Gelled vegetable desserts containing pea protein, k-carrageenan and starch

Due to recent animal diseases, cholesterol in take worries and strong demand for healthy food, there is a greater pressure for the direct consumption of vegetable proteins in food products. In this work, the objective is to develop alternative of strictly vegetable origin desserts based on gelled systems with required physical structure and perceived texture. For this reason, it is important to control the properties of the biopolymer mixtures and understand the phase separation behaviour un- der different physicochemical conditions. The firmness and storage modulus of different formulations of pea protein/k-carrageenan/starch systems processed and cooled at different conditions are compared with those parameters obtained for commercial products. Formulation and thermal conditions were determined to influence the texture and storage modulus of the mixed systems. Confocal microscopic images showed that phase separation between pea protein and k-carrageenan takes place, leading to the formation of two network systems. The binding of water effect, of the starch swollen granules, promotes the concentration of pea protein and k-carrageenan, reinforcing the gel structure

Rheological behaviour and microstructure of pea protein/K-carrageenan/starch gels with different setting conditions

The aim of this work was to study the rheological properties and microstructure of pea protein/k-carrageenan/starch gels as affected by different cooling conditions. Dynamic oscillatory measurements for mixed gels, cooled at different rates, were conducted in a stress- controlled rheometer in order to clarify the kinetics of gel formation and characterise the structure of the matured gels. Texture parameters were determined from the texture profile analysis using a texturometer. Microstructure was observed using confocal laser scanning microscopy. In order to understand the role of each hydrocolloid on the gel network, rheology of single component gels were also studied. The results showed that gel setting conditions had a significant influence on the phase separation process of pea protein and k-carrageenan, and hence on the final structure and textural properties of the mixed gel. Slower cooling promotes an extensive phase separation between pea protein and k-carrageenan. Consequently, the size of pea protein aggregates was larger at the lowest cooling rate and decreased with increasing cooling rate. At faster cooling, an increase in elastic modulus and texture parameters of the gels were observed. Comparison of cooling and maturation profiles for the mixed system with those obtained for the individual components suggested that the gelation mechanism of k-carrageenan should govern that of the multicomponent gel

Primordial Density Fluctuations in a Dual Supergravity Cosmology

We analyse the spectrum of energy density fluctuations of a dual supergravity model where the dilaton and the moduli are stabilized and sucessful inflation is achieved inside domain walls that separate different vacua of the theory. Constraints on the parameters of the superpotential are derived from the amplitude of the primordial energy density fluctuations as inferred from COBE and it is shown that the scale dependence of the tensor perturbations nearly vanishes.Comment: 13 pages, Latex, 3 figures (uses epsf.sty

Antioxidantes em azeites ‘Galega’ e ‘Azeiteira’ provenientes de frutos obtidos em duas épocas de colheita

No presente trabalho são determinados os biofenóis em azeites ‘Galega’ e ‘Azeiteira’ obtidos em duas épocas de colheita dos frutos e olivais em produção integrada. A separação da fracção fenólica foi feita por extracção líquido-líquido (ELL) e a análise dos compostos fenólicos obtida por cromatografia líquida de alta pressão (HPLC) com detecção por díodos (DAD). São também determinados: os tocoferóis por HPLC e fluorescência (FLD); os biofenóis totais por espectroscopia VIS; e a intensidade do sabor amargo (K225) por espectroscopia UV. Os azeites ‘Galega’ e ‘Azeiteira’ apresentam teores mais elevados de antioxidantes na colheita mais temporã indicando que – do ponto de vista nutricional, sensorial e da estabilidade deste alimento – não é benéfico retardar a época de colheita. O hidroxitirosol e a luteolina decrescem acentuadamente na segunda data de colheita para os azeites de cultivar ‘Azeiteira’. Os azeites ‘Galega’ apresentam teores mais elevados de α-tocoferol e ϒ-tocoferol

3D printed gluten-free cereal snack with incorporation of Spirulina (Arthrospira platensis) and/or Chlorella vulgaris

3D food printing is a recent technology promising to break cultural barriers by introducing new food sources such as microalgae, through innovative food shapes and textures, in a resource-scarce world whose sustainability is at stake because of the current intensive production of meat and agriculture products. The present work intends to create an innovative gluten-free cereal snack nutritionally improved by the incorporation of Chlorella vulgaris and Arthrospira platensis (“Spirulina”) biomass using 3D printing technology. Doughs without (control) or with microalgal biomass with different incorporation percentages (from 5 to 30 %) were tested and those showing the most adequate rheology (low viscoelastic moduli and apparent viscosity) and texture (low firmness, adhesiveness and high cohesiveness) properties for a correct printing process were selected and baked (control and 5 % microalgae incorporation). Nutritional characterization of the control and 5 % snacks was performed, in terms of total protein and lipid contents, ash, humidity, water activity, energy, and carbohydrates, as well as total phenolics, pigments and antioxidant activity. Physical traits of snacks, including their colour and size, were also analysed. Control snacks presented a lighter and yellow colour compared to snacks containing Chlorella and Spirulina, which had higher green chromaticity (Control: a* - 0.953, b* 21.3; Chlorella 5 %: a* - 2.20, b* 11.8; Spirulina 5 %: a* -1.05, b* 3.55). Nutritional characterization revealed that snacks containing Chlorella and Spirulina had both higher protein and essential minerals content. Overall, 5 % Spirulina snacks presented the best nutritional and sensory performance, with higher antioxidant activity, mineral and protein contents. These Spirulina-snacks deserved a positive sensory appreciation from consumersinfo:eu-repo/semantics/publishedVersio

Vegetable proteins and milk puddings

In recent years, interest in animal free foods has increased tremendously due to factors like BSE crisis, rise of nutritionally dependent illnesses, like diabetes type II, cardiovascular and digestive diseases, along with ethic orientations of denying animal intakes of any kind. The use of proteins from leguminous seeds as an alternative to the animal proteins in dairy desserts was studied. Lupin, pea and soya protein isolates were used in combination with k- carrageenan, gellan and xanthan gum, in order to obtain a synergistic effect. Milk puddings were also produced for comparison. Texture studies suggested that mixed protein /polysaccharide systems, with vegetable proteins and k- carrageenan or gellan gum, would be good systems to develop vegetable gelled desserts. Rheological oscillatory measurements were carried out to clarify the kinetics of gelation and characterise the microstructure of the best performing products. Results from time sweep tests showed that formulations with gellan gum present an industrial advantage over formulations with k-carrageenan, since the maturation time for gellan gels is of the order of 5 /10 h compared with 4 /6 days in the case of k-carrageenan. All the mixed gels presented the typical weak gel structure; therefore, it was possible to perform steady-state measurements, which allowed the observation of a shear-thinning behaviour for all gels

Efecto de las variables del proceso sobre el rendimiento y la calidad del aceite de almendra de yerivá (Syagrus romanzoffiana) mediante extracción acuosa

The fruit from jerivá (Syagrus romanzoffiana) has a kernel which is rich in oil, and has a pleasant smell that reminds one of coconut. It is rich in monounsaturated and saturated fatty acids, in addition to bioactive compounds. In this work, the effect of process variables on the yield and quality of jerivá kernel oil from aqueous extraction was evaluated using response surface methodology. The variables pH, time and temperature influenced the yield and the quality of the oil. High pH and time, along with mild temperature were suitable conditions to extract jerivá kernel oil by aqueous extraction, but excessively high pH, temperature and time negatively impacted the oil’s quality. pH was the only variable that significantly influenced free acidity, with a decrease in free acidity with the increase in pH. On the other hand, the increase in pH, time and temperature increased the peroxide value, which limited some conditions for obtaining jerivá kernel oil by aqueous extraction. The optimal conditions were found to be an extraction at pH 12, 25 °C and 60 minutes, which resulted in a yield of 39%, free acidity of 0.2% and a peroxide value of 5.8 meqO2·kg-1. Aqueous extraction yielded more unsaturated oil than that extracted with hexane, in addition to a higher proportion of caproic, oleic and linoleic acids, thus improving its nutritional characteristics and health benefits, despite decreasing its oxidative stability.La fruta de yerivá (Syagrus romanzoffiana) tiene un grano rico en aceite, que tiene un olor agradable que recuerda al coco, es rico en ácidos grasos monoinsaturados y saturados, además de compuestos bioactivos. En este trabajo, se evaluó el efecto de las variables del proceso sobre el rendimiento y la calidad del aceite de grano de yerivá a partir de la extracción acuosa utilizando la metodología de superficie de respuesta. Las variables pH, tiempo y temperatura influyeron en el rendimiento y la calidad del aceite. pH alto, elevado tiempo y temperatura suave fueron las condiciones adecuadas para extraer el aceite de grano de yerivá mediante extracción acuosa. Sin embargo, el pH, la temperatura y el tiempo excesivamente altos impactaron negativamente en la calidad del aceite. El pH fue la única variable que influyó significativamente en la acidez libre, con una disminución de la acidez con el aumento del pH. Por otra parte, el aumento del pH, el tiempo y la temperatura aumentaron el valor del peróxido, lo que limitó algunas condiciones para obtener aceite de grano de yerivá por extracción acuosa. Se encontró que la condición óptima fue una extracción a pH 12, 25 °C y 60 minutos, lo que resultó en un rendimiento del 39%, una acidez libre del 0,2% y un valor de peróxido de 5,8 meqO2·kg−1. La extracción acuosa produjo más aceite insaturado que el extraído con hexano, además de una mayor proporción de caproico, oleico y linoleico, mejorando sus características nutricionales y beneficios para la salud, a pesar de disminuir su estabilidad oxidativa

Influence of the sodium/proton replacement on the structural, morphological and photocatalytic properties of titanate nanotubes

Titanate nanotubes (TNT) with different sodium contents have been synthesised using a hydrothermal approach and a swift and highly controllable post-washing processes. The influence of the sodium/proton replacement on the structural and morphological characteristics of the prepared materials was analysed. Different optical behaviour was observed depending on the Na+/H+ samples' content. A band gap energy of 3.27\pm0.03 eV was estimated for the material with higher sodium content while a value of 2.81\pm0.02 eV was inferred for the most protonated material, which therefore exhibits an absorption edge in the near visible region. The point of zero charge of the materials was determined and the influence of the sodium content on the adsorption of both cationic and anionic organic dyes was studied. The photocatalytic performance of the TNT samples was evaluated in the rhodamine 6G degradation process. Best photodegradation results were obtained when using the most protonated material as catalyst, although this material has shown the lowest R6G adsorption capability.Comment: 22 pages, 8 figures, accepted for publication in Journal of Photochemistry and Photobiology A: Chemistr

Optimización de superficie de respuesta de múltiples objetivos en la extracción acuosa de aceite de semilla de macauba

Macauba (Acrocomia aculeata) is a promising tropical palm for the production of vegetable oil for both the food and non-food sectors. In this work, a multi-target response surface optimization of the aqueous extraction of Macauba kernel oil aimed to maximize the oil yield and minimize the free acidy and peroxide value. High yield was achieved at a high pH, long extraction periods and moderate temperatures, but these conditions contributed to elevating the peroxide value of the oil. On the other hand, pH presented the only significant effect on the oil’s acidity, which decreased with the increase in pH in the aqueous medium. Therefore, the multi-target response surface optimization based on a desirability approach showed that pH 11, room temperature (25 °C) and a 60 min agitation time was preferred to obtain high yield and low free acidity and peroxide values. These conditions resulted in 30% yield (63.1% of the yield obtained by solvent extraction), 0.3% free acidity, and a peroxide value of 2.9 meqO2/kg. The oil from the optimized aqueous extraction had a higher saturated fatty acid content compared to that from solvent extraction, especially fatty acids with < 14 carbon atoms, which can make the oil harder and more useful for producing special fats for specific food applications.La macauba (Acrocomia aculeata) es una prometedora palma tropical para la producción de aceite vegetal para los sectores alimenticio y no alimentario. En este trabajo, una optimización de superficie de respuesta de múltiples objetivos en la extracción acuosa de aceite de semilla de macauba tuvo como objetivo maximizar el rendimiento del aceite y minimizar el valor de acidez libre y peróxidos. Se logró un alto rendimiento a pH alto, tiempos prolongados y temperaturas moderadas, pero estas condiciones contribuyeron a elevar el índice de peróxido del aceite. Por otro lado, el pH presentó como único efecto significativo sobre la acidez del aceite, la disminución con el aumento del pH en el medio acuoso. Por lo tanto, la optimización de la superficie de respuesta de múltiples objetivos basada en un enfoque de idoneidad mostró que se prefería pH 11, temperatura ambiente (25 °C) y un tiempo de agitación de 60 minutos para obtener un alto rendimiento y bajos valores de acidez libre y peróxido. Estas condiciones dieron como resultado un rendimiento del 30% (63,1% del rendimiento obtenido por extracción con disolvente), un 0,3% de acidez libre y un índice de peróxido de 2,9 meqO2/kg. El aceite de la extracción acuosa optimizada tenía un mayor contenido de ácidos grasos saturados en comparación con el de la extracción con solventes, especialmente de ácidos grasos con < 14 átomos de carbono, lo que puede hacer que el aceite sea más duro y útil para producir grasas especiales para aplicaciones alimentarias específicas

Impact of acorn flour on gluten-free dough rheology properties

Gluten is a fundamental ingredient in breadmaking, since is responsible for the viscoelastic behaviour of the dough. The lack of gluten has a critical e ect on gluten-free dough, leading to less cohesive and less elastic doughs, and its replacement represents a challenge for bakery industry. However, dough rheology can be improved combining di erent ingredients with structural capacity and taking advantage from their interactions. Although acorn flour was used to bake bread even before Romans, nowadays is an underexploited resource. It presents good nutritional characteristics, particularly high fibre content and is naturally gluten free. The aim of this study was to use acorn flour as a gluten-free ingredient to improve dough rheology, following also market trends of sustainability and fibre-rich ingredients. Doughs were prepared with buckwheat and rice flours, potato starch and hydroxypropylmethylcellulose. Two levels of acorn flour (23% and 35% w/w) were tested and compared with control formulation. Micro-doughLAB was used to study mixing and pasting properties. Doughs were characterised using small amplitude oscillatory measurements (SAOS), with a controlled stress rheometer, and regarding Texture Profile Analysis (TPA) by a texturometer. Dietary fibre content and its soluble and insoluble fractions were also evaluated on the developed breads. Acorn flour showed promising technological properties as food ingredient for gluten-free baking (improved firmness, cohesiveness and viscoelasticity of the fermented dough), being an important fibre sourceinfo:eu-repo/semantics/publishedVersio