Tesis por compendio / [ES] El trabajo de investigación realizado en esta tesis se ha centrado en la aplicación de técnicas recientes e innovadoras en el estudio de la percepción de productos sin gluten. Primero, se estudió cómo tratar la información que hay en Twitter para conocer las opiniones de los consumidores sobre "sin gluten". Los temas más relevantes fueron 5 productos (pan, tarta, galleta, pizza, cerveza), situaciones de consumo, recomendaciones, lugares y aspectos relacionados con la celiaquía. Para explorar automáticamente la información de Twitter, se estudió utilizar redes de co-ocurrencia, que fueron útiles para interpretar los tweets, representar los aspectos más relevantes (ocurrencia) y ponerlos en contexto y en relación con otros (co-ocurrencia). Se observó que es posible automatizar sin un pre-tratamiento manual, permitiendo analizar de forma efectiva gran cantidad de información disponible online. Después, se estudiaron diferentes panes comerciales sin gluten en cuanto al comportamiento en boca para entender mejor los factores involucrados en la percepción de textura. Los panes (5 sin gluten; 2 normales) se caracterizaron en cuanto a propiedades mecánicas, estructura, fragmentación, saliva incorporada y consistencia y adhesividad del bolo. Las sensaciones de textura variaron a lo largo de la masticación, dependiendo de su estructura inicial, propiedades mecánicas, fragmentación, formación de bolo o actividad oral. Posteriormente, se estudió cómo los cambios en la estructura de panes sin gluten obtenidos por modificaciones en panificación (tiempo de fermentación e hidratación) afectan al procesamiento y actividad oral y las sensaciones de textura, que variaron principalmente según el tiempo de fermentación. Especialmente al principio, las diferencias en las sensaciones de textura se explicaron por las diferencias en la estructura y fragmentación en boca. Por último, se estudió la atención visual (con eye-tracking) y la respuesta de consumidores celíacos a paquetes de pan sin gluten, observando que el tipo de marca y la presencia del logo de certificación sin gluten influían en lo que miran. Todos los panes les dieron confianza, sin afectar la presencia del logo, pero condicionando lo que miran. El tipo de marca afectó la confianza y la expectativa de aceptabilidad, que fueron más altas para marcas específicas de sin gluten. La aceptabilidad también se explicó por otras características de cada pan. Se estudió la atención visual (eye-tracking) y las motivaciones de niños celíacos y sus padres al comprar galletas en comparación con los no celíacos. El patrón de fijación cambió en niños y padres: los niños celíacos se fijaron más en ingredientes, palabras y símbolos sin gluten, y menos en la imagen de las galletas; los padres de niños celíacos se fijaron más en ingredientes y símbolo sin gluten, y menos en la imagen de la galleta, nombre, dibujo e información nutricional. Para todos los niños y padres, lo más importante fue elegir una galleta que les gustara, pero solo los niños celíacos mostraron interés en la marca y por probar un producto nuevo. Otro motivo importante para los padres fue la salud, pero por diferentes atributos (padres de celíacos: certificación sin gluten o lista corta de ingredientes; padres de no celíacos: bajo en azúcar o grasa). El precio o la confianza fueron relevantes solo para los padres de niños celíacos. Esta Tesis ha aportado conocimiento sobre el uso y la practicidad de técnicas recientes en ciencia sensorial y del consumidor. La investigación confirma que se puede conseguir una comprensión plena de la compleja respuesta del consumidor recabando información desde perspectivas muy distintas. Sin embargo, para responder a cuestiones específicas en investigación, cada una de estas técnicas (análisis de las redes sociales, estudio del procesado oral de los alimentos o la técnica eye-tracking) puede contribuir de forma individual a entender mejor la aceptabilidad o la elección de alimentos del consumidor. / [CA] El treball de recerca realitzat en esta tesi s'ha centrat en l'aplicació de tècniques recents i innovadores en l'estudi de la percepció de productes sense glútens. Primer, es va estudiar com tractar la informació que hi ha en Twitter per a conéixer les opinions dels consumidors sobre "sense glútens". Els temes més rellevants van ser 5 productes (pa, pastís, galeta, pizza, cervesa), situacions de consum, recomanacions, llocs i aspectes relacionats amb la celiaquia. Per a explorar automàticament la informació de Twitter, es va estudiar utilitzar xarxes de co-ocurrència, que van ser útils per a interpretar els tuits, representar els aspectes més rellevants (ocurrència) i posar-los en context i en relació amb uns altres (co-ocurrència). Es va observar que és possible automatitzar sense un pre-tractament manual, permetent analitzar de manera efectiva gran quantitat d'informació disponible en línia. Després, es van estudiar diferents pans comercials sense glútens quant al comportament en boca per a entendre millor els factors involucrats en la percepció de textura. Els pans (5 sense glútens; 2 normals) es van caracteritzar quant a propietats mecàniques, estructura, fragmentació, saliva incorporada i consistència i adhesivitat de la bitla. Les sensacions de textura van variar al llarg de la masticació, depenent de la estructura inicial, propietats mecàniques, fragmentació, formació de bitla o activitat oral. Posteriorment, es va estudiar com els canvis en l'estructura de pans sense glútens obtinguts per modificacions en panificació (temps de fermentació i hidratació) afecten el processament i activitat oral i les sensacions de textura, que van variar principalment segons el temps de fermentació. Especialment al principi, les diferències en les sensacions de textura es van explicar per les diferències en l'estructura i fragmentació en boca. Finalment, es va estudiar l'atenció visual (amb eye-tracking) i la resposta de consumidors celíacs a paquets de pa sense gluten, observant que el tipus de marca i la presència del logotip de certificació sense gluten influïen en el que miren. Tots els pans els van donar confiança, sense afectar la presència del logotip, però condicionant el que miren. El tipus de marca va afectar la confiança i l'expectativa d'acceptabilitat, que van ser més altes per a marques específiques de sense glútens. L'acceptabilitat també es va explicar per altres característiques de cada pa. Es va estudiar l'atenció visual (eye-tracking) i les motivacions de xiquets celíacs i els seus pares en comprar galetes en comparació amb no celíacs. El patró de fixació va canviar en xiquets i pares: els xiquets celíacs es van fixar més en ingredients, paraules i símbols sense glútens, i menys en la imatge de les galetes; els pares de xiquets celíacs es van fixar més en ingredients i símbol sense gluten, i menys en la imatge de la galeta, nom, dibuix i informació nutricional. Per a tots els xiquets i pares, el més important va ser triar una galeta que els agradara, però només els xiquets celíacs van mostrar interés en la marca i per provar un producte nou. Un altre motiu important per als pares va ser la salut, però per diferents atributs (pares de celíacs: certificació sense gluten o llista curta d'ingredients; pares de no celíacs: baix en sucre o grassa). El preu o la confiança van ser rellevants solo per als pares de xiquets celíacs. Esta Tesi ha aportat coneixement sobre l'ús i la practicitat de tècniques recents en ciència sensorial i del consumidor. La investigació confirma que es pot aconseguir una comprensió plena de la complexa resposta del consumidor recaptant informació des de perspectives molt diferents. No obstant això, per a respondre a qüestions específiques en investigació, cada una d'estes tècniques (anàlisis de les xarxes socials, estudi del processament oral dels aliments o la tècnica eye-tracking) pot contribuir de manera individual a entendre millor l'acceptabilitat o l'elecció d'aliments del consumidor. / [EN] The research of this thesis is focused on the application of recent and innovative techniques to study the perception of gluten-free products. First, it was studied how to manage the information available on Twitter to get consumers' opinions about "gluten-free". The most relevant topics when talking about gluten-free on Twitter were five products (bread, cake, cookie, pizza, beer), situations of consumption, recommendations, places, and aspects related to coeliac condition. To automatically explore the information from Twitter, the possibility to use co-occurrence networks was studied. Co-occurrence networks were useful for interpreting tweets' content, representing the most relevant aspects mentioned (occurrence) and putting them into context and in relation to others (co-occurrence). It was found that automated without manual pre-treatment of text is possible, as an efficient analysis of big amounts of online data. Secondly, different commercial gluten-free breads were studied in terms of in-mouth behaviour to better understand the factors involved in texture perception. The breads (5 gluten-free; 2 regular) were characterised regarding mechanical properties, structure, fragmentation, saliva incorporated, and bolus consistency and adhesiveness. Texture sensations varied along mastication, depending on their initial structure, mechanical properties, fragmentation pattern, bolus formation or oral activity. Subsequently, it was studied how changes in structure of gluten-free breads achieved by modifications in breadmaking (fermentation time and hydration) affect oral processing, oral activity and texture sensations. Oral behaviour and texture perception varied mostly according to the fermentation time. Especially at the beginning, differences in texture sensations were explained by the differences in structure and how it fragmented in mouth. Lastly, visual attention (with eye-tracking technique) and response of coeliac consumers to gluten-free bread packages were studied, finding that the type of brand and presence of gluten-free certification logo influenced the visual behaviour. All gluten-free breads were perceived as trustworthy, not being affected by the presence of gluten-free certification logo, but conditioning the visual behaviour. The type of brand affected trust and expected acceptability, being both higher for brands specific of gluten-free. Liking was also explained by other individual characteristics of breads. Visual behaviour and motivations of coeliac children and their parents when purchasing biscuits were studied in comparison to non-coeliac ones. Eye-tracking showed that fixation pattern changed for coeliac children and their parents. Coeliac children fixated more on ingredients, gluten-free words and symbols, and less on biscuit image. Parents of coeliac children fixated more on ingredients and the gluten-free symbol, and less on biscuit image, product name, cartoon, and nutritional information. For all children and parents, liking was the most important reason for choosing a biscuit, but only coeliac children showed interest in brand and unknown products. Other important motivation for parents was health, but the attributes were different (parents of coeliac group: having gluten-free certification or a short ingredients list; parents of non-coeliac group: low sugar or fat contents). Price or trust were relevant motivations only for parents of celiac children. On overall, this Thesis provided knowledge about the usage and practicality of recent techniques or approaches in sensory and consumer science. This investigation confirms that a full understanding of complex consumer's response can be achieved by gathering consumer's information from different perspectives. However, for answering specific research questions, these different tools (social media exploration, food oral processing approach or eye-tracking technique) can individually contribute to better understand consumer acceptability or food choice. / Puerta Gil, P. (2022). Novel Techniques in Sensory and Consumer Research Applied to Understand Gluten-Free Products Perception [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/182293 / TESIS / Compendio

<p>The development of reliable, robust and low-cost sensor devices is growing in importance and an ongoing challenge. From environmental monitoring and household safety to food and biopharmaceutical industries, the necessity for specific analyte detection is crucial. Over the years researchers have come up with myriad materials that can be used for efficient sensing devices. The materials employed are governed by application and performance criteria as well as the sensing mechanism, which might be based on physical or chemical principles. In this thesis, two different types of electrochemical sensor technologies were examined with special attention paid to the application of the devices, the materials used, and their feasibility for scalable manufacturing.</p> <p>In the first study, binary mixtures of conducting and semiconducting nanomaterials were explored as promising candidates for the manufacturing of low-cost ethylene sensor on flexible substrates. Ethylene (C2H4) is a small plant hormone which has been shown to affect the growth and senescence of flowers, leaves and fruits. Currently available devices have demonstrated high ethylene sensitivities with great potential for technology size reduction; however, some are not practical for use outside of the laboratory, lack portability, or require more research to demonstrate their reproducibility and stability in different environments, as well as selectivity to C2H4 in large-scale applications. Conductometric gas sensors based on a combination of carbon nanotubes (CNTs) and exfoliated molybdenum disulfide (MoS2) coated with molecular receptors is demonstrated for the selective detection of ethylene, including details on materials preparation, manufacturing, and characterization. Mixtures of CNTs and exfoliated MoS2 were deposited onto screen-printed interdigitated electrodes on plastic substrates, with optimization for scalable and continuous manufacturing by roll-to-roll methods. C2H4 detection levels of 0.1 ppm were readily achieved with responses on the second timescale.</p> <p>The second sensor technology shows how thin-film potentiometric electrodes based on ion-selective membranes can be designed to tolerate sterilizing radiation while providing excellent performance and signal stability. This sensor's development was motivated by the expanding need for single-use bioreactor systems in the biopharmaceutical industry, which require strict control over cell culture conditions for several weeks or more. Until recently, critical analysis has been conducted mostly by offline or “at-line” sampling of aliquots withdrawn from the sterile bioreactor. The latter is inefficient and can increase the risk of contamination. Inspired by the challenges related to cost, integration and performance following irradiation a potentiometric pH electrode was developed, intended for single-use applications. It was shown to be radiation-tolerant while providing reliable data comparable to a commercial pH meter over a period of three months. The electrodes exhibited quasi-linear signal drifts of +0.28 mV/day or 0.005 pH units/day. Thin-film γ-irradiated electrodes could provide accurate pH readings in sterilized culture media using a single-point calibration, within 0.07 pH units of a commercial meter with glass electrode and daily calibration. Furthermore, to advance the development of market-ready sensors past the conceptual stage, a few automated processes for scalable membrane deposition were investigated.</p>

<p>    </p> <p>Additive manufacturing (or 3D printing) is one of the manufacturing processes which is currently being explored for its applicability under space boundary conditions, also known as in-space manufacturing. The space boundary conditions specifically affect material properties which in turn affect the printability of materials in space. Printing of soft materials in space is a novel application and the intent of this research was to print the softest of materials: edible materials, as a case study. 3D food printing is a novel food delivery method of using food products to either reproduce as a more aesthetically pleasing product or to print more nutrient-diverse foods. Launch of payload carrier and the boundary conditions of low Earth orbit including a vacuum environment, microgravity, temperature fluctuations, etc. These conditions make printing difficult, and my thesis is to overcome the boundary conditions (except microgravity) using a 3D soft material printer operating within a CubeSat. A CubeSat is a small satellite usually launched as an auxiliary payload used for basic Earth observation and radio communication. The printer must be able to survive launch and operation conditions, print within a simulated space environment, and adhere to the American Society for Testing and Materials (ASTM) specific definition of additive manufacturing. The 3D soft material printer was designed, fabricated, and tested using space and CubeSat boundary conditions for determining optimal design. Testing conditions including: (1) printing under Earth conditions showing it follows ASTM standards, (2) surviving NASA standards for vibration testing for microsatellites under launch conditions, (3) completing a print under a vacuum setting. The results of the testing would prove a small microsatellite could print in the vacuum of space and survive launch parameters. Further work would provide insight into the design of food printers being readily available in smaller sizes and its operability in microgravity condition. </p>