No abstract

Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques were used to study the effect of four food additives, agar, alginate, lecithin and glycerol, at three different concentrations, 0.5, 1 and 1.5%, on the molecular structure of potato puree prepared from commercial potato powder. Vibrational spectra revealed that the amylose-amylopectin skeleton present in the raw potato starch was missing in the potato powder but could be fully recovered upon water addition when the potato puree was prepared. FTIR peaks corresponding to water were clearly present in the potato powder, indicating the important structural role of water molecules in the recovery of the initial molecular conformation. None of the studied puree samples presented a crystalline structure or strong internal order. A comparison of the FTIR and XRD results revealed that the additives exerted some effects, mainly on the long-range order of the starch structure via interacting with and changing -OH and hydrogen bond interactions.

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. The printability of the potato puree and the mixtures was assayed by examining the consistency of the extrusions and the stability and accuracy of the printed patterns. The results indicate that better printing was achieved at a nozzle height of 0.5 cm and a nozzle diameter of 4 mm, with concentrations of alginate and agar between 0.5-1.5% and 0.5-1%, respectively, providing the best printability and end-product stability, which was attributed to their respective high mechanical characteristics and specific mechanical energy (SME) values. Scanning electron microscopy (SEM) revealed that more convolutions were induced in the potato puree upon the addition of agar or alginate, which increased the puree stability. Three-dimensional printing did not significantly affect the surface color parameters of the final product. This study showed that the 3D printing process is a critical factor for initializing the production of customized healthy products.

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.

In lower-and middle-income countries, uncontrolled use of antibiotics is causing antimicrobial resistance, affecting both animal welfare and public health. Meanwhile, studies on antibiotic use in these countries are limited. A crucial step to limit the spread of antimicrobial resistance (AMR) is to examine the use of these drugs and identify its determinants. The aim of our study, the first of its kind in Lebanon, was to assess dairy farmers' knowledge and awareness of antimicrobial use (AMU) and AMR. For this, 18 farmers from different regions, educational backgrounds, experience levels, and herd sizes were interviewed. Results showed that owners of larger farms were more aware of AMU and AMR, and trying to implement preventive actions, whereas nonsystematic antimicrobial use was prevalent among the smaller farms. Mastitis and laminitis were the most treated diseases, and antibiotics used were oxytetracycline, penicillin, streptomycin, and florfenicol. Overall, antibiotic use was found as a preventive measure and a treatment of nonbacterial diseases. Irregular uses were linked to easy access of farmers to antibiotics, interrupted relations with veterinary authorities, and lack of self-assessment and inspection. Lebanese dairy farmers and owners reported feeling disadvantaged in their local trade field, facing illegal competition and unauthorized farms and industries, and lacking support from the government. Training and awareness programs must be implemented, and policies and regulations must be set, to reduce antibiotic use and hinder the spread of AMR in Lebanon.

No abstract

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 behavior. Butter proved its ability to maintain stiff network formation with starch molecules forming lipid-starch complexes characterized by high retention properties and increased stability due to high thixotropic and yield stress values. The pseudo-plasticity combined with high self-supporting ability (high yield stress and mechanical values) comprised by MP samples allows them to better behave during advanced technological processes such as extrusion 3D food printing.

3D 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 estables