Academic literature on the topic 'High pressure homogenization (HPH)'

The behavior of sludge solubilization using high-pressure homogenization (HPH) treatment was examined by investigating the sludge solid reduction and organics solubilization. The sludge volatile suspended solids (VSS) decreased from 10.58 to 6.67 g/L for the sludge sample with a total solids content (TS) of 1.49% after HPH treatment at a homogenization pressure of 80 MPa with four homogenization cycles; total suspended solids (TSS) correspondingly decreased from 14.26 to 9.91 g/L. About 86.15% of the TSS reduction was attributed to the VSS reduction. The increase of homogenization pressure from 20 to 80 MPa or homogenization cycle number from 1 to 4 was favorable to the sludge organics solubilization, and the protein and polysaccharide solubilization linearly increased with the soluble chemical oxygen demand (SCOD) solubilization. More proteins were solubilized than polysaccharides. The linear relationship between SCOD solubilization and VSS reduction had no significant change under different homogenization pressures, homogenization cycles and sludge solid contents. The SCOD of 1.65 g/L was solubilized for the VSS reduction of 1.00 g/L for the three experimental sludge samples with a TS of 1.00, 1.49 and 2.48% under all HPH operating conditions. The energy efficiency results showed that the HPH treatment at a homogenization pressure of 30 MPa with a single homogenization cycle for the sludge sample with a TS of 2.48% was the most energy efficient.

High pressure homogenization (HPH) is an emerging technology with several possible applications in the food sector, such as nanoemulsion preparation, microbial and enzymatic inactivation, cell disruption for the extraction of intracellular components, as well as modification of food biopolymer structures to steer their functionalities. All these effects are attributable to the intense mechanical stresses, such as cavitation and shear forces, suffered by the product during the passage through the homogenization valve. The exploitation of the disruptive forces delivered during HPH was also recently proposed for winemaking applications. In this review, after a general description of HPH and its main applications in food processing, the survey is extended to the use of this technology for the production of wine and fermented beverages, particularly focusing on the effects of HPH on the inactivation of wine microorganisms and the induction of yeast autolysis. Further enological applications of HPH technology, such as its use for the production of inactive dry yeast preparations, are also discussed.

The effects of high-pressure homogenization (HPH) on the structural, physical, and rheological properties of lily pulp (15%, w/w) were investigated. Different pressures ranging from 0 MPa to 100 MPa were used. The focus was on evaluating the changes in the particle size distribution (PSD), structure, pulp sedimentation behavior, serum cloudiness (SC), total soluble solids (TSS), color, and rheological behavior of the pulps. PSD analysis showed that the diameter of suspended lily particles significantly decreased with an increasing homogenization pressure. The suspended particles observed through optical microscopy became small after homogenization, highlighting the effect of HPH on disrupting the suspended particles. Compared with the untreated pulp, the SC and sedimentation velocity of the homogenized pulps decreased due to the disruption of the suspended particles. The effects of HPH on the sedimentation index and SC exhibited an asymptotic behavior similar to that of the changes in the particle size of lily pulp. Moreover, HPH processing reduced the viscosity of lily pulp and increased the TSS and lightness of the homogenized pulps. HPH significantly modified the structural, physical, and rheological properties of lily pulp. The pulp homogenized above 60 MPa had good suspension stability. This finding indicates that HPH technology can be used to improve the stability of lily pulp.

High pressure homogenization (HPH) at 300 MPa in apple juice provides more than 5-log kill of ascospores of Saccharomyces cerevisiae, conidiospores of filamentous fungi, and sporulated black yeasts. HPH and heat treatment were more effective against vegetative cells than against the spores of yeasts used in this study. Ascospores of Talaromyces macrosporus and Neosartorya spinosa were resistant to HPH at 300 MPa. HPH of ascospores of T. macrosporus may result in activation.

Vegetative cells and spores of five strains of Alicyclobacillus acidoterrestris (N-1100, N-1108, N-1096, SAC, and OS-CAJ) were screened for their sensitivity to high pressure homogenization (HPH, 0 to 300 MPa) in Bacillus acidoterrestris thermophilic broth. The most and least resistant strains, SAC and OS-CAJ, respectively, were further tested for their sensitivity to inactivation or growth inhibition by dimethyl dicarbonate (DMDC, 250 ppm). The combined effects of HPH and DMDC were then evaluated against SAC spores over a 24-h period after treatment. HPH alone significantly inactivated (P < 0.05) vegetative cells of all five strains. SAC vegetative cells were least affected by HPH, with only about a 0.5-log reduction after the 300-MPa treatment. Spores were not significantly reduced by HPH for any of the five strains. DMDC reduced the initial vegetative cell population by 2 log CFU/ml and significantly increased the time to reach stationary phase. For spores, a 0.5-log decrease from the initial spore population was achieved and growth was not significantly delayed. No significant difference was found between the two strains. Treatment with DMDC plus HPH slightly enhanced the inactivation effect over a 24-h period compared with treatment with HPH alone, but these differences were statistically inconsistent. Although HPH and DMDC treatments may help control vegetative cells of A. acidoterrestris, these treatments may not provide adequate overall control. Neither treatment, alone or in combination, is very effective against spores.

With the increasing global spread of human noroviral infections and the emergence of highly virulent noroviral strains, novel inactivation methods are needed to control foodborne outbreaks. High pressure homogenization (HPH) is a novel method that can be applied for foodborne virus reduction in fluids being continuously processed. Our objective in the present study was to compare the titer reduction by HPH between feline calicivirus strain F9 (FCV-F9) and murine norovirus 1 (MNV-1) as surrogates for human noroviruses, and MS2 (single-stranded F-RNA coliphage) and somatic coliphage ϕX174 (single-stranded DNA) as indicators of fecal contamination. Duplicate experiments with each virus in phosphate-buffered saline were carried out with homogenization pressures of 0, 100, 200, 250, and 300 MPa, with exposure temperatures of 24, 46, 63, 70, and 75°C, respectively, for <2 s. FCV-F9 was found highly susceptible to HPH treatment pressures of 300 MPa, with a reduction of >4.95 log PFU/ml. Lower pressures of 250, 200, and 100 MPa resulted in reductions of 1.61, 0.60, and 0.18 log PFU/ml of FCV-F9, respectively, while MNV-1 was not reduced at these lower pressures. Coliphage ϕX174 showed no significant reduction at 300 MPa or lower homogenization pressures in comparison with MS2, which did show 3.3-log PFU/ml reduction at 300 MPa. Future studies using juices for industrial application of HPH to determine microbial inactivation with simultaneous retention of sensory and nutritional value of foods are needed.

Homogenization is used widely in the dairy industry to improve product stability and quality. High-pressure homogenization (HPH) of fluid foods up to pressures of 300 MPa has demonstrated excellent potential for microbial inactivation. Microbial inactivation can be enhanced during HPH with the inclusion of antimicrobial compounds. Escherichia coli K-12 cells, grown statically or in chemostat, were exposed to HPH processing pressures of 50 to 350 MPa in the absence or presence of the antimicrobial nisin. Valve temperature was regulated by a water bath and pressure, and temperature data were recorded continuously after process initiation. Survivors were enumerated via plating on nonselective growth media. Pressure and temperature at the valve outlet port exhibited a quadratic relationship (R2 = 0.9617, P < 0.05). Significant HPH-induced inactivation of the gram-negative microorganism was observed in the range of 100 to 250 MPa. Above 300 MPa, heat was the main factor promoting microbial inactivation, regardless of whether cells were grown in chemostat or statically. Chemostat-grown cells were significantly (P < 0.05) more resistant to HPH processing than were statically grown cells. Data indicate potential synergistic effects of nisin and HPH on the inactivation of bacterial contaminants. This study represents the first report of inactivation of a bacterium with HPH pressures in excess of 300 MPa in the presence and absence of an antimicrobial.

Lotus seed starch (LS), dispersed (3%, w/v) in deionized water was homogenized (0–180 MPa) with high-pressure homogenization (HPH) for 15 min. The effects of HPH treatment on the physicochemical properties of the starch system were investigated. The properties were affected by HPH to various extents, depending on the pressure. These influences can be explained by the destruction of the crystalline and amorphous regions of pressurized LS. The short-range order of LS was reduced by HPH and starch structure C-type was transformed into B-type, exhibiting lower transition temperatures and enthalpy. The LS absorbed a great deal of water under HPH and rapidly swelled, resulting in increased swelling power, solubility and size distribution. It then showed “broken porcelain-like” morphology with reduced pasting properties. Digestion of pressurized LS complex investigated by a dynamic in vitro rat stomach–duodenum model showed higher digestion efficiency and the residues exhibited gradual damage in morphology.

The effects of HPH (high-pressure homogenization) pre-treatment on the functional properties of OPIH (oyster protein isolates hydrolysates) were studied. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles, solubility, particle size distribution, zeta potential, surface hydrophobicity, emulsifying activity index and microstructure of emulsions were analyzed. Results indicated that HPH pre-treatment increased the accessibility of OPI to trypsin hydrolysis, resulting in decease in particle size, increase in solubility, absolute zeta potential, surface hydrophobicity and emulsifying activity index. In addition, HPH pre-treated OPIH emulsions became more uniform and the particle size of droplets decreased. These results revealed that HPH pre-treatment has the potential to modify the functional properties of OPIH.

AbstractThe effect of high-pressure homogenization (HPH) at 100–200 MPa (with up to 5 passes) on the quality and storage stability of apple juice was investigated. The microbiological quality, polyphenol oxidase (PPO), peroxidase (POD), polygalacturonase (PG) and pectinmethylesterase (PME) activity, particle size distribution (PSD), apparent viscosity, turbidity, concentration of vitamin C, individual polyphenols and their total content (TPC), antioxidant activity, and colour of fresh, HPH-treated apple juice were all evaluated. The highest reduction in microorganisms (1.4 log) and oxidoreductase activity (~20%) was observed at 200 MPa, while hydrolases did not change significantly. HPH led to significant disintegration of the tissue and a decrease in viscosity. Vitamin C decreased by 62%, while TPC increased by 20% after HPH. Significant correlations were observed between antioxidant activity, TPC, and individual polyphenols. Chlorogenic, ferulic, and gallic acid were most stable at 200 MPa. The optimal shelf-life of the juice was estimated as 7 days.

The aim of this PhD thesis was to evaluate the effect of a sub-lethal HPH treatment on some probiotic properties and on cell response mechanisms of already-known functional strains, isolated from Argentinean dairy products. The results achieved showed that HPH treatments, performed at a sub-lethal level of 50 MPa, increased some important functional and technological characteristics of the considered non intestinal probiotic strains. In particular, HPH could modify cell hydrophobicity, autoaggregation and resistance to acid gastric conditions (tested in in vitro model), cell viability and cell production of positive aroma compounds, during a refrigerate storage in a simulated dairy product. In addition, HPH process was able to increase also some probiotic properties exerted in vivo and tested for two of the considered strains. In fact, HPH-treated cells were able to enhance the number of IgA+ cells more than other not treated cells, although this capacity was time dependent. On the other hand, HPH treatment was able to modify some important characteristics that are linked to the cell wall and, consequently, could alter the adhesion capacity in vivo and the interaction with the intestinal cells. These modifications, involving cell outermost structures, were highlighted also by Trasmission Electron Microscopy (TEM) analysis. In fact, the micrographs obtained showed a significant effect of the pressure treatment on the cell morphology and particularly on the cell wall. Moreover, the results achieved showed that composition of plasma membranes and their level of unsaturation are involved in response mechanisms adopted by cells exposed to the sub-lethal HPH treatment. Although the response to the treatment varied according to the characteristics of individual strains, time of storage and suspension media employed, the results of present study, could be exploited to enhance the quality of functional products and to improve their organoleptic properties.

Ce travail de recherche se concentre sur l'extraction et le fractionnement des biomolécules à partir de microalgues par des traitements physiques: les champs électriques pulsés (CEP), les décharges électriques de hautes tensions (DEHT) et les ultrasons (US). Dans cette étude, trois espèces de microalgues Nannochloropsis sp., Phaeodactylum tricornutum (P. tricornutum) et Parachlorella kessleri (P. kessleri) ont été étudiées. Les espèces ont différentes formes cellulaires, structure et contenu intracellulaire. L'effet des techniques testées sur l'extraction des biomolécules a été mis en évidence à travers une analyse quantitative et qualitative: suivi du rendement des composés ioniques, des glucides, des protéines, des pigments et des lipides. Une étude comparative des traitements physiques (CEP, DEHT et US), à la même énergie, pour la libération des biomolécules intracellulaires à partir des trois espèces de microalgues, a permis de mieux comprendre les différents mécanismes de désintégration. Pour chaque microalgue, à la même énergie consommée, le traitement par DEHT s'est révélé le plus efficace en terme d'extraction des glucides, tandis que les US sont plus efficaces pour l'extraction des protéines et des pigments. Le traitement par CEP a été moins efficace en terme du rendement d’extraction. Cependant, la meilleure sélectivité (extraction des glucides) a été obtenue en utilisant les CEP ou les DEHT. Les prétraitements physiques (CEP, DEHT ou US) des suspensions plus concentrées suivis d'une homogénéisation haute pression (HHP) de suspensions diluées ont permis d'améliorer l'efficacité de l'extraction et de diminuer la consommation énergétique totale et le nombre de passages. Le prétraitement physique permet de réduire la pression mécanique de l’HHP, pour atteindre le même rendement d’extraction. Pour la valorisation maximale de la biomasse de microalgues, une procédure d'extraction assistée par DEHT (40 kV/cm, 1-8 ms) suivie de plusieurs étapes d'extraction aqueuses et non aqueuses semble être utile pour l'extraction sélective et le fractionnement de différentes biomolécules à partir de microalgues. Des effets significatifs du prétraitement HVED sur l'extraction par solvant organique des pigments (chlorophylles, caroténoïdes) et des lipides ont été observés
This research work focuses on extraction and fractionation of bio-molecules from microalgae using physical treatments: pulsed electric fields (PEF), high voltage electrical discharges (HVED) and ultrasonication (US) techniques. In this study, three microalgae species Nannochloropsis sp., Phaeodactylum tricornutum (P. tricornutum) and Parachlorella kessleri (P. kessleri) were investigated. These species have different cell shapes, structure and intracellular contents. The effects of tested techniques on extraction of bio-molecules have been highlighted in a quantitative and qualitative analysis by evaluating the ionic components, carbohydrates, proteins, pigments and lipids. A comparative study of physical treatments (PEF, HVED and US) at the equivalent energy input for release of intracellular bio-molecules from three microalgal species allowed us to better understand the different disintegration mechanisms. For each microalga at the same energy consumption, the HVED treatment proved to be the most efficient for extraction of carbohydrates, while the US treatment for extraction of proteins and pigments. In general, the smallest efficiency was observed for the PEF treatment. However, the highest selectivity towards carbohydrates can be obtained using the mild PEF or HVED technique. The preliminary physical treatments (PEF, HVED or US) of more concentrated suspensions followed by high pressure homogenization (HPH) of diluted suspensions allowed improving the extraction efficiency and decreasing the total energy consumption. The physical pretreatments permit to reduce the mechanical pressure of the HPH and number of passes, to reach the same extraction yield. For the maximum valorisation of microalgal biomass, extraction procedure assisted by HVED treatment (40 kV/cm, 1-8 ms) followed by aqueous and non-aqueous extraction steps seems to be useful for selective extraction and fractionation of different bio-molecules from microalgae. The significant effects of HVED pre-treatment on organic solvent extraction of pigments (chlorophylls, carotenoids) and lipids were also observed

El consumo de licuado de soja está experimentado un notable incremento debido a su consideración de producto saludable. El licuado de soja, además de ser una alternativa a la leche de vaca, sobre todo para las personas que poseen alguna intolerancia a los productos derivado de la leche, tiene componentes bioactivos (flavonoides, vitamina E y poliaminas) que pueden contribuir a prevenir algunas dolencias crónicas prevalentes en la sociedad actual. En este estudio se planteó la utilización de una tecnología emergente, la ultra alta presión de homogenización (UHPH) para la obtención de licuado de soja. Esta tecnología no térmica consiste en la aplicación de presiones de hasta 400 MPa utilizando un sistema de homogenización, especialmente diseñado para producir un efecto conservador, al mismo tiempo que se mejora la estabilidad coloidal y se mantiene la calidad nutricional y sensorial. Con esta hipótesis de partida, la UHPH podría ser una tecnología alternativa a las comúnmente aplicadas a nivel industrial. Por ello, en el planteamiento de este trabajo se incluyó el estudio comparativo de la UHPH con los tratamientos térmicos de pasteurización y UHT. En la primera parte de esta tesis se llevaron a cabo diferentes tratamientos UHPH (200 y 300 MPa con temperaturas de entrada de 55, 65 y 75ºC) con la finalidad de seleccionar las condiciones óptimas para obtener productos de buena calidad, tanto de almacenamiento en refrigeración, como de larga duración de almacenamiento a temperatura ambiente. El estudio se realizó a dos niveles independientes. Por una parte se evaluaron parámetros característicos de la calidad química, coloidal, enzimática y microbiológica de licuados de consumo habitual, y por la otra, se realizó un estudio con licuados inoculados con diversas cepas microbianas para conocer su cinética de destrucción frente a tratamientos UHPH. De estos estudios se concluyó que los tratamientos a 300 MPa produjeron licuado de soja con muy buena estabilidad coloidal y química y que, aplicando una temperatura de entrada de 85ºC en combinación con dicha presión, se alcanzó una excelente reducción de las esporas bacterianas. La segunda parte del trabajo consistió en el estudio de la evolución durante el almacenamiento de los licuados UHPH tratados en las condiciones óptimas seleccionadas del estudio previo. De este modo, se obtuvieron tanto licuados frescos similares a los pasteurizados, como licuados de larga duración, similares a los tratados por UHT. Para lograr este propósito, se evaluaron una serie de aspectos, tales como microbiológicos, estabilidad coloidal, cambios de color, parámetros químicos y sensoriales que permitieron evaluar la calidad global de los productos de soja, así como su aceptación por los consumidores. Los licuados de soja fresco y de larga duración alcanzaron respectivamente 1 y 6 meses de caducidad con mejor calidad que aquellos tratados térmicamente.
Soymilk consumption is experiencing a noticeable increase due to it being considered as a healthy product. Soymilk has often been used as an alternative to dairy milk for people who have intolerance to dairy products. Nowadays, it is known for its important health benefits that can contribute to the reduction of chronic illness commonly prevalent in the modern style life. This is due, primarily, to characteristics of protein fraction and minor components rich in antioxidant activity (flavonoids, tocopherols and poliamines) taking into account the excellent nutritional profile of soymilk. This thesis project was focused on the application of an emerging technology, Ultra High Pressure Homogenization (UHPH), in the production of soy vegetable milk. This non-thermal technology consists of a high pressure machine capable of applying pressures of up to 400 MPa using a special homogenizing system designed to produce a conserving effect, improving the colloidal stability while maintaining good nutritional and sensory qualities. Considering this hypothesis, UHPH could be an alternative technology to those commonly applied in the food industries. For that, a comparative study of UHPH with thermal treatments (pasteurization and UHT) was carried out in this work. In the first part of this thesis, different UHPH conditions (200 and 300 MPa at 55, 65 and 75ºC of inlet temperature) were performed on soymilk in order to select optimal treatment conditions for producing a good quality product whether intended for refrigeration or long-term storage at room temperature. In this first step, two independent evaluations were performed. On one hand, quality parameters related to chemical, enzymatic, microbiological and colloidal characteristics were evaluated and on the other hand, an inoculation study with different strain spores was carried out in order to determine the inactivation kinetic of the UHPH treatment. Results indicated that treatments at 300 MPa were able to produce soymilk with high chemical and colloidal stability. It is also worth noting that an excellent reduction of bacterial spores was reached applying inlet temperature of 85ºC at the same pressure. The second part consisted in the shelf-life evaluation of soymilk treated by UHPH using the selected optimal conditions determined in the previous step. As a result, soymilk was obtained with similar characteristics to those produced by pasteurization and with extended shelf-life similar to those obtained by UHT treatments. To achieve this purpose, microbiological aspects, colloidal stability, color changes, chemical parameters and sensory quality were applied to evaluate the overall quality of soymilk and its acceptance by the consumers. Refrigerated soymilk and that produced for an extended shelf-life respectively reached 1 and 6 months of storage in good conditions for consumption and with better quality than those obtained by thermal treatments.

El consumo de las bebidas de soja y de almendra está aumentando en Europa porque son útiles como alternativa a la leche de vaca para los individuos intolerantes a la lactosa, con alergia a las proteínas de la leche, o para aquellos que evitan la leche por otras razones. También su popularidad aumenta por los efectos beneficiosos para la salud que se le atribuyen. Las bebidas de soja y de almendra comerciales están normalmente procesadas por tratamientos térmicos, especialmente UHT, no sólo para estabilizarlas sino también para mejorar su palatabilidad y digestibilidad ya que, entre otros efectos, destruyen componentes indeseables, tales como los inhibidores de tripsina. No obstante, los tratamientos térmicos pueden afectar a sus componentes nutritivos y compuestos bioactivos. La ultra alta presión de homogeneización (UHPH) es una tecnología no térmica emergente que consiste en la aplicación de presiones de hasta 400 MPa utilizando un sistema de homogeneización, especialmente diseñado para producir un efecto conservador, al mismo tiempo que mejora la estabilidad coloidal. En el marco de un proyecto del Plan Nacional (AGL 2008-05430-C02-02) realizado en coordinación con el grupo del Centre Especial Planta de Tecnologia dels Aliments (CERPTA) de la Universidad Autónoma de Barcelona, se pretende aplicar la UHPH para la obtención de bebidas de soja y almendra y comparar los efectos de esta tecnología con los de los convencionalmente aplicados a este tipo de productos (pasteurización y UHT). En el primer apartado de esta memoria se valora el efecto que esta tecnología provoca sobre una serie de parámetros nutritivos y biofuncionales (perfil de aminoácidos, perfil de ácidos grasos, digestibilidad de las proteínas, disponibidad de la lisina, tocoferoles, fitoesteroles, aminas biógenas, poliaminas e isoflavonas), extendiendo el estudio a no solo al efecto inmediato del tratamiento si no también durante la vida útil de los productos. En términos generales, se concluye que los tratamientos por UHPH mantienen o mejoran, en comparación con los térmicos, el valor nutritivo y biofuncional de las bebidas de soja y de almendra. La soja aporta compuestos bioactivos, como las isoflavonas, cuyo consumo puede presentar efectos beneficiosos para la salud pero hay controversia sobre la seguridad de su consumo por parte de lactantes, ya que se he señalado que pueden ejercer tiene efectos endocrinos indeseables sobre el desarrollo y el sistema reproductor. En la segunda parte de esta tesis, se realiza una aproximación a una estimación de la exposición y del riesgo de estos compuestos bioactivos en productos derivados de la soja de mayor consumo. Aún no existen datos de consumo de productos derivados de soja en Europa, pero la estimación muestra que una dieta que incluya habitualmente productos derivados de la soja aporta contenidos de isoflavonas suficientes para lograr sus potenciales efectos beneficiosos. Por otro lado, el consumo de fórmulas infantiles a base de soja por lactantes supone un cierto riesgo de sufrir los efectos adversos de las isoflavonas, ya que su consumo sobrepasa los niveles de seguridad establecidos por el Panel de Expertos (NTP-CERHR). Además, los productos derivados de la soja, especialmente los fermentados, contienen niveles elevados de algunas aminas biógenas. La ingesta de algunos de estos productos de soja puede suponer un riesgo de aparición de los efectos adversos de estas aminas, especialmente cuando hay un tratamiento con fármacos específicos. En la tercera parte, se estudia algunos efectos biológicos de las poliaminas e isoflavonas. Las poliaminas son compuestos naturales con un papel reconocido como antioxidante endógeno en frente al estrés oxidativo celular. Se estudia su capacidad antioxidante in vitro y el mecanismo de acción y se concluye que su capacidad antioxidante es superior al de otros antioxidantes reconocidos (galato de octilo, palmitato de ascorbilo y α-tocoferol) y que su potencia antioxidante se debe a su capacidad para secuestrar metales y radicales libres. Por otro último, se estudia el metabolismo intracelular de las isoflavonas en células endoteliales por su importancia potencial en los mecanismos de acción cardioprotectores del sistema vascular. Se concluye que las isoflavonas entran en las células endoteliales y son metabolizadas mediante glucuronidación, sulfatación y metilación.
Soymilk and almond milk are particularly useful as an alternative of cow’s milk for people who are lactose-intolerant, allergic to milk proteins, or for those who avoid milk for other reasons, and their consumption also has potential health benefits. Ultra high pressure homogenization (UHPH) is a useful non-thermal technology to obtain safe and high-quality liquid foods. UHPH is based on the same principle as conventional homogenization, but it works at significantly higher pressures (up to 400 MPa). In the first part of this thesis, in the frame of the project “The application of Ultra high pressure homogenization (UHPH) to produce high quality vegetable milks (soy and almond)” (AGL 2008- 05430- C02-02), the aim was to study the effects of the UHPH treatment on the nutritional and biofunctional compounds of soymilk and almond milk compared to conventional thermal pasteurization and UHT treatments. As a result, it was concluded that UHPH treatments maintained or improved the nutritional and biofunctional value of soymilk and almond milk, compared to conventional thermal pasteurization and UHT treatments. Soybean provides bioactive compounds, such as isoflavones, whose consumption has potential beneficial health effects for adults and also could have significant effects on the endocrine and reproductive system development in infants. In the second part of this thesis, an estimation of exposure and risk of these bioactive compounds in soybean products was performed. In general, the consumption of these products provides similar or higher isoflavone contents to achieve the beneficial effects. On the other hand, the consumption of soybean based infant formulas could involve a potential risk to infants. Additionally, the fermented soybean products contain high levels of certain biogenic amines. Adverse effects of some biogenic amines as a result of the consumption of the soybean products in general would be unlikely, except for individuals under specific drug therapies. In the third part, some biological effects of polyamines and isoflavones were studied. The mechanism by which polyamines act as antioxidants was evaluated by in vitro methods, concluding that it seems to be related to its ability to chelate metals. Furthermore, the intracellular metabolism of isoflavones in endothelial cells was studied because it can be important in the elucidation of the mechanism of action of isoflavones in the cardiovascular system.

An industrial Fourier transform infrared (FTIR) milk analyser has been adapted for the proximate analysis of fresh or cooked meat and meat products. Stable freeze-dried samples of ground beef and bologna were prepared for the calibration of an FTIR spectrometer equipped with a 37-mum transmission cell maintained at a constant temperature of 65°C and were analysed for fat, protein, moisture, and ash by the official methods of analysis of the Association of Official Analytical Chemists (AOAC) prior to instrumental measurement. The requirement to prepare a "milk-like" emulsion of meat for FTIR analysis led to the development of two prototype high-pressure homogenizers specifically designed to produce analytical volumes of emulsions in which the largest residual colloids present in suspension would have dimensions smaller than 1 mum. Emulsified samples were examined by transmission electron microscopy and laser light scattering spectroscopy to determine the size distribution of fat globules and the dimensions of the residual insoluble fragments of protein.
"Milk-like" emulsions of meat passed three times through a high-pressure homogenizer operating at 20,000 psi (138 MPa) had an average fat globule diameter of less than 320 nm. Also, the use of high-pressure homogenization eliminated the need to filter out insoluble proteins from connective tissues prior to the infrared analysis, resulting in a more accurate determination of the protein content in the meat samples. The results of validation studies conducted with both fresh and freeze-dried samples demonstrated that it is possible to analyse meat samples simultaneously for fat, protein, carbohydrates and moisture with good accuracy in approximately 7½; minutes per sample employing existing FTIR instrumentation used for the routine analysis of milk and dairy products.

El principal objetivo de esta tesis ha sido evaluar la capacidad de la tecnología de ultra alta presión de homogeneización (UHPH) como alternativa a la pasteurización convencional para garantizar la seguridad y calidad de los alimentos líquidos. Para probar la eficacia de la UHPH y garantizar la seguridad microbiana de los alimentos se inoculó Listeria monocytogenes y/o S. enterica serovar Senftenberg 775W en diferentes alimentos líquidos como son huevo entero líquido, leche y zumo de frutas (naranja y uva). y se trataron a 150, 200 y 250 MPa en el caso del huevo liquido y a 200, 300 y 400 MPa en el de leche y zumos de frutas, realizándose la evaluación de su supervivencia durante el almacenamiento en refrigeración a 4ºC durante 20 días en las muestras de huevo y 12 días en las muestras de leche y zumo de frutas. Los recuentos de células viables y dañadas se realizaron utilizando agar triptona soya enriquecida con extracto de levadura y el mismo medio suplementado con sal. Para evaluar los factores que pudieran afectar a la inactivación bacteriana en la eficacia del tratamiento UHPH, se estudió la influencia de la concentración bacteriana baja (3 log CFU/ml) y alta (7 log CFU/ml) en huevo y leche, así como la influencia del contenido de grasa en leche (0.3, 3.6, 10, y 15% de grasa). Adicionalmente, con la finalidad de explicar algunos de los resultados de supervivencia de los patógenos inoculados en los zumos de frutas se estudió la eficacia a la respuesta de ácido tolerancia (ATR) en la protección de Listeria monocytogenes y S. enterica en fase exponencial o estacionaria en zumo de naranja y uva conservados a 4 y 25ºC. En huevo, el tratamiento a 250 MPa disminuyo los recuentos de Salmonella enteritidis serovar Senftenberg 775W a niveles similares a los obtenidos en la pasteurización térmica, produciéndose una disminución posterior por debajo de los límites de detección durante el almacenamiento 4ºC, aunque se detecto su presencia. En las muestras de leche (0.3 and 3.6%), se observó que 300 y 400 MPa dañaban considerablemente a L. monocytogenes, pero durante el almacenamiento fue capaz de recuperarse y desarrollarse. No obstante, los mayores valores de letalidad se consiguieron en las muestras de leche con un contenido de 15 y 10% de grasa. En las zumos, el tratamiento a 400 MPa inactivó completamente Salmonella enteritidis serovar Senftenberg 775W, este cepa se mostró mas sensible que L. monocytogenes a los tratamientos UHPH aplicados. Sin embargo, al finalizar el periodo de almacenamiento del zumo de uva control y homogenizado no se detectaron recuentos de L. monocytogenes, lo que podría ser atribuido a la presencia de compuestos naturales de la uva con efecto antilisteria. La respuesta de ácido tolerancia se indujo a L. monocytogenes y Salmonella enteritidis serovar Senftenberg 775W para evaluar si se presentaba un efecto protector ante estrés por acidez. Se observó que las células en fase estacionaria mostraban una resistencia natural a pH bajos. Tomando como modelo al zumo de naranja, se evaluó el efecto de la UHPH en la actividad enzimática (pectin metilesterasa) y microbiológica (bacterias aerobias mesófilas, psicotrófas, ácido lácticas y levaduras), en los atributos físicos (turbidez y distribución del tamaño de partícula), en las propiedades bioactivas (contenido de Lacido ascórbico, carotenoides y polifenoles), en la actividad antioxidante y en otros los parámetros generales de calidad (color, pH, °Brix, acidez titulable, azúcares reductores y índice de oscurecimiento no enzimático). Los tratamientos UHPH aplicados consistieron de dos temperaturas de entrada (10 o 20ºC), tres niveles de presión (100, 200 y 300 MPa) y dos tiempos de retención (≤ 0.7 o 30 segundos). Los resultados se compararon con los resultados obtenidos por pasteurización térmica (1 o 2 min a 90 ºC). Los tratamientos de UHPH iguales o superiores a 200 MPa fueron igualmente efectivos que la pasteurización para el control de la actividad enzimática y de las bacterias alterantes del zumo no apreciándose actividad enzimática ni incremento de los recuentos microbianos tras 50 días de almacenamiento a 4ºC. Los zumos tratados por UHPH tuvieron la mejor distribución de tamaño de partícula y los mejores valores de turbidez en comparación con los zumos pasteurizados, obteniendo una mayor reducción de del tamaño de partícula en las muestras tratadas a 300 MPa. La retención de L-acido ascórbico y carotenoides dependió de la presión aplicada y específicamente de la temperatura alcanzada durante el tratamiento. El contenido de flavonoides se incrementó en el zumo con los tratamientos por UHPH, obteniendo el mayor contenido a 200 y 300 MPa. Además, los zumos tratados por UHPH mostraron niveles de capacidad equivalente antioxidante trolox (TEAC) mayores que los de los zumos frescos o pasteurizados. Además, se realizó un estudio sensorial de preferencia y aceptabilidad en zumo homogeneizado en las condiciones consideras de elección (20ºC de temperatura de entrada y 300 MPa) y se evaluó la vida útil a 6ºC y 20ºC por 90 días. En el estudio de aceptabilidad, la muestras tratada por UHPH obtuvieron la menor puntuación en términos de valoración de color con respecto a la muestra pasteurizada. Durante los 90 días de almacenamiento a 6ºC los recuentos de las muestras tratadas por UHPH así como las pasteurizadas se mantuvieron por debajo del límite de detección (1 Log CFU/ml).
The main objective of this thesis has been to evaluate the capacity of the ultra-high pressure homogenization (UHPH) technology as alternative to the conventional pasteurization in ensuring the safety and quality of liquid foods. To test the effectiveness of the technology to guaranty the microbial safety of foods we inoculated strains of Listeria monocytogenes and/or S. enterica serovar Senftenberg 775W into different liquid foods such as whole egg, milk and fruit juices (orange and grape). They were submitted to a single cycle of UHPH treatment at 150, 200 and 250 MPa for liquid whole egg and at 200, 300, and 400 MPa for milk and fruit juices. The effectiveness of the UHPH treatments over low (3 log CFU/ml) and high (7 log CFU/ml) bacteria loads was evaluated in both liquid whole egg and milk. Moreover, the influence of milk fat content (0.3, 3.6, 10, and 15% of fat) in the Listeria monocytogenes inactivation by UHPH treatments was also studied. Samples counts were followed during of storage at 4ºC over 20 days for liquid whole egg and 15 days for milk and fruit juices. Viable and injured bacterial counts were evaluated by means of a differential plating method using tryptone soy agar enriched with yeast extract and the same medium supplemented with salt. Additionally, with the purpose to explain some of the results of the survival of pathogens inoculated in fruit juices, the effectiveness of the response acid tolerance (ATR) on the protection in the exponential or stationary phase of Salmonella Seftenberg and L. monocytogenes inoculated in orange and grapefruit juice during their conservation at 4 °C and 25ºC was studied. In liquid whole egg, UHPH treatments at 250 MPa effectively reduced Salmonella enteritidis serovar Senftenberg 775W to similar levels than reported for thermal pasteurization. Surviving Salmonella counts decreased below the detection limit during the storage of the liquid egg at 4ºC, although Salmonella was immunologically detected during all the storage period. In milk samples which a low fat concentration (0.3 and 3.6 %), pressures of 300 and 400 MPa damaged considerably L. monocytogenes cells but they were able to recover and grow up during the subsequent cold storage. Nevertheless, higher lethality values were achieved in milk with the highest fat content (15 and 10%). In fruit juices, UHPH treatments at 400 MPa inactivated completely Salmonella enteritidis serovar Senftenberg 775W, being this strain more sensitive than L. monocytogenes to the UHPH treatments applied. However, in grape juice L. monocytogenes viable counts were undetectable at the end of storage in both control and pressurized samples, which could be attributed to the presence of natural compounds with antilisterial effect. Acid tolerance response (ATR) was induced in L. monocytogenes and Salmonella enteritidis serovar Senftenberg 775W to assess if it was able to protect cells from a most severe acid stress. Cells in stationary phase, used on the UHPH experiment with juices, showed a natural resistance to low pH values. Taking orange juice as food model, we also evaluated the effect of UHPH treatments on enzymatic activity (pectin methylesterase PME) and microbiological (mesophilic aerobic bacteria, psychrotrophic aerobic bacteria, lactic-acid bacteria and yeast) spoiling activity, as well as on physical attributes (cloud stability and particle size distribution), bioactive properties (L-ascorbic, carotenoid and polyphenol content), antioxidant activity and other general quality parameters (color, pH, °Brix, titratable acidity, reducing sugars and non-enzymatic browning index). In this case the UHPH treatments used consisted in combinations of two inlet temperatures (10 or 20ºC), three pressures (100, 200 or 300 MPa) and two holding times (≤ 0.7 or 30 seconds). Results were compared with two thermal pasteurization treatments (1 or 2 min at 90 ºC). UHPH treatments above 200 MPa were as effective as pasteurization to control both PME activity and spoilage bacteria in orange juice. Neither pectin methyl esterase activity nor microbial counts increased significantly after 50 days of storage at 4ºC. UHPH treated juices showed a better particle size distribution and cloudiness values than the pasteurized juices. In particular, the smallest particles were observed in samples treated at 300 MPa. L-ascorbic acid and carotenoid retention of orange juice depended on the high pressure used and more specifically on the maximum temperature achieved during the UHPH treatment. Content of flavonoids in orange juice increased after the UHPH treatments, achieving the maximum concentration in the samples treated at 200 and 300 MPa. Moreover, UHPH treated juices showed higher levels of trolox equivalent antioxidant capacity (TEAC) values than did fresh and heat-treated samples. Additionally, a preliminary sensorial test of preference and acceptability was made with the orange juice treated at 20ºC of inlet temperature and 300 MPa. Moreover with these samples a shelf-life test was carried out by 90 days at 6ºC and 20ºC. In the consumer acceptability study, the UHPH samples in term of color obtained the lowest score. Microbial counts of both UHPH treated and pasteurized samples kept below of the detection limit (1 Log CFU/ml) during the 90 days of storage at 6ºC.

Alguns decênios atrás, o advento da nanotecnologia abriu perspectivas inovadoras permitindo alcançar novos alvos. Na área farmacêutica, as nanopartículas abriram alternativas ineditas de acesso para tratar órgãos e tecidos. Dentre as diversas nanopartículas existentes, este trabalho assentou sobre as nanopartículas lípidicas sólidas porque elas permitem a utilização de substâncias naturais, que representam um interesse cada vez maior devido às suas potencialidades diversificadas e comprovadas. Assim, foram escolhidos o óleo de copaíba e a alantoína devido às suas propriedades farmacológicas. Da mesma maneira que existem vários tipos de nanopartículas, existem várias técnicas para produzi-las. Neste estudo, o método por homogeneização à alta pressão foi selecionado devido às diversas vantagens. Para validar essas opções tecnológicas e caracterizar as nanopartículas, análises morfológicas, físico-químicas e térmicas foram realizadas. O segundo propósito desta pesquisa foi a avaliação do potencial antifúngico das nanopartículas contra fungos leveduriformes e filamentosos multirresistentes, devido às diversas propriedades microbiológicas do óleo de copaíba. Consequentemente, diversos ensaios micológicos foram feitos a fim de determinar onde e como essas nanopartículas agiram sobre esses fungos. Os resultados mostraram que a produção de nanopartículas lípidicas sólidas homogêneas e estáveis físico-quimicamente foi possível. Além disso, essas nanopartículas, compostas por substâncias naturais, demonstraram atividade antifúngica contra fungos multiresistentes, fato que não ocorreu com as matérias-primas isoladas. A nanotecnologia foi fundamental e levou a desenvolver suspensões antifúngicas.
Some decades ago, the advent of nanotechnology has opened new perspectives allowing reaching new targets. In the pharmaceutical area, nanoparticles have opened new ways for treating organs and tissues. Among the various existing nanoparticles, this work was based on solid lipid nanoparticles because they permitted the use of natural substances which represent a growing interest due to their diverse and proven strengths. So, copaiba oil and allantoin were chosen. Just as there are several types of nanoparticles, there are several techniques to produce them. In this study, the method of high pressure homogenization was selected because of several advantages. To validate these technological options and characterize nanoparticles, morphological, physico-chemical and thermal analysis were performed. The second purpose of this research was to evaluate the antifungal potential of nanoparticles against multiresistant yeasts and filamentous fungi due to various microbiological properties of copaiba oil. Consequently, many mycological tests were performed to determine where and how these nanoparticles acted on these fungi. The results showed the production of homogeneous and physico-chemically stable solid lipid nanoparticles is possible and, moreover, these nanoparticles produced with natural substances demonstrated their antifungal activity against multiresistant fungi, which did not happen with isolated raw materials. The nanotechnology was fundamental and led to develop antifungal suspensions.

Abstract Laser Powder Bed Fusion (L-PBF) processes are becoming more viable in place of traditional castings in a variety of industries. To compete, novel material grades are being considered with additive manufacturing (AM). In maximizing performance and manufacturing efficiency through AM, a novel approach to heat treatment and Hot Isostatic Pressing (HIP) processing needs to be considered. It has been shown that combining key heat treatment processes with (HIP) by utilizing fast cooling rates can benefit static properties as well as improve turn-around time for HIP processing [1,2]. Argon pressures up to 207 MPa with cooling rates above 170°C per minute are now available in production sized HIP systems to design ideal HIP cycles for high pressure heat treatment. Additive manufacturing with high pressure heat treatment is in need of further investigation for establishing new qualification standards. This study investigates designed High-Pressure Heat Treatment cycles to consider mechanical performance on LPBF CoCr. The combined cycles investigate possible alternatives to historically accepted two step HIP then heat treat processing by combining densification with homogenization treatment into one step. Tensile, fatigue, hardness, microstructure and Charpy impact performance are explored to seek optimal properties and with streamlined thermal processing. It was found that all trial conditions exceeded Electron Beam Melted (EBM) AM CoCr expectation, but traditional processing provided a slight advantage in ultimate tensile stress. One of the novel processes explored, “common” was found to provide a slight improvement on yield stress and direct hardness. Published fatigue data is rare for CoCr, however data generated from this study showed a slight advantage to the “common” HPHT process primarily for lower applied stress levels. Microstructures were comparable across all trial processes. It is recommended that each novel processing route be considered as viable alternatives to traditional processing, but that the “common” processing may prove advantageous for both mechanical properties and streamlined manufacturing.

Composites can undergo micro damage leading to variations of the mechanical properties. The micro damage can be the result of high internal pressures and/or exposure to physical trauma. Modeling techniques, such as homogenization, are effective outside of these critical regions. However they break down in regions where the micro damage is occurring. To account for this, an algorithm has been developed to detect and implement a multiscale method on elements that observe a critical strain. The remaining model uses the homogenization method to simulate the composite. The elements surrounding the multiscale elements are adapted to act as a transition from multiscale to the homogenization. The multiscale approach is based on the partition of unity paradigm, allowing macro-scale computations to be performed with the micro-structural features explicitly considered. The model has been validated by comparing it to experimental results of a composite overwrapped steel tube section subjected to high internal pressures.

The considered structure is a nuclear reactor vessel, composed of two concentric inner and outer structures, with water in the annular space between. Previous dynamic analysis showed that this water lead to strong fluid structure interaction coupling the structures. The annular space is filled by regularly spaced cylinders, which are linked to the inner structure. Their influence was neglected in the first studies. Recent analyses, using homogenization methods, show that these cylinders increase the FSI coupling in the vessel. The homogenization methods is based on general principles developed in the study of tube bundles, and very well established, from a physical and numerical point of view. Even if it seems reasonable to have a high degree of confidence in the results obtained with this homogenization methods, it is still interesting to validate the results of the “homogenization analysis” with a comparison with “direct calculations”, taking into account the real geometry of the system. The paper presents the main results of the validation. The main limitation of the “direct calculations” is the size of the mesh and the computer time. The main limitation for the “homogenization analysis” is that the actual modeling does not take into account the anisotropy in the Fluid Structure Interaction in the annular space.