Antonio Bernal Guerrero

Linear and non-linear viscoelasticity of low-in-cholesterol mayonnaise / Viscoelasticidad lineal y no lineal de mayonesas con bajo contenido en colesterol

Five different mayonnaise products were prepared with constant composition except for the type of egg product used. The linear viscoelastic functions were superposed using a time-temperature su perposition method and the shift-factor showed an Arrhenius-like temperature dependence. The ther mal susceptibility was found to be higher for processed-egg-containing mayonnaise and when egg yolk was used instead of whole egg as the emulsifier. Transient flow curves always showed a stress overshoot, but a stress undershoot was found for whole-egg-containing emulsions at high shear rates. Processed yolk gave rise to higher storage modulus values than did native yolk. This effect lost sig nificance when yolk was diluted by native egg white. Mayonnaise made from egg yolk was always more viscous and did not show a stress undershoot in transient flow. The non-linear relaxation modulus was factorized as the product of the linear relaxation modulus and the damping function. Hence, the Wagner model was able to predict the transient flow of these emulsions fairly well. However, this model failed at low shear rates. This fact may be explained on the basis of wall-slip phenomena.

Competencia emprendedora e identidad personal : una investigación exploratoria con estudiantes de Educación Secundaria Obligatoria

With the Education Act of 2006 established the basic competencies, among which is the competence for autonomy and personal initiative or, in other words, entrepreneurship competence. This competence is not limited to its economic dimension, but training embraces intellectual, moral and social. Probably, these broader aspects of learning are more significantly related to what may seem the economic and productive education. Given the paucity of empirical work on the ideas of students about their education as entrepreneurs, and considering the educational and social interest of these investigations, we explored the thinking of the students who complete secondary education, according to their identity status, gender, and type of public or private schools. We conducted a descriptive study, selecting eight schools in the south of Spain, contextualized in the mediational model student-centered, with a design biphase, considering technical and quantitative and qualitative instruments. For the typological classification of subjects according to identity status, the questionnaire was administered EOMEIS-2, and the evaluation of the ideas of the students devised a questionnaire on the entrepreneurship competence. This research seems to show that, generally, individuals with a personal identity achieved better together as entrepreneurs. This may mean that personal identity is at the heart of entrepreneurship, separating it from just a vision or business economist. And possibly also assume that attention to personal identity is an excellent means of significantly improving the productive dimension of education.

Thermal gelation of mixed egg yolk/kappa-carrageenan dispersions

This study aims to evaluate the effect of gum content and pH on the thermal gelation of mixed egg yolk/κ-carrageenan (EY/κC) dispersions, monitored by linear viscoelastic measurements. Heat processing induces dramatic changes in the microstructure and viscoelastic properties of EY/κC systems, which may be attributed to a multistage mechanism that yields an interparticle gel network. An increase in κC content generally induces an enhancement in viscoelasticity. A reduction in pH hinders this enhancement and causes an anticipation of the multistage process, which confirms the importance of the electrostatic interactions of EY/κC dispersions. The viscoelastic properties of EY/κC gels generally fit a master mechanical spectrum, which suggests that the protein matrix generally dominates the microstructure of EY/κC gels. However, SEM images reveal formation of a κC network at low pH, at which some κC autohydrolysis may also play a role. Electrostatic attractions seem to favour interactions among EY aggregates and κC into the carrageenan network.

Identidade narrativa e plasticidade cerebral: algumas propostas pedagógicas

Os novos recursos da sociedade da informacao, juntamente com os novos conhecimentos sobre o desenvolvimento humano e sobre o funcionamento do cerebro, oferecem uma nova perspectiva sobre os processos de construcao da identidade e abrem novas possibilidades ao sujeito no seu processo de autoformacao e autodeterminacao. A construcao narrativa da identidade e a plasticidade neuronal remetem para uma antropologia da complexidade que deve ter em consideracao tanto as condicoes de risco, de incerteza e de racionalidade incompleta atraves das quais se vai configurando a identidade do sujeito, como as novas possibilidades de realizacao pessoal que estas representam. Por isso, apresentamos algumas propostas pedagogicas que poderao coadjuvar a realizacao das promessas da plasticidade e da narratividade.

Development of Biocomposite Superabsorbent Nanomaterials: Effect of Processing Technique

Nanoclay particles have been usually introduced into protein-based bioplastics to obtain composite materials, showing enhanced mechanical properties. However, the addition of partially exfoliated nanoclay particles in these protein matrices may also involve an increase of others properties such as water absorption capacity, which may lead to the obtention of super absorbent biodegradable materials. Processing technologies exerted a remarkable influence on the techno-functional properties of the soy-based bioplastics studied in this research. On the one hand, extrusion technique led to bioplastics which showed enhanced mechanical properties. On the other hand, injection moulding technique yielded to non-exfoliated nanoclay particles within the protein matrix, which involved improvements of water absorption capacity. The development of superabsorbent protein-based biodegradable materials implied a deep knowledge of physicochemical properties of proteins and processing conditions of bioplastics. Extrusion or injection moulding techniques could be selected to obtain tailored protein-based bioplastics with enhanced properties.

Influence of pH value on microstructure of oil-in-water emulsions stabilized by chickpea protein flour:

Food industry is highly interested in the development of healthier formulations of oil-in-water emulsions, stabilized by plant proteins instead of egg or milk proteins. These emulsions would avoid allergic issues or animal fat. Among other plant proteins, legumes are a cost-competitive product. This work evaluates the influence of pH value (2.5, 5.0 and 7.5) on emulsions stabilized by chickpea-based emulsions at two different protein concentration (2.0 and 4.0 wt%). Microstructure of chickpea-based emulsions is assessed by means of backscattering, droplet size distributions and small amplitude oscillatory shear measurements. Visual appearances as well as confocal laser scanning microscopy images are obtained to provide useful information on the emulsions structure. Interestingly, results indicate that the pH value and protein concentration have a strong influence on emulsion microstructure and stability. Thus, the system which contains protein surfaces positively charged shows the highest viscoelastic properties, a good droplet size distribution profile and non-apparent destabilization phenomena. Interestingly, results also reveal the importance of rheological measurements in the prediction of protein interactions and emulsion stability since this technique is able to predict destabilization mechanisms sooner than other techniques such as backscattering or droplet size distribution measurements.

Percepciones de adolescentes sobre la educación según la identidad personal

Adolescence is an important period in the process of constructing personal identity, particularly at times of educational transition. One such transition occurs at the end of compulsory secondary education and it results in an important biographical assessment of the school career that the adolescent has pursued. One factor that appears to be fundamental in this career is the dynamic of human relations. Focusing our attention on students, we have examined their perceptions of this matter, shaped by their level of personal maturity and linked to their awareness of their identity status or style. A biographical-narrative approach was used with a sample of 121 students, using quantitative and qualitative techniques and instruments (EOM-EIS-II questionnaire, autobiographical accounts, interviews and discussion groups). We have observed differences in young people’s perceptions depending on their level of maturity. At the same time, by comparing their perceptions as a whole, we can see that their family (the main agent in the construction of their identity) and peer group, more than school, are the most highly valued areas. Quality educational processes appear to require careful interpersonal relationships, regardless of the areas in which they are developed. Corroborating various deficiencies in human relationships through adolescents’ perceptions alerts us to their importance. The need to find suitably contextualized models for convergence between the main areas in which our students develop is also shown. This study involves the identification of certain elements that play a role in advancing the process of achieving personal identity. These require attention if the development of personal maturity during the compulsory stages of our school system is to be improved.