Non-pressurized Samples Research Articles

Improvement on durability of concrete by early age continuous loading treatment

This study investigated the effect of different pressure levels of continuous loading (2.5 MPa, 5.0 MPa, 7.5 MPa, and 10.0 MPa) on the enhancement of concrete durability and proposed the underlying mechanisms behind. To evaluate the efficiency of continuous loading, in addition to compressive strength, the durability, including chloride ion permeability, freeze-thaw resistance and carbonation resistance of the concree were determined, and the micro-scale investigation, including pore structure, microhardness, hydration product and microstructures were conducted. The results showed that, compared to reference (non-pressurized sample), the continuous loading process increased the 28d compressive strength of concrete by 10.3% to 27.4%, decreased chloride ion migration coefficient by 34% to 48.9%, increased freeze-thaw cycles by 20%, and reduced the carbonation depth by 12.3% to 36.2%. The improved performance was attributed to the enhancement of pore structure and reduction of ITZ width, which was a result of multiple factors such as increased compaction and improved movement of free water.

Integrated analysis approach of water and solids for root cause of injectivity decline of water injection well – A case study

Accurate sampling and analysis of injection and flow back water and solids are pivotal to identify the root causes of injectivity decline of water injection well. The present paper is focussed on case study of detailed characterization of injection and flowback water and solids using combination of techniques such as X-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy, inductively coupled plasma optical emission spectroscopy, ion chromatography and water isotope analyser in investigating the cause of injectivity decline. The present study emphasizes the effect of pressurized and non-pressurized water sampling on water analysis results, their scaling tendencies and correlation with compositions of solids encountered. Surface pressurized injection water sample pH result was found acidic with a higher dissolved iron and lower total suspended solids (TSS). Non-pressurized water samples showed comparatively higher pH due to release of CO2. Langelier saturation index (LSI) and ScaleSoftPitzer™ program SI of pressurized water sample showed lower scaling tendency than the non-pressurized water sample. Non-pressurized water samples contained significantly higher concentrations of TSS than the pressurized water sample indicated precipitation of salts in non-pressurized sample. Composition of TSS revealed presence of iron-based compounds, calcite and gypsum. Geochemical and water isotope analysis showed identical composition of injection and flowback water. XRD and XRF analysis of trapped solids revealed different forms of iron oxides and iron sulphides as major phase along with appreciable amount of calcite and quartz. XRF analysis also showed traces of Cr, Mo, and Ni in trapped solids indicated corrosion of tubing/pipes. Solid composition correlates with scaling tendency predicted by ScaleSoftPitzer™ program SI. Presence of iron in pressurized injection water and iron compounds in solids indicate iron-based scale/corrosion as key reason for reduction in injectivity of the well. Systematic sampling, accurate and integrated analysis of water and solids can help to find the dominant causes of injectivity decline and direct oilfield engineers at well site to take appropriate remedial and preventive action.

Effect of Vacuum Impregnation and High Hydrostatic Pressure Treatments on Shelf Life, Physicochemical, and Sensory Properties of Seabream Fillets

Marination is commonly used to preserve fish, which, in combination with other non-thermal technologies, such as vacuum impregnation and high hydrostatic pressure, may help to preserve freshness and extend shelf life. In addition, marination may mask changes in physicochemical properties and the sensory attributes of fish resulting from intense pressurization treatments. In this study, we evaluated the effects of vacuum impregnation (50 mbar for 5 min) alone or in combination with a moderate pressurization treatment (250 MPa for 6 min) on the physicochemical properties, microbiological and oxidative stability, and sensory properties of refrigerated seabream fillets. Compared to conventional marination, vacuum impregnation alone had no effect on the aforementioned properties, except for a higher perception of lemon aroma (0.9 vs. 1.6). However, vacuum impregnation with pressurization reduced the total viable mesophilic aerobic bacteria to counts below 4 log colony forming units (CFU)/g after 16 days of storage at ≤ 2 °C, compared to 6 log CFU/g with conventional marination. Additionally, the color and texture were affected by the pressurization treatment. However, color was more susceptible, and at the beginning of storage, lightness was higher in the pressurized samples than in the control (52 vs. 78). Regardless, this whitening effect and other minor changes in texture and sensory properties compared to conventional marination with vacuum impregnation with pressurization can be considered of little relevance considering the increase in shelf life, the lack of lipid oxidation (maintained at low and similar levels as those of the non-pressurized samples), and the intrinsic whitening effects of certain marinades.

Rapid increase in intradiscal pressure in porcine cervical spine units negatively impacts annulus fibrosus strength

Vertebral endplate fracture is generally accepted to occur as a result of excessive, typically rapid, pressure developed within the intervertebral disc. Clinical evidence of disc disorders later in life following endplate fracture suggests that the disc is also impacted by the fracture event. There is an abundance of evidence to indicate that loss of disc pressure at the time of fracture alters annulus fibrosus loading which could impact disc health long-term. However, little is known regarding the isolated impact of the rapid disc pressurization during the fracture event. This study sought to determine if rapid disc pressurization impacts mechanical properties of the annulus. Intervertebral discs of porcine cervical functional spine units (FSU) were pressurized via rapid injection of hydraulic fluid (standard motor oil). FSUs were subsequently grouped according to whether the pressurization resulted in endplate fracture (‘fracture’; n = 9) or not (‘non-fracture’; n = 13). Annular tensile properties and lamellar adhesion strength were quantified for both fractured and non-fractured samples. A third group was also examined in which FSUs did not undergo the pressurization protocol (‘control’; n = 10). Annular tensile properties were not found to be statistically different between the three conditions (p > 0.05). Lamellar adhesion strength, in contrast, was found to be, on average, 53% lower in specimens which were pressurized compared to control, non-pressurized samples (p = 0.03). Further, no statistical differences in adhesion strength was found between fractured and non-fractured pressurized samples (p = 0.990) indicating that rapid pressurization , and not the presence of an endplate fracture, impacted the mechanical properties of the annulus. Decreased lamellar adhesion strength increases the potential of delamination, which can lead to disc disorders.

Degassing behavior of noble gases from groundwater during groundwater sampling

Noble gases dissolved in groundwater have been used to evaluate characteristics such as origin, residence time and recharge temperature. Although obtaining samples without degassing is highly desired, in certain cases, degassing during sampling is unavoidable. This study investigated the degassing behavior of noble gases during sampling and evaluated the correction methods that can be applied. Groundwater samples were obtained from an underground laboratory and a deep borehole. The amount of exsolved gas was estimated by comparing pressurized and non-pressurized samples. Henry's model, which assumes equilibrium between gas and water, and a diffusion model were applied to the results. In addition, the compositions of gases extracted into an evacuated vessel or hollow fiber contactor were also compared with those of pressurized groundwater samples. The results indicated that significant degassing occurred in unpressurized samples, but equilibrium was achieved between gas and water when the total dissolved gas pressure (TDGP) was relatively small (up to 4.2 atm). Therefore, the d’Ne value, defined as the difference between the Ne concentration of air-saturated water and a sample normalized by the Ne concentration of air-saturated water, could be used in Henry's model to correct exsolution. However, inclusion of the effects of excess air and contamination is problematic. However, when TDGP was high (32 atm in this study), the degassing behavior completely changed and could not be predicted by Henry's model. During extraction of noble gases using an evacuated vessel and hollow fiber contactor, degassing was observed to take place following the diffusion model. As a result, fractionation between Ne vs. Kr and Xe was significant. Thus, although we could extract dissolved Ne with a high recovery ratio (over 0.85), the ratios of Kr/Ne and Xe/Ne were found to be significantly smaller than those in groundwater. The gases extracted by an evacuated vessel or hollow fiber contactor appeared to be applicable only for evaluating He/Ne.

Analysis of the bacterial biodiversity of peaches under refrigerated storage after treatment by high hydrostatic pressure

This study aimed at determining the effect of high hydrostatic pressure (HHP) treatments on the bacterial biodiversity of processed peaches. Peach cubes in peach juice inoculated with epiphytic microbiota recovered from peach surfaces were pressurized at 600MPa for 8min at temperatures of 22°C and of 45°C. Non-pressurized samples were used as controls. Samples were chill stored for 15 days. Application of HHP treatments reduced viable counts of total aerobic mesophiles and yeasts and molds, and delayed recovery of survivors. Pyrosequencing analysis revealed that 35.7% of operational taxonomic units (OTUs) from peaches samples belonged to Actinobacteria (mainly Couchioplanes, Bifidobacterium and Propionibacterium), 31.1% to Firmicutes (mainly Streptococcus, Lactobacillus and Enterococcus) and 28.8% to Proteobacteria (mainly Reyranella, Methylobacterium, Acetobacter, Dyella, Sphingomonas, Tatumella, Enterobacter, Prevotella and Gluconobacter). During storage of control samples, the relative abundances of Gluconobacter and Lactobacillus increased. Application of HHP treatments reduced the relative abundance of Actinobacteria and Firmicutes while Proteobacteria increased. The opposite was observed during storage of the treated samples. Increasing the treatment temperature to 45°C decreased the relative abundance of Actinobacteria. Results from the present study indicate that peach microbiota is strongly influenced by refrigeration storage and by application of HHP treatments.

Effect of high pressure processing on physicochemical and microbiological properties of marinated beef with reduced sodium content

Abstract High pressure processing (HPP) is one of the newer technologies that has shown great potential for manufacturing meat products with reduced sodium content. The aim of this study was to evaluate the effect of HPP applied at different levels in the inactivation of Listeria innocua and Enterococcus faecium inoculated in marinated beef (Longissimus lumborum) with reduced sodium content, as well as its influence on the physicochemical properties of the meat. Samples were inoculated with 106 CFU/g of L. innocua and E. faecium, and marinated with solutions in different concentrations of NaCl (1 or 2%) and citric acid (1 or 2%) for 18 h and treated with high pressure (300, 450 or 600 MPa). Samples treated with 600 MPa were also evaluated regarding physicochemical stability after 14 days of refrigerated storage. Different marinating solutions were not sufficient to reduce initial microbial loads in the non-pressurized samples, but the combination with high pressure caused six log cycle reductions of both microorganisms. The treatment with 2% salt/2% citric acid was the most effective for each pressure considered for both bacteria. No significant changes were observed in the water activity of the samples, however samples with higher concentration of citric acid showed lower (p Industrial relevance The result from this study shows the benefits of using HPP as an alternative meat processing technology to develop a meat product with reduce sodium content. Meat processed by this method have better nutritional quality and extended shelf life as compared to conventional processing. The step taken in this study will aid the meat processing industry for the development of microbiologically safe meat product with low sodium content by the application of high pressure processing.

Assessment of changes in crystallization properties of pressurized milk fat

The aim of the study was to demonstrate the use of fractal image analysis as a possible tool to monitor the effect of pressurization on the crystallization pattern of anhydrous milk fat. This approach can be useful when developing new products based on milk fat. The samples were subjected to different hydrostatic pressure (100, 200, 300, and 400 MPa) and temperature (10 and 40°C) treatments. The crystallization microphotographs were taken with a scanning electron microscope. The image analysis of scanning electron microscope photographs was done to determine a fractal dimension. Milk-fat pressurization under the applied parameters resulted in slight, but statistically significant, changes in the course of crystallization curves, related to the triacylglycerol fraction crystallizing in the lowest temperature (I exothermic effect). These changes were dependent on the value of pressure but not dependent on the temperatures applied during the process of pressurization (at either 10 or 40°C). In turn, significant differences were observed in crystallization images of milk-fat samples subjected to this process compared with the control sample. The results of additional fractal analysis additionally demonstrated the highest degree of irregularity of the surface of the crystalline form for the nonpressurized sample and the samples pressurized at 200 and 300 MPa at 10°C. The lowest value of fractal dimension—indicative of the least irregularity—was achieved for the fat samples pressurized at 400 MPa, 10°C and at 100 MPa, 40°C. The possibilities of wider application of the fractal analysis for the evaluation of effects of parameters of various technological processes on crystallization properties of milk fat require further extensive investigations.

Magnetocaloric effect and critical behaviour in Mn2–pyridazine–[Nb(CN)8] molecular compound under pressure

A comprehensive study of magnetocaloric effect (MCE) and critical behaviour in the ferrimagnetic Mn2–pyridazine–[Nb(CN)8] molecular magnet under hydrostatic pressure is reported. The pressure-induced structural changes provoke the strengthening of magnetic interaction between Mn and Nb centres. Consequently, an increase of critical temperature Tc is observed from 43 K for a sample at ambient pressure (A) to 52.5 K for a sample under a pressure of 1.19 GPa (AHP). The magnetocaloric effect was determined by the magnetization measurements. The application of a hydrostatic pressure of 1.19 GPa causes a decrease in the maximum value of magnetic entropy change ΔS, which for AHP is equal to 4.63 J mol−1 K−1 (7.73 J kg−1 K−1) at μ0ΔH = 5 T, while for A it is 5.36 J mol−1 K−1 (8.95 J kg−1 K−1) for the same magnetic field change. The temperature-dependent parameter n obtained for AHP, describing the field dependence of MCE, is consistent with other critical exponents determined from magnetization measurements. The critical exponents allow us to classify AHP to the 3D Heisenberg universality class, similar to the case of the non-pressurized sample.

High pressure treatments on the inactivation of Salmonella Enteritidis and the physicochemical, rheological and color characteristics of sliced vacuum-packaged dry-cured ham

The effect of high pressure (HP) on Salmonella Enteritidis in sliced dry-cured ham stored under temperature abuse (8°C) during 60d was investigated. After treatment, reductions of S. Enteritidis were 1.06, 2.54 and 4.32 log units in ham treated at 400, 500 and 600MPa for 5min at 12°C, compared to non-pressurized samples. After 60d, counts of S. Enteritidis in ham treated at 400 and 500MPa were 2.56 and 2.66 log units lower than in non-treated ham, whereas the pathogen was only detected after enrichment in ham treated at 600MPa. Lipid oxidation increased with storage and pressurization, whereas total free amino acid contents were similar in HP and control samples after 60d. Dry-cured ham treated at the highest pressures exhibited lower shear resistance, whereas the maximum force to compress the sample was slightly changed. Color (L*, a* and b*) varied with pressurization and storage. Changes induced by HP in dry-cured ham were attenuated during storage.

Volatile compounds in ground beef subjected to high pressure processing: A comparison of dynamic headspace and solid-phase microextraction

The effect on the volatile profile of cooked beef meat, previously subjected to high pressure (400 MPa, 10 min at 12 °C) followed by a 3-d refrigerated storage, was investigated by comparing two extraction techniques i.e. dynamic headspace and solid-phase microextraction. Dynamic headspace was more efficient in extracting 2,3-butanedione and secondary alcohols. Solid-phase microextraction, being more efficient in extracting substances such as 1-alcanols, ethyl esters and acids, permitted to better categorize the effects caused in the volatile fraction by refrigerated storage and high pressure processing. The volatile fraction of cooked control beef meat contained high amounts of diketones and low amounts of methyl ketones, secondary alcohols, aldehydes and fatty acids. While diketones nearly disappeared after the 3-d refrigerated storage, the other compounds together with ethanol and ethyl esters increased significantly. Pressurized beef samples underwent fewer changes than non-pressurized samples during refrigerated storage, leading to a volatile profile closer to that of control beef.

Inhibition of Listeria monocytogenes in Cooked Ham through Active Packaging with Natural Antimicrobials and High-Pressure Processing

Enterocins A and B and sakacin K at 200 and 2,000 activity units (AU)/cm2, nisin at 200 AU/cm2, 1.8% potassium lactate, and a combination of 200 AU/cm2 of nisin and 1.8% lactate were incorporated into interleavers, and their effectiveness against Listeria monocytogenes spiked in sliced, cooked ham was evaluated. Antimicrobial-packaged cooked ham was then subjected to high-pressure processing (HPP) at 400 MPa. In nonpressurized samples, nisin plus lactate–containing interleavers were the most effective, inhibiting L. monocytogenes growth for 30 days at 6°C, with counts that were 1.9 log CFU/g lower than in the control after 3 months. In the other antimicrobial-containing interleavers, L. monocytogenes did not exhibit a lag phase and progressively grew to levels of about 8 log CFU/g. HPP of actively packaged ham slices reduced Listeria populations about 4 log CFU/g in all batches containing bacteriocins (i.e., nisin, sakacin, and enterocins). At the end of storage, L. monocytogenes levels in the bacteriocin-containing batches were the lowest, with counts below 1.51 log CFU/g. In contrast, HPP moderately reduced L. monocytogenes counts in the control and lactate batches, with populations gradually increasing to about 6.5 log CFU/g at the end of storage.

Biogenic amines in pressurized vacuum-packaged cooked sliced ham under different chilled storage conditions

This work was undertaken to study how storage conditions (at constant temperatures of 2 ± 1 and 12 ± 1 °C and temperature fluctuations at 7 ± 5 °C) affect microbial development and the production of biogenic amines in vacuum-packaged cooked sliced ham subjected to high pressure (400 MPa/10 min/30 °C). Initially, the product exhibited low levels of contamination. Microbiological changes during storage depend on the processing (non-pressure and pressure treatment) and the chilled storage conditions. Generally, microbial growth in pressurized samples was similar to that in the non-pressurized samples, although the total viable count and lactic flora were lower and growth was delayed. Processing and storage conditions affected the formation of each amine differently. The most important changes were in tyramine, which formed more quickly in non-pressurized products stored at 12 °C and with temperature fluctuations. The formation of biogenic amines in these products can be prevented not only by ensuring good manufacturing practices and applying high pressure but also by ensuring the right chilled storage conditions.

109 HYDROSTATIC PRESSURE INDUCED INCREASE IN POST-THAW MOTILITY OF FROZEN BOAR SPERMATOZOA

Formerly we reported that a sublethal shock, high hydrostatic pressure (HHP), significantly improves the post-thaw survival of frozen mouse blastocysts and post-thaw motility of frozen bull sperm, presumably from the HHP induced changes in the protein profile [e.g. heat shock proteins (HSPs)] (Pribenszky et al. 2005 Rep. Fert. Dev. 17, 199–200; Pribenszky et al. 2005 Anim. Rep. Sci. 87, 143–150). We now report the effect of HHP on the motility of fresh boar semen, and we compare post-thaw motility of HHP-treated frozen boar semen with non-pressurized frozen-thawed controls. Pressurization was done both at RT and at body temperature (BT). Exp. 1: Semen was extended with Beltsville thawing solution (BTS), centrifuged, diluted with lactose-egg yolk diluent with a final concentration of 6% glycerol and 0.5% Equex (Minitüb, Tiefenbach, Germany) to a sperm concentration of 3 × 109/mL. Diluted sperm were loaded into 0.25-mL straws (IMV, Paillette Crista, France) at RT. Straws were heat sealed then assorted to one of the treatment groups (100, 200, 400, or 800 bar for 40, 80, or 120 min). Non-pressurized samples were left at RT for the corresponding time. For freezing, straws were put at 15°C for 3 h, and then 5°C for 2 h, followed by 3 cm above LN2 for 10 min before plunging into LN2. Exp. 1 was repeated on two boars. Exp. 2: Sperm was treated with 400 bar for 80 min at RT or BT, and was then prepared and frozen as described above, together with non-pressurized controls. Exp. 2 was repeated in five boars. For evaluation, straws were thawed in a 37°C water bath for 2 min. Motility was analyzed with CASA SpermVision 3.0 (Minitüb). For hypothesis testing, a linear mixed model was fit to the motility data. The analysis was carried out in R statistical software. In Exp. 1, the 100-, 200-, and 400-bar treatments did not affect motility; 800 bar treatments resulted in reduced motility compared to control. After 5 h of cold acclimatization, only the groups with 800 bar treatments and the non-pressurized controls had significantly reduced motility. After freezing-thawing motility (% ± SE) in groups pre-treated for 80 min with 200 or 400 bar was 43.2 ± 5.24 and 42 ± 3.24, respectively; control: 23.2 ± 1.83 motility in groups pre-treated for 120 min with 200 or 400 bar was 51 ± 2.33; 55.5 ± 3.63, respectively; control: 41.88 ± 2.97. The pre-treated groups displayed significantly enhanced motility compared to the nontreated controls. In Exp. 2, the HHP treatment performed at BT yielded the highest post-thaw motility compared to the HHP treatment at RT, or the non-pressurized controls (59.75 ± 2.59; 46.43 ± 2.05; 37.37 ± 2.19, respectively). All of these results differed significantly from each other. In conclusion, HHP treatment, simply inserted before the freezing step, can significantly increase post-thaw motility and yield consistent acceptable results. The effect of the treatment is even stronger at BT, but great care has to be taken to maintain BT from the time of sperm collection till the end of the treatment. Further experiments are being conducted concerning the pressure-induced alterations in the protein profile of boar spermatozoa (fresh and frozen-thawed). This work was supported by OTKA061975 and TST050157.

High pressure treatment of dry-cured Iberian ham. Effect on radical formation, lipid oxidation and colour

The effect of high-pressure treatment (200, 400, 600 and 800 MPa) on radical formation in solid samples of dry-cured Iberian ham and in ham slurries was evaluated using the spin-trapping technique and electron spin resonance (ESR) spectroscopy. In addition, hexanal was, as a secondary lipid oxidation product, assessed by gas chromatography. The effect of pressure treatments on ESR signals determined in the spin-trapping assay following pressure treatment in solid samples of dry-cured Iberian ham was not statistically significant. However, the lowest level of pressure applied initiated radical formation and promoted lipid peroxidation, whereas intermediate to high levels of pressure seemed to promote further reaction and disappearance of free radicals. Pressure significantly affected hexanal content in the same way as seen for formation of free radicals. Regarding the slurries prepared from dry-cured ham, pressure significantly increased the tendency of radical formation as seen from the ESR signals and significantly increased the hexanal content. The different pattern between solid ham and ham slurries points toward an initiation mechanism associated with the membrane phospholipids for oxidation. In addition, surface colour (L*, a* and b* values and percent reflectance values) of non-pressurized and pressurized (200–800 MPa) dry-cured Iberian ham samples was assessed. Non-pressurized samples showed a higher lightness than pressurized samples, and redness significantly decreased with pressure treatment.

Extension of shelf life of chilled hake (Merluccius capensis) by high pressure/Prolongación de la vida útil de merluza (Merluccius capensis) sometida a altas presiones conservada en refrigeración

Vacuum packed hake muscle subjected to 400 MPa (three 5-min cycles) at 7 °C proved to be more stable at chilled temperatures (2-3 °C), and sensorially acceptable, until 43 days of storage in comparison with the nine days for the non-pressurized hake. The lot pressurized at 400 MPa had the appearance of cooked muscle. The microbial load was initially reduced by two log units by pressurization at 400 MPa. Trimethylamine nitrogen (TMA-N) values were also very low. Pressurization had no effect on dimethylamine nitrogen (DMA-N) production. The lot pressurized at 400 MPa showed slower increase in drip loss from day 15 of storage. In the lot subjected to 200 MPa (three 5-min cycles) at 7 °C, which retained the appearance of raw fish, microorganisms were one log unit lower than in the non-pressurized sample and TMA-N was lower. In conclusion, the chilled shelf life was prolonged by about one week in the lot pressurized at 200 MPa and about two weeks in the lot pressurized at 400 MPa.

Oyster Preservation by High-Pressure Treatment

The purpose of this study was to analyze the effect of 10-min continuous pressure and pulsed pressure in two 5-min steps (400 MPa at 7°C) on the microbial flora, total volatile bases, pH, and texture of purified and unpurified oysters. High-pressure treatment reduced the number of all the target microorganisms (total viable count, H2S-producing microorganisms, lactic acid bacteria, Brochothrix thermosphacta, and coliforms), in some cases by around 5-log units. The difference between the counts in the control and the pressurized oysters remained stable throughout 41 days of storage at 2°C. No Salmonella spp. were detected in either the control batch or the pressurized batches during this storage period. Deterioration of the oyster was accompanied by increased total volatile bases, mainly in the nonpressurized samples. The pH was practically constant in the pressurized oysters and fell slightly in unpressurized samples. As for mechanical properties, shear strength values were higher in pressurized than in unpressurized oysters. Step-pulse pressurizing (400 MPa at 7°C in two 5-min pulses) produced no apparent advantages over continuous pressurizing based on any of the indices used.

High pressure/thermal treatment of meat batters prepared from freeze–thawed pork

Various meat batters were prepared from pork subjected to different freeze–thaw cycles. These batters were pressurized (300 MPa, 30 min) at low, non-denaturing temperature (10°C) followed by heating (70°C) (PLT+H) and at high, denaturing temperature (70°C) (HUPC). Nonpressurized (NP), heated-only (70°C) sample were also produced. Freezing of meat influenced water binding and textural properties of meat batters; the influence on texture was affected by thermal and pressure conditions. Pressure prior to heating produced a coarse, irregular and loose protein matrix, favoring the formation of weaker gel structures than were found in non-pressurized samples. Pressurization at denaturing temperatures reduced the level of protein denaturation induced by the thermal treatment. The resulting gel structures had better water binding properties but were weaker than non-pressurized samples and samples pressurized prior to heating.

Heating of Chicken and Pork Meat Batters under Pressure Conditions: Protein Interactions

Protein molecular interactions involved in the formation of the protein network of pork and chicken gels made by heating (70 °C) under pressure (200 and 400 MPa) were studied. Gel properties were influenced both by pressure treatment and by species. In both species, pressurization favored gels that had better water binding properties but were less hard and chewy. Nondenatured proteins were thermally detected in the batters after all of the combined pressure/heat processes. Heating-under-pressure conditions caused breakdown of myosin molecules, so that salt soluble protein content was higher than in nonpressurized samples. Keywords: High pressure−thermal treatments; comminuted meat; protein interaction; electrophoresis; texture; DSC

High‐pressure‐cooked Low‐fat Pork and Chicken Batters as Affected by Salt Levels and Cooking Temperature

ABSTRACTThe application of high pressure (200 and 400 MPa, 30 min) favored water and fat binding properties of chicken and pork batters even at low ionic strength. Textural properties of meat batters (particularly hardness and chewiness, and to a lesser extent springiness and cohesiveness) were influenced by cooking temperature. High pressures influenced the texture of batters, so that pressurized samples were less hard, cohesive, springy or chewy than nonpressurized samples; this effect was not related to on salt concentration. High pressure treatment limited the formation of gel structures, which probably was associated with its preserving effect against thermal denaturation of meat proteins.