Synthesis and Biological Activities of Cyclodepsipeptides of Aurilide Family from Marine Origin

Aurilides are a class of depsipeptides occurring mainly in marine cyanobacteria. Members of the aurilide family have shown to exhibit strong cytotoxicity against various cancer cell lines. These compounds bear a pentapeptide, a polyketide, and an α-hydroxy ester subunit in their structure. A large number of remarkable studies on aurilides have emerged since 1996. This comprehensive account summarizes the biological activities and total syntheses of natural compounds of the aurilide family as well as their synthetic analogues.     

Baked product texture: Correlations between instrumental and sensory characterization using Flash Profile

Fifteen wheat doughs with various compositions have been selected and baked in order to obtain products with densities in the range of commercial bread values (0.25–0.35 g/cm³). A quick sensory profiling technique (Flash Profile), based on the combination of free choice profiling and a comparative evaluation of the whole product set was used. The sensory jury had to focus on the sensory perception of crumb texture (tactile and visual). The treatment of collected data by Generalized Procustes Analysis shows that products were perceived differently by the panel. The main differences concern the uniformity and the size of gas cells but also mechanical properties of corresponding crumb for which attributes like hardness, springiness and crumbliness were used. Instrumental characterization was performed using uniaxial compression (Young's modulus) and image analysis based on texture granulometry (fineness and homogeneity of cell distribution). A Multiple Factor Analysis allowed assessing the correlations between the sensory attributes and the instrumental measurements. Density and Young's modulus are positively correlated with the sensory elasticity. The instrumental and sensory measurements of the size and of the homogeneity of the cells distribution are correlated.     

Effect of the drying rate on the complex viscosity of wheat flour dough transforming into crust and crumb during baking

This study aimed at characterizing the effect of hydrothermal dynamics on the dough rheology, in order to develop a complete dough viscosity model valid at different locations during baking. The dough rheology was characterised using dynamic mechanical thermal analysis (DMTA). Temperature and water content (WC) were monitored during DMTA. At high heating rates (15–30°C/min), relevant to the top crust, viscosity behaved as if WC was kept constant, in spite of dehydration (37%); such similarity was valid up to 80°C (stage A). Beyond, the viscosity decrease observed in the samples at constant WC was replaced by a long-lasting plateau (stage B, 3–4 × 10⁶ Pa.s), attributed to WC reduction below ∼37%. Above the boiling water temperature, the logarithm of viscosity increased linearly with decreasing WC (stage C). At lower heating rates (5°C/min), relevant to the bottom crust, viscosity was two-fold higher than that at higher heating rates, suggesting lower oven-rise. The viscosity decrease, observed at high temperatures (>80°C) for samples at constant WC, was not observed if drying occurred late (case of crumb beneath the crust); instead, viscosity increased up to levels close to that of the top crust (2–3 × 10⁷ Pa.s at WC∼20%). Despite these deviations, viscosity as a WC function was modelled with a unique equation set.     

Evolution of castalagin and vescalagin in ethanol solutions. Identification of new derivatives.

Brandies, cognac, armagnac, whiskeys, and rums are aged in oak barrels to improve their organoleptic properties. During this period, numerous compounds such as ellagitannins are extracted from the wood and can subsequently be transformed into new derivatives by chemical reactions. Model solutions of castalagin and vescalagin have been studied to determine the behavior of polyphenols in ethanol-water. Upon prolonged exposure to 40 and 70% (v/v) ethanol at room temperature, hemiketal derivatives containing ethoxy groups have been characterized by LC/MS and NMR. These compounds further evolve to afford the corresponding ketals. They have also been detected in the extracts of oak wood stored under similar conditions.     

Electric field x-ray scattering measurements on tobacco mosaic virus

The feasibility of electric field x-ray solution scattering with biological macromolecules was investigated. Electric field pulses (1.25 to 5.5 kilovolts per centimeter) were used to orient tobacco mosaic virus in solution (4.5 milligrams per milliliter). The x-ray scattering is characteristic of isolated oriented particles. The molecular orientation and its field-free decay were monitored with a time resolution of 2 milliseconds by means of synchrotron radiation and a multiwire proportional area detector. The method should also be applicable to synthetic polymers and inorganic colloids.     

Influence of Shaping and Orientation of Structures on Rheological Properties of Wheat Flour Dough Measured in Dynamic Shear and in Biaxial Extension

Characterization of the rheological properties of wheat flour dough during mixing and baking without modifying its structure or mechanical properties is not easy. In this work, the effect of dough setting pre‐orientation and strain orientation during characterization are assessed for differently structured wheat flour doughs (various water contents and addition of glucose oxydase). Rheological properties were measured in dynamic shear as rotational (CSL²100 fitted with a cone‐plate geometry) or radial (CP20 fitted with a plate‐plate geometry) small deformation mode and in lubricated squeezing flow and relaxation called large deformation mode. In comparison with radial shearing, rotational shearing induces a much larger preorientation of the network and thus a strain‐hardening phenomenon that affects the rheological measurements (storage modulus is overestimated) but relaxes, at least partially, during a rest period. Consequently, a longer period of time has to be allotted (allowing stress relaxation) before starting measurements. Plate‐plate geometry induces less preorientation and allows measurement a few minutes after setting. However, it has less discrimination of the differently structured dough than the cone‐plate geometry used in rotational mode. Results which partially agree with those of the CP20 are obtained using the lubricated squeezing flow followed by stress relaxation.     

The viscoelastic properties of processed cheeses depend on their thermal history and fat polymorphism

Both the composition and the thermal kinetics that are applied to processed cheeses can affect their texture. This study investigated the effect of the storage conditions and thermal history on the viscoelastic properties of processed cheese and the physical properties of the fat phase. The microstructure of processed cheese has been characterized. Using a combination of physical techniques such as rheometry, differential scanning calorimetry, and X-ray diffraction, the partial crystallization of fat and the polymorphism of triacylglycerols (TG; main constituents of milk fat) were related to changes in the elastic modulus and tan δ as a function of temperature. In the small emulsion droplets (<1 μm) dispersed in processed cheeses, the solid fat phase was studied at a molecular level and showed differences as a function of the thermal history. Storage of processed cheese at 4 °C and its equilibration at 25 °C lead to partial crystallization of the fat phase, with the formation of a β' 2 L (40.9 ?) structure; on cooling at 2 °C min(-1), the formation of an α 3 L (65.8 ?) structure was characterized. The cooling of processed cheese from 60 to -10 °C leads to the formation of a single type of crystal: α 3 L (72 ?). Structural reorganizations of the solid fat phase characterized on heating allowed the interpretation of the elastic modulus evolution of processed cheese. This study evidenced polymorphism of TG in a complex food product such as processed cheese and allowed a better understanding of the viscoelastic properties as a function of the thermal history.