Influence of some oenological practices on the aromatic and sensorial characteristics of white Verdejo wines

Changes in the aromatic composition as well as sensory characteristics in Verdejo white wines were analysed based on two factors: the winemaking methodology and the storing time of wine in bottles. The volatile components were determined by GLC‐MS, and the sensory profile was designed and assessed according to the ISO 11035 standard. The results showed that when wines were made in oak barrels, either completely or partially, which means the wines were in contact with the lees, the levels of 1‐octanol, ethyl heptanoate and ethyl decanoate were significantly affected (P < 0.05); the softness sensation was also influenced (P < 0.05). However, the amount of time the wines were stored in bottles significantly affected (P < 0.05) the levels of 1‐hexanol, ethyl heptanoate, ethyl octanoate, ethyl decanoate, hexyl acetate, isoamyl acetate and isoamyl lactate and also an odour note (tropical fruit). The compounds with higher OAV values belong to the groups of esters and fatty acids. For these reasons, the composition and the quality of the aroma of Verdejo white wines appear to be significantly affected both by use of oak barrels in winemaking and the time the wines are stored in bottles.     

FEM modelling and experimental characterization of microbeams in presence of residual stress

Out-of-plane bending tests are here used to experimentally validate some numerical models of microbeams actuated by the electric field. Out-of-plane bending microcantilevers and clamped–clamped microbeams often suffer the presence of residual strain and stress, respectively, which affect their static and dynamic behaviour and pull-in voltage. In case of microcantilever an accurate modelling has to include the effect of an initial curvature due to microfabrication process, while in double clamped microbeams constraints may impose a pre-loading caused by a tensile stress. So-called geometrical nonlinearity sometimes occurs, when microcantilever exhibits large displacement, or because of the mechanical coupling between axial and flexural behaviours in double clamped microbeams. Modelling this kind of nonlinearity is an additional goal of this study. Experiments demonstrated a good agreement with results of FEM approaches proposed. In the case of microbridges numerical models are used to identify the residual stress. A reverse analysis is implemented, the axial pre-stress is calculated by means of the measured pull-in voltage.     

Aluminium,nickel, cadmium and lead in candy products and assessment of daily intake by children in Spain

Aluminium (Al), nickel (Ni), cadmium (Cd) and lead (Pb) levels in a total of 263 samples of 12 types of candies widely consumed in Spain, were evaluated. Samples were analysed using an ICP-MS method after acidic sample mineralization. Concentration ranges of Al, Ni, Cd and Pb were 21.28–62.91 µg g^?1, 0.40–1.27 µg g^?1, 0.12–1.01 µg g^?1 and 1.03–7.14 µg g^?1, respectifgvely. Statistically significant positive correlations were calculated between concentrations of Ni–Al and Pb–Cd (p-values < 0.05). Taking into consideration the relatively high metal content, together with the high caloric density of these products, as well as high content of particular nutrients such as sugars that can induce development of certain pathologies like obesity and caries, indicate that frequent consumption of candy products is not recommended.     

An improved finite point method for tridimensional potential flows

At the local level, successful meshless techniques such as the Finite Point Method must have two main characteristics: a suitable geometrical support and a robust numerical approximation built on the former. In this article we develop the second condition and present an alternative procedure to obtain shape functions and their derivatives from a given cloud of points regardless of its geometrical features. This procedure, based on a QR factorization and an iterative adjust of local approximation parameters, allows obtaining a satisfactory minimization problem solution, even in the most difficult cases where usual approaches fail. It is known that high-order meshless constructions need to include a large number of points in the local support zone and this fact turns the approximation more dependent on the size, shape and spatial distribution of the local cloud of points. The proposed procedure also facilitates the construction of high-order approximations on generic geometries reducing their dependence on the geometrical support where they are based. Apart from the alternative solution to the minimization problem, the behaviour of high-order Finite Point approximations and the overall performance of the proposed methodology are shown by means of several numerical tests. Sergio Idelsohn is ICREA Research Professor at CIMNE.     

Ru Promoted MgO and Al-Modified MgO for Ethanol Upgrading

Topics in Catalysis - Mg-containing oxides are widely studied as effective catalysts for ethanol upgrading due to their capacity to promote dehydrogenation and coupling reactions. In such systems,...     

PTR-TOF-MS monitoring of in vitro and in vivo flavour release in cereal bars with varying sugar composition

In the present study, PTR-TOF-MS was applied to better understand the influence of sugar composition on flavour release in a strawberry flavoured cereal bar system. To achieve this, measurements were made both statically from the headspace above cereal bar samples (in vitro) and dynamically from flavour release in the nose space during consumption (in vivo). An artificial strawberry flavour of known constituents (17 flavour active volatile compounds) was used in the preparation of cereal bars. For in vitro measurements, eight samples varying in the glucose syrup solids 42DE to polydextrose ratio were assessed. Measurements clearly showed that the level of glucose syrup solids substitution by polydextrose influenced the release of the added flavour compounds. In addition, distinguishable differences were detected for the release of volatile compounds between samples with different levels of glucose syrup solids and polydextrose during in vivo measurements. The improved mass resolution, sensitivity and speed of PTR-TOF-MS enabled direct comparisons between the rate compounds reached the nose space, maximum nose space concentration of compounds, and the time after which compounds were no longer detected in the nose-space.     

The effect of chemistry on the polymerization, thermo-mechanical properties and degradation rate of poly(β-amino ester) networks

Poly(β-amino ester) networks are gaining attention as a scaffold material for tissue engineering applications where it is important to have tailorable degradation rate and elastic modulus. The objective of this work is to characterize and understand the relationships between chemical structure, polymerization, thermo-mechanical properties, and degradation in poly(β-amino esters) networks. The networks were synthesized from a primary amine with systematically varied molar ratios and chemical structures of diacrylates. Fundamental trends were established between the chemical structure, conversion during polymerization, macromer molecular weight, rubbery modulus, and degradation rate. The thermo-mechanical properties were dependent upon both polymerization steps. The rubbery modulus was tailorable over a range of several MPa by changing molar ratio and diacrylate molecular weight. The degradation rate ranged from hours to months depending upon the composition. Select chemical structures showed degradation rate independent of modulus. This work provides a basis for designing poly(β-amino esters) networks with specific thermo-mechanical properties and degradation rates for biomedical scaffolds.