Heat-induced gelation of egg yolk as a function of pH. Does the type of acid make any difference?

The objective of this study was to assess the influence of reducing pH from its native value on the heat-induced gelation behaviour of egg yolk by monitoring its linear viscoelastic properties. Three acids differing in their location in the Hofmeister series were used (hydrochloric, citric, and phosphoric acids) at pH between 2 and 6. The viscoelastic measurements were carried out under small amplitude oscillatory shear, using parallel plate geometry by means of: (i) stress sweep tests to delimit the linear viscoelastic range at different temperatures; (ii) temperature ramp tests to monitor egg yolk protein gelation; and (iii) frequency sweep tests at 20 °C, after the thermal cycle. The microstructure of gels was also evaluated by Cryo-scanning Electronic Microscopy (CryoSEM). Egg yolk undergo dramatic changes in rheological and microstructural properties, when processed at high temperature, depending on pH and the type of acid used. Generally, four different regions take place over heat treatment: (i) a fluid-like region showing a moderate decrease in viscoelastic properties with temperature (ii) a sol-gel transition region involving denaturation, aggregation of protein molecules and association of aggregates to form a gel network; (iii) a plateau region for G′ and G″ and (iv) a reinforcement of the gel network through the regeneration of physical interactions during cooling. This pattern may show a strong dependence on pH and the acid involved. Both effects tend to decrease as the thermal treatment proceeds. Heat treatment also reveals large differences in gel microstructure, depending on pH and on the type of acid used

3D reconstruction of weeds using depth cameras

El objetivo de este estudio fue optimizar el ángulo de posicionamiento del sensor Kinect para la reconstrucción de la estructura tridimensional de Xanthium strumarium L., Datura stramonium L. y Chenopodium album L., utilizando para ello algoritmos que permiten la captura y combinación de imágenes de profundidad y RGB. Se han comparado diferentes ángulos, fijando en cada uno de ellos el sensor Kinect de forma estática respecto de la planta objetivo. Los resultados han confirmado la correlación entre la biomasa de malas hierbas y el área estimada con el sensor. La estimación de la altura de las plantas también fue adecuada, con una media de 2cm de error dependiendo de la posición del sensor. Sin embargo, aunque el sensor ha mostrado su capacidad para la creación de modelos tridimensionales, el adecuado posicionamiento del sensor es fundamental para la correcta reconstrucción de plantas. La posición ideal del sensor debe ser elegida de acuerdo a la especie a medir y su estado fenológico. Estos resultados sugieren que Kinect es una herramienta útil para caracterizar de forma rápida y fiable las malas hierbas, con importantes ventajas sobre otros sensores debido a su bajo coste, bajo requerimiento energético y alta frecuencia de transmisión de imágenes.The objective of this study was to optimize the positioning angle of a Kinect sensor for reconstructing the three dimensional structure of weeds, using Kinect fusion algorithms to generate a 3D point cloud from the depth video stream. The sensor was mounted in different positions facing the plant in order to obtain depth (RGB-D) images from different angles. The results confirmed the correlation between ground truth (e. g. weed biomass) and the measured area with Kinect. In addition, plant height was accurately estimated with a few centimeters error. However, although the Kinect sensor has shown its ability for plant reconstruction, proper positioning of the sensor is critical for correct reconstruction of plants. The best position of the sensor must be chosen according to the species to be measured and their growth stage. These results suggest that Kinect is a promising tool for a rapid and reliable weed characterization, with several important advantages such as low cost, low power requirement and a high frame rate

Formation of soy protein-based superabsorbent materials through optimization of a thermal processing

Superabsorbent materials are used in a wide range of products (e.g. personal care, controlled-release of nutrients in agriculture). The present study pretends the development of biodegradable materials from a natural source, a soy protein isolate, which eventually would help to diminish the environmental issues associated to the use of common synthetic materials. Moreover, the present work focuses on the modulation of the water uptake exclusively through the modification of the parameters of the thermal processes carried out during the development of those materials. Firstly, the protein isolate is blended with the plasticizer (glycerol) in a 1/1 ratio. Then, the homogeneous blend is injected using different mould temperatures and, subsequently, the bioplastics obtained are submitted to a dehydrothermal treatment (tdeshid) consisting on the storage of the samples at 50 ºC for a certain time (tdeshid). When the mould temperature is 70 ºC, superabsorbent materials are always obtained at tdeshid, shorter than 12 h. Conversely, viscoelastic properties increase as DHT treatment is longer, reducing the swelling that takes place during water absorption, and resulting more compact matrices. Thus, the present study proves how thermal processing modulation can solely determine the superabsorbent ability of soy protein-based biodegradable materials.Los materiales superabsorbentes son aplicables en campos tan diversos como productos de higiene personal o liberación controlada de nutrientes en agricultura. El presente estudio pretende el desarrollo de materiales biodegradables a partir de una materia prima natural, un aislado de proteína de soja, cuya aplicación supondría una disminución en el uso de materiales sintéticos, repercutiendo beneficiosamente en el medio ambiente; y la modulación de su capacidad de absorción de agua, que se modificará exclusivamente variando las condiciones de los procesos térmicos a los que son sometidas durante su obtención. En primer lugar, el aislado se mezcla con glicerina (plastificante)en una proporción 1/1, para después inyectar la masa homogénea utilizando diferentes temperaturas de moldeo (Tmold). Posteriormente, son sometidas a un tratamiento deshidrotérmico. o almacenamiento a 50ºC, durante cierto periodo de tiempo (tdeshid). Cuando la Tmold utilizada es 70ºC, se obtienen siempre materiales superabsorbentes, cuando el tdeshid seleccionado sea menos de 12h. Por otra parte, las propiedades viscoelásticas aumentan con la duración del tratamiento deshidrotérmico, provocando un menor hinchamiento durante la absorción de agua, resultando matrices menos porosas. Así, el presente estudio permite comprobar cómo modulando exclusivamente las condiciones de procesado pueden conseguirse capacidades superabsorbentes para materiales biodegradables basados en soja.Ministerio de Economía y Competitividad de España-CTQ2015-71164-

Desarrollo de materiales superabsorbentes biodegradables procesados a partir de subproductos agroindustriales

Actualmente se admite la necesidad cada vez más apremiante de desarrollar nuevos materiales con mayor sostenibilidad. Los materiales superabsorbentes constituyen un claro ejemplo, lo cual implica que estén basados en materias primas renovables, de menor coste e impacto ambiental. A pesar de ello, la comercialización de productos superabsorbentes basados en materias primas de origen natural, que sean biocompatibles y biodegradables se encuentra aún bastante limitada, existiendo una evidente necesidad de impulsar la investigación en el sector. El trabajo pretende contribuir a satisfacer esa necesidad, estableciéndose como objetivo principal desarrrollar nuevos materiales que presenten gran capacidad de absorción de agua (absorbentes y superabsobentes), que puedan ser procesados mediante técnicas de eficacia contrastada en la industria de fabricación de plásticos. Todo ello a partir de fuentes naturales renovables tales como proteínas procedentes de subproductos de la industria agroalimentaria. Además de su capacidad absorbente estos materiales deben presentar propiedades mecánicas y biodegradabilidad apropiadas para que puedan suponer una alternativa a los fabricados con polímeros sintéticos. Como resultado del trabajo se pretende adquirir el conocimiento científico y establecer las bases tecnológicas necesarias para conseguir matrices absorbentes y superabsorbentes biodegradables. Asimismo, se evaluará su potencial en productos SAB para higiene personal y para horticultura.There is an increasing need to shift towards the development of sustainable and environmentally friendly materials in the world market nowadays. Superabsorbents polymers (SAP) are a good example of this new type of materials, being based on renewable natural components with a lower cost. Notwithstanding, the productionand commercialization of biocompatible and biodegradable SAP are still very limited, which makes the need of research on this field pretty clear. This work pretends to cover that need establishing as its main objective the development of new materials that display a great water absorption capacity (absorbents and superabsorbents). These materials will be produced from natural renewable sources (proteins obtained as agro-food industry byproducts) through techniques commonly used in the plastic industry. These materials not only should possess a great water absorption capacity but they should present proper mechanical properties and biodegradability, so they could represent an attractive choice to those obtained from synthetic polymers. Eventually, the acquisition of scientific knowledge and the establishment of the technological base needed for the success in the development of those biodegradable SAP matrixes will be pursued with the different activities. Moreover, the potential of SAP materials produced for hygienic and horticulture applications will be studied.Ministerio de Economía y Competitividad (España) proyecto “Desarrrollo de Materiales superabsorbentes biodegradables procesados a partir de subproductos agroindustriales (SABio)” CTQ2015-71164-

Efecto del procesado sobre las propiedades y morfología de bioplásticos de proteína de soja

La industria de los plásticos ha crecido notablemente en los últimos años. Este crecimiento, ligado a la baja biodegradabilidad de estos materiales, ha causado un grave problema medioambiental. La presente investigación pretende la obtención de materiales con alta capacidad de absorción de agua, que sean biodegradables y obtenidos a partir de fuentes renovables. Deberían además poseer propiedades mecánicas adecuadas para constituir una alternativa real a los plásticos sintéticos. Estos bioplásticos son obtenidos mediante un proceso con diferentes etapas: una de mezclado de los componentes para conformar una masa homogénea; y una segunda de inyección en la que, aplicando presión, la masa es introducida en un molde de forma deseada. La capacidad de absorción de agua es afectada por la composición y las condiciones de procesado. El presente documento estudia cómo la temperatura y duración de la etapa de moldeo, además del tratamiento dehidrotérmico, modifican la capacidad de absorción del bioplástico. Los resultados concluyen que la capacidad de absorción de agua aumenta con menores temperaturas y tiempos de moldeo, a la vez que aumenta cuando el tratamiento dehidrotérmico es más corto. Asimismo, los módulos viscoelásticos poseen una tendencia a disminuir cuando la capacidad de absorción de agua en las muestras aumenta.The remarkable growth experienced by the production and demand of the plastic industry during the last few years has resulted in a serious environmental issue associated specially to their low biodegradability. This work is focused on the manufacture of bioplastics with high water absorption capacity, obtained from renewable sources. Bioplastics produced should have adequate mechanical properties to be able to replace eventually synthetic plastics in specific markets. In order to obtain these bioplastics, two steps were carried out: the first one consists of a mixing stage to achieve a homogenous blend that is injection-molded during the second step. The water uptake capacity of these samples is influenced by both the formulation and the processing conditions of the blends. The present study is focused on the evolution of water uptake values when either the molding conditions (temperature and duration) or the length of a post-dehydrothermal treatment are modified. Results indicated an improvement in the water uptake when lower mold temperatures and shorter compaction stages were used. An analogous improvement was observed when the dehydrotermal process was shorter. Mechanical properties usually decreased as the water uptake of samples was improved.Plan Propio de la Universidad de Sevilla Proyecto: 2017/00000962MINECO (España)/FEDER (UE) proyecto CTQ2015-71164-

Low-Cost Three-Dimensional Modeling of Crop Plants

Plant modeling can provide a more detailed overview regarding the basis of plant development throughout the life cycle. Three-dimensional processing algorithms are rapidly expanding in plant phenotyping programmes and in decision-making for agronomic management. Several methods have already been tested, but for practical implementations the trade-off between equipment cost, computational resources needed and the fidelity and accuracy in the reconstruction of the end-details needs to be assessed and quantified. This study examined the suitability of two low-cost systems for plant reconstruction. A low-cost Structure from Motion (SfM) technique was used to create 3D models for plant crop reconstruction. In the second method, an acquisition and reconstruction algorithm using an RGB-Depth Kinect v2 sensor was tested following a similar image acquisition procedure. The information was processed to create a dense point cloud, which allowed the creation of a 3D-polygon mesh representing every scanned plant. The selected crop plants corresponded to three different crops (maize, sugar beet and sunflower) that have structural and biological differences. The parameters measured from the model were validated with ground truth data of plant height, leaf area index and plant dry biomass using regression methods. The results showed strong consistency with good correlations between the calculated values in the models and the ground truth information. Although, the values obtained were always accurately estimated, differences between the methods and among the crops were found. The SfM method showed a slightly better result with regard to the reconstruction the end-details and the accuracy of the height estimation. Although the use of the processing algorithm is relatively fast, the use of RGB-D information is faster during the creation of the 3D models. Thus, both methods demonstrated robust results and provided great potential for use in both for indoor and outdoor scenarios. Consequently, these low-cost systems for 3D modeling are suitable for several situations where there is a need for model generation and also provide a favourable time-cost relationship

Propietats reològiques i microestructurals de gels prebiòtics de inulina

La inulina es un carbohidrato no digerible que está presente en muchos vegetales, frutas y cereales. En la actualidad, se extrae industrialmente de la raíz de la achicoria y se utiliza ampliamente como ingrediente en alimentos funcionales (e.g. productos lácteos). En este trabajo de investigación se estudió el comportamiento reológico de geles de inulina, a diferentes contenidos del polisacárido (15, 20, 25 %) y sales de calcio (lactato o cloruro, a 0, 2,5 o 5 %). Se observó, de forma general un aumento en los módulos de cizalla de almacenamiento y viscoso (G’ y G’’, respectivamente) al incrementarse la concentración de inulina o la presencia de cloruro de calcio en la solución original a partir de la que se forma el gel. Por otra parte, ambos módulos generalmente disminuyeron con la presencia de lactato de calcio. La adición de cloruro de calcio, por tanto, permitirá la formación de un gel reforzado, con el beneficio adicional de la presencia de calcio, lo cual lo convierte en un buen punto de partida para la producción de alimentos funcionales.Inulin is a non-digestible oligosaccharide that is pres-ent in many vegetables, fruits, and cereals. Nowadays, it is industrially extracted from chicory root and is widely used as an ingredient in functional foods (e.g. dairy products). In this research work, the rheological behavior of inulin gels was studied at different inulin (15, 20, 25 %) and calcium salts contents (lactate or chloride, at 0, 2.5 or 5 %). In general, an increase in the storage and viscous shear moduli (G ‘and G’ ‘, respec-tively) was observed when increasing inulin content or when Calcium chloride was present in the original solution that led to the formation of the gel. On the other hand, both viscoelastic moduli generally decreased in the presence of Calcium lactate. The addition of Calcium chloride, therefore, allows the formation of a reinforced gel with the additional benefit of including Calcium in the formulation, which would be a good starting point for the production of functional foods.La inulina és un carbohidrat no digerible que està present en molts vegetals, fruites i cereals. En l’actu-alitat, s’extreu industrialment de l’arrel de la xicoira i s’utilitza àmpliament com a ingredient en aliments funcionals (p.e. productes làctics). En aquest treball de investigació es va estudiar el comportament reològic de gels de inulina, a diferents continguts del polisacàrid (15, 20, 25%) i sals de calci (lactat o clorur, a 0, 2,5 o 5%). Es va observar, de forma general un augment en els mòduls de cisalla d’emmagatzematge i viscós (G’ i G’’, respectivament) a l’incrementar-se la concentració de inulina o la presència de clorur de calci en la solució original a partir de la qual es forma el gel. D’altra ban-da, tots dos mòduls generalment van disminuir amb la presència de lactat de calci. L’addició de clorur de calci, per tant, permetrà la formació d’un gel reforçat, amb el benefici addicional de la presència de calci, la qual cosa el converteix en un bon punt de partida per a la producció d’aliments funcionals.MINECO (Spain) and FEDER CTQ2015-71164-PMICINN (España) and FEDER RTI2018-097 100-B-C2

High pressure-induced rheological transitions in egg protein dispersions

Eggs have been one of the first multifunctional ingredients, well known for their whipping, gelling and emulsification properties, where the proteins are the dominant component. Egg yok is an ingredient of high nutritional value with unique sensory properties and excellent functionalitu used in the manufacture and stabilisation of egg-containing fodstuffs and provides an inexpensive source of high quality protein. Processing conditions such as temperature and ultra high pressure (UHP) involve complete or partial denaturation of most food systems, including egg yolk. However, pressure processing does not effect the sensory and nutrional characteristics of fresh products (i.c. natural colour, flavour, taste, texture and vitamins) and allows to be obtained gels with a unique texture since pressure is instantaneously uniformly felt trhrough the food. Moreover an increasing demand of high quality, minimally processed, aditive-free an microbiologically safe foodstuff have lately made UHP technology fairly attractive. On the other hand, variables properties of the system. The main objetive is to study the influence of UHP processing on the rheology and microstructure of egg yolk dispersions. First of all, this work focuses on pressure-induced transitions. The effect of protein concentration and pH is also evaluate

Rheology and Water Absorption Properties of Alginate–Soy Protein Composites

Composite materials based on proteins and carbohydrates normally offer improved water solubility, biodegradability, and biocompatibility, which make them attractive for a wide range of applications. Soy protein isolate (SPI) has shown superabsorbent properties that are useful in fields such as agriculture. Alginate salts (ALG) are linear anionic polysaccharides obtained at a low cost from brown algae, displaying a good enough biocompatibility to be considered for medical applications. As alginates are quite hydrophilic, the exchange of ions from guluronic acid present in its molecular structure with divalent cations, particularly Ca2+, may induce its gelation, which would inhibit its solubilization in water. Both biopolymers SPI and ALG were used to produce composites through injection moulding using glycerol (Gly) as a plasticizer. Different biopolymer/plasticizer ratios were employed, and the SPI/ALG ratio within the biopolymer fraction was also varied. Furthermore, composites were immersed in different CaCl2 solutions to inhibit the amount of soluble matter loss and to enhance the mechanical properties of the resulting porous matrices. The main goal of the present work was the development and characterization of green porous matrices with inhibited solubility thanks to the gelation of alginate.Ministerio de Ciencia e Innovación (MCI)/Agencia Estatal de Investigación (AEI)/Fondo Europeo de Desarrollo Regional (FEDER) RTI2018-097100-B-C21Spanish Ministerio de Universidades PRE2019- 08981

A school-based randomized controlled trial to promote cycling to school in adolescents: The PACO study

“Cycling and Walk to School” (PACO, by its Spanish acronym) that aims to promote cycling to and from school and physical activity (PA) in adolescents. This study will examine the effects of this intervention in cycling and active commuting to and from school (ACS), PA and several ACS-related factors based on self-determination theory (SDT) and a social-ecological model (SEM). A total of 360 adolescents attending six high schools (three experimental and three control) from three Spanish cities will participate in this randomized controlled trial. The intervention (four cycling sessions; 1–2 h per session, one session per week) will be conducted by the research staff; the control group will continue their usual activities. PA levels will be measured by accelerometers, whereas ACS and the other study variables will be self-reported using questionnaires at baseline and post-intervention. The primary outcomes will be: rates of cycling to school, ACS and PA levels. In addition, SDT-related variables and individual, interpersonal, community, and environment variables relevant to ACS will be based on SEM. The findings will provide a comprehensive understanding of the short-term effects of this school-based intervention on cycling to school behaviour, ACS and PA levels in Spanish adolescents