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In today's world, fossil fuels and the precious energy stored within their bonds are becoming less and less favorable for a variety of reasons; primarily because of the simple fact that they are in high demand and (as far as we can tell) will soon be in short order. Secondly, the price of gasoline in the United States has jumped from just over $1/gallon in the 1990's to well over $3/gallon a mere decade later. Both the production and consumption of fossil fuels have negative energy and environmental effects. What is modern society to do in the face of such adversity? How can humanity in general mediate the entrenched power house that is crude oil? Enter Chemical Engineers.
One of the most promising, readily available and easily introducible forms of fuel is ethanol (grain alcohol, C2H5OH). During the summer of 2007, I worked on a research project with Dr. Nada Assaf-Anid and Dr. James Patrick Abulencia from the Chemical Engineering Department, looking at how to make ethanol more efficiently. This was the chief goal of the project.
What is Fermentation? In order to understand the hypotheses and variables involved with the aforementioned experimentation, a brief tutorial in the theory of ethanol fermentation is necessary. Ethanol is an organic molecule which falls under the category of "alcohols." Ethanol is primarily produced via fermentation.
Fermentation is a generalized term which has implications in various forms of anaerobic cell respiration, however, for our purposes it pertains to using a type of yeast to convert carbohydrates into alcohols and carbon dioxide. The net formula for the fermentation of glucose via baker's yeast is shown below:
As seen in the equation, the yeast is a catalyst which essentially converts the glucose (sugars) into ethanol and carbon dioxide.
The yeast is considered a catalyst because it aids in speeding the rate of the chemical reaction and is not "used up" during the course of the reaction. Even though the yeast speeds this decomposition, it still needs time to metabolize the sugars (technically referred to as substrate). Therefore, finding ways to enhance the yeast's metabolism would increase the rate of ethanol output.
The Research
The Basic Parameters The chief concern of the project was to see if fermentation could be made more efficient. In order to achieve this, our hypothesis was that the addition of a certain amount of nutrient will speed up the fermentation. The "nutrient" in question is a co-enzyme known as Niacin (a.k.a. Nicotinic Acid or Vitamin B3). This vitamin serves several purposes in living organisms and can be found in many foods including broccoli, sweet potatoes and even baker's yeast (the type of yeast used in this experimentation).
Fermentation can and does occur spontaneously in nature because most fruits contain sugars and some also contain wild yeasts. The combination of the two allow fermentation to occur. However, this un-controlled reaction is unpredictable. In order to assure a reproducible product, an experimentally determined dry mass of particular yeast strain should be used consistently. In this experiment, Saccharomyces Cerevisiae, (a.k.a. Brewer's Yeast, Ale Yeast or simply Baker's Yeast) was the strain of choice. This is because it is extremely easy to find, and is used in a variety of industrial scale ethanol applications such as beer and wine production.
How the Research Commenced This experiment had its roots in the fall of 2006 when two senior Chemical Engineering students: Henry Baez and Laura Dupcak first started the project under Dr. Anid. They researched the background and theory involved and laid the framework for future experimentation.
My Research
In research applications, before one can go about changing a variable to observe the change it produces, it is absolutely necessary for a "control" to be produced. The control is just as important as the experimentation itself because, if a researcher doesn't have a control to compare his results with, how can he observe what has really changed from experiment to experiment?
Following this protocol, my first order of business was to produce a reliable and accurate control run. At first I tried to reproduce the previously performed experiments in hopes of getting some legitimate results. However, after a period of trial and error, it was determined that some major changes had to be incorporated. Along the way, many improvements were made and eventually, the baseline data was obtained.
The experimental procedure employed by my predecessors also underwent some modifications. The improved procedure included modifying the reaction vessel in order to make it air tight, utilizing a density meter to analyze the alcohol content of samples and taking special care to ensure the reactor was completely sterile. The basic procedure started with making the solutions to be fermented. These solutions were water based and contained high concentrations of glucose, as well as malt extract, yeast extract and peptone which are nutrients for the yeast. These four constituents made up the basic "wort." The wort was sterilized along with the entire 7 liter reactor vessel and once cool, it would be placed into the reactor along with the yeast culture. Once all of the contents were placed in the reactor, the solution is stored and fermentation begins to take place. Readings were taken every hour to check for four properties: specific gravity, Brix%, turbidity and pH. The specific gravity is a measure of density and the Brix% is a measure of glucose concentration. Both of these things are extremely useful and can be equated to ethanol production. The turbidity is a measure of the "cloudiness" of a solution and is directly related to the growth of the yeast cells; the higher the turbidity, the more yeast cells there are. The pH is important to monitor because if the pH is allowed to drop too low, the solution would become too acidic and the yeast would die.
Once the experiment was running smoothly, the only variable adjusted was the amount of glucose initially placed into the reactor. As with most chemical reactions, the greater mass of substrate introduced, the greater the theoretical product yield. Put simply; the more sugar the glucose have to consume, the more ethanol they can theoretically make.
However, in fermentation there is a limiting factor: the stability of the yeast. Once the ethanol concentrations reach a certain level the yeast start to die due to the toxicity of the very ethanol they produced. Theoretically the maximum concentration possible is 16-18% Alcohol by Volume (which is about 3-4 times the concentration of an average beer). In fact, any alcoholic beverage which has greater than 18% ABV is either fortified with concentrated ethanol or is distilled; a process which separates the ethanol from water and other constituents.
Some of the successful trials performed included 6%ABV, 12% ABV and 16%ABV. The amount of alcohol produced was directly proportional to the amount of substrate added in the beginning of the experiment. In other words, it was generally observed that the more glucose introduced, the more ethanol could be produced. However, the amount of alcohol is not as important as how quickly it was produced. Our results showed that the reaction rates measured over the first 6 hours were almost identical for both the 6%ABV, 12%ABV and 16%ABV trials (700g, 1500g & 2400g of Glucose, respectively). This is important to know since, doubling the reactant concentration usually increases the chemical kinetics of a reaction.
Figure 1 is a graph which plots specific gravity vs. time over the first 48 hours (see note*). Specific gravity is a measure of density compared to that of water. For example, the specific gravity of water is 1/1, while the specific gravity of something less dense than water (like ethanol) is approximately .990/1, the specific gravity of something thick like syrup could be 1.5/1. The initial wort is full of glucose and nutrients which make the solution sticky and dense. As the yeast convert the glucose into ethanol, the amount of "thick" sugar is consumed while the amount of "thin" alcohol is produced. Notice how the specific gravity of the 2400 grams of glucose is much higher than that of the 700 gram sample since the more sugar there is, the thicker the initial wort.
The change in specific gravity is ultimately equated to alcohol produced. Hence, the change in specific gravity for the 2400 gram trial is much greater than for the 700 gram trial. The "Initial" trial depicted in Figure 1 is an example of an extremely low glucose concentration in the wort. The lack of sugar means that close to no alcohol could be produced.
What's Next
The preliminary baseline experimentation proved to be extremely time consuming and I could not see the research through to the "Niacin Stage" before the summer ended. However, palpable results were achieved and I have passed on the project to two senior research students: Anna Daversa and Kelly Cassidy. Their challenge will be to study how the rate of fermentation varies with differing amounts of Niacin.
While all of the following is speculative conjecture, my personal hypothesis is that the Niacin (being a coenzyme so vital to fermentation) will increase the rate of fermentation. However, I also believe that there will be an optimal amount to add. If a less than optimal amount is introduced, the reaction will proceed at a slower than optimal rate. However if a more than optimal amount is added one of two things could occur. At lower excess concentrations the Niacin will probably undergo what is referred to as "diminishing returns." For example, 25 grams of Niacin is considered optimal, adding 30 grams or 40 grams, while costing more, would most likely yield the same rate of reaction that 25 grams would. Hence, the "return" of a faster reaction rate is nonexistent and 25 grams would be far more economical. I also believe that, when extremely large amounts of the Niacin are added, it will actually become reaction-inhibiting because excess amounts of any "good" thing can become bad for a living organism like yeast.
Conjecture aside, there is only one way to definitively gather empirical data: experimentation. Research is a wonderful tool, a tool which has made all advances in science possible. Academia has become a pivotal part of scientific and engineering research. In that tradition, I only view my work as one small link at the beginning of a long chain of trial, tribulation and ultimately; discovery.
One of the most promising, readily available and easily introducible forms of fuel is ethanol (grain alcohol, C2H5OH). During the summer of 2007, I worked on a research project with Dr. Nada Assaf-Anid and Dr. James Patrick Abulencia from the Chemical Engineering Department, looking at how to make ethanol more efficiently. This was the chief goal of the project.
What is Fermentation? In order to understand the hypotheses and variables involved with the aforementioned experimentation, a brief tutorial in the theory of ethanol fermentation is necessary. Ethanol is an organic molecule which falls under the category of "alcohols." Ethanol is primarily produced via fermentation.
Fermentation is a generalized term which has implications in various forms of anaerobic cell respiration, however, for our purposes it pertains to using a type of yeast to convert carbohydrates into alcohols and carbon dioxide. The net formula for the fermentation of glucose via baker's yeast is shown below:
As seen in the equation, the yeast is a catalyst which essentially converts the glucose (sugars) into ethanol and carbon dioxide.
The yeast is considered a catalyst because it aids in speeding the rate of the chemical reaction and is not "used up" during the course of the reaction. Even though the yeast speeds this decomposition, it still needs time to metabolize the sugars (technically referred to as substrate). Therefore, finding ways to enhance the yeast's metabolism would increase the rate of ethanol output.
The Research
The Basic Parameters The chief concern of the project was to see if fermentation could be made more efficient. In order to achieve this, our hypothesis was that the addition of a certain amount of nutrient will speed up the fermentation. The "nutrient" in question is a co-enzyme known as Niacin (a.k.a. Nicotinic Acid or Vitamin B3). This vitamin serves several purposes in living organisms and can be found in many foods including broccoli, sweet potatoes and even baker's yeast (the type of yeast used in this experimentation).
Fermentation can and does occur spontaneously in nature because most fruits contain sugars and some also contain wild yeasts. The combination of the two allow fermentation to occur. However, this un-controlled reaction is unpredictable. In order to assure a reproducible product, an experimentally determined dry mass of particular yeast strain should be used consistently. In this experiment, Saccharomyces Cerevisiae, (a.k.a. Brewer's Yeast, Ale Yeast or simply Baker's Yeast) was the strain of choice. This is because it is extremely easy to find, and is used in a variety of industrial scale ethanol applications such as beer and wine production.
How the Research Commenced This experiment had its roots in the fall of 2006 when two senior Chemical Engineering students: Henry Baez and Laura Dupcak first started the project under Dr. Anid. They researched the background and theory involved and laid the framework for future experimentation.
My Research
In research applications, before one can go about changing a variable to observe the change it produces, it is absolutely necessary for a "control" to be produced. The control is just as important as the experimentation itself because, if a researcher doesn't have a control to compare his results with, how can he observe what has really changed from experiment to experiment?
Following this protocol, my first order of business was to produce a reliable and accurate control run. At first I tried to reproduce the previously performed experiments in hopes of getting some legitimate results. However, after a period of trial and error, it was determined that some major changes had to be incorporated. Along the way, many improvements were made and eventually, the baseline data was obtained.
The experimental procedure employed by my predecessors also underwent some modifications. The improved procedure included modifying the reaction vessel in order to make it air tight, utilizing a density meter to analyze the alcohol content of samples and taking special care to ensure the reactor was completely sterile. The basic procedure started with making the solutions to be fermented. These solutions were water based and contained high concentrations of glucose, as well as malt extract, yeast extract and peptone which are nutrients for the yeast. These four constituents made up the basic "wort." The wort was sterilized along with the entire 7 liter reactor vessel and once cool, it would be placed into the reactor along with the yeast culture. Once all of the contents were placed in the reactor, the solution is stored and fermentation begins to take place. Readings were taken every hour to check for four properties: specific gravity, Brix%, turbidity and pH. The specific gravity is a measure of density and the Brix% is a measure of glucose concentration. Both of these things are extremely useful and can be equated to ethanol production. The turbidity is a measure of the "cloudiness" of a solution and is directly related to the growth of the yeast cells; the higher the turbidity, the more yeast cells there are. The pH is important to monitor because if the pH is allowed to drop too low, the solution would become too acidic and the yeast would die.
Once the experiment was running smoothly, the only variable adjusted was the amount of glucose initially placed into the reactor. As with most chemical reactions, the greater mass of substrate introduced, the greater the theoretical product yield. Put simply; the more sugar the glucose have to consume, the more ethanol they can theoretically make.
However, in fermentation there is a limiting factor: the stability of the yeast. Once the ethanol concentrations reach a certain level the yeast start to die due to the toxicity of the very ethanol they produced. Theoretically the maximum concentration possible is 16-18% Alcohol by Volume (which is about 3-4 times the concentration of an average beer). In fact, any alcoholic beverage which has greater than 18% ABV is either fortified with concentrated ethanol or is distilled; a process which separates the ethanol from water and other constituents.
Some of the successful trials performed included 6%ABV, 12% ABV and 16%ABV. The amount of alcohol produced was directly proportional to the amount of substrate added in the beginning of the experiment. In other words, it was generally observed that the more glucose introduced, the more ethanol could be produced. However, the amount of alcohol is not as important as how quickly it was produced. Our results showed that the reaction rates measured over the first 6 hours were almost identical for both the 6%ABV, 12%ABV and 16%ABV trials (700g, 1500g & 2400g of Glucose, respectively). This is important to know since, doubling the reactant concentration usually increases the chemical kinetics of a reaction.
Figure 1 is a graph which plots specific gravity vs. time over the first 48 hours (see note*). Specific gravity is a measure of density compared to that of water. For example, the specific gravity of water is 1/1, while the specific gravity of something less dense than water (like ethanol) is approximately .990/1, the specific gravity of something thick like syrup could be 1.5/1. The initial wort is full of glucose and nutrients which make the solution sticky and dense. As the yeast convert the glucose into ethanol, the amount of "thick" sugar is consumed while the amount of "thin" alcohol is produced. Notice how the specific gravity of the 2400 grams of glucose is much higher than that of the 700 gram sample since the more sugar there is, the thicker the initial wort.
The change in specific gravity is ultimately equated to alcohol produced. Hence, the change in specific gravity for the 2400 gram trial is much greater than for the 700 gram trial. The "Initial" trial depicted in Figure 1 is an example of an extremely low glucose concentration in the wort. The lack of sugar means that close to no alcohol could be produced.
What's Next
The preliminary baseline experimentation proved to be extremely time consuming and I could not see the research through to the "Niacin Stage" before the summer ended. However, palpable results were achieved and I have passed on the project to two senior research students: Anna Daversa and Kelly Cassidy. Their challenge will be to study how the rate of fermentation varies with differing amounts of Niacin.
While all of the following is speculative conjecture, my personal hypothesis is that the Niacin (being a coenzyme so vital to fermentation) will increase the rate of fermentation. However, I also believe that there will be an optimal amount to add. If a less than optimal amount is introduced, the reaction will proceed at a slower than optimal rate. However if a more than optimal amount is added one of two things could occur. At lower excess concentrations the Niacin will probably undergo what is referred to as "diminishing returns." For example, 25 grams of Niacin is considered optimal, adding 30 grams or 40 grams, while costing more, would most likely yield the same rate of reaction that 25 grams would. Hence, the "return" of a faster reaction rate is nonexistent and 25 grams would be far more economical. I also believe that, when extremely large amounts of the Niacin are added, it will actually become reaction-inhibiting because excess amounts of any "good" thing can become bad for a living organism like yeast.
Conjecture aside, there is only one way to definitively gather empirical data: experimentation. Research is a wonderful tool, a tool which has made all advances in science possible. Academia has become a pivotal part of scientific and engineering research. In that tradition, I only view my work as one small link at the beginning of a long chain of trial, tribulation and ultimately; discovery.
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