh and peel plum purée

Physicochemical parameters (instrumental color, soluble solid content, titratable acidity, and pH), bioactive compounds (total phenols and anthocyanins), total antioxidant activity, and enzymatic activity of polyphenol oxidase (PPO) were evaluated after the application of hydrostatic high-pressure (HP) treatment on a plum purée (cv. Crimson Globe, with red flesh and peel). Different pressure levels (400, 500, and 600 MPa) were applied at different processing times (1, 150, and 300 s). HP-treated purées were compared with the untreated purée. The inactivation of indigenous microorganisms (total aerobic mesophilic and psychrotrophic counts, and molds and yeasts) of the plum purée after all high-pressure treatments was sufficient to reduce spoilage microorganisms present in plum purée to undetected levels in most of HP-treated purées. No significant changes were observed in pH and soluble solid content after processing. The combined treatments (pressure level and processing time) did not reach a sufficient inhibition of PPO enzyme. Processing induced a significant increase in L*, a*, hue, and chroma, which could enhance the redness perception of treated purées. All HP-treated purées showed a slight reduction in anthocyanins and antioxidant activity after processing. Nevertheless, total phenols were not significantly affected by HP-treatments. In conclusion, high-pressure processing keep most quality parameters and nutritional compounds levels, although, it did not achieve the inhibition of browning related enzymes, which could reduce the shelf-life of plum products during storage. High-pressure processing is one of the most successful technologies to obtain high-quality fruit purées. However, the application of this technology to certain products presents some difficulties due to high-pressure and usually does not affect the activity of browning related enzymes. The present study evaluates the effect of high-pressure treatments on the color, bioactive compounds, and polyphenol oxidase enzyme of plum purée. This is one of the first studies about the application of high pressure technology for the preservation of red flesh and peel plum. High-pressure treatments did not achieve the total inactivation of the polyphenol oxidase enzyme, however, total phenols and anthocyanins were well preserved after the treatments. Our results also show that redness and color luminosity of plum HP-treated purées were well retained. Therefore, high pressure processing offers the opportunity to processing plum purée with fresh-like properties. Nevertheless, the storage of the product could be limited due to the lack of effect of the pressure on the enzyme activity.

Effects of High-Pressure Treatments on the Redox State of Porcine Myoglobin and Color Stability of Pork During Cold Storage

This study investigated the effects of high-pressure treatment on the redox states of myoglobin (Mb) species and the associated color stability of porcine during cold storage. Mb was denatured with increasing pressure and temperature. Ferric Mb exhibited more denaturation at the given pressure and temperature conditions as compared to its ferrous analog, part of ferric Mb was reduced back into ferrous form by high-pressure treatment, and the maximum reduction was shown at the pressure level of 150 MPa at 50 °C. Based on the model study, metMb reduction was favorable when the pressure was below 170 MPa, while Mb denaturation was dominant at higher pressures. Pressure treatment of pork resulted in irreversible Mb denaturation, which prevented the restoration of meat color during cold storage, despite the fact that pressure treatment also improved the metMb-reducing activity of pork. Thus, the results of this study demonstrated that pressure-treated pork color was affected by a balance of the redox systems and by the degree of Mb denaturation. In addition, pressurization at around 150–200 MPa was determined to be ideal in terms of improving the color stability of pressurized pork during storage.