Fermentation Affect In Beer Fermentation Affect In Bread
(The pictures above are the affects of the respiration of yeast in beer and bread in alcoholic fermentation).
Alcoholic fermentation is also used to produce fuels, and antibiotics like penicillin.
Why Do The Conditions Need To Be Optimised For Fermentation?
The intention of optimising the conditions for fermentation is so that the enzymes involved in the process of respiration can work at their best. The reason bakers and brewers optimise the conditions (like temperature and concentration of glucose) is so that when respiration takes place, the enzymes are active and will allow the yeast cells to respire a hell of a lot more rapidly. The more the glucose is in the solution, the more energy the yeast cell will get, and the faster it will respire, producing larger amounts of ethanol and carbon dioxide (which is wanted). So, to supply the respiring yeast with optimised conditions, the temperature should be set at 35°C - 40°C and the concentration of glucose in the solution should be as high as possible (the higher the better).
Affecting Factors
The factors which affect the rate of respiration of yeast are:
- Temperature
- Concentration of glucose (depending on process)
Temperature~
All kinds of microorganisms have certain optimum temperatures. This is because when energy is necessary, even human cells need the right conditions to perform certain tasks. Enzymes speed up the process of what enters and leaves the cell. If our environmental temperature went exceedingly high or low, our cells and muscles would not be able to function properly because the conditions are unsettled for the enzymes to work best and the reactions that happen inside a cell will be too slow for life to go on. In this case we say that the enzymes are denatured. Therefore all organisms (including fungi) need to be at an optimum temperature to perform best. The optimum (best working) temperature for yeasts is 37°C, just like us humans. If the temperature falls below or rises above that temperature, the rate of respiration will decrease.
Concentration of glucose~
The rate (speed) of respiration is also affected by the concentration of glucose. Glucose is required for anaerobic respiration as oxygen is not available. The concentration of glucose does not affect the rate of anaerobic respiration in humans, but is certainly required in both aerobic and anaerobic respiration in humans. The glucose and oxygen enter the cell, and carbon dioxide and water (and some energy) leave the cell. These are all transported out of the body in different ways. In yeast the same happens, but there is no body, just a cell. So the glucose and oxygen enter the cell, and carbon dioxide and water (and some energy) leave the cell. But when there is no oxygen, the yeast uses glucose to respire, and when the glucose enters the cell, it leaves as ethanol and carbon dioxide (and some energy). In this case, the more glucose there is, the better (and faster) the enzymes are going to catalyze the reactions inside the cell. Hence, the concentration of glucose is proportional to the rate of respiration of yeast, in a solution: as the concentration of glucose increases, so does the rate of respiration of yeast.
But I am going to base my investigation on the concentration of glucose, but will keep the temperature in concern.
What Variables Could Be Changed?
The variables that could be changed in this practical are the concentration of glucose and the temperature. We cannot possibly change the amount of yeast as that is what we are observing. We changed the concentration of he glucose to monitor the affect of it on the respiration of yeast. The class did separate experiments, each group testing different concentrations of glucose. The temperature was altered and corrected for the condition to be right for the enzymes to work best in. all this was part of the preliminary test to adjust certain measures in order to carry out the final experiment in optimised conditions. If the experiment was to vary the yeast instead of the glucose, the investigation aim would have been ~ what affect does the amount of yeast have on its respiration in a fixed concentration of glucose in a solution (which is a totally different investigation and out of the question). Therefore yeast is not a variable in this investigation.
What I Will Do
I will (as it says in my experiment aim) investigate how the concentration of glucose in a solution affects the rate of respiration of yeast cells. I will carry out a practical experiment and decide my conclusion in accordance with the outcomes. I will set up a practical with the following apparatus:
- Water Bowl
- Conical Flask
- Bung
- Delivery Tube
- Additional Rubber Tube
- Measuring Cylinder
- Water Bath (heater)
- Ingredients (yeast and sugar)
- Water
Will use the heater to heat up the solution up to 35°C – 40°C, in which the yeast will be respiring (inside the conical flask). The water will be filled in a water bowl and a tube will be delivering carbon dioxide (released from the yeast) into a measuring cylinder under the water in side the water bowl. This is because there is no other way how we can measure carbon dioxide using the available equipment; therefore the bubbles of carbon dioxide will be measured underwater. The carbon dioxide given off in a limit of time will be recorded and then put into a table. The different concentrations of glucose will be experimented by separate groups of students in the class. So then, after all the results are put into one table, we will have our conclusion.
Diagram of Apparatus Setup
My Prediction
According to the anaerobic respiration theory, I predict that the concentration of glucose affects the rate of respiration in yeast chiefly. I predict that as the concentration of glucose becomes higher in the solution, the rate of anaerobic respiration is proportionally increased, and more carbon dioxide is given of in the same amount of time. This is because glucose is the only chemical used for anaerobic respiration and increasing the concentration of this will make the yeast respire faster. I declare that the concentration of glucose is a solution is directly proportional to the rate of anaerobic respiration of yeast. I expect my conclusion to agree with my prediction.
Fair Testing and Safety
Safety ~
Safety in this experimental investigation is vital because we are using materials that can deliver lethally toxic chemicals. As anaerobically respiring yeast produces ethanol, which is alcohol which is noxious to us humans, we should be incredibly careful that we do not inhale, consume or be directly in contact with any form of that chemical. This is the main reason why we wear safety glasses. As we will be using apparatus which is made of glass, it will be dangerous for students to behave insensibly as the result could lead to a hospital visit. We should take extra precautions with the water heater and the hot water itself as students could be burned if the apparatus is handled inappropriately. In all cases, the same conclusion leads to the safety of the experiment: the students should carry out every action with caution and thoughtfulness.
Fair Testing ~
As the class is investigating different concentrations of glucose in separate groups, regulations have to be kept for the conditions of the investigation to be the same for each and every practical. As we are observing reactions in different conical flasks, the amount of water essentially needs to be the same for the glucose to be dissolved into. Increasing the amount of water will decrease the concentration of glucose, and vice versa: the volume of water for every experiment is set at a fix amount of 100cm³ (measured out with a measuring cylinder). As the chemical reaction inside the cell occurs best in 35°C-40°C environmental temperature, we need every single solution (in which the yeast will respire) to be at precisely this temperature. The water will be heated to the correct temperature in a water heater and left at that temperature for a specific amount of time. The time in which the glucose will be recorded vitally needs to be permanent for each group of investigators, for if one group let the yeast respire for longer than the rest, their outcomes might me abnormally dissimilar and against the expected pattern, forming a weak correlation on the graph. It is absolutely vital for the yeast in every solution to be equal, as a variation in the quantity could cause the experiment to go tremendously flawed. The yeast should be weighed very accurately, and the same goes for the amount of glucose. The mass of glucose should be measured with absolute care, even though different groups are investigating different measures. A slight measurement mistake could unknowingly ruin the whole investigation, and if the quantities of both the yeast and the glucose are incorrect, the entire experimentation would be spoiled. It is recommended for the measuring cylinders to be the same sort, because the same apparatus would give more precise results than apparatus manufactured from different brands. To gin accuracy in my outcomes, I will also repeat the investigation once.
Method of Investigation
To obtain a high mark, I must elucidate my experimentation method clearly and thoroughly. The intention of carrying out this practical investigation was, basically, to study what affect the concentration of glucose in a solution has on the anaerobic respiration of yeast. The method in which we carried out this investigation was simple and effective. We started off by preparing the apparatus setup. The conical flask was filled with 100cm³ of water using the measuring cylinder, and the water bowl was maximally filled. Then, the water bath (heater) was set to the appropriate temperature (37°C-40°C) to let it heat up the water while we prepare. By the time the water bath had heated up the water within, we had added the assigned amount of glucose along with 3g of live yeast to the 100cm³ of water in the conical flask. Then we lidded the conical flask with a bung, which had a delivery tube attached to it. This delivery tube was considered to deliver the gas for collection (carbon dioxide) released by the anaerobic respiration of yeast. An additional rubber tube was attached to the delivery tube to extend the length of it. The water bowl, which was approximately 6 inches in depth and had, roughly, a 10 inches radius, came in use from beyond this point. A measuring cylinder was placed under the water in the water bowl so that there was no possible chance of any air being present when the carbon dioxide was being measured. The extension of the delivery tube was flexible and could be bent to different positions. The extended delivery tube was placed inside the measuring cylinder so that the gas given off could be measured accurately. When the gas is measured underwater, the bubbles collected can be measured, seeing as that is the only gas visible as an air gap, surrounded by water. The conical flask was then placed in the heated water bath and left for the respiration to continue, and for carbon dioxide to collect in the measuring cylinder. The total amount of gas was measured and recorded after 5 minutes of continuous respiration of the yeast. Each group then announced their results and the outcomes were recorded in a table. These results granted us a conclusion for us to analyse. Before carrying out the main final experiment, we did preliminary work. This was for two basic reasons.
Preliminary Experimentation
Before we carried out our concluding investigation, we decided to perform a sample test to, firstly, reconfirm ourselves to use the best working amounts of glucose, and secondly, to acquire some familiarity with what procedures the actual investigational experiment will involve. These two practices are vitally important to keep mature for this experiment’s method to progress acceptably.
We kept the amount of yeast the same (3g), but varied the glucose and carry out two experiments with two different concentrations of glucose (2g & 4g of sugar), increasing by two each time. The results below are the results for the preliminary test.
As you can see, these outcomes were similar to each other and the rest of the varied results would be too. So we decided to raise the quantity of the glucose from 4g onwards, increasing y two each time. With a new amount of glucose in mind, we also had to do a pretest on these quantities as well.
As we can all make out, these results were pleasing and were not as close to each other. Once we had these authenticating outcomes, we were more than ready to advance to the next level.
Ultimate Investigation and Outcomes
After deciding to use the above quantities of glucose, we carried out the experiment twice, because one set of results would not strengthen or support the conclusion as much as possible. We carried the repeated investigation exactly the same way as the first time (the procedure is stated in the “method of investigation” section). Therefore, we had a table concluding the outcomes of all experiments, and have drawn an identical table below.
For there to be a straightforward understanding of the correlation between the respiration and concentration of glucose, a graph represents the average outcomes and shows the relation on the following page. Now, the time has come for me to analyse and conclude my investigational experiment.
Conclusion/Scrutiny of Investigation
The whole aim of this investigation was to experiment and discover how the concentration of glucose in a solution affects the rate of anaerobic respiration of yeast. Well, as the theories affirm, the higher the level of glucose in anaerobic respiration, the more energy is released. Now that might mean more lactic acid for humans, but this is the release of carbon dioxide and ethanol for yeast. If the temperature remains constant all the way through the experiment, at approximately 37°C, as the concentration of glucose increases, so will the rate of respiration of yeast.
The theory for anaerobic respiration of yeast is fairly logical. All cells must respire to release used energy, and for that, fresh energy supply must be granted to the cells. Yeast is a fungus and its cells have no such valuable function for them to live. But for humans, their properties and reaction/respiration product is beneficial as many food products are created using the fermentation of yeast. Therefore, we must appreciate the properties of yeast as they grant us the benefit of magnificent food.
The graph for the outcomes is rather sufficient. By this I mean to say that the line of best fit is perfect, as it increases proportionally. The plotted scatter graph is relatively decent as both the subject matters are relative, giving us a strong correlation and also causing me to feel satisfied because the conclusion matches and agrees with my prediction. All the points are increasing as the concentration of glucose increases, apart from the final outcome which drops tremendously on the graph. This situation worries me as that plotted coordinate was hypothetically intended to be at a higher location on the graph. But as there is s logical hypothesis in every theme of science, I figured that this situation must also have a valid explanation.
The reasons I assume that this outcome was abnormal are that the group, that carried out the investigation with that particular assigned amount of glucose, accidentally made an error measuring the carbon dioxide, collecting the carbon dioxide or carrying out the experiment. Or maybe, as there is a limit to the amount of sugar that can be dissolved in water, the sugar did not dissolve suitably/completely and the concentration of the glucose in the solution was exceedingly decreased.
Even after this flawed final outcome, the line of best fit clearly symbolises that the rate at which yeast anaerobically respires is proportional to the concentration of glucose in the solution it respires within. The unusual plot does not disturb the line of best fit.
Hence, we come to an undoubted conclusion that clarifies the aim of this investigation:
The Rate Of Respiration Of Yeast Is Proportional To The Concentration Of Glucose In The Solution It Respires In.
Evaluation of Experimentation
The evaluation of an investigation is to state the ways is which the process and procedure of the experiment could have been improves to deliver more firm and certain results. It is also a way to express my own opinions on how the method and apparatus of the investigation could have been enhanced. In section I will be covering a variety of situations that could be improved for better and more superior conditions. We must bear in mind that the technology at our educational level is not as advance.
We could have improved the way we measured the total carbon dioxide by using a pressure measurer for precise and accurate measurement. If the conical flask that the yeast was respiring had a sensor within it that read how much carbon dioxide was released, the outcomes would have been scientifically pronounced “better”. Below is an example of a carbon dioxide sensor.
The temperature that we set the water bath to was not measured afterwards, but just assumed to be correct. So to make this matter improved, we could have fetched a reasonable thermometer to assure ourselves that the temperature of the solution was correctly between 35°C and 40°C (preferably at precisely 37°C). Below is an example of a thermometer.
If more time was allowed, I would have assured my outcomes many times by repeating the investigations several times. As I only have two sets of outcomes, it is annoying to see that there is a margin gap between the two sets of results. As more sets of results would have been recorded, the average outcomes, for the graph, would have been more precise.
The way we timed our experiment was by looking at the wall clock. But in actual fact, we were being really inaccurate. We might have gone up to a minute’s difference. For the sake of the accuracy of the investigation, we should have set a stopwatch as soon as we had begun the investigation. Below is an example of a stopwatch. This is a precise stopwatch as it is a digital one instead of an analogue one with hands.
Whatever the state of the equipment, the apparatus we used was the best we could use at our stage of educational experience. We cannot argue why we did not get more advanced equipment as the equipment we used was accurate, but imperfect. I can surely say that, for a satisfactory experiment, this investigation was a complete success.
Additional Investigations
Additionally, we could have taken the following investigation(s) into action:
- An investigation into how the temperature affects the rate of respiration of yeast.
- (Maybe) What affect salt and sugar (as a combination) have on the rate of respiration of yeast? Do they stabilise or do they have a different affect than what is expected?
