Efecto de un tratamiento previo por altas presiones hidrostáticas sobre la alteración lipídica de jurel chileno (Trachurus murphyi) refrigerado

Lipid damage evolution was analyzed in chilled Chilean jack mackerel (Trachurus murphyi) previously treated with high hydrostatic pressure (HHP) technology. Different pressure levels and pressure holding times were tested. In addition, fish corresponding to pre- and post-rigor mortis (RM) stages were comparatively studied. Previous HHP treatment led to a marked lipid hydrolysis inhibition in chilled fish. Increasing the pressure level and pressure holding time led to a lower free fatty acid content, with the effect of pressure being more relevant. According to the analysis of different types of lipid oxidation indexes, no effect of the previous HHP treatment on the lipid oxidation development could be determined in chilled jack mackerel. Concerning the effect of the RM stage of raw fish, a higher primary and secondary lipid oxidation development was observed in fish corresponding to the post-RM condition throughout the chilled storage; although a definite effect on lipid hydrolysis could not be found.Se estudió la evolución de la alteración lipídica en jurel chileno (Trachurus murphyi) refrigerado previamente tratado a altas presiones hidrostáticas (HHP). Se aplicaron distintos valores de presión y tiempo de presurización; asimismo, se analizó de forma comparativa la respuesta al proceso del pescado inicial en estados pre- y post-rigor mortis (RM). El tratamiento previo por HHP produjo inhibición de la hidrólisis lipídica en pescado refrigerado, siendo más intenso el efecto de la presión que el del tiempo de presurización. De acuerdo con el análisis de distintos índices de oxidación, no se concluyó un efecto determinante sobre la oxidación lipídica por parte del tratamiento previo de HHP. En relación al efecto del estado de RM del pescado inicial, se observó una oxidación primaria y secundaria mayor en jurel correspondiente a la condición post-RM durante la conservación en refrigeración; sin embargo, no se detectó un efecto claro sobre la hidrólisis lipídica

Improving the rheometry of rubberized bitumen: experimental and computation fluid dynamics studies

Multi-phase materials are common in several fields of engineering and rheological measurements are intensively adopted for their development and quality control. Unfortunately, due to the complexity of these materials, accurate measurements can be challenging. This is the case of bitumen-rubber blends used in civil engineering as binders for several applications such as asphalt concrete for road pavements but recently also for roofing membranes. These materials can be considered as heterogeneous blends of fluid and particles with different densities. Due to this nature the two components tends to separate and this phenomenon can be enhanced with inappropriate design and mixing. This is the reason behind the need of efficient dispersion and distribution during their manufacturing and it also explains while realtime viscosity measurements could provide misleading results. To overcome this problem, in a previous research effort, a Dual Helical Impeller (DHI) for a Brookfield viscometer was specifically designed, calibrated and manufactured. The DHI showed to provide a more stable trend of measurements and these were identified as being ‘‘more realistic” when compared with those obtained with standard concentric cylinder testing geometries, over a wide range of viscosities. However, a fundamental understanding of the reasons behind this improvement is lacking and this paper aims at filling these gaps. Hence, in this study a tailored experimental programme resembling the bitumen-rubber system together with a bespoke Computational Fluid Dynamics (CFD) model are used to provide insights into DHI applicability to perform viscosity measurements with multiphase fluids as well as to validate its empirical calibration procedure. A qualitative comparison between the laboratory results and CFD simulations proved encouraging and this was enhanced with quantitative estimations of the mixing efficiency of both systems. The results proved that CFD model is capable of simulating these systems and the obtained simulations gave insights into the flow fields created by the DHI. It is now clear that DHI uses its inner screw to create a vertical dragging of particles within a fluid of lower density, while the outer screw transports the suspended particles down. This induced flow helps keeping the test sample less heterogeneous and this in turns allows recording more stable viscosity measurements

Pressurization of some starches compared to heating: Calorimetric, thermo-optical and X-ray examination

Starch suspensions (30%), from pea and corn samples, with amylose (AML) contents ranging from 28% to 75%, were pressurized between 150 and 650 MPa for 30 min at room temperature. Differential scanning calorimetry (DSC), assisted by thermo-optical polarized microscopy (TPM) and X-ray diffractometry (XRD), was used to demonstrate the difference between pressure-gelatinization and heat gelatinization. The higher amylose content made the starch more resistant to pressure-induced gelatinization. Normal corn (28% AML) and pea starches (35% AML) partially gelatinized at 400 MPa and up, however pressurization produced low-quality gels with granular structure. Conversely, high amylose corn starches (55% and 70% AML) did not gelatinize at all (even at 650 MPa), although the starch suspensions underwent slight increases in viscosity. Retrogradation occurred either concurrently or immediately after pressurization as opposed to long-term thermal retrogradation. XRD revealed that a second scan produced vitrification and possible resistant starch formation in gelatinized/gelled starches. © 2008 Elsevier Ltd. All rights reserved.Partial funding from CICYT (Project MAT2004-00496) is acknowledgedPeer Reviewe

Pressurization of some starches compared to heating: Calorimetric, thermo-optical and X-ray examination

Starch suspensions (30%), from pea and corn samples, with amylose (AML) contents ranging from 28% to 75%, were pressurized between 150 and 650 MPa for 30 min at room temperature. Differential scanning calorimetry (DSC), assisted by thermo-optical polarized microscopy (TPM) and X-ray diffractometry (XRD), was used to demonstrate the difference between pressure-gelatinization and heat gelatinization. The higher amylose content made the starch more resistant to pressure-induced gelatinization. Normal corn (28% AML) and pea starches (35% AML) partially gelatinized at 400 MPa and up, however pressurization produced low-quality gels with granular structure. Conversely, high amylose corn starches (55% and 70% AML) did not gelatinize at all (even at 650 MPa), although the starch suspensions underwent slight increases in viscosity. Retrogradation occurred either concurrently or immediately after pressurization as opposed to long-term thermal retrogradation. XRD revealed that a second scan produced vitrification and possible resistant starch formation in gelatinized/gelled starches. © 2008 Elsevier Ltd. All rights reserved.Partial funding from CICYT (Project MAT2004-00496) is acknowledgedPeer Reviewe

Configuración de subjetividad en mujeres en situación de discapacidad: un abordaje desde discapacidad, cuerpo y género

This research aims to find ways in which women that are in disability shape their subjectivity. In literature, the theme of body is addressed from occupational therapy; however it is consider necessary to investigate the constitution of an intervention subject that is specifically identified socially as a woman and disabled and, thus, provide new insights into our practice. The concept of subjectivity in this research is approached from the axes of gender, disability and corporeality. Taking into account the various meanings to address, we decided to use narrative productions, a qualitative methodology, with a narrative research design. This methodology understands knowledge as a co-construction between the team and the subject of study. The sample is given by key informants and snowball. As a result of the research process, experiences and knowledge of the participants and the research team culminates in a narrative production authoring each participant and a collective narrative generated by the research team are articulated. The main conclusions point out how from the experience of disability restructuring the discourses and practices of women participants was necessary, oriented to the use of public space.La presente investigación tiene por objetivo conocer distintas maneras en que mujeres que se encuentran en situación de discapacidad configuran su subjetividad. En la literatura se abarca el tema del cuerpo desde la terapia ocupacional; sin embargo consideramos que es necesario indagar sobre la constitución de la/el sujeta/o de intervención, específicamente aquel identificado socialmente como mujer y discapacitada/o y así aportar nuevas reflexiones dentro de nuestra práctica profesional. El concepto de subjetividad se aborda en esta investigación desde los ejes de género, discapacidad y corporalidad. Tomando en cuenta los diversos significados a abordar, se decidió utilizar producciones narrativas, una metodología cualitativa, con un diseño narrativo de investigación Dicha metodología entiende el conocimiento como una co-construcción entre el equipo y las/los sujetas/os de estudio. La muestra se da a través de informantes claves y bola de nieve. Como resultado del proceso investigativo se articulan experiencias y saberes de las participantes y el equipo investigador lo cual culmina en una producción narrativa de autoría de cada participante y una narrativa colectiva generada por el equipo investigador. La principales conclusiones apuntan a cómo a partir de la vivencia de una situación de discapacidad fue necesario una reestructuración de los discursos y las prácticas de las mujeres participantes orientadas hacia el uso del espacio público