Effect Of High Hydrostatic Pressure Treatment Research Articles

Effect of High-Pressure Treatments on the Properties of Food Packaging Materials with or without Antimicrobials.

The aim of this research work was the comparative study of the different properties of interest in the case of plastic materials for food use before and after being subjected to treatment by high hydrostatic pressure (HHP) as well as the impact of additivation with antimicrobials. This method of food preservation is currently on the rise and is of great interest because it is possible to extend the shelf life of many foods without the need for the use of additives or thermal processing, as is the case with other preservation methods currently used. The effects of HHP treatment (680 MPa for 8 min) on plastic materials commonly used in the food industry were studied. These materials, in sheet or film form, were polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), multilayer polyethylene terephthalate-ethylene-vinyl alcohol copolymer-polyethylene (PET-EVOH-PE), multilayer polyethylene-polyethylene terephthalate (PE-PET), polyvinyl chloride aluminum (PVC-AL), and polylactic acid (PLA), which were provided by manufacturing companies in the sector. PE, PP, and PLA activated with tyrosol, zinc oxide, or zinc acetate were also tested. The phenomena and properties, such as overall migration, thermal behavior, oxygen barrier, and physical properties were analyzed before and after the process. The results show that the HHP process only slightly affected the properties of the materials. After pressurization, oxygen permeability increased greatly in PVC-AL (from 7.69 to 51.90) and decreased in PLA (from 8.77 to 3.60). The additivation of the materials caused a change in color and an increase in oxygen permeability. The additivated PE and PP showed migration values above the legal limit for certain simulants. The HHP treatment did not greatly affect the mechanical properties of the additivated materials. The main increases in the migration after HHP treatment were observed for PE activated with tyrosol or zinc oxide and for PS activated with zinc oxide. Activated PLA performed the best in the migration studies, irrespective of the HHP treatment. The results suggest that activated PLA could be used in HHP food processing as an inner antimicrobial layer in contact with the food packed in a container with the desired oxygen permeability barrier.

High Hydrostatic Pressure Treatment of Oysters (Crassostrea gigas)-Impact on Physicochemical Properties, Texture Parameters, and Volatile Flavor Compounds.

High hydrostatic pressure (HHP) treatment is a non-thermal processing technology, which is widely used in the food processing field at present. In this study, the effects of HHP treatment (100~500 MPa for 5 min) on the physicochemical properties, texture parameters, and volatile flavor compounds of oysters were investigated. The results showed that HHP treatment increased the water content while reducing the crude protein and ash content of the oyster. Texture parameters showed that HHP treatment improved the hardness, springiness, chewiness, and cohesiveness of oysters, compared with the control group. In addition, the saturated fatty acid (SFA) content was slightly increased after HHP treatment, while the difference in monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) content was not significant. Furthermore, HHP increased hexenoic aldehyde, 2,4-heptadienal, 1-octene-3-ol, and 2-octen-1-ol and decreased the contents of 3. 6-nadien-1-ol, 3-octanone, and 2-undecanone, suggesting that HHP might inhibit the fishiness of oyster and showed a positive effect on its flavor. Based on the above results, HHP improved the edible qualities such as texture properties and volatile flavor of oysters. This meets the requirements of consumers on the edible quality of seafood and provides new ideas for the development of seafood.

High hydrostatic pressure treatment of Arthrospira (Spirulina) platensis extracts and the baroprotective effect of sugars on phycobiliproteins

The effect of High Hydrostatic Pressure (HHP) (600 MPa; 300 s) upon phycobiliproteins from Spirulina platensis extract, in aqueous systems, has been investigated along with the potential baroprotective ability of several sugars (sucrose, trehalose and glucose) at different concentrations (20%, 40% w/w). Phycobiliproteins stability and technological functionality were assessed through spectroscopical and colour analysis, and radical scavenging ability.HHP treatment resulted in a decrease of the phycobiliproteins concentration with allophycocyanin being the most sensitive towards HHP stress (p ≤ 0.05). Addition of saccharides had a positive effect on phycocyanin stability with a higher residual concentration after HHP treatment (p ≤ 0.05) irrespective of the type and concentration of sugars added in the system, whilst baroprotective effects on allophycocyanin and phycoerythrin were observed only at the highest (40%) concentrations tested (p ≤ 0.05). After the HHP treatment, colouring ability of Spirulina platensis extract resulted in being directly correlated to phycocyanin concentration variation (R2 = 0.75). Addition of sugars preserved the antioxidant activity of the extract subject to high pressure regardless of the sugar type. Industrial relevanceSpirulina platensis has become a popular ingredient among manufacturers and consumers, especially for its technological functionality and nutritional properties. Nevertheless, processing and storage may result detrimental for its performance in foods. High hydrostatic pressure is a successful, non-thermal technology that is finding increasing applications in the food industry though processing costs of food products stabilized by HHP result, nowadays, being 7 to 15-fold higher than thermal pasteurization. However, consumers today are willing to pay higher prices for higher quality products with better sensory profiles and nutritional properties. Moreover, compared to thermal pasteurization, HHP is a rather new technology whose cost-effectiveness and environmental impact is expected to improve over time, with a consequent reduction of the gap among performance of these two technologies. Hence, this study focused on the effects of HHP treatments on aqueous Spirulina platensis extracts, alone or added with small saccharides to evaluate their potential baroprotective abilities, providing results of interest for application in food product design and development.

High Hydrostatic Pressure Modulates the Folate and Ascorbic Acid Accumulation in Papaya (Carica papaya cv. Maradol) Fruit

High hydrostatic pressure (HHP) has previously induced de novo carotenoid (provitamin A) biosynthesis in papaya fruit tissue, possibly as a response to the oxidative stress. Papaya is also an excellent source of other vitamins, such as tetrahydrofolate (THF), its derivatives (folates, vitamin B9), and ascorbic acid (vitamin C). This work evaluated the immediate effects of HHP treatments (50–400 MPa for 3–60 min) on folate and ascorbic acid contents of fresh-cut papaya fruit. Folates and ascorbic acid were characterized by high-performance-liquid-chromatography with electrochemical and diode-array detections (HPLC-EC and DAD, respectively). Ascorbic acid levels increased in all conditions (4–28%) when compared with non-treated controls. 5-Methyl-THF (5-CH3-THF) (73%) and THF (22%) were the main folate species present in papaya fruit. HHP treatments increased 5-CH3-THF and total folate contents by 35% and 25%, at lower (50–100 MPa) and higher (400 MPa) pressures for 30 min, respectively. Folate molecule contains a glutamyl tail, involved in its function as a cofactor, tissue localization, and stability. 5-CH3-THF from papaya fruit exists with a very long polyglutamyl tail (Glu1–17). Both pressure and time increased concentrations of 5-CH3-THF Glu1 species (up to 250%), mainly at the 100 and 400 MPa/30 min conditions, whereas the polyglutamyl forms (Glu2–17) were not affected. Results documented, for the first time, that specific HHP treatments can positively modulate accumulation of vitamins B9 and C in papaya fruit.

Effects of high hydrostatic pressure on the structural characteristics of parvalbumin of cultured large yellow croaker (Larimichthys crocea)

Parvalbumin (PV) induces IgE-mediated allergic reactions and is an important allergen in fish species. The effects of high hydrostatic pressure (HHP) treatment (300, 450, 600 MPa; 10 min) on the structural characteristics of PV in cultured large yellow croakers (Larimichthys crocea) were investigated. The effects of HHP treatment were analyzed by free sulfhydryl content, surface hydrophobicity, circular dichroism spectroscopy (CD), laser Raman spectroscopy, and endogenous fluorescence spectroscopy. The results showed that after HHP treatment, the free sulfhydryl content in PV decreased slightly and the surface hydrophobicity increased, indicating changes in the tertiary structure of PV. CD showed that with increase in pressure, the content of α-helix in the secondary structure of PV decreased slightly. This indicated that the stability of the secondary structure of PV was affected by HHP treatment. The secondary structure of PV was dominated by α-helix and that the α-helix content in PV also increased. The redshift of endogenous fluorescence spectroscopy decreases the fluorescence intensity. Practical applications Parvalbumin (PV) in the large yellow croaker is the main allergen with a molecular weight of 12 kDa. It is an allergy risk to consumers. The application of high hydrostatic pressure (HHP) treatment of 200 to 400 MPa could be successfully applied to changes of the tertiary and secondary structure of PV. This suggests a direct and important relationship between the structural characteristics and allergenicity of PV. The application of HHP treatment effectively reduced the allergenicity of PV. It is useful to desensitization of the large yellow croaker before processing.

High hydrostatic pressure effect in extraction of 5-methyltetrahydrofolate (5-MTHF) from egg yolk and granule fractions

Abstract High hydrostatic pressure (HHP) and centrifugation were combined to produce a 5-methyltetrahydrofolate (5-MTHF)-enriched extract from egg yolk. This study focused on the effect of HHP treatment (200–600 MPa; 5, 10 min) in extraction of 5-MTHF from egg yolk and granule. Specifically, HHP-treatment at 400 MPa for 5 min significantly (p Industrial relevance: HHP combined with centrifuge separation was used an efficient and eco-friendly process for improving the recovery of water soluble vitamin 5-MTHF extracted from egg yolk granule. HHP treatment at 400 MPa for 5 min was the optimum condition where a higher concentration of 5-MTHF separated from granule. This study shows promising results in relation to applications of HHP in improving extraction and recovery of bioactive components from egg yolk and the future applications of granules as an ingredient in the food industry.

High hydrostatic pressure treatments enhance volatile components of pre-germinated brown rice revealed by aromatic fingerprinting based on HS-SPME/GC–MS and chemometric methods

Germination favors to significantly enhance functional components and health attributes of whole-grain brown rice (BR), but the production of germinated BR (GBR) compromises the typical rice flavor perception due to soaking process. Simultaneously, high hydrostatic pressure (HHP) is considered as an effective processing technique to enhance micronutrients utilization efficiency of GBR and improve products flavor, but no information about the effects of HHP treatments on volatile fingerprinting of GBR has been reported. Therefore, the objective of this work was to apply HHP to improve the flavor and odor of GBR grains by exploring HHP-induced changes in aroma compounds. GBR grains were obtained by incubating at 37°C for 36h, and subsequently subjected to HHP treatments at pressures 100, 300 and 500MPa for 15min, using 0.1MPa as control. Headspace solid-phase micro extraction coupled to gas chromatography mass spectrometry was used to characterize process-induced shifts of volatile organic compounds fingerprinting, followed by multivariate analysis. Our results confirmed the significant reduction of total volatile fractions derived from germination process. Contrarily, the following HHP treatments greatly enhanced the flavor components of GBR, particularly characteristic odorants including aldehydes, ketones, and alcohols. Principal component analysis further indicated the different influence of germination and high pressure on the changes in volatile components. Partial least square-discrimination analysis suggested that 4-vinylguaiacol was closely linked to germination, whereas E,E-2,4-decadienal, E-2-hexenal, E,E-2,4-heptadienal and benzyl alcohol could be considered as volatile biomarkers of high pressure.

High hydrostatic pressure as a method to preserve fresh-cut Hachiya persimmons: A structural approach.

The "Hachiya" persimmon is the most common astringent cultivar grown in California and it is rich in tannins and carotenoids. Changes in the microstructure and some physicochemical properties during high hydrostatic pressure processing (200-400 MPa, 3 min, 25 ℃) and subsequent refrigerated storage were analyzed in this study in order to evaluate the suitability of this non-thermal technology for preservation of fresh-cut Hachiya persimmons. The effects of high-hydrostatic pressure treatment on the integrity and location of carotenoids and tannins during storage were also analyzed. Significant changes, in particular diffusion of soluble compounds which were released as a result of cell wall and membrane damage, were followed using confocal microscopy. The high-hydrostatic pressure process also induced changes in physicochemical properties, e.g. electrolyte leakage, texture, total soluble solids, pH and color, which were a function of the amount of applied hydrostatic pressure and may affect the consumer acceptance of the product. Nevertheless, the results indicate that the application of 200 MPa could be a suitable preservation treatment for Hachiya persimmon. This treatment seems to improve carotenoid extractability and tannin polymerization, which could improve functionality and remove astringency of the fruit, respectively.

Changes in tannin solubility and microstructure of high hydrostatic pressure–treated persimmon cubes during storage at 4 °C

Condensed tannins are important bioactive compounds largely present in persimmon (Diospyros kaki L.f.). The aim of this work was to study the effect of the structural changes occurred during refrigerated storage in persimmon cubes treated with high hydrostatic pressure (HHP) on the solubility and location of tannins, and some physicochemical properties. Persimmon cubes were submitted to 200 MPa for 3 and 6 min at 37 °C and stored at 4 °C for 28 days. The microstructural study was carried out by low-temperature scanning electron microscopy, light microscopy and transmission electron microscopy. The physicochemical properties studied were total soluble tannins (TST), total soluble solids (TSS), pH, lightness, firmness and cohesiveness. Microstructural studies showed that HHP treatment causes cell wall and membrane disruption in persimmon tissue. Retraction of the tonoplast and loss of cell turgor were greater as the storage time increased. Precipitated tannins inside and outside the cells and a progressive separation of adjacent cells during the storage time could be observed. Significant (P < 0.05) decreases in TST, TSS and lightness as well as a significant (P < 0.05) increase in pH took place in HHP-treated samples after 7 days of storage. Samples treated for 3 min showed higher firmness than the rest of the samples during the whole storage period, whereas HHP-treated samples showed higher cohesiveness than the control samples. The effects of HHP treatments and later storage at 4 °C on microstructure, tannin solubility and extractability, and some physicochemical properties of persimmon cubes depend on the treatment conditions and the storage time. HHP treatment might decrease persimmon astringency as well as increase bioactive compounds accessibility.

The effects of high hydrostatic pressure treatment on the flavor and color of grated ginger.

High hydrostatic pressure (HHP) was applied to grated ginger in order to inactivate quality-degrading enzymes in a non-thermal manner. The effects of HHP treatment on the flavor and the color of the grated ginger were investigated just after treatment and during storage. After HHP treatment (400 MPa, 5 min), geraniol dehydrogenase (GeDH) was inactivated to less than 5%, but the activity of polyphenol oxidase (PPO) was reduced only to 37%. Heat treatment (100 °C, 10 min) inactivated GeDH to 43% and PPO to about 10%. In storage, the reduction of geranial, neral, and citronellal to the corresponding alcohols was observed in the untreated and the heat-treated ginger, while it was not in the HHP-treated grated ginger. In the HHP-treated sample, terpene aldehydes almost disappeared without the formation of the corresponding alcohols. Browning was not observed immediately after HHP treatment, while it was complete in the heat-treated sample. The color change during storage appeared to reflect the residual activity of PPO.

Ascorbic Acid Is the Only Bioactive That Is Better Preserved by High Hydrostatic Pressure than by Thermal Treatment of a Vegetable Beverage

Variations in levels of antioxidant compounds (ascorbic acid, total phenolics, and total carotenoids), total antioxidant capacity, and color changes in a vegetable (tomato, green pepper, green celery, onion, carrot, lemon, and olive oil) beverage treated by high hydrostatic pressure (HHP) were evaluated in this work. The effects of HHP treatment, four different pressures (100, 200, 300, and 400 MPa) and four treatment times for each pressure (from 120 to 540 s) were compared with those of thermal treatment (90-98 °C for 15 and 21 s). High pressure treatment retained significantly more ascorbic acid in the vegetable beverage than thermal treatment. However, no significant changes in total phenolics were observed between HHP treated and thermally processed vegetable beverage and unprocessed beverage. Color changes (a*, b*, L, chroma, h°, and ΔE) were less for pressurized beverage than thermally treated samples compared with unprocessed beverage.

Cessation of Cytokinesis inSchizosaccharomyces pombeduring Growth after Release from High Hydrostatic Pressure Treatment

On the basis of our previous study concerning the effect of high hydrostatic pressure treatment (HPT) on Escherichia coli FtsZ ring (bacterial cytoskeleton) formation, we aimed to determine the effect of HPT on the growth properties of a representative eukaryotic microbe, Schizosaccharomyces pombe, in relation to the behavior of genuine cytoskeletons. Microtubules were visualized with GFP-linked alpha-tubulin. Actin-related cytoskeletons were fluorescently stained with rhodamine-phalloidin. We observed growth retardation of about 10 h in post growth after HPT (75 MPa, 30 min, 28 degrees C), which caused only a little loss of viable cells. In accordance with the period of growth retardation, cessation of cytokinesis and disappearance of the contractile ring (composed of actin, myosin II, and other proteins), directly participates in cytokinesis, continued for 18 h after HPT. On the other hand, the microtubules disappeared only for 6 h after HPT. Based on these observations, the contractile ring was the site most sensitive to HPT resulting in the cessation of cytokinesis.

The effect of the high hydrostatic pressure technology on livestock products monitored by NIR spectroscopy and chemosensor array

Experiments were performed to study the effects of high hydrostatic pressure (HHP) and gamma irradiation, respectively, from two aspects. The effects of HHP treatments on minced pork meat exposed to 50–800 MPa for 20 min and stored at 4 °C for a period of 1 week were examined. The immediate effects of HHP on egg white samples were compared to that of irradiation. Egg white samples were subjected to irradiation (3 kGy) and HHP treatment (400 MPa, 5 min) and measured immediately after treatments. The recorded electronic nose data and near infrared spectra were evaluated using different methods of multivariate qualitative analyses.

Effects of pressure- and thermal-pasteurization on volatiles of some berry fruits

In principle, high hydrostatic pressure (HHP) processing offers the possibility to preserve berry products while affecting their volatile components less than heat pasteurization. Therefore, we performed preliminary investigations to compare effects of HHP treatment (600 MPa, 5 min, at ambient temperature) and heat pasteurization (80 °C, 5 min) on volatile composition of raspberry, strawberry and blackcurrant purees measured by ‘electronic nose’ at 25 °C. Changes in the head space volatiles could be monitored by this method. Taking into account the confusion matrix of the discriminant analysis, heat-treatment had a more significant effect on volatile compounds than HHP. So, application of HHP treatment can retain volatiles of berry products.

High-hydrostatic-pressure treatment impairs actin cables and budding in Saccharomyces cerevisiae

We previously reported that the postgrowth of Escherichia coli K-12 after high-hydrostatic-pressure treatment (HPT) as moderate as 75 MPa for 30 min at 37 degrees C induced the formation of elongated cells due to an HPT-induced disorder in FtsZ ring formation, which is essential for cell division. Because an FtsZ ring is known as a bacterial cytoskeleton, we examined the effect of HPT on a eukaryotic cytoskeleton, such as actin cables (long bundles of actin filaments), of Saccharomyces cerevisiae. We found that actin cables disappeared after HPT (100 MPa) and were not reorganized until 3.5 h of growth after HPT. As long as actin cables disappeared, budding did not start. We also demonstrated that the in vitro polymerization of actin monomers was highly sensitive to HPT.

128 IMPROVED POST-THAW MOTILITY, VIABILITY, AND FERTILITY ARE ACHIEVED BY HYDROSTATIC PRESSURE-TREATED BULL SEMEN

Previously, we reported that high hydrostatic pressure (HHP) significantly improves post-thaw survival of frozen mouse and IVP bovine blastocysts, presumably from the induction of shock proteins (Pribenszky et al. 2005 Anim. Repr. Sci. 87, 143–150; 2005 Repr. Dom. Anim. 40, 338). We also have reported increased post-thaw survival of HHP-treated boar and bull semen (Pribenszky et al. 2004 Repr. Fert. Dev. 17, 199–200; 2005 Repr. Fert. Dev. 18, 162–163). We now report further data on the effect of HHP treatment on motility, viability, and fertility of frozen–thawed bull semen. HHP treatments were executed by a computer-controlled pressurizing device (Cryo-Innovation, Ltd., Budapest, Hungary). Semen of 21 bulls was diluted individually to a sperm concentration of 8 � 107 mL-1 with AndroMed� or Triladyl� extenders (MiniT�b, Tiefenbach, Germany). Diluted sperm was loaded into 0.25-mL straws at 25�C, and then divided into 2 groups: one group was treated with a HHP pulse defined and optimized earlier (30 MPa for 90 min); the other group was held at 5�C for the corresponding time. After HHP, treated samples also were placed at 5�C for 3–4 h. After equilibration at 5�C, samples were frozen (10 min at -110�C, and then plunged into LN2). Straws were thawed in a 35�C water bath for 30 s. Progressive motility was assessed by the CASA system (MiniT�b). Experiments were replicated twice for each bull. Paired t-test was used to analyze data. HHP treatment significantly increased the post-thaw motility of the frozen semen of the bull population examined. The mean of the differences was 21.14% (95% confidence interval: 13.56–28.72); P = 1.08 � 10-5. The post-thaw motility of 3, 7, and 5 of the 21 bulls increased by an additional 35–60%, 25–35%, and 10–25%, respectively; no effect was seen for 6 of the bulls. Four of the 7 bulls with low (3–19%) post-thaw motility were improved to the range of 43–70% by HHP treatment. Semen of 10 bulls was the subject of viability analysis individually. Sperm head, tail, and acrosome membrane integrity were evaluated with Kovacs-Foote staining (Kovacs and Foote 1992 Biotech. Histochem. 67, 119–124) and counting 300 sperm/sample. Paired t-test was used to analyze data. With HHP treatment, the proportion of the cells with intact tail, head, and acrosome increased significantly (P d 0.008). Eighty-two cows were inseminated with HHP-treated frozen–thawed semen; the 60 days non-return rate was 90.24%, whereas the 60 days non-return rate in the same population and time without treatment was 82.3% (n = 4789). Data were analyzed with the exact binomial test. HHP treatment significantly improved the non-return rate (P = 0.035; 95% confidence interval: 0.83–1.00). HHP treatment substantially increases the post-thaw semen quality of the bull population. Also, the semen of a proportion of bulls with very low semen freezability can be increased to the range where it can be frozen commercially. Further investigations are needed, including large-scale field trials incorporating the insemination of the otherwise low freezers and the biological background of the process. This work was supported by GVOP-TST050157 and Besamungsanstalt Klessheim.

Modification of whey protein concentrate hydrophobicity by high hydrostatic pressure

The objective of this study was to evaluate the influence of high hydrostatic pressure (HHP) treatments on hydrophobicity of whey protein concentrate (WPC). An increase in binding affinity or decrease in apparent dissociation constant indicates increased hydrophobicity, which is positively correlated with functional properties. The effects of HHP treatment (600 MPa, 50 °C, 0 to 30 min) on intrinsic fluorescence of WPC and the binding properties of WPC for aromatic 1-anilino-naphthalene-8-sulfonate (ANS) and aliphatic cis-parinaric acid (CPA) probes were studied. HHP treatment of WPC resulted in an increase in intrinsic tryptophan fluorescence intensity and a 4 nm red shift after 30 min of treatment, which indicated changes in the polarity of tryptophan residues microenvironment of whey proteins from a less polar to a more polar environment. There was an increase in the number of binding sites of WPC for ANS from 0.16 to 1.10 per molecule of protein after HHP treatment for 30 min. No significant changes in the apparent dissociation constant of WPC for ANS were observed after HHP treatment, except for an increase from 1.8 × 10 −5 M to 3.3 × 10 −5 M after 30 min of HHP treatment. There were no significant changes in the number of binding sites of WPC for CPA. However, increased binding affinities of WPC for CPA were observed after the come-up time or 10 min of HHP treatment, with a decrease of apparent dissociation constant from 2.2 × 10 −7 M to 1.1 × 10 −7 M. The binding sites of WPC may become more accessible to the aliphatic hydrophobic probe CPA after the come-up time or 10 min of HHP treatment. These results indicate that HHP treatment of WPC yields increases in the number of binding sites for an aromatic hydrophobic probe, while aliphatic hydrophobic binding affinity of WPC is enhanced after come-up time or 10 min of HHP treatment. Industrial Relevance Text The functionality of protein molecules depends on hydrophobic, electrostatic, and steric parameters of the protein structure. Modifications of proteins that enhance hydrophobicity show promise for improving functional properties of foods. An increase in binding affinity or decrease in apparent dissociation constant indicates increased hydrophobicity. High hydrostatic pressure (HHP) affects the hydrophobicity of beta-lactoglobulin (β-LG), the primary protein in whey, and increases the binding affinity of β-LG for 1-anilino-naphthalene-8-sulfonate and cis-parinaric acid. However, little work has been done regarding the effects of HHP on whey protein concentrate (WPC) hydrophobicity and flavor-binding properties, and whether the presence of multiple proteins in WPC has significant influence on the behavior of whey proteins during HHP treatments. WPC is a good candidate for testing the practical utility of the application of HHP to modify the functional properties of a complex protein system since it is in the form that the ingredient is utilized in a number of food applications. The current work describes the effects of HHP on hydrophobicity of WPC and potential applications.

USE of HYDROSTATIC PRESSIJRE to PRODUCE HIGH QUALITY and SAFE FRESH PORK SAUSAGE

The effects of high hydrostatic pressure (HHP) on the survival of microor ganisms and quality changes of fresh pork sausages were investigated. Pork sausage inoculated with Listeria monocytogenes at 1O7 CFU/gram was prepared and subjected to HHP at 414 and 552 MPa, at treatment temperatures of 25 and SOC. for various time intervals to examine pressure effects on inactivation of bacteria. At a pressure of 414 MPa and SOC for 2 min, the microorganisms in fresh pork sausages were completely inactivated. Partial discoloration of meat was observed after 10 min of pressurization above 414 MPa at either temperature. The effect of HHP treatment on the physical and rheological properties of sausage was also studied. the sausages increased infirinness with an increase in the pressure applied. the pressure-treated sausages were generally lighter in color as compared with the heat-treated sausages. The optimal pressure/temperature/time conditions that resulted in minimum quality changes with microbiologically safe fresh pork sausages was 414 MPa and SOC for 2 min.