Fermentation of Apple Cider
“Science knows no country, because knowledge belongs to
humanity, and is the torch which illuminates the world. Science is the highest personification of the nation because that nation will remain the first which carries the furthest the works of thought and intelligence.” – Louis Pasteur, Great French Scientist (1822-1892).
Fermentation is chemical changes in organic substances produced by the action of enzymes. This general definition includes virtually all chemical reactions of physiological importance, and scientists today often restrict the term to the action of specific enzymes, called ferments, produced by minute organisms such as molds, bacteria, and yeasts. Generally, fermentation results in the breakdown of complex organic substances into simpler ones through the action of catalysts (Encarta).
Fermentation , originally, is the foaming that occurs during the manufacture of wine and beer, a process at least 10,000 years old. That the frothing results from the evolution of carbon dioxide gas was not recognized until the 17th century. Louis Pasteur in the 19th century used the term fermentation in a narrow sense to describe the changes brought about by yeasts and other microorganisms growing in the absence of air (anaerobically); he also recognized that ethyl alcohol and carbon dioxide are not the only products of fermentaion (Britannica).
In the 1920s it was discovered that extracts of muscle catalyze, in the absence of air, the formation of lactate from glucose and that the same intermediate compounds formed in the fermentation of grain are produced by muscle. An important generalization thus emerged: that fermentation reactions are not peculiar to the action of yeast but also occur in many other instances of glucose utilization (Britannica).
Glycolysis, which means dissolution of sugar, was originally defined around 1930 as the splitting of sugar into lactate. It can be further defined as that form of fermentation , characteristic of cells in general, in which the six-carbon organic acid, pyruvic acid (or its ionized form pyruvate), coupled with the transfer of chemical energy to the synthesis of adenosine triphosphate (atp). The pyruvate may then be oxidized, in the presence of oxygen, through the tricarboxylic acid cycle, or in the absence of oxygen, be reduced to lactic acid, alcohol, or other products. The sequence from glucose to pyruvate is often called the Embden-Meyerhof pathway after two German biochemists, who, in the late 1920s and 1930s, postulated and analyzed experimentally the critical steps in that series of reactions. The term fermentation now denotes the enzyme-catalyzed, energy-yielding pathway in cells by which fuel molecules such as glucose are broken down anaerobically. In most cells the enzymes occur in the soluble portion of the cytoplasm. The reactions leading to the formation of pyruvate thus are common to sugar transformation in muscle, yeasts, some...