Maturation, chemical changes

The condition of any soil represents a stage in the changing process of soil evolution. Soils develop, mature and change with the passage of time. Whereas the time required for a true soil to develop from the parent rock of the earth may be thousands of years, rapid changes can result in a few years when soils are cultivated, irrigated, or otherwise subjected to man s manipulation. The type of soil that develops from the parent material will depend upon the various physical, chemical and biological factors of the environment. 

Coal is a rich source of carbon and has been a valuable source of fuel for centuries. It is classified by both coal type and coal rank. Coal type is determined by the nature of the original biomass that led to the formation of the coal. Coal rank signifies the degree of maturation or chemical change in coal and usually determines coal quality. The calorific value, moisture content, elemental analysis, volatile matter, ash, and fixed carbon content are important qualities of coal. 

The chemical changes that take place in detached fruit are directly, or indirectly, related to the oxidative and fermentative activities collectively referred to as biological oxidations. Once the fruit is harvested, respiration, the process concerned with the oxidation of predominantly organic substances by the cell, assumes the dominant role, and the fruit no longer depends on absorption of water and minerals by the root, on conduction by vascular tissues, and on the photosynthetic activity of the leaves. After harvest, the fruit lives an independent life by utilizing substrates accumulated during maturation.385... 

Various physico-chemical changes occur in the structural components of the para-casein matrix during maturation these changes are mediated by the residual rennet, microorganisms and their enzymes, and changes in mineral equilibrium between the serum and para-casein matrix. The type and level of the physico-chemical changes depend on the cheese variety, cheese composition and ripening conditions. These may include ... 

This review focuses upon the post-translational modification and chemical changes that occur in elastin. Outlined are the steps currently recognized as important in the assembly of pro-fibrillar elastin subunits into mature fibers. Descriptions of some of the proposed mechanisms that appear important to the process are also presented. It will be emphasized that from the standpoint of protein deterioration, elastin is a very novel protein. Under normal circumstances, the final product of elastin metabolism, the elastin fiber does not undergo degradation that is easily measured. Unlike the metabolism of many other proteins, deterioration or degradation is most evident biochemically in the initial stages of synthesis rather than as a consequence of maturation. Since the presence of crosslinks is an essential component of mature elastin, a section of this review also addresses important features of crosslink formation. 

If sufficiently abundant, this material can cause suppression of vitrinite reflectance and will fluoresce under UV/blue light when immature (Price Barker 1985 Wilkins et al. 1992). With increasing maturity all the components in Fig. 4.3 become increasingly similar in chemical composition and follow evolution paths leading towards the origin. The chemical changes lead to... 

In studying the effect of heat on calcium carbonate, Black measured the loss of weight involved. He also measured the quantity of calcium carbonate that would neutralize a given quantity of acid. This was a giant step toward the application of quantitative measurement to chemical changes, a method of analysis that was soon to come to full maturity with Lavoisier. 

Thus, in terms of the chemical origin of coal, certain of the plant tissues contain chemical constituents of markedly similar molecular structures but there must be some attempt to recognize that incorporation into the coal precursor of a particular plant tissue (or a large part of the tissue of that particular plant) can also occur. While the maturation process may cause chemical changes to the individual chemical constituents of the tissue, this same maturation process(es) may also cause physical changes to the tissue (in to) that may cause it to appear as a recognizable entity in the coal (ASTM, 2011a-d). 

Long-term chemical changes also take place in the maturation vessel such as esterification and certain reductions. During the post-fermenting treatment of beer it is necessary to promote clarification of the beer and, by stabilizing treatment, ensure that turbidity due to chemical precipitation or growth of micro-organisms does not occur. 

Gangwar, B. M. and Tripathi, R. S. (1973). A study on physico-chemical changes during growth, maturity and ripening in mango. Punjab Horticulture Journal 13, 230-236. 

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