The effect of processing and other factors on the colour characteristics of some red wines

Red wines were made from the same batch of Cascade grapes (Seibel 13.053) at Long Ashton by three different processing methods (a) extraction on the skins, (b) thermovinification and (c) carbonic maceration and were analysed at intervals. The wine made by thermovinification was much more coloured than that fermented on its skins, but it contained less anthocyanin and more polymeric pigment. The wine made by carbonic maceration was the least coloured, despite containing anthocyanins similar in amount to those in the thermovinified wine, and it appeared more brown. The red colour differences were attributed to variations in the physicochemical state of the anthocyanins and were expressed numerically in terms of their degrees of ionisation. There was a remarkably exact linear relationship between wine colour density and the degree of ionisation of the anthocyanins in the three wines.Factors affecting anthocyanin ionisation were studied in the Long Ashton wines and in some commercial young Beaujolais wines. Exposure to air augmented colour, increased anthocyanin polymerisation and, in some of the commercial wines, actually increased the amount of anthocyanins, presumably by oxidation of unknown colourless forms. The effects of adding acetaldehyde were even more striking. Large increases in the degree of ionisation of the anthocyanins occurred concurrently with losses of anthocyanins by further transformations into polymeric pigments. Of the Long Ashton wines, that made by thermovinification contained an excess of acetaldehyde over bisulphite, which was probably a factor augmenting its colour.lt was concluded that these fermentation and storage factors were superimposed upon the main effects which were attributed to the different mechanisms of anthocyanin-phenolic interactions operative under the various extraction procedures.Der Einfluß der Weinbereitung und anderer Faktoren auf die Farbmerkmale von RotweinenIn Long Ashton wurden aus demselben Lesegut von Cascade-Trauben (Seibel 13.053) Rotweine nach drei verschiedenen Verfahren - (a) Vergärung auf der Maische, (b) Maischeerhitzung, (c) Kohlensäuremazeration - hergestellt und in bestimmten zeitlichen Abständen analysiert. Der Wein nach (b) war viel intensiver gefärbt als derjenige nach (a); er enthielt jedoch weniger Anthocyan- und mehr polymere Farbstoffe. Der Wein nach (c) war am schwächsten gefärbt, obgleich er einen ähnlichen Anthocyangehalt aufwies wie nach (b) hergestellter Wein; außerdem war er stärker braun getönt. Die Unterschiede in der Rotfärbung wurden auf Schwankungen im physiko-chemischen Zustand der Anthocyane zurückgeführt und zahlenmäßig durch den Ionisationsgrad ausgedrückt. Zwischen der optischen Dichte der Rotweine und dem Ionisationsgrad ihrer Anthocyane bestand eine auffällig genaue lineare Beziehung. Bei den Weinen aus Long Ashton und einigen jungen Beaujolais-Weinen aus dem Handel wurden die Faktoren untersucht, welche die Ionisierung der Anthocyane beeinflussen. Einwirkung von Luft verstärkte die Färbung, steigerte die Polymerisation der Anthocyane und erhöhte bei einigen kommerziellen Weinen, wohl durch Oxidation unbekannter farbloser Vorstufen, den tatsächlichen Anthocyangehalt. Ein Zusatz von Acetaldehyd war noch wirkungsvoller: Ein beträchtlicher Zuwachs ionisierter Anthocyane war begleitet von Anthocyanverlusten durch verstärkte Umwandlung in polymere Farbstoffe. Bei den Weinen aus Long Ashton überwog in den nach (b) hergestellten das Acetaldehyd gegenüber dem Bisulfit, wodurch wahrscheinlich die Färbung vertieft wurde.Die unterschiedliche Ausprägung der Rotweinfärbung ist in erster Linie durch das angewandte Extraktionsverfahren bedingt, wobei Anthocyane und Phenole in verschiedener Weise miteinander reagieren. Im Verlauf der Gärung und Lagerung wird der Farbcharakter durch weitere Faktoren abgewandelt

Tristimulus measurements (CIELAB 76) of port wine colour

Tristimulus colour values were measured using the CIELAB 76 convention and compared with conventional measurements on 87 freshly-made and ageing single cultivar port wines from 5 sites for up to 6 years. There were high correlations between a* (redness) and A520nm, and saturation and colour density, and a high negative correlation between L* (Lightness) and colour density. There was little correlation between b* (yellowness) and A420nm; consequently hue angle did not correspond to tint. Amongst the tristimulus parameters, there were high correlations between L* or saturation and a*. In individual ports L* varied linearly but negatively with hue angle, but in the group of ports examined there was no significant relationship between L* and hue angle because of adc;litional variable phenolic browning depending upon cultivar. In model anthocyanin solutions increasing L* (by decreasing pigment concentration or increasing pH) caused a linear reduction in hue angle but an increase in tint; the latter was attributed to dissociation of associated anthocyanin molecules. Measurement of hue angle in ageing ports gives an indication of the relative occurrence of two competing ageing mechanisms, involving or not involving acetaldehyde. Hue angle is a more discriminating parameter for expressing the colour nuance of red wines than tint

Probing modified gravity with magnetically levitated resonators

We present an experimental procedure, based on Meissner effect levitation of neodymium ferromagnets, as a method of measuring the gravitational interactions between milligram masses. The scheme consists of two superconducting lead traps, with a magnet levitating in each trap. The levitating magnets behave as harmonic oscillators and, by carefully driving the motion of one magnet on resonance with the other, we find that it should easily be possible to measure the gravitational field produced by a 4 mg sphere, with the gravitational attraction from masses as small as 30 μg predicted to be measurable within a realistic measurement time frame. We apply this acceleration sensitivity to one concrete example and show the abilities of testing models of modified Newtonian dynamics

Comparing periodic-orbit theory to perturbation theory in the asymmetric infinite square well

An infinite square well with a discontinuous step is one of the simplest systems to exhibit non-Newtonian ray-splitting periodic orbits in the semiclassical limit. This system is analyzed using both time-independent perturbation theory (PT) and periodic-orbit theory and the approximate formulas for the energy eigenvalues derived from these two approaches are compared. The periodic orbits of the system can be divided into classes according to how many times they reflect from the potential step. Different classes of orbits contribute to different orders of PT. The dominant term in the second-order PT correction is due to non-Newtonian orbits that reflect from the step exactly once. In the limit in which PT converges the periodic-orbit theory results agree with those of PT, but outside of this limit the periodic-orbit theory gives much more accurate results for energies above the potential step.Comment: 22 pages, 2 figures, 2 tables, submitted to Physical Review

The colours, pigment and phenol contents of young port wines: Effects of cultivar, season and site

95 port wines were made under standard small scale conditions from grapes of 16 individual cultivars grown at 5 different sites in the Douro valley in northern Portugal during 1977-1983. Grape specific grayity and pH values were measured. The ports were analysed immediately after fortification for colour, pigment and phenol contents and pH. Cultivar variations were up to 12-fold in total pigments, 14-fold in colour density, but only 3.6-fold in total phenols . Seasonal vari ations were up to 2-fold in total pigments and colour density and 1.6-fold in total phenols . Because of seasonal effects and variation in the numbers of each cultivar examined, cultivar characteristics were compared by their mean values with reference to an arbitrarily chosen standard cultivar (Touriga Nacional). Statistical analysis confirmed that the variation in total pigments was affected much more by cultivar than by season. Souzão, Tinta da Barca and Touriga Nacional ports (all from Tua) were the most coloured and contained most pigments. Mourisco (Tua) and Tinta Cão (Baixo Corgo) were the least coloured and contained least pigments. Port colour was dependent principally on pigments content and pH, but small effects attributed to anthocyanin selfassociation and co-pigmentation were also discerned. Differences between sites were generally not significant, apart from some characteristics of Touriga Nacional from Pinhão compared with Tua and Vilariça. which were attributed to the particular strain of fruit at Pinhäo. Nevertheless, there was some indication that the inferior status of Baixo Corgo compared with Cima Corgo fruit may be attributed not only to its generally lower pigments content, but also to smaller percentages of the pigments being expressed in coloured forms

Population Genomics of Early Events in the Ecological Differentiation of Bacteria

Genetic exchange is common among bacteria, but its effect on population diversity during ecological differentiation remains controversial. A fundamental question is whether advantageous mutations lead to selection of clonal genomes or, as in sexual eukaryotes, sweep through populations on their own. Here, we show that in two recently diverged populations of ocean bacteria, ecological differentiation has occurred akin to a sexual mechanism: A few genome regions have swept through subpopulations in a habitat-specific manner, accompanied by gradual separation of gene pools as evidenced by increased habitat specificity of the most recent recombinations. These findings reconcile previous, seemingly contradictory empirical observations of the genetic structure of bacterial populations and point to a more unified process of differentiation in bacteria and sexual eukaryotes than previously thought.National Science Foundation (U.S.) (Grant DEB-0918333)Woods Hole Center for Oceans & Human HealthGordon and Betty Moore FoundationUnited States. Dept. of Energy. Genomes To Lif

Interaction and Localization of One-electron Orbitals in an Organic Molecule: Fictitious Parameter Analysis for Multi-physics Simulations

We present a new methodology to analyze complicated multi-physics simulations by introducing a fictitious parameter. Using the method, we study quantum mechanical aspects of an organic molecule in water. The simulation is variationally constructed from the ab initio molecular orbital method and the classical statistical mechanics with the fictitious parameter representing the coupling strength between solute and solvent. We obtain a number of one-electron orbital energies of the solute molecule derived from the Hartree-Fock approximation, and eigenvalue-statistical analysis developed in the study of nonintegrable systems is applied to them. Based on the results, we analyze localization properties of the electronic wavefunctions under the influence of the solvent.Comment: 4 pages, 5 figures, the revised version will appear in J. Phys. Soc. Jpn. Vol.76 (No.1

Dynamics of quantum systems

A relation between the eigenvalues of an effective Hamilton operator and the poles of the $S$ matrix is derived which holds for isolated as well as for overlapping resonance states. The system may be a many-particle quantum system with two-body forces between the constituents or it may be a quantum billiard without any two-body forces. Avoided crossings of discrete states as well as of resonance states are traced back to the existence of branch points in the complex plane. Under certain conditions, these branch points appear as double poles of the $S$ matrix. They influence the dynamics of open as well as of closed quantum systems. The dynamics of the two-level system is studied in detail analytically as well as numerically.Comment: 21 pages 7 figure

Scattering properties of a cut-circle billiard waveguide with two conical leads

We examine a two-dimensional electron waveguide with a cut-circle cavity and conical leads. By considering Wigner delay times and the Landauer-B\"{u}ttiker conductance for this system, we probe the effects of the closed billiard energy spectrum on scattering properties in the limit of weakly coupled leads. We investigate how lead placement and cavity shape affect these conductance and time delay spectra of the waveguide.Comment: 18 pages, 11 figures, accepted for publication in Phys. Rev. E (Jan. 2001

Patterns of Blunt Use Among Rural Young Adult African-American Men

http://dx.doi.org/10.1016/j.amepre.2011.08.02