Carbon maceral concentrates

Fig. 1. An amplified outline scheme of the making of various wiaes, alternative products, by-products, and associated wastes (23). Ovals = raw materials, sources rectangles = wines hexagon = alternative products (decreasing wine yield) diamond = wastes. To avoid some complexities, eg, all the wine vinegar and all carbonic maceration are indicated as red. This is usual, but not necessarily tme. Similarly, malolactic fermentation is desired in some white wines. FW = finished wine and always involves clarification and stabilization, as in 8, 11, 12, 13, 14, 15, 33, 34, followed by 39, 41, 42. It may or may not include maturation (38) or botde age (40), as indicated for usual styles. Stillage and lees may be treated to recover potassium bitartrate as a by-product. Pomace may also yield red pigment, seed oil, seed tannin, and wine spidts as by-products. Sweet wines are the result of either arresting fermentation at an incomplete stage (by fortification, refrigeration, or other means of yeast inactivation) or addition of juice or concentrate.

Studies initiated by the author in CSIRO (13) seek to throw light on the role of the various macerals by studying the conversion, under catalytic hydrogenation conditions, in Tetralin as vehicle, of maceral concentrates from a high volatile bituminous coal. Some preliminary results, given in Fig. 3, show conversions as almost complete for the hand picked vitrain (>90% vitrinite) from a high volatile bituminous coal (Liddell seam N.S.W., 83.6% carbon and 43% volatile matter both expressed on a dry ash-free basis). However, it is evident that the conversion of the whole coal increases rapidly with increase in hydrogen pressure (under otherwise similar conditions - batch autoclave, 4h. 400°C). 

Table 12.19 compares free run and press juice composition for traditional (crushed grapes) and carbonic maceration winemaking. In carbonic maceration press wines, the alcohol content is higher (caused by ethanol fixation) and the acidity lower (due to malic acid degradation). These wines also have lower concentration of phenolic componnds and other extracted components their dissolntion is diminished. 

Table 12.20 (Flanzy et al., 1987) compares the composition of traditionally made wines (crushed grapes) and wines having nndergone carbonic maceration (effected at 25 and 35°C). The importance of temperature in anaerobic metabolism is shown. At 35°C, this techniqne permits the same tannic structure as traditional winemaking. In general, density and dry extract, fixed acidity and phenolic compound concentrations are lower with carbonic...

H/C = atomic hydrogen-to-carbon ratio V = vitrinite content of coal VM volatile matter St = total sulfur TRM = total reactive macerals The adequacies of these reactivity correlations, expressed as a percentage of the total variation in the data set explained by the model, were 80.0%, 79.2%, and 47.5% respectively. A later paper in the series (21) concentrated on the development of reactivity correlations for a set of 26 high volatile bituminous coals with high sulfur contents, and extended the models previously developed in include analyses of the liquefaction products and coal structural features. These structural features included the usual... 

Results on Unheated Samples. The results obtained in Southampton for the set of British samples are shown in Figures 2 and 3. In Figure 2 the spin concentration of each maceral is plotted against the carbon content (daf) of the associated vitrinite, and the points for each set of macerals from one coal are joined by a vertical line. It can be seen that the vitrinite series forms a well-defined narrow band which curves upwards sharply at about 90% carbon, and the data resemble closely those presented earlier by Austen and Ingram for whole coals. The values of exinites form a wider, approximately horizontal band lying a little below the vitrinite band, while the fusinite data appear to vary at random but lie consistently well above the vitrinite band and are appreciably higher than vitrinites of the same carbon content (90-92%) would be. 

Free Radicals in Macerals. Electron spin resonance (ESR) has been used to study carbon free radicals in coals, and to some extent, separated macerals. The technique provides information on radical density and the environment of the radicals. The resonance position, termed the g-value, is dependent on the structure of the molecule which contains the free electron. The line width is also sensitive to the environment of the unpaired electron. In an early study, Kroger (71) reported that the spin concentration varied between maceral groups with liptinite < vitrinite inertinite. For this limited set of samples the spin concentration increases with rank for liptinites and vitrinites and decreases for the micrinite samples. On the other hand, van Krevelen (72) found the same general results except... 

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