Accelerated fermentations

Use Ammonium salts, medicine (expectorant), baking powders, smelling-salts, fire-extinguishing compounds, pharmaceuticals, textiles (mordant), fermentation accelerator in wine manufacture, organic chemicals, ceramics, washing wool. 

These preparations have not yet been proven to initiate recalcitrant malolactic fermentations. Accelerating this phenomenon by several days is an advantage, but is not essential. 

Oxygen, when introduced into fish-farming ponds and pools, particularly trout pools, enables these fish to increase their food intake and hence grow more rapidly (see Aquaculture chemicals). Fermentation operations are accelerated by sparging with oxygen (see Aeration,biotechnology Ferl ntation). 

In the wet method, as practiced in Colombia, freshly picked ripe coffee cherries are fed into a tank for initial washing. Stones and other foreign material are removed. The cherries are then transferred to depulping machines which remove the outer skin and most of the pulp. However, some pulp mucilage clings to the parchment shells that encase the coffee beans. Fermentation tanks, usually containing water, remove the last portions of the pulp. Fermentation may last from twelve hours to several days. Because prolonged fermentation may cause development of undesirable flavors and odors in the beans, some operators use enzymes to accelerate the process. 

There are many reactions in which the products formed often act as catalysts for the reaction. The reaction rate accelerates as the reaction continues, and this process is referred to as autocatalysis. The reaction rate is proportional to a product concentration raised to a positive exponent for an autocatalytic reaction. Examples of this type of reaction are the hydrolysis of several esters. This is because the acids formed by the reaction give rise to hydrogen ions that act as catalysts for subsequent reactions. The fermentation reaction that involves the action of a micro-organism on an organic feedstock is a significant autocatalytic reaction. 

Schnell-gang, m. rapid motion, high speed, -garung, /. quick (or accelerated) fermentation,... 

The known changes in polyphenolic material have already been noted. Fermentation also results in slight loss of extractable caffeine. Decreases of 5 to 7% have been observed.31 Higher-than-normal fermentation times and temperatures accelerate this effect. The fate of caffeine made unavailable during fermentation is not definitely known. It has been demonstrated that caffeine interacts with polyphenols,80-81 so it is likely that the alkaloid becomes complexed with the most insoluble thearubigen fractions that do not become part of the beverage.31... 

Black tea quality as determined by theaflavin levels is also affected by storage conditions. Low temperatures, low moisture levels, and low oxygen availability retard theaflavin loss. Residual peroxidase activity, which accelerates theaflavin loss on storage, is diminished by acid treatment during fermentation.94... 

This type of autocatalytic reaction is a simplification of many biological reactions such as fermentation, where the reaction produces products (species B in the previous example), which accelerates the rate. In fermentation, yeast cells in the solution produce enzymes that catalyze the decomposition of sugar to produce ethanol as a byproduct of yeast reproduction. Since the yeast population increases as the reaction proceeds, the enzyme concentration increases, and the process appears to be autocatalytic. A highly simplified description of fermentation might be... 

Heat generation by exothermic combustion reaction can also accelerates combustion processes (as it also does slightly for fermentation), and we call this thermal autocatalysis which will be discussed more in Chapters 5, 6, and 10. 

We have previously encountered examples of chemical autocatalysis, where the reaction accelerates chemically such as in enzyme-promoted fermentation reactions, which we modeled as A + B 2B because the reaction generates the enzyme after we added yeast to initiate the process. The other example was the chain branching reaction such as H. -I-O2 —> OH - -0 just described in hydrogen oxidation. The enzyme reaction example was nearly isothermal, but combustion processes are both chain branching and autothermal, and therefore they combine chemical and thermal autocatalysis, a tricky combination to maintain under control and of which chemical engineers should always be wary. 

Cockcroft A. E., M. McDermott, J. H. Edwards, and P. McCarthy. Grain exposure— symptoms and lung function. Eur JRespirDis 1983 64(3) 189-196. Lupton J. R., J. L. Morin, and M. C. Robinson. Barley bran flour accelerates gastrointestinal transit time. J Am Diet Assoc 1993 93(8) 881-885. Thorbum A., J. Muir], and]. Proietto. Carbohydrate fermentation decreases hepatic glucose output in healthy subjects. Metabolism 1993 42(6) 780-785. 

Fermented liquors, wines, meads and beer were known in all countries from the most ancient times. Their use at the time of Dioscorides and Pliny was extensive and excessive. They naturally entered largely into medicine. It is worthy of note that Dioscorides ascribes injurious action to their continual use, and advises they be used only as occasional stimulants. The effect of new wine in accelerating the pulse may be avoided, he says, by adding water and boiling until this is again evaporated. That the reason for this lies in the elimination or reduction of the alcohol content was beyond the understanding of the time. 

Formic and oxalic acids and their salts in the presence of mineral acid reduce arsenic acid and arsenates the reaction is accelerated by boiling.10 Tartaric acid does not appear to form complexes with arsenic acid 11 such as are formed with arsenious acid. Certain sugars, namely fructose and less rapidly sucrose, but not glucose, maltose or lactose, form labile esters of arsenic acid during fermentation in the presence of this acid the reaction is purely a chemical one and not biochemical.12... 

The arsenate considerably accelerates the fermentation of hexose diphosphate,10 and inhibits the combination of sucrose with phosphoric acid (phosphorylation).11... 

The power consumption by impeller P in geometrically similar fermenters is a function of the diameter Dl and speed N of impeller, density p and viscosity p. of liquid, and acceleration due to gravity g. Determine appropriate dimensionless parameters that can relate the power consumption by applying dimensional analysis using the Buckingham-Pi theorem. 

He sought a chemical explanation of the problem of why crops responded differently to fermentation. After finding out part of the chemical conversion that occurred in leaf tobacco during fermentation, he sought a catalyst to accelerate and improve this process. The first indication for the presence of alkaloid transformation products in the fermented leaves was... 

Microbiological action in starch dispersions results in a drop in pH, loss of viscosity and the development of odor. Retrogradation may be accelerated by the drop in pH or especially if butanol, which complexes with amylose, is generated via starch fermentation. Sulfate-reducing bacteria will cause black deposits due to reaction with iron in the process water. For quality control, preservatives are added to starch slurry, cooked starch, surface size and coating color. 

The concept and technique of submerged-culture fermentations to accelerate what were originally surface reactions were first used extensively in the pharmaceutical industry. It was apparent to enological researchers in several countries that the same principles could be applied to production of flor sherry. 

The reaction rate determines the application potential and/or the need of improvement to accelerate the conversion. For example, the production of biogas via fermentation of biomass and the onboard production of H2 via steam reforming of CH3OH require different times for a certain degree of conversion. However, for the biogas production the time is of less importance, as one can simply wait and/or increase the size of the fermentation vessel. This is obviously not possible for the onboard production of H2 in a vehicle. 

Promotion action of additives on biological growth in considered kinetic theory is taken into account by introduction into equation (22) in an explicit form of dependence of coefficients of birth b and chain propagation p on promoter concentration. This dependence may be approximated by equation of Mono type for organisms or Michaelis-Menten for fermentative catalysis. Equation (22) for x1=x2= k wi= 0 and f=2 is solved in relation to Ci(t). Theoretical curves qualitatively correctly (Figure 6) reflects acceleration of growth of cells of mouse embryo Balb/c 3T3 [22] with increase of serum concentration containing stimulators. 

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