Secondary constituents

After the dissipation of cosmic gases (approximately 4 x 109 years ago) several gaseous materials were liberated from the solid Earth. The substances formed in this way are termed secondary constituents. These atmospheric components were due either to volcanic, desorption and thermal processes or to chemical reactions. 

At an early age the iron in the upper part of the mantle was in a reduced state (as evidenced by very old iron minerals see Junge, 1966). The presence of reduced iron means that the gases and vapours given off by the solid mantle were also reduced otherwise they would have oxidized the iron. Probably, the secondary atmosphere consisted mainly of methane, ammonia and water vapour.2 

At this time in the Earth s history the carbon dioxide abundance was higher than its present value since this gas accumulated in the absence of a biosphere. Rutten (1966) speculated that the atmospheric C02 level was 10 times PAL (present atmospheric level) about 3 x 109 years ago. On the other hand the presence of H20 in the atmosphere led, by photochemical dissociation, to the formation of free radicals and molecular oxygen. An estimate of the importance of these reactions is necessary to give some idea of the oxygen level in pre-biospheric times. The photodissociation of water vapour can be represented as follows (Suess, 1966)  

Two atomic oxygens formed in this way can combine to yield molecular oxygen  

2 The laboratory experiments of Miller (1953) proved Oparin s hypothesis, according to which the organic compounds necessary for the formation of the life were produced in a reducing atmosphere. 

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Pedro, G. (1982). The conditions of formation of secondary constituents. In "Constituents and Properties of Soils" (M. Bonneau and B. Souchier, eds), pp. 63-81. Academic Press, New York. 

McClure, J.w. "Secondary Constituents of Aquatic Angio-sperms"in Photochemical Phylogeny, J.B. Harborne... 

Tropospheric 03 is a secondary constituent formed by chemical reactions in the atmosphere involving several precursors (NOx, hydrocarbons and CO). The concentrations of these precursors are controlled by the atmospheric oxidation processes, which are regulated by hydrogen radicals OH and H02. 

Honey contains an extensive diversity of phenolic compounds as secondary constituents, notably flavonoids and phenolic acids (Arraez-Roman et al., 2006 Baltrusaityte et al., 2007 Estevinho et al., 2008). The flavonoid content reaches about 6000 mg/kg, consisting mainly of flavanones and flavones (Anklam, 1998). The main flavonoids are myricetin, tricetin, quercetin, hesperidin, luteolin, kaempferol, pinocembrin, chrysin, pinobanksin,... 

Plantago major presents an exception because it is the only dicot tested exhibiting BOA-N-glucosylation comparable with com. As the species colonizes disturbed localities it is possibly under a strong selection pressure. Carduus nutans and Daucus carota are able to co-exsist with Agropyron repens, a very aggressive monocot that contains benzoxazinones as secondary constituents, which are released by root exudation. This association may explain the relatively well developed detoxification capacity. 

In addition to the conventional listing of major constituents, a commercial blend may be formulated to contain one or more of the secondary constituents, calcium, magnesium, or sulfur, which are used to correct local soil deficiencies. These are normally specified in a separate listing. The importance of these, too, cannot be overlooked as, for example, fertilization of a sulfur deficient soil with soluble sulfate has given over 1100% rapeseed (canola) crop improvement [69]. 

The primary constituent of whiskey is ethyl alcohol, the characteristic flavour is due to small quantities (rarely exceeding per cent, of the alcohol present) of esters, acids, higher alcohols and aldehydes produced during malting, fermentation, distillation, and maturing. These products are known as " secondary constituents. ... 

The flavour of newly-distilled whiskey is crude and unpleasant, particularly in the case of pot still whiskey, which contains more secondary products than the patent still. By storage in wooden casks changes are bro light about iu the character of the secondary constituents, with the result that the flavour is improved this process is maturing. Patent still spirit costs less to manufacture than pot still, and if the two are mixed, a milder, more uniform, and cheaper product is obtained by mixing immature pot stfll spirit—which is naturally cheaper than the fully matured article—with patent still whiskey, the unpleasant taste of the former is toned down so that the mixtiue becomes more palatable. The proportion of pot still whiskey in cheap blends depends on the price the cheapest may contain as little as 10 per cent. 

Glycerine from Molassesv—Pasteur in 1858 observed that glycerin, and succinic acid, in traces are products of the so-called alcoholic fermentation of the sugars. There is every reason to believe that the glycerine formed in this way owes its or in directly to the sizars, and not to the secondary constituents always present in those ftmdamental liquids, worts, must, etc., met with iir commerce. Despite numerous atteiopts to obtain glycerine in quantities which would be commercially profitable, up to quite recently no success has been met with. 

By this method alkaloid salts are transferred to polar solvents. It also helps in removing pigments, sugars and other secondary constituents. 

Distillation.—On the conclusion of the fermentation, the liquor, now called wash, is ready for distillation. In Scotch pot still practice two distillations are required for preparing whiskey from the wash. The first takes place in the wash still. The distillation is continued until all the alcohol has been driven off from the wash and collected in one distillate. The liquor remaining in the still is termed pot ale or burnt ale and is either run to waste or dried for fertilizer. The distillate, which is technically termed low wines, contains all the alcohol and secondary constituents from the wash, and considerable water. The low wines are transferred to a second and smaller still and arc redistilled. Three fractions are obtained from this distillation. The first is termed foreshots, the second constitutes the clean or finished whiskey, the third is called feints. The foreshots and feints are collected together, while the residue in the still, called spent lees is run to waste like the pot ale. 

The volatile secondary constituents, which pass over with the alcohol into the low wines receiver, on the distillation of the wash, are thus incorporated as far as possible with the finished whiskey finally produced. There can be no doubt, however, that a portion escapes with the spent lees since it is known that partial decomposition is undergone during the process of distillation, e.g. certain esters are easily decomposed when boiled with water under such conditions as those which obtain during distillation in the wash or low wines stills and the products of decomposition may wholly or partially remain in the spent lees and may consequently be absent from the whiskey. 

The extent to which the loss of secondary constituents may thus occur and affect the character of the whiskey depends largely upon the variety of pot still employed, and the manner of its operation whether, for instance, the process of distillation be carried on slowly or rapidly and it also depends on the strength at which the whiskey fraction is run. 

Actually, comparative analysis of old and new whiskey shows a somewhat greater content of secondary constituents in the old matured whiskies, especially in the relative amounts of volatile acids and aldehydes. The esters also increase, but to a lesser extent, while the furfural and higher alcohol contents remain practically unaltered. Of course, whiskey stored in wooden barrels increases in proof due to a relatively more rapid diffusion of water through the pores of the wood. In obtaining the analytical results noted above, this change is compensated by... 

The fine flavor and bouquet result from the secondary constituents of the brandy and are dependent upon a number of factors, principally raw materials, operating methods, aging, etc. The secondary constituents consist of various esters (acetic, butyric, oenanthic, valerianic), acetic acid, volatile oils, tannin, fixed acid and coloring matter. Ethyl pelargonate (oenanthic ester) and other volatile constituents are thought to be mainly responsible for the flavor. 

Distillation.—In the Cognac district the brandy is made either by the large distilleries or by the farmer himself right at the vineyards. It receives very little rectification, when distilled, in order to conserve the secondary constituents which produce the bouquet and flavor. 

Analyses of Typical Brandies.—Girard and Cuniasse ( Manuel Pratique de L Analyse des Alcools, 1899) state that the sum of the secondary constituents, referred to as the coefficient of impurity, is seldom less than 300 in genuine brandy made from wine. They give various analyses of brandies from which the following have been chosen ... 

Other analyses of unidentified brandies listed as commercial cognacs and thought to be wine brandy cut with rectified alcohol showed total secondary constituents ranging from 202 to 283. These were compared with analyses of industrial alcohol (al-cools d industrie) showing total secondary constituents ranging from 9 to 40.9. 

Redistillation to remove dark-colored secondary constituents (Fig. 89)... 

Classification. Extenders are mainly natural minerals that are converted into a usable form by working natural deposits, separating secondary constituents, and comminution (micronization). Synthetic products such as precipitated carbonates [e.g., calcium carbonicum praecipitatum (ccp), precipitated sulfates (e.g., blanc fixe), precipitated and pyrogenic silica, and silicates are used for optical brightening. Synthetic fibers (generally organic) are used for reinforcement. The classification of extenders used in surface coatings is summarized in Table 4.1. 

Chemical Composition. The extenders should be chemically inert in the paint. Secondary constituents (e.g., iron ions) may produce color changes. Sulfates, sulfides, alkali, alkaline-earth, and heavy-metal ions may cause problems due to their chemical reactivity and toxicity, and also affect abrasion and weather resistance. 

The abrasion of a mineral decreases with the particle size. Abrasion is low if a mineral does not contain any secondary abrasive constituents. Thus, for example, the abrasion of talc increases with the content of secondary constituents such as quartz and calcium carbonate. Abrasion can also be reduced by subjecting the material to surface treatment, normally with stearic acid or stearates. 

Components The shoots contain large amounts of silicic acid in the cell walls (up to 8%). The fatty acids found in H. t. contain 23-30 C-atoms. Secondary constituents of Equisetum species include alkaloids (e.g., palustrine), numerous flavones (e.g., 6-chlo-roapigenin), and flavonols as well as their dihydro derivatives, phenol- and hydroxycinnamic acids (e.g., 2,3-0-di-( )-caffeoyl-mew-tartaric acid in E. ar-vense), indanone derivatives and novel styrylpyrones such as, e.g., equisetumpyrone. The secondary product pattern reveals interspecific and intraspecific differences whereby the latter depend on the state of development. ... 

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