Ethanol content

Table 3.3. Influence of temperature and ethanol content on the enantiomeric excess of the Diels-Alder reaction between 3.8c and 3.9 catalysed by [Cu(L-tryptophan)] in aqueous...

The effect of temperature, although significant, is not nearly as great as that from the ethanol content and is greatest at low concentrations of the polar solvent. It is clear, that the solute retention is the least at high ethanol concentrations and high temperatures, which would provide shorter analysis times providing the selectivity of the phase system was not impaired. The combined effect of temperature and solvent composition on selectivity, however, is more complicated and to some extent... 

Acetone and Aldehydes. Determine the acetone and ethanol content in accordance with ASTM D1612. The sample is reacted with Nessler s reag and the turbidity that is produced is compared to a standard contg the equivalent of 0.003 weight % acet... 

Acetone and Ethanol (Grade AA only). Determine the acetone and ethanol content by the elution method of gas chromatography using internal standards... 

As found by the earlier workers451,454, reaction takes place upon the small amount of free base present since ortho, para-substitution occurs. Observed second-order rate coefficients increased with increasing ethanol content of the medium, being approximately twice as large for 85 vol. % ethanol as for 20 vol. %, and this was found to derive from the change in concentration of free base with ethanol content of the medium for when this change is allowed for, the rate coefficient for... 

Huidobro, J. F., Estrella, R. M., de Andrade, B. P. C., Sanchez, M. P., Sancho, M. T., Muniategui, S., and Simal-Lozano, J. (1994). Enzymatic determination of primary normal alcohols as apparent ethanol content in honey. /. Agric. Food Chem. 42,1975-1978. 

Enzymes of the yeast are deactivated at higher ethanol concentrations => fermentation alone does not produce beverages with an ethanol content greater than 12-15%. 

Hydrolysis and analysis The purified and dried polymer (0.1 g) and 1 ml of aqueous HC1 (0.1 mol l 1), together with a measured amount of acetone (as internal GLC standard), was heated for 1 h at 100 °C in a sealed tube to hydrolyse the polymer. The solution was then neutralised and the ethanol content was determined by GLC by means of a calibration graph. As polymers of 4 and 5 are strongly hydrophobic and are thus hydrolysed only very slowly in water, they were hydrolysed in aqueous dioxane. 

FIGURE 7.1 NIR spectra from different fermentations of rye with yeast. The seven spectra have been measured in reflection mode in opaque mashes. Wavelength interval is 1100-2300 nm the number of data points is 241. The samples differ in the ethanol contents (62.2-84.1 g/L). 

The effect of ultrasound increased with increased ethanol content and decreased temperature giving rate enhancements up to 20-fold at 10 °C in 60% w/w. 

An example of such behavior is met with in aqueous ethanol (EtOH) at, say, 75°C. At Xboh< 0.24, the heat of mixing is negative (heat is evolved on mixing the components), but at higher ethanol contents it is positive (heat is absorbed and the mixture cools). In the equimolar mixture AH = 220 but AGab = 960 J mol, due to a negative entropy of mixing, but since... 

The majority of commercial developments which relate to the automation of GC and HPLC pay little attention to sample preparation. There are few examples where pretreatment is not required. A fully automated system was developed by Stockwell and Sawyer [23] for the determination of the ethanol content of tinctures and essences to estimate the tax payable on them. An instrument was designed and patented which coupled the sample pre-treatment modules, based on conventional AutoAnalyzer modules, to a GC incorporating data-processing facihties. A unique sample-injection interface is used to transfer samples from the manifold onto the GC column. The pretreated samples are directed to the interface vessel hy a simple hi directional valve. An ahquot (of the order of 1 ml) can then he injected on to the GC column through the capillary tube using a time-over pressure system. 

Batch crystallization studies of D-fructose from aqueous ethanolic solutions demonstrate that crystal growth rate is dependent on supersaturation (possibly to the 1.25 power), ethanol content and temperature. It appears that solution viscosity also has an effect. Growth rates of up to 1 pm/mln were measured. 

No nucleatlon occurs provided the supersaturation is kept below a value equivalent to 35 C of subcooling. There Is a size spread effect, but it decreases with high ethanol contents. The results Indicate that a practical process Is feasible to grow large fructose crystals by the addition of ethanol to aqueous fructose solutions. 

A size spread effect was observed. It is comparable with the growth dispersion effects found by Shiau and Berglund (10). The effect decreased with increasing ethanol content. 

The presence of solutes other than ethanol might be expected to reduce the mole fractions of ethanol and water and influence the nonideality of the ethanol-water system. However, both Williams (1983), who modelled a batch wine fermentation, and Rottenbacher (1985), in ethanol sorption experiments with yeast pellets in a fluidized bed, established that the ethanol-water-yeast system behaves as if the water and ethanol content of the pellets were a simple ethanol-water solution supported by a solid matrix which influences neither mole fractions nor activity coefficients. 

Normally, 90 to 98% of an ingested dose of ethanol is metabolized by the liver. Most of the remaining 2 to 10% is excreted unchanged in the urine and expired air. The ethanol content in the urine is normally about 130% of the blood concentration and is quite constant the expired air contains about 0.05% of the blood ethanol level, a concentration that also is remarkably consistent. 

Poncet-Legrand, C. et ak, Flavan-3-ol aggregation in model ethanolic solutions incidence of polyphenol structure, concentration, ethanol content and ionic strength. Langmuir 19, 10563, 2003. 

Semivolatile and non-volatile compounds of wood change the colour of the distillate and contribute to an up-rounded flavour. The wooden barrels which are permeable allow air to pass in and cause ethanol to evaporate thus, the ethanol content decreases and the aroma gets more intense, complex, and concentrated. Also harsher aroma constituents are removed and the spirit changes to mellow. The period of maturation depends on the size of the casks used, the alcoholic strength, as well as the temperature and humidity in the warehouse which leads to a smoother flavour. For production of neutral highly rectified distilled spirits like vodka, grain spirit, or white rum, the quality of water is of utmost importance to the flavour. In vodka production different treatments of water like de-... 

In hot-climate viticulture it is a common practice to lower the high ethanol content of wines made from overripe fruit by partial dealcoholisation. This objective can be achieved by vacuum distillation, where the spinning cone column technique allows even more viscous liquids to be processed. Alternatively, a water-ethanol fraction can be separated from wine by reverse osmosis, followed by distillation of the water-ethanol permeate to yield high-grade ethanol and pure water. The latter will be added back to the treated wine. 

---