Assessing the microstructural and rheological changes induced by food additives on potato puree

The effects of agar, alginate, lecithin and glycerol on the rheological properties of commercial potato puree were investigated and interpreted in terms of starch microstructural changes, and the applicability of the Cox-Merz rule was evaluated. Each additive was applied separately at two concentrations (0.5 and 1%). Microscopic observations revealed more swollen starch aggregations in lecithin and glycerol compared with those of potato puree and agar, consequently affecting the rheological properties of potato puree. All samples exhibited shear thinning non-Newtonian behaviour. Rheological measurements were strongly concentration dependent. At 0.5% concentration, additives exerted decreases in all the rheological properties of potato puree in the order of glycerol > alginate > lecithin > agar, while at 1% concentration, the order changed to glycerol > lecithin > alginate, whereas 1% agar behaved differently, increasing all rheological values. This study also showed that agar and alginate in addition to potato puree could be valuable and advantageous for further technological processes, such as 3D printing.Peer ReviewedPostprint (updated version

Impact of mechanical and microstructural properties of potato puree-food additive complexes on extrusion-based 3D printing

This paper studies the applicability of extrusion-based 3D printing for constructing novel shapes from potato puree and the effects of four additives (agar, alginate, lecithin, and glycerol) added separately at three concentrations (0.5, 1, 1.5%) on the internal strength, mechanical properties, microstructure, and color of potato puree.Postprint (updated version

Study and characterization of microstructural and physio-chemical properties of potato products for 3D food printing

Cotutela Universitat Politècnica de Catalunya i Lebanese UniversityPremi extraordinari doctorat UPC curs 2017-2018. Àmbit de Ciències3D food printing is a precise digitalized process that is based on monitoring the characteristics of the printed substrate in accordance with the process parameters. In this thesis mashed potatoes were first mixed with different food additives (agar, alginate, lecithin and glycerol) at different concentrations (0.5, 1 and 1.5%) in order to compare how each additive would affect the yield stress, viscosity, thixotropy, mechanical properties as well as the internal microstructure of potato puree. It was observed that agar and alginate enhanced the rheological and mechanical properties of puree by forming a stronger internetwork structure thus providing better printing with many build up shapes and that are stable post deposition. On the other hand, lecithin and glycerol decreases the rheological and mechanical properties of puree and thus although the extrusion was smooth, end printed products were unstable and collapsed instantly. Additionally, to inspect the reason behind obtaining those rheological and mechanical values a further investigation at the molecular level (applying FTIR and XRD) was done. It was revealed that additives such as glycerol and lecithin can penetrate the starch granules and induce a more intense effect on the structure as their respective concentrations increase by either suppressing (ex, glycerol) or enhancing (ex lecithin) the starch structure. In contrast, long polymeric molecules such as agar and alginate interact partially via the surface of the starch granules modifying partially the conformation of starch structure, which confirms the previous deductions from the rheological properties part. Furthermore, FTIR spectra showed that the skeleton formed by the amylose/amylopectin is somehow hidden in the dehydrated potato flakes, but was covered almost completely upon the addition of water such as to complement that of an original raw potato FTIR spectra, proving that water molecules have a central role in the maintenance of the starch structure conformation. To verify this hypothesis, task 4 was developed in order to make sure after what time of water reduction is the starch conformation altered (using this time potato tubers) and to identify whether the starch structure is modified more by the effect of the water removal or the heat treatment (microwaved and boiling). Findings showed that microwaved (MP) and boiled (BP) potato were more susceptible for water evaporation by freeze drying expressed via the following microstructural changes only after 6 hours of lyophilization; 1- obtaining an IR spectrum with much lower intensities (dried spectrum) compared to the initial spectrum, 2- undergoing a major transformation from gelatinized swollen starch to some recoiling towards a dried starch granule (SEM figures), 3- exhibiting an increase in the intensity of their respective XRD patterns. Moreover, RP took around 24 hours to reach a dried stage that was characterized by some ruptured granules embedded within leached starch matrix, an FTIR spectra that resembles in intensity that of BP and MP, possessing two peaks at 485 cm-1 and 620 cm-1 and that were assigned as a distinctive for a dried potato starch spectrum. Concluding that water removal sublimes the effect of the heat processing treatment, being the major contributor in the modifications of the starch structure. MP and BP were then used as basic samples for 3D printing trials while adding to each different food substrates at 1% concentration with respect to the weight (butter, olive oil, alginate and agar) except for carrots which were added at a ratio of 1/3 of the respective potato weight. All MP samples showed higher rheological and mechanical properties that lead to more stable printed products. Best printability was accounted with butter insertion which elevated the yield stress and thixotropy, thus increasing structural integrity and maintaining higher retaining shape property while preserving smooth extrusion and creamy surface structure.La impresión 3D de alimentos es un proceso digitalizado preciso que se basa en el monitoreo de las características del sustrato impreso de acuerdo con los parámetros del proceso. En esta tesis, se ha utilizado como substrato el puré de patatas mezclado con diferentes aditivos alimentarios (agar, alginato, lecitina y glicerol) a diferentes concentraciones (0,5, 1 y 1,5%) para poder comparar el efecto de cada aditivo sobre las propiedades reologicas (límite elástico, viscosidad, tixotropía), mecánicas y la microestructura interna del puré de patata. Los resultados han permitido observar que el agar y el alginato mejoraron las propiedades reológicas y mecánicas del puré al formar una estructura de interconexión más fuerte, proporcionando una mejor impresión con diversidad de formas y estables después de la deposición. Por otro lado, el uso de lecitina y glicerol disminuyeron las propiedades reológicas y mecánicas del puré y, por lo tanto, aunque la extrusión fue posible, los productos finales impresos fueron inestables y se colapsaron al instante. Adicionalmente, para validar la obtención de esos valores reológicos y mecánicos, se realizó una investigación adicional a nivel molecular aplicando FTIR y XRD. Los resultados indicaron que los aditivos glicerol y lecitina pueden penetrar en los gránulos de almidón e inducir un efecto más intenso sobre la estructura a medida que aumentan la concentración, suprimiendo (glicerol) o potenciando (lecitina) la estructura del almidón. Por el contrario, moléculas poliméricas largas como agar y alginato interactúan parcialmente a través de la superficie de los gránulos de almidón modificando parcialmente la conformación de su estructura, lo que confirmó los resultados previos de las propiedades reológicas. Además, los espectros FTIR mostraron que el esqueleto formado por la amilosa / amilopectina que esta " oculto" en las escamas de patata deshidratada, con la adición de agua vuelve a tener prácticamente el espectro original de FTIR de la patata cruda, lo que demuestra que las moléculas de agua tienen un papel central en el mantenimiento de la conformación de la estructura del almidón. Para verificar la hipótesis, de que " la reducción del agua puede alterar la conformación y estructura del almidón del tubérculo de patata" se procedió a comprobar el efecto de la eliminación de agua (liofilización) o el efecto del tratamiento térmico (cocción en microondas o hervido). Los resultados mostraron que la evaporación del agua por liofilización presentaba cambios micro-estructurales superiores a las cocinadas en microondas (MP) o hervida (BP) ya que con solo 6 horas de liofilización se obtuvo; un espectro FTIR con intensidades mucho más bajas (espectro seco) en comparación con el espectro inicial; se observó mediante SEM una transformación importante del almidón hinchado (gelatinizado) hacia un gránulo de almidón seco y se incrementó la intensidad de sus respectivos patrones de X-RD. Además, en la patata cruda (RP) se tardó alrededor de 24 horas en alcanzar la deshidratación, que se caracterizó por algunos gránulos rotos incrustados dentro de la matriz del almidón lixiviado, un espectro FTIR que se asemeja en intensidad al de BP y MP, (picos a 485 cm-1 y 620 cm-1) que fueron asignados como un distintivo para un espectro de almidón de patata deshidratada. Concluyendo que la eliminación del agua por sublimación produce efectos micro-estructurales superiores al del procesamiento térmico, siendo el agua el principal contribuyente de las modificaciones de la estructura del almidón. Para finalizar, se usaron estos dos tratamientos: cocción al microondas (MP) y hervido (BP) para las pruebas de impresión 3D. Los resultados obtenidos indicaron que todas las muestras MP mostraron mejores propiedades reológicas y mecánicas lo que nos permitió obtener productos impresos más establesAward-winningPostprint (published version

Practices and challenges in clinical data sharing

The debate on data access and privacy is an ongoing one. It is kept alive by the never-ending changes/upgrades in (i) the shape of the data collected (in terms of size, diversity, sensitivity and quality), (ii) the laws governing data sharing, (iii) the amount of free public data available on individuals (social media, blogs, population-based databases, etc.), as well as (iv) the available privacy enhancing technologies. This paper identifies current directions, challenges and best practices in constructing a clinical data-sharing framework for research purposes. Specifically, we create a taxonomy for the framework, identify the design choices available within each taxon, and demonstrate thew choices using current legal frameworks. The purpose is to devise best practices for the implementation of an effective, safe and transparent research access framework

IDENTIFYING FACTORS THAT INFLUENCE CONFLICT MANAGEMENT STYLES OF LEBANESE NURSING STUDENTS’ WITH THEIR CLINICAL EDUCATORS

Conflicts in nursing career between students’ and clinical educators result certainly in negative outcomes for the students’ as stress and low assertiveness level, but can be successfully managed. The conflict management styles of the students’ should be well known in detail in order to attain positive outcomes. The present study aims to identify factors that influence conflict management styles of Lebanese nursing students’ with their clinical educators. This study was conducted at different universities and institutions, using a descriptive correlational design. A random sample of 360 nursing students’ was used. Data was collected using one tool consisting of two parts: Demographic data and The Rahim Organizational Conflict Inventory-II (ROCI-II). Study results illustrate that 78.9%, and 76.6% of nursing students’ respectively used integrating and compromising styles, 76.1% used dominating and avoiding styles and 67.7% used the obligating style of conflict management with their clinical educators. Furthermore, 41.1 % of nursing students’ had conflict experiences from clinical areas. On the other hand, 26.9 % and 70.6% had sometimes and rarely experienced conflicts with their clinical educators respectively. Other variables influence their perception of conflict management styles such as age, class year, academic qualification level, family income, previous conflict with preceptors, frequency of experiencing conflict, feeling successful in conflict management and conflict experiences environment. Consequently, it is recommended that clinical educators should attend workshops about stress management and coping strategies for nursing students’, in order to maintain a healthy learning environment and motivate students’ to express their opinions and enhance their autonomy

A new PCA-based utility measure for synthetic data evaluation

Data synthesis is a privacy enhancing technology aiming to produce realistic and timely data when real data is hard to obtain. Utility of synthetic data generators (SDGs) has been investigated through different utility metrics. These metrics have been found to generate conflicting conclusions making direct comparison of SDGs surprisingly difficult. Moreover, prior research found no correlation between popular metrics, concluding they tackle different utility-dimensions. This paper aggregates four popular utility metrics (representing different utility dimensions) into one using principal-component-analysis and checks whether the new measure can generate synthetic data that perform well in real-life. The new measure is used to compare four well-recognized SDGs.Comment: 20 pages, 5 figures, 8 tables, 1 appendi

Genomic and protein structural maps of adaptive evolution of human influenza a virus to increased virulence in the mouse

Adaptive evolution is characterized by positive and parallel, or repeated selection of mutations. Mouse adaptation of influenza A virus (IAV) produces virulent mutants that demonstrate positive and parallel evolution of mutations in the hemagglutinin (HA) receptor and non-structural protein 1 (NS1) interferon antagonist genes. We now present a genomic analysis of all 11 genes of 39 mouse adapted IAV variants from 10 replicate adaptation experiments. Mutations were mapped on the primary and structural maps of each protein and specific mutations were validated with respect to virulence, replication, and RNA polymerase activity. Mouse adapted (MA) variants obtained after 12 or 20-21 serial infections acquired on average 5.8 and 7.9 nonsynonymous mutations per genome of 11 genes, respectively. Among a total of 115 nonsynonymous mutations, 51 demonstrated properties of natural selection including 27 parallel mutations. The greatest degree of parallel evolution occurred in the HA receptor and ribonucleocapsid components, polymerase subunits (PB1, PB2, PA) and NP. Mutations occurred in host nuclear trafficking factor binding sites as well as sites of virus-virus protein subunit interaction for NP, NS1, HA and NA proteins. Adaptive regions included cap binding and endonuclease domains in the PB2 and PA polymerase subunits. Four mutations in NS1 resulted in loss of binding to the host cleavage and polyadenylation specificity factor (CPSF30) suggesting that a reduction in inhibition of host gene expression was being selected. The most prevalent mutations in PB2 and NP were shown to increase virulence but differed in their ability to enhance replication and demonstrated epistatic effects. Several positively selected RNA polymerase mutations demonstrated increased virulence associated with >300% enhanced polymerase activity. Adaptive mutations that control host range and virulence were identified by their repeated selection to comprise a defined model for studying IAV evolution to increased virulence in the mouse

Assessing mechanical and rheological properties of potato puree: Effect of different ingredient combinations and cooking methods on the feasibility of 3d printing

The effects of agar, alginate, butter, olive oil, and carrots on the mechanical and rheological properties of potato puree prepared by two different cooking methods (microwave heating (MP) and boiling (BP)) were investigated and interpreted in terms of starch microstructural changes. Microscopic observations revealed more aggregated and densely concentrated starch granules in MP samples. This consequently led to a significant increase (p < 0.05) in mechanical and rheological properties up to five times more than BP samples. All samples exhibited shear thinning non-Newtonian behaviorPostprint (published version