In many chemical reactions, for example, fermentation, the outcome of the products formed is depended on the number of reactants mixed or used in the reaction. Therefore, the amount of sugar used determines the amount of alcohol being produced as the increase in the amount of sugar produces a subsequent amount of reactants that are meant to be used in the fermentation reaction. The source of sugar is determined by the flavor of the alcohol yielded after fermentation. For example, sugars obtained from grapes and fermented to produce wine, rum is made from the fermentation of sugar cane, and grain starches are used for the production of vodka, whiskey, and beer. (the United States. Dept. of Energy, 27)
What is Fermentation?
Fermentation involves the conversion of sugars to alcohol and carbon dioxide by microorganisms and yeast in absence of oxygen or air. The sugar could be a simple sugar such as glucose or fructose, or a more complex sugar such as sucrose. Sucrose is a monosaccharide or dimer; this means it is made up of a single molecule of glucose linked to a single molecule of fructose. The use of sucrose in the fermentation process, the first stage is always breakage of the link that holds the two simple sugars by an enzyme. The glucose then undergoes a process known as glycolysis. It is broken down into two pyruvate sugar molecules. In the presence of oxygen, the pyruvate molecules undergo conversion into carbon dioxide and water. In anaerobic conditions, fermentation occurs, and the sugars are converted to alcohol.
Fermentation refers to the chemical breakdown of substances microorganisms such as yeast, bacteria, and other microorganisms. The process involves the emission of heat and bubbling which is scientifically referred to as effervescence. In the practical world, fermentation is involved in the manufacturing of beer, wine, and other forms of liquor in which there is the conversion of sugar into ethyl alcohol. In this regard, therefore, sugar is an important element in the entire process of fermentation. It is the main constituent of the process as the bacteria and yeast act on it to produce alcohol. ( United States. Dept. of Energy, 29)
Yeast on the other hand is a fungus that requires energy to develop, live and grow. The energy required by yeast, therefore, comes from sugar during the process of fermentation; just like the human body requires energy from sugar and other forms of carbohydrates for its daily functions and supply of energy. Like in the process of respiration, yeast uses oxygen to release the energy required. In this case, the higher the supply of sugar the more active the yeast becomes and hence the faster it grows. However, Yeast does not do well in so much sugar though, for example; Honey. When oxygen is short, however, like it is in a ball of dough, yeasts react to give alcohol and carbon dioxide in form of bubbles which makes the dough rise. The alcohol produced is however poison to yeast and to people as well and hence reduces the rate of growth of the yeast if its contents get too high. This explains why alcohol is never more than 12% in wine.
What Kinds of Sugars That Affect the Effectiveness of Yeast and Hence Slowing or Increase the Rate of Fermentation?
The common sugars that are involved in fermentation include but are not limited to; glucose, fructose, sucrose, and lactose. Other forms of sugars that may influence the rate of fermentation include the following: maltose, molasses or treacle, raw sugar, demerara or turbinado and invert sugar. ( United States. Dept. of Energy, 42)
An experiment to determine the impacts of these sugars on fermentation gives the following results for each of the sugars. Glucose produces the highest amount of carbon dioxide due to the highest gas bubbles formed. A gas by-product in fructose results in 0mm of carbon dioxide and is, therefore, the least of the four sugars. A line slope is used as the best fit to analyze and determine average rates present in carbon dioxide production in a span of 20 minutes time frame. Glucose gives the most efficient with 12.64mm of carbon (IV) oxide in one minute. Sucrose produces 9.27mm of carbon IV oxide per minute in the process of fermentation. The rate of fructose functioning with the yeast is 3.99mm of carbon (IV) dioxide per minute. Any control that does not yield produce carbon dioxide signifies the absence of sugar, In measuring the amount of sugar in sucrose and glucose the rate of carbon iv oxide production remains constant throughout the tests while that of fructose starts slowly but increases steadily with time; however, for fructose, the rate of carbon dioxide production in fructose remains at a constant 0 throughout the test.
There are a number of reasons why these different sugars react and behave this way. For each sugar, there is an indication of how it affects the rate of fermentation and hence an indication of different levels of reaction. The hypothesis is supported to show that all the forms of sugar produce energy. Glucose however is the most efficient since the carbon dioxide produced by each sugar is directly related to energy produced in the process of fermentation since carbon iv oxide is a byproduct of ethanol in the process of fermentation. In a control test to determine the presence of sugar, the control that contains no sugar produces no energy. This is so because there is a requirement of sugar for fermentation and glycolysis to take place. The reason why glucose produces the greatest rate of energy production is due to the fact that it also produces a high rate of carbon dioxide. When uptake of glucose and fructose are studied with a pair of brewing of yeast containing equal concentrations of glucose and fructose, preferential glucose uptake is observed with each yeast strain. Glucose can be calculated to take up an estimate of twice the rate of fructose in the two strains. Although there is a strain difference that is apparent for the actual rates of glucose and fructose uptake. (OByrne, Paul, 88)
When fermentation is conducted with 20% sucrose, first; sucrose is rapidly hydrolyzed to glucose and fructose through the action enzyme invertase before the uptake of either sugar. The outcome of such a test shows a preferential uptake of glucose over fructose for both yeast strains when sucrose was used as a substrate (the United States. Dept. of Energy, 51)
Sucrose, on the other hand, produces the second-highest rate of carbon dioxide because of the same reason; energy production in glucose is higher than in sucrose due to the level of carbon dioxide production between the two sugars. The energy production rate in fructose was however 3 times lower than in energy production in glucose. This depicts that glucose is directly used in the process of the glycolysis cycle and does not require extra energy for its conversion into a usable form. This is therefore the reason why glucose is more efficient in the fermentation process.
Sucrose requires a catalyst in form of an enzyme and additional energy input to be able to break down into glucose and fructose so as to enable it to be processed in glycolysis. Fructose as well cannot be used immediately in the glycolysis chain but can be altered or broken so as to join the chain as intermediates. This process however requires the conversion of non-glucose into soluble or usable forms hence reducing their efficiency when compared to glucose. In order to minimize errors in such tests, one should avoid adding yeast to fructose solution after glucose and fructose solutions start fermenting. The fermentation process takes time to reach its maximum energy production rate. ( United States. Dept. of Energy, 54)
When yeast is used to carry out fermentation which is mostly referred to as anaerobic respiration that is; to convert monosaccharides into carbon (IV) and ethanol, cells become effective in different sugars for fermentation. The rate of carbon dioxide fermentation in yeast cells is therefore measured by monitoring the pressure that accumulates with time in the sugar being tested. If yeast is fed with 5% eleven sugar solutions, that means three trials for each and every sugar, that means that it is calculated and compared, Yeast produces a very high carbon (IV) oxide formation rate in sucrose compared to all the other types of sugars. (OByrne, Paul, 91)
The results of the other sugars come in the order of glucose being second, maltose, fructose, and then galactose. While the use of a two-sample test is used, the rate of yeast cells in fermentation can be found to be relatively higher when using sucrose than in the use of all other sugars. It is also highest in Splenda than in all other sugars except for powdered sugars, and also relatively higher when using dark brown sugar than all of the other sugars apart from that of powdered sugars. Variation in dates may be argued to be as a result of specific enzymes available in each sugar. In this case, when comparing maltose and sucrose; maltose does not result in any carbon dioxide yield; hence the rate of carbon dioxide production in sucrose is higher than that in maltose Saccharomyces cerevisiae. (OByrne, Paul, 100)
Carbon Dioxide Production
When taking maltose against glucose, maltose is not transported through the membrane to enter yeast cells and get metabolized in the cell. In cases where glucose is contaminated, some carbon dioxide should be produced as yeast can metabolize glucose. Maltose contains two molecules of glucose and hence the difference in the cases of fermentation and yeast reaction. It is therefore transported in an organism as a disaccharide. Maltose is a disaccharide is for this reason transported across yeast cells through the means of active transport.
Monosaccharides on the other hand get transported through yeast cells by a simple diffusion method. The difference in carbon dioxide production is therefore as a result of the difference in affinities of enzymes from within the cells that trigger intracellular metabolism. An increase in affinity of the substrate increases the reaction rate, low affinity depicts that larger amounts of the substrate are required before the same rate of reaction is seen. Kiases phosphorylate hexoses, for example, glucose and fructose pose a high affinity whereas glucosidases that hydrolyze disaccharides that have lower substrate affinity. (OByrne, Paul, 105)
The explanation for this is that the slower rate of carbon dioxide production with disaccharides such as maltose is that it takes time before active transport accumulates enough maltose in the cell for an appreciable level of enzyme activity to occur. Apart from the already discussed sugars, there are so many forms of sugars that influence fermentation in one way or the other, a summary of these sugars and their effects on fermentation is given as follows:
D-glucose is formed through enzymatic hydrolysis of starch such as corn, rice, wheat, and potato. An introduction of heat energy and bacterial enzymes helps in hydrolyzing starch into small carbohydrates. The starch that has been hydrolyzed partially is then completely hydrolyzed to Glucose using the glucoamylase enzyme from Aspergillus niger. The solution is then purified by filtration and concentrated through the process of evaporation. ( Zymomonas Mobilis.,17)
White sugar: when white sugar is treated and made to produce juice from it, it passes through a machine. The liquid produced is molasses. Plain White Sugar is high octane to fermentation because the yeast is able to easily break it down to form glucose and fructose and thus into beneficial acetic and gluconic acid. (Zymomonas Mobilis., 24)
Honey is made up of fructose, glucose, water, and other nutrients Honey kills bacteria and pathogens by a process called osmotic pressure and which contains hydrogen peroxide that is also a bactericide. The fermentation of honey by...
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