Dissertations / Theses: 'High pressure processing'

1

Lakshmanan, Ramamoorthi. "High-pressure processing of cold-smoked salmon." Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415299.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

King, Alexander J. "High Pressure Processing of Corn and Wheat Starch :." Connect to this title online, 2005. http://hdl.handle.net/1811/298.

Full text

Abstract:

Thesis (Honors)--Ohio State University, 2005.
Title from first page of PDF file. Document formattted into pages: contains 46 p.; also includes graphics. Includes bibliographical references (p. 42-46). Available online via Ohio State University's Knowledge Bank.

APA, Harvard, Vancouver, ISO, and other styles

3

Al-Zubaydi, Ahmed. "High-pressure torsion processing of AZ91 magnesium alloy." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/386345/.

Full text

Abstract:

AZ91 magnesium alloy has been successfully processed at room temperature by high–pressure torsion as well as at elevated temperatures. Ultrafine grains and nano–sized particles of β–phase have developed with increasing number of turns. The hydrostatic pressure, the geometry of the processing zone and the unidirectional nature of torsional straining during the HPT processing have facilitated processing of AZ91 alloy at room temperature. Extensive grain refinement and twinning segmentation of the coarse grains have been observed in the microstructures processed at room temperature and elevated temperatures, respectively. The twins have been observed at all processing temperatures during processing and their distribution was proportional to the processing temperature and number of turns. The morphology and distribution of the β–phase have altered during processing, with fragmentation of coarse clusters of the β–phase into nano–sized particles and the alignment of these particles in the direction of torsional strain being observed. Microstructural homogeneity has gradually developed at a relatively low number of turns using the lower processing temperature and continued with increasing number of turns. A significant improvement in the strength of the alloy has been found after HPT processing at all processing temperatures. The dislocation density has developed significantly for the alloy processed at room temperature rather than at elevated temperatures with increasing number of turns. An experimental Hall–Petch relationship has emphasized a significant dependence of the strength on grain size for the alloy processed at room temperature. The high–strain rate superplasticity, low–temperature superplasticity, and thermal stability of the processed alloy have been observed and attributed to the ultrafine–grained microstructures produced by HPT at room temperature and the dispersion of nano–sized β–phase particles. Grain–boundary sliding was the main deformation mechanism during the high–strain rate superplasticity regime. Glide–dislocation creep accommodated by grain–boundary sliding was the deformation mechanism operating during the low–temperature superplasticity regime. At high temperature and slow strain rate grain–boundary sliding was accommodated by a diffusion creep mechanism.

APA, Harvard, Vancouver, ISO, and other styles

4

Thumthanaruk, Benjawan. "The effect of high pressure processing on polyphenoloxidase /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486463321626645.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Ramaswamy, Raghupathy. "Thermal behavior of food materials during high pressure processing." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1190122901.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Shook, Carla Marie. "The effects of high pressure processing on diced tomatoes." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392909096.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Lou, Fangfei. "Survival of Nonculturable Human Noroviruses during High Pressure Processing." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408727004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Michel, de Arévalo Aymeé. "Phytosterol enrichment in vegetable oil by high pressure processing." Aachen Shaker, 2008. http://d-nb.info/994829892/04.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Lecky, Matthew. "Continuous high pressure carbon dioxide processing of watermelon juice." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0011651.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Zhu, Songming 1961. "Phase transition studies in food systems during high pressure processing and its applications to pressure shift freezing and high pressure thawing." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84862.

Full text

Abstract:

High-pressure (HP) depresses the phase-transition point of water especially in the case of ice-I (down to -21°C at about 210 MPa). This phenomenon has several potential advantages in food processing applications, such as pressure shift freezing (PSF) and HP thawing. However, scientific knowledge available in this area is still relatively limited. The main objectives of this research were to investigate the phase-transition behavior of foods under pressure processing in the context of PSF and HP thawing techniques and to evaluate their impact on product quality.
Distilled water and fresh pork muscle were tested by a HP differential scanning calorimeter (DSC) using isothermal pressure scan (P-scan) and isobaric temperature scan (T-scan). P-scan tests showed that the phase-transition temperature (T) of pork was a function of the weighted-average pressure (P¯1--2): T = -1.17 - 0.102P¯1--2 - 0.00019 P&d1;21-2 (R2 = 0.99) that was much lower than that of pure ice. The phase-change latent heat of pork was estimated by P-scan. T-scan indicated the phase-transition point at a constant pressure, but it showed less accurate than P-scan. The ratio (Rice, %) of ice crystals formed by rapid release of pressure (P) was evaluated using the HP DSC: Rice-water = 0.115P + 0.00013P2 (R2 = 0.96) for water, and Rice-pork = 0.084P + 0.00012P2 (R2 = 0.95) for pork muscle. In the developed method, the pressure-dependent thermal properties of test materials are not required.
A preliminary study on ice-crystal formation was carried out using small gelatin gel samples frozen by conventional air freezing (CAF), liquid immersion freezing (LIF) and PSF at different pressures. The ovoid structure left from ice crystals was evaluated for area, equivalent diameter, roundness and elongation. The diameter (mean +/- S.D.) was 145 +/- 66, 84 +/- 26, 91 +/- 30, 73 +/- 29, and 44 +/- 16 mum for the treatments of CAF, LIF and PSF at 100, 150 and 200 MPa, respectively. Roundness and elongation did not show a clear trend with different freezing tests. Similar experiments using small-size Atlantic salmon (Salmo salar) resulted in the diameter of 110 +/- 41, 17 +/- 8.4, 16 +/- 8.8, 8.2.5 and 5.0 +/- 2.1 mum for CAF, LIF and PSF at 100, 150 and 200 MPa, respectively. The roundness was 0.38 +/- 0.14, 0.55 +/- 0.21, 0.57 +/- 0.18, 0.63 +/- 0.14 and 0.71 +/- 0.14 for the above treatments, respectively. (Abstract shortened by UMI.)

APA, Harvard, Vancouver, ISO, and other styles

11

Damar, Sibel. "Processing of coconut water with high-pressure carbon dioxide technology." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015541.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Teixeira, Bárbara Patrícia Boucinha. "Natural substances and high pressure processing to preserve sea bass." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11032.

Full text

Abstract:

Doutoramento em Química
Esta tese teve como objectivo estudar estratégias de conservação de pescado fresco, recorrendo ao uso de extractos e óleos essenciais de plantas e do processamento por alta pressão (HPP), usando filetes de robalo como um caso de estudo modelo. Relativamente aos extractos e óleos essenciais, avaliaram-se as suas propriedades antibacterianas e antioxidantes. Os extractos aquosos quente de poejo e de orégão e o óleo essencial de cravinho apresentaram a maior actividade antioxidante. Os óleos essenciais foram mais eficientes do que os extractos para inibir o crescimento das estirpes bacterianas testadas, tendo-se observado os menores valores de concentração mínima inibitória nos óleos essenciais de orégão, citronela, alho e orégão Espanhol. De seguida, estudou-se o efeito dos óleos essenciais de orégão Espanhol e de limão na conservação de filetes de robalo fresco tendo em conta critérios microbiológicos, químicos, físicos e sensoriais. A aplicação do óleo essencial de orégão Espanhol aumentou o tempo de vida útil dos filetes sob o ponto de vista bacteriano, mas não em termos sensoriais. A combinação dos óleos essenciais de orégão Espanhol e de limão melhorou o efeito antioxidante e reduziu a intensidade do odor e a sua eficácia em relação às Enterobacteriaceae, comparando com o tratamento com óleo essencial de orégão Espanhol per se. No sentido de reduzir o odor conferido pelos óleos essenciais realizou-se um estudo de conservação para avaliar o efeito de películas com óleos essenciais (citronela, alho e tomilho) em filetes de robalo, recorrendo a uma teste de desafio bacteriano. As películas sem óleos essenciais aumentaram o tempo de vida útil sob o ponto de vista bacteriano, mas este efeito não foi observado com a incorporação dos óleos essenciais nas películas. Em relação ao HPP, testaram-se diversas condições (nível de pressão, tempo de pressurização e taxa de pressurização) e avaliaram-se os efeitos na actividade enzimática, na qualidade global e na conservação de filetes de robalo fresco. Em geral, o aumento do nível de pressão e do tempo de pressurização diminuiu a actividade da fosfatase ácida e das enzimas proteolíticas, a carga bacteriana e a capacidade de retenção de água, enquanto que os filetes ficaram mais brancos. O HPP revelou potencial para o desenvolvimento de novos produtos: mais brancos, não translúcidos, mais firmes e com maior tempo de frescura e estabilidade microbiológica. Em conclusão, os óleos essenciais e o HPP têm potencial para conservar pescado fresco, devido aos seus efeitos na qualidade bacteriana. Ainda assim, mais esforços devem ser feitos no sentido de reduzir a transferência de odor dos óleos essenciais para o pescado e os efeitos do HPP no aspecto do pescado e na oxidação lipídica.
This thesis aimed to study extracts and essential oils from plants and high pressure processing (HPP) to preserve fresh fish, using sea bass fillets as a case study model. Considering extracts and essential oils, their antibacterial and antioxidant properties were evaluated. The hot water extracts of European pennyroyal and oregano and the essential oil of clove showed the highest antioxidant activities. The essential oils were more efficient than the extracts to inhibit the growth of the bacterial strains tested, being oregano, citronella, garlic, and Spanish oregano essential oils those with the lowest values of minimum inhibitory concentration. Then, the effect of essential oils (Spanish oregano and lemon) in the preservation of fresh sea bass fillets was studied taking into account microbiological, chemical, physical, and sensory criteria. The application of Spanish oregano essential oil increased the microbiological shelf life of sea bass fillets, but not the sensory shelf life. The combination of Spanish oregano and lemon essential oils enhanced the antioxidant effect and reduced the odour intensity and its efficacy against Enterobacteriaceae, compared to the treatment with Spanish oregano essential oil per se. To reduce the essential oils odours imparted to fillets, a preservation study was carried out to evaluate the effect of films with essential oils (citronella, garlic, and thyme) in sea bass fillets, using a microbiological challenge test. Films without essential oils increased the shelf life of sea bass fillets taking into account microbiological criteria, but the incorporation of essential oils in films did not. Regarding HPP, several conditions (pressure level, pressure holding time, and pressurization rate) were tested and its effects were evaluated in the activity of enzymes, in the overall quality, and in the preservation of fresh sea bass fillets. In general, the increase in pressure level and holding time decreased the activities of acid phosphatase and proteolytic enzymes, bacterial load, and water holding capacity, while fillets became whiter. HPP showed potential to create new products: whiter, not translucent, firmer, and with increased freshness period and microbiological stability. In conclusion, essential oils and HPP showed potential to preserve fresh fish, due to their effects in microbiological quality. Still, more efforts should be done to reduce the essential oils odour imparted to fish and the effects of HPP in fish appearance and lipid oxidation.

APA, Harvard, Vancouver, ISO, and other styles

13

Volk, Stephanie Paige. "Impact of high-pressure processing on soy and egg proteins." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1473269.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Parker, Claire. "The effects of high pressure on protein polysaccharide interactions." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270261.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Chugtai, Afsha. "An investigation of the factors affecting pressure resistance of Staphylococcus aureus and spores of Bacillus species." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270931.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Maitland, Jessica. "High Hydrostatic Pressure Processing Reduces Salmonella enterica from Diced and Whole Tomatoes." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/33608.

Full text

Abstract:

Fresh and fresh-cut tomatoes have been associated with numerous outbreaks of salmonellosis in recent years. While the exact routes of contamination are unknown, high pressure processing (HPP) is being evaluated as a post harvest treatment to eliminate Salmonella enterica from tomatoes. The objectives of the study were to determine the potential for of HPP to reduce S. enterica serovars Newport, Javiana, Braenderup and Anatum (clinical isolates from tomato outbreaks) in tryptic soy broth (TSB) and to determine the effect of HPP to reduce the most pressure resistant S. enterica serovar from fresh diced and whole tomatoes. Five ml portions of broth containing 8 log CFU/ml of one of the four serovars (nalidixic acid resistant) were packaged in sterile stomacher bags and subjected to one of three different pressures (350, 450, or 550 MPa) for 120s. Samples were enumerated by surface plating onto tryptic soy agar supplemented with 50 ppm nalidixic acid (TSAN) and incubated at 35Â°C for 48 hours. The most pressure resistant S. enterica serovar evaluated was Braenderup. Subjecting the broth culture to 350, 450 and 550 MPa resulted in a 4.53, 5.74 and 7.09 log reduction in S. Braenderup, respectively. Diced tomatoes (150g) and whole red round tomatoes (150g; packaged in 350ml of 1% CaCl2) were inoculated with S. Braenderup, to obtain 6 log CFU/g throughout the sample and subjected to the same pressure treatments as described above. After HPP, diced tomatoes were homogenized for 1 minute and then plated on TSAN. Whole tomatoes were surface sampled, and then homogenized for 1 minute. Surface and homogenate samples were plated on TSAN supplemented with 1% pyruvic acid (TSANP). Significant reductions of S. Braenderup concentrations in diced tomatoes (P < 0.05) were seen after processing at 350 (0.46 CFU/g), 450 (1.44 log CFU/g), and 550 MPa (3.67 log CFU/g). In whole tomatoes, significant reductions (P < 0.05) were also seen at 350 (1.41 log CFU/g), 450 (2.25 log CFU/g) and 550 MPa (3.35 log CFU/g). There were no differences in visual appearance between fresh and HPP diced and whole tomatoes. HPP may be an effective post harvest strategy to reduce low levels of S. enterica contamination in diced tomatoes.
Master of Science in Life Sciences

APA, Harvard, Vancouver, ISO, and other styles

17

Clinch, Michael. "The thermomechanical processing of aluminium alloys for high pressure gas cylinders." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326551.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Nackerman, Colleen Clare. "Storage Stability of Polyglutamyl 5-Methyltetrahydrofolate in Broccoli After High-Pressure Processing." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397731474.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Lukas, Anthony R. "Use of High Pressure Processing to Reduce Foodborne Pathogens in Coconut Water." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/24760.

Full text

Abstract:

Juices have been implicated in numerous foodborne outbreaks over the last couple of decades. The FDA requires a 5-log10 reduction in juice products, which is most commonly achieved through pasteurization. However, pasteurization deteriorates some sensorial properties and nutritive value. Coconut water (CW; classified as a juice), is rapidly gaining popularity increasing over 300% since 2005. CW has not been implicated in a microbial outbreak, but is thermally processed to achieve the required 5-log10 CFU/ml reduction, which results in negative organoleptic properties. The objectives of this study are to determine whether E. coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes can grow in CW, and evaluate the use of High Pressure Processing (HPP) to reduce populations of these bacteria in CW. The three pathogens were inoculated separately into CW and bacterial populations were enumerated over 24 hours. All three bacteria reached at least 8-log10 CFU/ml after 24 hours, which was not significantly different from the control (TSB). CW was then inoculated with each pathogen and processed using HPP (400, 5000, or 600 MPa) for 120 seconds. The D-glucose, D-fructose, sucrose, and phenol oxidase levels in the CW were assessed before and after treatments. Following processing, the pathogens were enumerated from the CW. All three pathogens were reduced by more than 6-log10 CFU/ml following treatments of 500 and 600 MPa, enough to achieve the mandatory 5-log CFu/m reduction. There were no significant changes in the D-glucose, D-fructose, sucrose, and phenol oxidase activity after any of the treatments.
Master of Science in Life Sciences

APA, Harvard, Vancouver, ISO, and other styles

20

Hiremath, Nikhil Davangere. "Studies on high pressure processing and preservation of mango juice : pressure destruction kinetics, process verification and quality changes during storage." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82251.

Full text

Abstract:

Thermal processing is the primary mode of preservation of mango products, which can be considerably damaging to the delicate quality of mango. HP processing could thus be a potential alternative for extending the shelf-life of mango products. Establishing HP processing technology need data on microbial inactivation kinetics and shelf-life study of the product. The objective of this research was therefore to evaluate the application of HP treatment for inactivation of microorganisms (pathogenic and spoilage type) and to evaluate the shelf-life of HP treated mango juice.
HP destruction kinetics of three common spoilage microorganisms, Leuconostoc mesenteroides, Zygosaccharomyces bailii and Pichia membranaefaciens and two pathogenic microorganisms, Escherichia coli O157:H7 and Listeria monocytogenes Scott A, were evaluated at 250-550 MPa with 0-60 min holding time at room temperature with species specific initial counts between 10 6 to 108 CFU/mL.

APA, Harvard, Vancouver, ISO, and other styles

21

Evert, Arriagada Katherine. "Effect of high pressure processing (HPP) on starter-free fresh cheese shelf-life." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/116081.

Full text

Abstract:

La Alta Presión Hidrostática (APH) es una tecnología no térmica capaz de extender la vida útil de los alimentos al mismo tiempo que mantiene sus características nutricionales y organolépticas. El queso fresco es una variedad no madurada, de coagulación enzimática o ácida, y que generalmente es consumido poco después de su elaboración. El queso fresco tradicional es obtenido por coagulación enzimática y es un medio ideal para el crecimiento bacteriano, ya que en su fabricación no se utilizan fermentos lácticos, posee una elevada actividad de agua y un alto contenido en proteína y grasa. El principal objetivo de esta tesis fue evaluar el efecto de la APH para extender la vida útil de un queso fresco tradicional obteniendo un producto de alta calidad. Para este propósito, se realizó un estudio preliminar con quesos comerciales de pequeño formato (80 g) a nivel de planta piloto con el fin de determinar la capacidad de la APH para inhibir el crecimiento de microorganismos causantes de deterioro. Los quesos fueron tratados a 300 y 400 MPa (5 min a 6°C) y se evaluaron diferentes parámetros microbiológicos, de de composición y físico-químicos durante su almacenamiento en frío. Los resultados mostraron que la APH no modificó la composición del queso fresco y produjo sólo pequeños cambios en el color (más amarillo) y la textura (más firme), cuando se comparó con un queso no tratado. Además, la aplicación de 300 y 400 MPa aumentó la vida útil de los quesos a 14 y 21 días, respectivamente. La siguiente fase fue determinar la vida útil de un queso comercial (250 g) tratado a 500 MPa (5 min a 18°C) bajo condiciones industriales siguiendo también su evolución microbiológica, de composición, físico-química y sensorial durante 21 días de almacenamiento en frío. En este caso, los quesos presurizados alcanzaron una vida útil de entre 19 y 21 días al compararlos con los quesos no tratados que fue de entre 7 y 8 días. Sin embargo, el tratamiento de 500 MPa afectó significativamente a las características de color, textura, microestructura y sensoriales del queso, pero no así su preferencia por parte de un panel de catadores. Es importante destacar que la APH fue capaz de mantener las características de aroma del queso a lo largo de su vida útil, retrasando la formación de compuestos volátiles responsables de sabores extraños. Adicionalmente, se realizó un ensayo de inoculación con Listeria spp. con el fin de evaluar la efectividad de la APH (300-600 MPa durante 5 min a 6°C) para asegurar la inocuidad alimentaria. Se seleccionaron tres cepas bacterianas (L. monocytogenes Scott A y CECT 4031, y su marcador, L. innocua CECT 910) para estudiar la inactivación y la generación de daño sub-letal después del tratamiento y su evolución durante 15 días de almacenamiento a 4°C. Con el tratamiento de 300 MPa no se consiguió inactivar ninguna de las cepas inoculadas. Sin embargo, tanto los tratamientos de 500 MPa y 600 MPa se lograron importantes reducciones de Listeria spp. Por otra parte, la presurización del queso fresco entre 300-600 MPa no produjo significativamente daño sub-letal, apreciándose diferencias en el comportamiento entre las cepas estudiadas. Así, se observó que L. monocytogenes CECT 4031 fue la más sensible a la APH y Scott A la más resistente. En los quesos tratados el crecimiento de esta bacteria durante el almacenamiento en frío no fue inhibido. Los recuentos en los quesos tratados a 300 MPa no fueron distintos a los del queso control para todas las cepas y nivel de inoculo utilizados.
High pressure processing (HPP) is a non-thermal technology able to extend the shelf-life of a number of food products while maintaining their sensory and nutritional quality. Fresh cheese is unripened rennet or acid-coagulated type and is usually consumed after manufacturing. Traditional fresh cheese is obtained by rennet coagulation and it may serve as an ideal medium for bacterial proliferation, since no starter culture is added, and considering its high water activity and its high protein and fat contents. The main objective of this thesis was to evaluate the effect of HPP technology for extending the shelf-life of a starter-free fresh cheese, and in order to obtain a high quality product. For this purpose, a preliminary study at pilot plant scale using small commercial cheeses (80 g) was carried out with the aim to determine the HPP capacity to inhibiting the outgrowing of spoilage microorganisms. In this sense, cheeses were treated at 300 and 400 MPa (5 min at 6ºC) and their microbiological, compositional and physico-chemical evolution during cold storage was evaluated. Results indicated that HPP did not affect cheese composition and provoked only little changes in colour (more yellow) and textural (firmer) properties of fresh cheese when compared with untreated cheese. Besides, 300 and 400 MPa were able to extend fresh cheese shelf-life to 14 and 21 days, respectively. The next step was to determine the shelf-life of commercial fresh cheeses (250 g) treated at 500 MPa (5 min at 18ºC) at industrial scale, by following their microbiological, compositional, physico-chemical and sensorial evolution during cold storage of 21 days. This time, pressurised cheeses achieved a shelf-life of about 19-21 days compared to 7-8 days of the untreated cheese. However, 500 MPa significantly affected colour, microstructural, textural and sensory characteristics, but the preference for the treated cheese was not affected. It is also worth noting that HPP was able to maintain the aroma characteristics of cheese throughout its shelf-life, leading to a delay in the formation of volatile compounds responsible for off-flavours. Additionally, an inoculation study with Listeria spp. was carried out in order to evaluate the effectiveness of the HPP (300-600 MPa for 5 min at 6°C) to assure food safety. Three bacterial strains (L. monocytogenes Scott A and CECT 4031, and its surrogate L. innocua CECT 910) were selected to study the initial inactivation achieved, the sublethal damage generated and microbial growth during 15 days of storage at 4°C. Treatment at 300 MPa did not inactivate any of the strains inoculated. Conversely, 500 and 600 MPa were effective to achieve significant reductions of pathogen counts in fresh cheese. On the other hand, treatment of fresh cheese within the range of 300-600 MPa did not produce significant sublethal injury. Regarding behaviour differences among Listeria strains, it was observed that L. monocytogenes CECT 4031 was the most sensitive and L. monocytogenes Scott A the most resistant to HPP. Finally, growth during cold storage was not prevented since viable cells remain after the treatment. Counts of cheeses treated at 300 MPa were not different from untreated cheese counts, for all strains and inocula level used. On the other hand, differences in rate of growth among strains were observed. Scott A strain showed the lowest rate for all conditions studied. These results confirm that the fresh cheese, due to their characteristics of pH and aw, is able to support growth of Listeria spp.

APA, Harvard, Vancouver, ISO, and other styles

22

Singh, Ajaypal. "Evaluation of high pressure processing for improving quality and functionality of egg products." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110635.

Full text

Abstract:

The main objective of this study was to evaluate the effect of high pressure treatments on liquid rheology, color, texture and functional properties of egg products, specifically egg white (EW), egg yolk (EY) and whole liquid egg (WLE). High pressure processing is a novel and innovative method for extending the shelf-life and enhancing quality of foods. Various experimental designs and statistical analyses were used to study the effect of high pressure on all three components – EW, EY and WLE all initially in the liquid state. Since the egg components transformed from the flowing liquid state to a viscous liquid to soft gel and finally to a solid gel structure with the increase in pressure severity, a single rheological technique was not suitable to study all of them. The liquid rheology was studied using conventional steady and dynamic shear viscometry, the viscous to semi-solid samples was assessed using a back-extrusion rheology and finally the solid gels were assessed using a texture profile analysis. These studies generally indicated the progressive increase in rheological properties (toward texture build-up) with an increasing severity of pressure treatment (higher pressure and higher treatment times). HP treatment caused significant changes in the viscoelastic properties and these changes correlated well with functional properties. It was observed that high pressure induces gelling in the egg components which is caused by crossover of viscous and elastic moduli. This phenomenon caused significant enhancement of functional properties like water holding capacity and foaming properties in egg components. HP treatment also resulted in desirable changes in color with enhancement of brightness and yellow color. As with heat processing, the egg white turned white following HP treatment.Avidin is an anti-nutritional component present in egg. If not inactivated, it will bind biotin which is essential for the functioning of thyroid glands. Hence, it is essential that the avidin present in raw egg be inactivated prior to consumption of the egg. Heat treatment is usually used to inactivate avidin. In this study, HP treatment was evaluated and found to be more effective than heat for inactivating the anti-nutritive avidin.The last part of the study was focused on the effect of HP treatment on the functional properties of egg components, especially the degree of hydrolysis and antioxidant activity. These changes were mainly due to partial unfolding of proteins and exposition of buried peptide bonds which are responsible for antioxidant activity which leads to their enhancement. DPPH (1, 1-diphenyl-2 picrylhydrazyl) radical scavenging assay showed higher antioxidant activity in pressure treated sample than the control sample.
L'objectif principal de cette étude était d'évaluer l'effet d'un traitement à haute pression (HP) sur la rhéologie liquide, la couleur, la texture et les propriétés fonctionnelles des ovoproduits, en particulier le blanc d'oeuf (BO), le jaune d'oeuf (JO) et l'œuf entier liquide (OEL). Le procédé de haute pression est une méthode nouvelle et innovatrice pour augmenter la durée de conservation et améliorer la qualité des aliments. Divers modèles expérimentaux et analyses statistiques ont été utilisés pour étudier l'effet des hautes pressions sur les trois produits d'oeufs – BO, JO et OEL, tous initialement à l'état liquide. Étant donné qu'avec l'augmentation de la pression les produits d'œufs se transforment d'un état liquide limpide à un état liquide plus visqueux, à un gel mou et enfin à une structure de gel solide, une technique rhéologique unique n'était pas appropriée pour tous les étudier. La rhéologie liquide a été étudiée en utilisant la method conventionnelle de viscosité de cisaillement dynamique et stationnaire, les échantillons visqueux à semi-solides ont été évalués à l'aide de la une rhéologie d'extrusion inversée et, enfin, les gels solides ont été évalués en utilisant une analyse du profil de texture. Ces études ont généralement indiqué l'augmentation progressive des propriétés rhéologiques (vers la texture plus rigide) avec l'augmentation de la pression émise (pression et temps de traitement plus élevés). Le traitement HP a provoqué des changements significatifs des propriétés viscoélastiques et ces changements sont en bonne corrélation avec les propriétés fonctionnelles. Il a été observé que la haute pression induit la gélification des ovoproduits qui est causée par croisement des modules visqueux et élastique. Ce phénomène a causé une amélioration significative des propriétés fonctionnelles telles que la capacité de rétention d'eau et les propriétés moussantes des ovoproduits. Le traitement HP a également entraîné des changements souhaitables dans la couleur avec l'amélioration de la luminosité et la couleur jaune. Comme avec le traitement thermique, le blanc d'oeuf est devenu opaque avec le traitement. L'avidine est un composant antinutritionnel présent dans l'œuf. S'il n'est pas inactivé, il se liera à la biotine qui est essentielle pour le fonctionnement de la glande thyroïde. Par conséquent, il est essentiel que l'avidine présente dans l'œuf cru soit inactivée avant sa consommation. Le traitement thermique est généralement utilisé pour inactiver l'avidine. Dans cette étude, le traitement HP a été évalué et jugé être plus efficace que la chaleur pour inactiver l'avidine antinutritive. La deuxième partie de l'étude était axée sur l'effet du traitement HP sur les propriétés fonctionnelles des produits d'oeufs, en particulier le degré d'hydrolyse et de l'activité antioxydante. Ces changements sont principalement dus à un dépliement partiel de protéines et à l'exposition des liaisons peptidiques responsables de l'activité antioxydante qui conduit à leur amélioration. Le test de réduction du radical stable DPPH (1, 1-diphényl-2 picrylhydrazyl) a montré une activité antioxydante plus élevée pour l'échantillon traité sous pression que pour l'échantillon de contrôle.

APA, Harvard, Vancouver, ISO, and other styles

23

Zare, Zahra. "High pressure processing of fresh tuna fish and its effects on shelf life." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18212.

Full text

Abstract:

Tuna is highly perishable and has been implicated in histamine poisoning because of high histidine levels in the muscle. There is high demand for fresh tuna fillet and steaks for Japanese type foods, and as a grilled item in restaurants. Demand for fresh, additive-free and safe seafood products has stimulated efforts to discover novel methods to prolong the shelf life of fresh products with minimum loss of quality. High pressure processing was investigated for its effects on quality and useful shelf life of fresh tuna. Fresh tuna was subjected to various pressure treatments (220 MPa, 200 MPa, 150 MPa), holding times (30 min, 15 min) and temperature (below 20oC). The pressure treated and control (untreated) samples were analyzed for initial physicochemical properties and subsequent changes during chilled storage. Color parameters (L*, a* and b* values), texture, drip loss, pH, sensory attributes, endoprotease activity, TBA, TVB and histamine levels were all evaluated. All the pressure-treated samples lost their glossiness, and their redness decreased with pressure and holding time. Pressure treatment increased yellowness of the samples, and the ‘b’ values increased throughout storage. High pressure processing above 150 MPa resulted in firmer muscles with higher springiness. High pressure also resulted in increased drip loss for all pressure treated samples. However during chilled storage increase in drip loss was significantly faster in untreated samples than in pressure treated samples. Proteolytic activity did not change significantly during storage, unlike the TVB levels that increased during storage. Pressure treatments at 220 MPa/30 or 15 min, and 200 MPa/30 min reduced TVB values the most. None of applied pressure conditions induced major changes in initial pH values. Also no consistent pattern was observed for TBA levels, although the levels were low and indicative of high quality products. Histamine formation was inhibited by pressure treatment
Le thon est fortement périssable et a été impliqué dans l’empoisonnement de l’histamine à cause de niveau très élevé d’histidine dans la chair du poisson. Il y a un forte demande pour le filet de thon frais et de steaks de type japonais de même que les grillades. La demande pour les produits frais de mer, sans additifs et sûrs a stimulé le milieu scientifique afin de découvrir de nouvelles méthodes pour prolonger la durée de vie des produits frais avec la perte minimale de qualité. Le traitement à haute pression a été évalué pour ses effets sur la qualité et la durée de vie du thon frais. Le thon frais a été soumis aux divers traitements de pression (220 MPa, 200 MPa, 150 MPa), avec les temps de rétention de 30 minutes et 15 minutes, et une température sous 20ºC. Les échantillons pressurisés et non pressurisés ont été analysés pour leurs propriétés physicochimiques initiales ainsi que les changements associés au stockage. Les paramètres de couleur (CIE L*, a* et b*), la texture, l’exsudat, pH, les attributs sensoriels, l'activité endo-protéase, TBA, TVB et le niveau d’histamine ont été évalués. Tous les échantillons pressurisés ont perdu leur lustre, et leur rougeur a diminué avec la pression et le temps de rétention. La pressurisation a augmenté le jaune des échantillons et les valeurs de ‘b’ ont augmentés au cours du stockage. Le traitement à haute pression au-dessus de 150 MPa a augmenté la fermeté des muscles ainsi qu’une élasticité plus élevée. Par le fait même, le traitement à haute pression a causé l'augmentation de l’exsudat de tous les échantillons pressurisés. Cependant, l’exsudat était significativement plus rapide sur les échantillons non traités que sur les échantillons pressurisés. L'activité protéolytique n'a pas changé significativement durant le stockage, à la différence des niveaux de TVB qui ont augmenté durant le stockage. La pressurisation à 220 MPa/

APA, Harvard, Vancouver, ISO, and other styles

24

Michel, de Arévalo Aymeé [Verfasser]. "Phytosterol enrichment in vegetable oil by high pressure processing / Aymeé Michel de Arévalo." Aachen : Shaker, 2009. http://d-nb.info/1156518350/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Mat, Yusoff Masni. "Aqueous enzymatic extraction of Moringa oleifera oil with high pressure processing pre-treatment." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/69033/.

Full text

Abstract:

Moringa oleifera (MO) is a plant species of Indian subcontinent. Its pods contain kernels, which upon maturation consists of up to 35% protein and 41% oil (w/w). This oil is extractable using solvents such as hexane, but this is generally not looked upon favourably due to safety and environmental concerns. This thesis explores the use of aqueous enzymatic extraction (AEE) as an alternative, which involves incubating a mixture of MO kernels, water and enzymes under controlled conditions. Given that the oil globules are predominantly surrounded by proteins and cellulose, the enzymes used in this study were protease and cellulase. Centrifugation of the incubated mixture resulted in four distinct layers: free oil at the top, followed by an oil-in-water cream emulsion, an aqueous phase, and a residual solid meal at the bottom. The highest oil recovered in the free layer at the top following AEE was approximately 73% (w/w), measured in relation to the use of hexane. Another disadvantage of AEE in relation to organic solvent extraction is that a significant part of oil released from the cell ends up in the emulsified layer. Therefore, high pressure processing (HPP) pre-treatment was applied to the kernels prior to AEE, which resulted in increase in free oil quantity and a reduction in emulsion layer thickness. It is hypothesized that HPP modifies the MO protein structure into a form that lowers its emulsifying ability. The use of HPP considerably simplifies downstream oil separation steps. Storage tests showed that enzymatic extraction resulted in MO oil having better oxidative stability than the hexane-extracted oil. The MO oil also contained up to 75% oleic acid and high tocopherol contents, which contributed to its enhanced oxidative stability.

APA, Harvard, Vancouver, ISO, and other styles

26

Yan, Bing. "High Pressure Homogenization of Selected Liquid Beverages." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471376403.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Boyd, William Alastair. "The effect of high hydrostatic pressure on the microbial quality of apple juice." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326356.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Abdel, Karim Pia. "High pressure processing as an alternative food preservation technology and its applications for fruits and vegetables." Kansas State University, 2011. http://hdl.handle.net/2097/9958.

Full text

Abstract:

Master of Science
Food Science Institute
James L. Marsden
Consumers demand for high quality, natural and fresh tasting food, free from preservatives and additives, with a clean label and an extended shelf life has increased. High pressure processing (HPP), also known as high hydrostatic pressure, is a non-thermal food preservation technique that has the potential to meet these demands. It is an opportunity to preserve food, by applying intensive pressure in the range of 300-900 MPa, without adversely affecting organoleptic, textural and nutritional qualities as thermal processing like pasteurization and sterilization may do. In a typical high pressure batch cycle, the food prepackaged in a high-barrier flexible pouch or a plastic container is loaded into a perforated basket that goes into the pressure vessel; the pressure is then increased to the processing target pressure (come-up time); the product is held at the desired pressure for 3 to 10 minutes (pressure holding time); after which the pressure is released in usually few seconds (decompression time) and the product can be unloaded at this point. The pressure is applied uniformly in all directions simultaneously and this is known as isostatic pressure. Pressurization is usually accompanied by a moderate and uniform temperature increase called adiabatic heating. However, the food product usually rapidly returns to its initial temperature at decompression. With the recent shift in consumer lifestyle toward healthy living and healthier food, the consumption of raw fruits and vegetables has increased in popularity. However, as per the Centers of Disease Control and Prevention, fruits and vegetables have recently been associated with multiple foodborne disease outbreaks; the effect of high pressure processing on microbial safety, quality and sensory characteristics of fruits and vegetables has therefore been widely investigated as an alternative to traditional food processing and preservation methods. HPP inactivates microorganisms and quality-deteriorating enzymes and has limited effects on covalent bonds resulting in minimal modifications of food-quality attributes such as color, flavor and nutritional values. However, depending on the fruit or vegetable, high pressure could induce chemical or biochemical reactions that can affect their quality attributes.

APA, Harvard, Vancouver, ISO, and other styles

29

Ocampo-Garcia, Nora Fabiola. "Influence of high pressure processing on populations of Salmonella enterica in fresh green-mature tomato fruits and subsequent ripening." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/42701.

Full text

Abstract:

The objective of this work was to determine the effect of high pressure processing (HPP) on fresh tomato-associated outbreak isolates of Salmonella enterica in broth and on green mature tomato fruits. Nalidixic acid resistant (to 50 ppm) cultures of Salmonella enterica ser. Newport and Salmonella enterica ser. Braenderup were suspended in tryptic soy broth to a concentration of approximately 8 log CFU/ml and subjected to 350, 450, and 550 MPa for 120 s. Samples were serially diluted in peptone water, and surface plated onto tryptic soy agar supplemented with nalidixic acid (50 ppm; TSAN) and incubated at 35Â°C for 48 h. Reductions of 5.64, 6.30, and 6.61 log CFU/ml in S. Newport, and reductions of 4.10, 5.22, and 6.35 log CFU/ml in S. Braenderup at 350, 450, and 550 MPa, respectively, were observed. Green tomato fruits inoculated with S. Newport or S. Braenderup to an initial concentration of approximately 6 log CFU/g were sealed in a bag containing 350 ml of 1% CaCl2 and subjected to the same pressure treatments described above. The whole tomato fruits were pummeled in a stomacher and samples were surface plated onto TSAN supplemented with 1% pyruvic acid. Reductions of 1.55, 2.89, and 4.26 log CFU/g for S. Newport and 1.22, 2.26, and 3.77 log CFU/g for S. Braenderup at 350, 450, and 550 MPa, respectively, were observed. Bagged (350 ml 1% CaCl2) samples of non-inoculated green tomato fruits were subjected to the same conditions described above. HPP treated tomatoes were then subjected to an ethylene gas (125 ppm; 0.7 cc/min) for 5 to 6 days. Pressured tomato fruits did not ripen. Even though HPP effectively reduced populations of S. enterica, it adversely affects the ripening characteristics of green mature tomato fruits.
Master of Science in Life Sciences

APA, Harvard, Vancouver, ISO, and other styles

30

Buzrul, Sencer. "High Hydrostatic Pressure (hhp) Applications In Food Science: A Study On Compression Heating, Microbial Inactivation Kinetics, Pulsed Pressure And High Pressure Carbon Dioxide Treatments." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12609466/index.pdf.

Full text

Abstract:

In this study the action of high hydrostatic pressure (HHP) on compression heating of liquid foods and pressure transmitting fluids, inactivation of Escherichia coli and Listeria innocua in different food media (milk and fruit juices), pulsed pressure and high pressure carbon dioxide treatments was investigated. The experimental results in this study allowed pointing out some important results: (i) The thermal effects of compression should be taken into account when HHP pasteurization processes are developed. Initial temperature of the food product and compression rate should carefully be selected in order to compensate the compression heating
(ii) The HHP inactivation kinetics need not follow traditional first-order kinetics, hence alternative inactivation models are ought to be found. Weibull model can be used for HHP inactivation kinetics of microorganisms
(iii) The pulsed pressure treatment could be an alternative to continuous HHP, but optimization should be done between the pulse holding time, the number of pulses and the pressure level to reach the desirable number of log-reduction of microorganisms (E. coli and L. innocua) compatible with an industrial application
(iv) The storage duration and storage temperature after HHP treatment should carefully be optimized to increase the safety of HHP treated fruit juices since the growth of injured microorganisms can be avoided during storage
(v) The high pressure carbon dioxide (HPCD) treatment in combination with pulsed pressure can be an efficient way to inactivate the microorganisms in skim milk and to reduce the maximum pressure level for the desired log-reduction.

APA, Harvard, Vancouver, ISO, and other styles

31

Somerville, Jeremy Alan. "The Effects of Pressure-Assisted Thermal Processing on the Quality Attributes of Black Beans (Phaseolus vulgaris L.)." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1262196760.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Dhakal, Santosh. "Impact of High Pressure Processing on Immunoreactivity and SomePhysico-chemical Properties of Almond Milk." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374017194.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Bigikocin, Erman. "Effect Of High Hydrostatic Pressure (hhp) And High Dynamic Pressure (hdp) On Stability And Rheological Properties Of Model Oil-in-water Emulsions." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612416/index.pdf.

Full text

Abstract:

High pressure applications are alternatives to conventional methods in food processing. They provide interesting modifications in food structures which leads to new product formulations. The aim of this study is to identify the effects of two different treatments, high hydrostatic pressure (HHP) and high dynamic pressure (HDP) on stability and rheological properties of model oil-in-water emulsions. Microfluidization was selected among the HDP homogenization techniques. The performance of each process was analyzed in terms of rheological modifications and emulsion stability improvements compared to the coarse emulsions which were prepared with colloid mill homogenization. Stability of emulsions was determined comparatively by using an analytical photo-centrifuge device employing a novel analysis technology. Whey protein isolate (WPI) was used as an emulsifier in combination with a food polysaccharide as a stabilizer. The polysaccharides used were xanthan gum, guar gum and locust bean gum which are widely used stabilizing ingredients in food industry. The effective disruption of oil droplets and the degradation of polysaccharides by the shear forces under high pressure in HDP microfluidization yielded finer emulsions with lower viscosities. The finer emulsions obtained with this homogenization technique led to distinctive improvements in emulsion stability. On the other hand, the improvements in stability by HHP treatment were due to the thickening of the emulsions mainly induced by protein unfolding. The corresponding increases in viscosity were intensified in emulsion formulations with higher oil content. Apart from these, HHP treatment was found to be relatively more contributing to the enhancements in viscoelastic properties.

APA, Harvard, Vancouver, ISO, and other styles

34

Ratphitagsanti, Wannasawat. "Approaches for Enhancing Lethality of Bacterial Spores Treated by Pressure-Assisted Thermal Processing." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253465446.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Solbraa, Even. "Equilibrium and Non-Equilibrium Thermodynamics of Natural Gas Processing." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-96.

Full text

Abstract:

The objective of this work has been to study equilibrium and non equilibrium situations during high pressure gas processing operations with emphasis on utilization of the high reservoir pressure. The well stream pressures of some of the condensate and gas fields in the North Sea are well above 200 bar. Currently the gas is expanded to a specified processing condition, typically 40-70 bar, before it is recompressed to the transportation conditions. It would be a considerable environmental and economic advantage to be able to process the natural gas at the well stream pressure. Knowledge of thermodynamic- and kinetic properties of natural gas systems at high pressures is needed to be able to design new high pressure process equipment.

Nowadays, reactive absorption into a methyldiethanolamine (MDEA)solution in a packed bed is a frequently used method to perform acid gas treating. The carbon dioxide removal process on the Sleipner field in the North Sea uses an aqueous MDEA solution and the operation pressure is about 100 bar. The planed carbon dioxide removal process for the Snøhvit field in the Barents Sea is the use of an activated MDEA solution.

The aim of this work has been to study high-pressure effects related to the removal of carbon dioxide from natural gas. Both modelling and experimental work on high-pressure non-equilibrium situations in gas processing operations have been done.

Few experimental measurements of mass transfer in high pressure fluid systems have been published. In this work a wetted wall column that can operate at pressures up to 200 bar was designed and constructed. The wetted wall column is a pipe made of stainless steel where the liquid is distributed as a thin liquid film on the inner pipewall while the gas flows co- or concurrent in the centre of the pipe. The experiments can be carried out with a well-defined interphase area and with relatively simple fluid mechanics. In this way we are able to isolate the effects we want to study in a simple and effective way.

Experiments where carbon dioxide was absorbed into water and MDEA solutions were performed at pressures up to 150 bar and at temperatures 25 and 40°C. Nitrogen was used as an inert gas in all experiments.

A general non-equilibrium simulation program (NeqSim) has been developed. The simulation program was implemented in the object-oriented programming language Java. Effort was taken to find an optimal object-oriented design. Despite the increasing popularity of object-oriented programming languages such as Java and C++, few publications have discussed how to implement thermodynamic and fluid mechanic models. A design for implementation of thermodynamic, mass transfer and fluid mechanic calculations in an object-oriented framework is presented in this work.

NeqSim is based on rigorous thermodynamic and fluid mechanic models. Parameter fitting routines are implemented in the simulation tool and thermodynamic-, mass transfer- and fluid mechanic models were fitted to public available experimental data. Two electrolyte equations of state were developed and implemented in the computer code. The electrolyte equations of state were used to model the thermodynamic properties of the fluid systems considered in this work (non-electrolyte, electrolyte and weak-electrolyte systems).

The first electrolyte equation of state (electrolyte ScRK-EOS) was based on a model previously developed by Furst and Renon (1993). The molecular part of the equation was based on a cubic equation of state (Scwarzentruber et.al. (1989)’s modification of the Redlich-Kwong EOS) with the Huron-Vidal mixing rule. Three ionic terms were added to this equation – a short-range ionic term, a long-range ionic term (MSA) and a Born term. The thermodynamic model has the advantage that it reduces to a standard cubic equation of state if no ions are present in the solution, and that public available interaction parameters used in the Huron-Vidal mixing rule could be utilized. The originality of this electrolyte equation of state is the use of the Huron-Vidal mixing rule and the addition of a Born term. Compared to electrolyte models based on equations for the gibbs excess energy, the electrolyte equation of state has the advantage that the extrapolation to higher pressures and solubility calculations of supercritical components is less cumbersome. The electrolyte equation of state was able to correlate and predict equilibrium properties of CO₂-MDEA-water solutions with a good precision. It was also able to correlate high pressure data of systems of methane-CO₂-MDEA and water.

The second thermodynamic model (electrolyte CPA-EOS) evaluated in this work is a model where the molecular interactions are modelled with the CPA (cubic plus association) equation of state (Kontogeorgios et.al., 1999) with a classical one-parameter Van der Walls mixing rule. This model has the advantage that few binary interaction parameters have to be used (even for non-ideal solutions), and that its extrapolation capability to higher pressures is expected to be good. In the CPA model the same ionic terms are used as in the electrolyte ScRK-EOS.

A general non-equilibrium two-fluid model was implemented in the simulation program developed in this work. The heat- and mass-transfer calculations were done using an advanced multicomponent mass transfer model based on non-equilibrium thermodynamics. The mass transfer model is flexible and able to simulate many types of non-equilibrium processes we find in the petroleum industry. A model for reactive mass transfer using enhancement factors was implemented for the calculation of mass transfer of CO₂ into amine solutions. The mass transfer model was fitted to the available mass transfer data found in the open literature.

The simulation program was used to analyse and perform parameter fitting to the high pressure experimental data obtained during this work. The mathematical models used in NeqSim were capable of representing the experimental data of this work with a good precision. From the experimental and modelling work done, we could conclude that the mass transfer model regressed to pure low-pressure data also was able to represent the high-pressure mass transfer data with an acceptable precision. Thus the extrapolation capability of the model to high pressures was good.

For a given partial pressure of CO₂ in the natural gas, calculations show a decreased CO₂ capturing capacity of aqueous MDEA solutions at increased natural gas system pressure. A reduction up to 40% (at 200 bar) compared to low pressure capacity is estimated. The pressure effects can be modelled correctly by using suitable thermodynamic models for the liquid and gas. In a practical situation, the partial pressure of CO₂ in the natural gas will be proportional to the total pressure. In these situations, it is shown that the CO₂ capturing capacity of the MDEA solution will be increased at rising total pressures up to 200 bar. However, the increased capacity is not as large as we would expect from the higher CO₂ partial pressure in the gas.

The reaction kinetics of CO₂ with MDEA is shown to be relatively unaffected by the total pressure when nitrogen is used as inert gas. It is however important that the effects of thermodynamic and kinetic non- ideality in the gas and liquid phase are modelled in a consistent way. Using the simulation program NeqSim – some selected high-pressure non-equilibrium processes (e.g. absorption, pipe flow) have been studied. It is demonstrated that the model is capable of simulating equilibrium- and non-equilibrium processes important to the process- and petroleum industry.

APA, Harvard, Vancouver, ISO, and other styles

36

GUPTA, ROCKENDRA. "Pressure Assisted Thermal Processing: Tomato Carotenoid Stability during Processing and Storage and Feasibility of Using Chemical Markers for Evaluating Process Uniformity." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1293632615.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Daryaei, Hossein, and s3088498@student rmit edu au. "Application of high pressure processing for extending the shelf-life of fresh lactic curd cheese." RMIT University. Applied Science, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080821.155923.

Full text

Abstract:

Outgrowth of spoilage yeasts and moulds and post-processing acidification can limit the shelf-life of some fermented dairy products including fresh lactic curd cheeses. The possibility of using high pressure processing (HPP) for controlling these problems was investigated in a commercially manufactured fresh lactic curd cheese (pH 4.3-4.4) and fermented milk models (pH 4.3-6.5). The effects of HPP at 300 and 600 MPa on inactivation of glycolytic enzymes of lactic acid bacteria were also evaluated. Fresh cheeses made from pasteurised bovine milk using a commercial Lactococcus starter preparation were treated with high pressures ranging from 200 to 600 MPa (less than or equal to 22°C, 5 min) under vacuum packaging conditions and subsequently stored at 4°C for 8 weeks. Treatment at greater than or equal to 300 MPa substantially reduced the viable count of Lactococcus and effectively prevented the outgrowth of yeasts and moulds for 6 to 8 weeks without adversely affecting the sensory and textural attributes of the product. However, it had no significant effects (p less than 0.01) on variation of titratable acidity during storage. Fermented milk models were prepared by individually growing Lactococcus lactis subsp. lactis C10, Lactococcus lactis subsp. cremoris BK5, Streptococcus thermophilus TS1, Lactobacillus acidophilus 2400 and Lactobacillus delbrueckii subsp. bulgaricus 2517 in UHT skim milk and diluting the resulting fermented milk with UHT skim milk up to pH 6.5. Pressure treatment of the milk models at pH 5.2 resulted in substantial inhibition of post-processing acidification during storage and markedly reduced the viable count of Lactococcus at both 300 and 600 MPa and other bacteria only at 600 MPa. Treatment of the milk model at 600 MPa decreased the viable counts of Candida zeylanoides and Candida lipolytica (wildtype spoilage yeasts of lactic curd cheese, added as challenge cultures) from 105 CFU mL-1 to below the detection limit (log 0 CFU mL-1) at all pH levels tested (pH 4.3-6.5) and effectively controlled their outgrowth for 8 weeks. Treatment of milk model at 300 MPa had a similar effect only on C. zeylanoides. The viable count of C. lipolytica was reduced by 2.6, 2.4 and 2.3 logs by treatment at 300 MPa at pH levels of 4.3, 5.2 and 6.5, respectively, which subsequently recovered by 2.9, 2.8 and 3.2 logs within 3 weeks. Glycolytic enzymes of various starter bacteria showed different responses to pressure treatment. The lactate dehydrogenase in L. lactis subsp. lactis and Lb. acidophilus was quite resistant to pressures up to 600 MPa, but it was almost completely inactivated in S. thermophilus at pressure levels as low as 300 MPa. The â-galactosidase in Lb. acidophilus was more pressure stable than â-galactosidase in S. thermophilus and Phospho-â-galactosidase in L. lactis subsp. lactis. The findings of this study suggests HPP at 300-600 MPa as an effective method for controlling the outgrowth of some spoilage yeasts and moulds in fresh lactic curd cheeses. The results obtained with selected lactic acid bacteria in fermented milk models can be used to assist in establishing HPP operating parameters for development of new generation cultured dairy products, of reduced acidity and extended shelf-life.

APA, Harvard, Vancouver, ISO, and other styles

38

Nguyen, Loc Thai. "Quality and Thermophysical Properties of Pressure Treated Foods." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259093512.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Rubio, Celorio Marc. "Technologies to determine quality parameters and the effect of high pressure processing on dry-cured ham." Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/319951.

Full text

Abstract:

The research for new technologies able to determine quality parameters as well as study the effect of High Pressure Processing (HPP) on dry-cured ham is of scientific interest because the information obtained is useful for understanding the changes to which the product is subjected. Besides, this information is valuable for the dry-cured ham industry, as it could provide products which are better characterized for consumers and of higher quality. The main objective of this thesis was to study the potential of different technologies to determine quality parameters of dry-cured ham and elucidate the effect of HPP on the product. The technologies tested in this thesis appear to be promising as tools to determine quality parameters in dry-cured ham. Some of them are currently available for industry and others could be implemented online in the future.
La investigació en noves tecnologies que permetin determinar paràmetres de qualitat, així com estudiar l'efecte de las altes pressions hidrostàtiques (HPP) en pernil curat és d'interès científic perquè la informació obtinguda pot ser útil per entendre els canvis als quals està sotmès el producte. A més, aquesta informació pot tenir un valor important per a la indústria del pernil curat, permetent-li oferir als consumidors productes de més qualitat i millor caracteritzats. L'objectiu principal d'aquesta tesi va ser estudiar el potencial de diferents tecnologies per determinar paràmetres de qualitat del pernil curat i per estudiar l'efecte de les altes pressions en aquest producte. Les tecnologies estudiades en aquesta tesi són prometedores com a eines per a determinar paràmetres de qualitat en pernil curat. Algunes d'elles ja estan actualment disponibles per a la indústria i d’altres podrien arribar a implentar-se en línia en un futur.

APA, Harvard, Vancouver, ISO, and other styles

40

Mussa, Dinna Mathemi. "High pressure processing of milk and muscle foods, evaluation of process kinetics, safety and quality changes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0027/NQ50227.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Reineke, Kai [Verfasser], and Dietrich [Akademischer Betreuer] Knorr. "Mechanisms of Bacillus spore germination and inactivation during high pressure processing / Kai Reineke. Betreuer: Dietrich Knorr." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2013. http://d-nb.info/1032693401/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Mussa, Dinna Mathemi. "High pressure processing of milk and muscle foods : evaluation of process kinetics, safety and quality changes." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35473.

Full text

Abstract:

High pressure (HP) kinetics of the microbial destruction and changes in the physicochemical characteristics of milk and pork were studied. Raw milk samples containing indigenous microflora of approximately 106 CFU/mL were heat sealed in dual peel sterilization pouches and subjected to HP treatment from 150--400 MPa with holding times ranging 5--120 min. The kinetic parameters (rate constant, k and decimal reduction time, D) for the microorganisms, alkaline phosphatase, color and viscosity were evaluated, based on first order kinetics and the pressure dependence of kinetic parameters was evaluated using pressure destruction time (PDT) and Arrhenius models. Kinetic data was well described by the first order model (R 2 > 0.90).
The application of pressure pulse was explored for pressure destruction of microorganisms as well as changes in physical-chemical characteristics of pork chops. Pork chops (2 days post-rigor) were subjected to HP treatment from 200--350 MPa for 0--120 min. Results showed that pressure changes of pork variables followed a dual effect consisting of an instantaneous pressure kill (IPK) with the application of pressure pulse (no holding) and a subsequent first order rate of destruction during the pressure hold time. The IPK values were pressure dependent and increased with pressure level. Parameters k and D indicated a higher rate of pressure destruction of microorganisms compared to quality attributes.
Kinetics of pressure destruction of Listeria monocytogenes Scott A were studied in relation to those of indigenous microorganism of milk and pork. The IPK was more pronounced with L. monocytogenes than with indigenous microflora. However, the kinetic parameters (k and D values) indicated a larger pressure resistance for L. monoctyogenes. HP processes were developed based on the standard plate count (SPC) kinetic data for indigenous microflora of milk as well as L. monocytogenes in milk and pork. The results showed that SPC kinetics permitted good estimation of microbial destruction in low pressure-lethality processes of milk and pork but its application at higher pressure-lethality levels were inaccurate. On the other hand, processes established based an destruction of L. monocytogenes were more predictable. Pressure pulse application to microbial lethality was also well predicted.
The shelf-life of milk and pork increased with the level of applied pressure lethality, but Q10 values suggested that low storage temperature was nevertheless required to control microbial growth and maintain quality. Storage of HP treated park offered some improvement in the texture but resulted in large color changes and drip losses. L. monocytogenes were not detected in any of the stored milk samples HP treated to achieve a lethality ≥10D.

APA, Harvard, Vancouver, ISO, and other styles

43

Cetin-Karaca, Hayriye. "ANTIMICROBIAL EFFICACY OF NATURAL BIOACTIVE COMPOUNDS AND HIGH PRESSURE PROCESSING AGAINST POTENTIAL PATHOGENS IN INFANT FOODS." UKnowledge, 2015. http://uknowledge.uky.edu/animalsci_etds/57.

Full text

Abstract:

This study investigated the antimicrobial efficacy of bioactive plant compounds along with high pressure processing (HPP) against pathogens Bacillus cereus and Cronobacter sakazakii in infant formula and infant rice cereal. The influence of these applications on antimicrobial activity, shelf-life and sensory attributes of infant foods were examined. Trans-cinnamaldehyde (TC), (-)-Epigallocatechin gallate (EGCG) and [10]-Gingerol (GI) were incorporated (0.05%) in infant rice cereal reconstituted with infant formula. The cereal was inoculated with either B. cereus (ATCC 14579) or B. cereus spores (107-108 log CFU g-1). All the samples were stored at 7, 23 or 37°C for 0, 4, 8 and 24 h. TC showed the highest antimicrobial activity by inhibiting the B. cereus and its spores up to 2.72 and 3.8 log CFU g-1, respectively. HPP (600 MPa for 5 m), and TC (0.05-0.1%) along with Chitosan (CH) (1%), were applied to reconstituted powder infant formula which was inoculated with either 3 strains of C. sakazakii (ATCC 29544, ATCC 12868, and ATCC BAA 894) or 5 strains of B. cereus spore (ATCC 14579, ATCC 33018, ATCC 12826, ATCC 4342, and Difco Spores) cocktail (107-108 log CFU ml-1). All the samples were stored at 7, 23 or 45°C for 5-8 weeks. HPP and TC (0.1%) combination exhibited the highest inhibition (P < 0.05) by reducing the B. cereus spores 2.97 log CFU ml-1 after 7 d. C. sakazakii was fully inactivated by HPP, TC (0.05%) and C (1%) combination following 8 weeks of storage at 7 and 23°C and 2 weeks storage at 45°C. The combination of HPP and bioactive compounds exhibited additive antimicrobial effect. Gradual decrease (P < 0.05) in pH was observed in rice cereal and non-HPP formula samples due to the microbial growth and metabolic activity. Significant differences (P < 0.05) were found in color, aroma and general appearance of EGCG and GI applied cereal samples, while TC only did exhibit a cinnamon taste. In summary, the antimicrobial findings suggest that TC, EGCG, GI and CH could be incorporated in infant foods along with HPP as natural and safe alternatives to synthetic preservatives and thermal applications.

APA, Harvard, Vancouver, ISO, and other styles

44

Ngarize, Sekai. "Effects of high pressure and heat processing on the structure and rheological properties of food proteins." Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/844100/.

Full text

Abstract:

This study evaluated the effect of heat and high pressure processing of whey protein isolate, beta-lactoglobulin, egg albumen, ovalbumin and their binary mixtures. Rheological studies of whey proteins (15% w/w) in distilled water indicated that gels made by heating at 90°C for 30 min were stronger and more elastic compared with pressure-treated gels (400-600 MPa for 20 min). Gel strengths at higher pressure (650-800 MPa) were similar to heated samples, hi contrast, egg albumen proteins (15% w/w) in distilled water showed no gelation below 500 MPa but increased in strength with increasing pressure, although values remained below those of heat- induced gels. Heat and pressure treatment of whey/egg albumen protein mixtures (10:5) produced gels stronger than expected indicating synergistic interactions. Sucrose influenced gelation and interactions, with 20% sucrose being the optimal for egg albumen and whey proteins. Sucrose addition produced weaker pressure-treated gels compared with heated gels. Addition of 1% NaCl produced stronger whey protein gels compared with egg albumen but weaker mixed whey/egg albumen gels. Combined heat (50°C or 60°C) and pressure (600 MPa) produced weaker gels compared with heat treatment alone, but stronger gels than pressure treatment alone for both whey and egg albumen proteins and mixtures. Values increased with increasing temperature due to greater protein unfolding, as shown by Differential Scanning Calorimetry. FT Raman spectroscopy indicated that both heat and high pressure affected alpha-helix, beta-sheet structure, hydrophobic interactions and disulphide bonds. Heat caused greater changes in disulphide bonds and beta-sheet structures but pressure produced greater changes in hydrophobic interactions. Self deconvolution of the Amide I band showed quantitative changes in secondary structures. Random coil increased in high pressure treated (600 MPa, 30 min) beta-lactoglobulin, whereas, for ovalbumin, beta-turns doubled. The different mechanisms of gelation observed for heating and high pressure treated egg albumen, whey proteins and their mixtures can provide novel textures.

APA, Harvard, Vancouver, ISO, and other styles

45

Jordan, Carly N. "Encephalitozoon cuniculi: diagnostic test and methods of inactivation." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/34162.

Full text

Abstract:

Encephalitozoon cuniculi is a zoonotic protozoan parasite in the phylum Microspora that has been shown to naturally infect several host species, including humans, rabbits and dogs. Currently, serological diagnosis of infection is made using the immunofluorescense assay (IFA) or enzyme-linked immunosorbent assay (ELISA). Although these methods are sensitive and reliable, there are several drawbacks to both tests. Cross-reactivity between other Encephalitozoon species is common, and specialized equipment is required for IFA and ELISA. Most wildlife species are unable to be tested using these methods, because species-specific antibodies are required. One goal of this work was to develop a new serological test for diagnosing E. cuniculi infection that would be more practical for use in small veterinary and medical clinics. The effectiveness of the agglutination test was examined in CD-1 and C3H/He mice infected with E. cuniculi or one of 2 other Encephalitozoon species. The results indicate that the agglutination test is 86% sensitive and 98% specific for E. cuniculi, with limited cross-reactivity to E. intestinalis. The test is fast and easy to conduct, and requires no specialized equipment or species-specific antibodies. Recent reports of microsporidial DNA in crop irrigation waters suggest that unpasteurized juice products may be contaminated with E. cuniculi. High pressure processing (HPP) is an effective means of eliminating bacteria and extending the shelf life of products while maintaining the sensory features of food and beverages. The effect of HPP on the in vitro infectivity of E. cuniculi spores was examined. Spores were exposed to between 140 and 550 MPa for 1 min, and then spores were loaded onto cell culture flasks or were kept for examination by transmission electron microscopy (TEM). Spores treated with between 200 and 275 MPa showed reduction in infectivity. Following treatment of 345 MPa or more, spores were unable to infect host cells. No morphologic changes were observed in pressure-treated spores using TEM. The effect of disinfectants on in vitro infectivity of E. cuniculi spores was also examined. Spores of E. cuniculi were exposed to several dilutions of commercial bleach, HiTor and Roccal, and 70% ethanol for 10 minutes and then loaded onto Hs68 cells. The results of this study showed that all concentrations of disinfectants tested were lethal to E. cuniculi spores. Encephalitozoon cuniculi spores are more sensitive to disinfectants than are coccidian oocysts and other parasite cysts.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

46

Jośī, Dilīpa. "REAL-TIME DIGITAL CONTROL FOR BIOMASS LIQUEFACTION SYSTEM (HIGH PRESSURE, TEMPERATURE, MICROPROCESSOR, AUTOCLAVE)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275423.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Lou, Fangfei. "Inactivation of Selected Non-enveloped and Enveloped Viruses by High Pressure Processing: Effectiveness, Mechanism, and Potential Applications." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1312912697.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Suklim, Kannapha. "Effects of high hydrostatic pressure processing on Bacillus cereus spores in fresh blue crab meat (Callinectes sapidus)." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/26905.

Full text

Abstract:

The Food and Drug Administration has recently expressed concern for the safety of seafood and seafood products. One of the concerns is the presence of Bacillus cereus in fresh blue crab meat. Bacillus cereus is a spore-forming pathogen whose spores survive the customary thermal treatments applied during cooking and pasteurization; therefore it could potentially present a health concern to consumers as the microorganism could increase to pathogenic levels. The objectives of this study were to evaluate the effects of a post-processing method i.e. high hydrostatic pressure treatment on the quality of fresh crab meat and to evaluate the effectiveness of high pressures on the inactivation of B. cereus spores. Fresh blue crab meat was pressurized at 300 and 550 MPa at 25Â° C for 5 min and stored at 4Â° C for 31 days to determine the pressurization effects on the microbiological, physical, and sensory quality of the meat. A pressure of 300 MPa caused a 1 log reduction in total aerobic plate count and a 3 day lag period, whereas 550 MPa inactivated 2 logs in total aerobic plate count with no evident lag phase. Physical and sensory qualities of pressurized crab meat were not statistically different from the untreated crab meat (P>0.05). A pressure of 300 MPa extended the shelf-life from 17 to over 24 days with the prevalence of Carnobacterium piscicola at the time of spoilage. Crab meat treated with 550 MPa was not rejected by sensory panels at day 31 and Enterococcus spp. was identified as the predominant microorganism. High hydrostatic pressure (550 MPa at 40Â° C for 15 min) inactivated less than 1 log (0.66 log) of B. cereus spores inoculated in fresh crab meat. The meat essentially had a protective effect on pressure inactivation of the spores. During storage (31 days), surviving B. cereus was suppressed and outgrown by the other pressure resistant microflora at a storage temperature of 12Â° C. At 4Â° C, B. cereus could compete with the other pressure-resistant microflora and was isolated even at the end of the storage period (day 31); however, diarrheal toxin was not detected in any stored samples.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

49

Munj, Hrishikesh. "CO2 ASSISTED PROCESSING OF BIOCOMPATIBLE ELECTROSPUN POLYMER BLENDS." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1400693315.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Zhou, Yuqun. "Development of a bench scale high pressure fluidised bed reactor for the processing of coal and biomass." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/8903.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'High pressure processing'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles