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I'm doing a lab soon and I need to find a way to measure fermentation rate to a relatively high degree of accuracy without using a specialized sensor. It should ideally be done with easy to find tools at home or in the classroom.
How do you measure the respiration rate of yeast?
These factors include pH, temperature, nutrient availability, and the concentration of available nutrients. By determining which factors affect the yeast activity, these variables can be controlled in the fermentation process.
Also, how do you measure yeast? Envelopes of yeast generally weigh 1/4 ounce each and measure approximately 2-1/4 teaspoons. If your recipe calls for less yeast, just measure the amount called for in your recipe from an individual packet, then fold the packet closed and store remaining yeast in the fridge for next time.
Herein, how do you measure respiratory rate?
- Measure the amount of glucose consumed.
- Measure the amount of oxygen consumed.
- Measure the amount of carbon dioxide produced.
How does substrate affect the rate of respiration in yeast?
The more the enzyme of a particular substrate, the faster the rate of breakdown and therefore the more CO2 is produced. If there is plentiful of O2 then yeast would respire aerobically with sugars, producing H2O and CO2 as waste products.
4 Answers 4
I doubt anyone has tried this on a normal home brew scale because your "graduated cylinder/bottle" would need to hold 100 or 200 gallons of CO2 to capture all the CO2 for a batch. Even if you found a way to record the volume and reset, you still would need quite a large vessel during the most active stages of fermentation. You would also have the problem of leaks (standard homebrew equipment is not PSI tested, but it usually doesn't matter since there is postive pressure inside during active fermentation and you only care to keep air out). People have tried the "flow meter" approach (counting bubbles and such). But we have solved this problem in a much more efficient way. It's called taking an original gravity reading and a final gravity reading.
For a standard 5gal(18.9 litre) carboy fermented to 12% alcohol content by weight (not volume, 14.5% by volume) approx 1100 litres (264 gallons) of CO2 at 1 atm, 68F. But if you knew that, you would also know that 2.268 kg of ethanol had been produced allowing the simple math to calculate % alcohol by either weight or volume.
The prediction, assuming 100% conversion, is that each molecule of sugar produces 2 molecules of ethanol and 2 molecules of CO2. Using atomic weights 0.51 x weight of the sugar tells you how much ethanol you can produce. That ethanol weight divided by the ethanol weight + the weight of the water used will give you % ethanol by weight, you would then use the density to calculate % alcohol by volume.
One could use CO2 production by unit of time (measure how long it takes to collect a liter of CO2) would be indication of how active fermentation was, but it would not indicate (assuming a constant temperature and pressure) whether it was because you were a) running out of sugar for the yeast to consume, b) yeast was dieing off from alcohol concentration, c) yeast was dieing because of infection, d) yeast was dieing because of pH. Though over several batches of recording these rates, taking SG readings, pH readings, do yeast counts you would be able to use the rate of CO2 generation as an indication of % alcohol as well as an indication of whether your pitch rates were consistent.
Fermentation in yeast
Yeasts are eukaryotic, single celled fungi that lack mitochondria. Since they lack mitochondria, they are unable to go through the last two steps of cellular respiration: the citric a cid c ycle and the electron t ransport c hain. Like cellular respiration, yeast are able to break down a glucose (C 6 H 12 O 6 ) molecule and use the chemical energy released to synthesize ATP from ADP and P. However, this process yields far few synthesized ATP, a net of two ATP compared with cellular respiration’s net of 25ATP. Unlike cellular respiration, this process can occur in the absence of oxygen (O 2 ).
The general equation for yeast fermentation is:
In yeast, two byproducts are given off and no longer utilized by the yeast: carbon dioxide and ethanol. The carbon dioxide gas given off by yeast causes bread to rise, and ethanol is what makes beer and wine alcoholic. When you bake bread, the temperature elevates above ethanol’s boiling point removing it from bread. In this experiment, we will detect the production of carbon dioxide as a byproduct of fermentation in brewer’s yeast.
Parameters of Bioprocess and its Measurement
There are a large number of physical, chemical and biological parameters that can be measured during fermentation/bioprocessing (Table 19.6) for data analysis and appropriate control. Some special sensors have been developed to carry out measurements in the bioreactors. The basic requirement of all the sensors is that they must be sterilizable. The measurements of the parameters (listed in Table) can be done either directly in the bioreactor or in the laboratory.
Important Parameters that can be measured during bioprocessing are :
O2 concentration (dissolved)
Waste gases concentration (e.g. CO2)
Activities of specific enzymes
Energetics (ATP concentration)
There are pH electrodes that can withstand high temperature (sterilization) pressure and mechanical stresses, and yet measure the pH accurately. Combination electrodes (reference electrode, glass electrode) are being used. In fact, electrodes are also available for measuring several other inorganic ions.
Oxygen electrodes and CO2 electrodes can be used to measure O2 and CO2 concentrations respectively. The electrodes are amperometric in nature. They are however, susceptible for damage on sterilization. In a commonly used technique, O2 and CO2 respectively can be measured by the magnetic property of O2 and the infrared absorption of CO2. This can be done by using sensors.
Use of Mass Spectrometer:
The mass spectrometer is a versatile technique. It can be used to measure the concentrations of N2, NH3, ethanol and methanol simultaneously. In addition, mass spectrometer is also useful to obtain information on qualitative and quantitative exchange of O2 and CO2.
Use of Gas-permeable Membranes:
The measurement of dissolved gases, up to 8 simultaneously, can be done almost accurately by using gas-permeable membranes. The advantage is that such measurement is possible to carry out in the nutrient medium.
Use of Computers:
Computers are used in industrial biotechnology for data acquisition, data analysis and developing fermentation models.
By employing on-line sensors and computers in fermentation system, data can be obtained with regard to the concentration of O2 and CO2, pH, temperature, pressure, viscosity, turbidity, aeration rate etc. Certain other parameters (e.g. nutrient concentration, product formation, biomass concentration) can be measured in the laboratory i.e. off-line measurements. The information collected from on-line and off-line measurements can be entered into a computer. In this fashion, the entire data regarding a fermentation can be processed, stored and retrieved.
The data collected on a computer can be used for various calculations e.g. rate of substrate utilization, rate of product formation, rates of O2 uptake and CO2 formation, heat balance, respiratory quotient. Through computer data analysis, it is possible to arrive at the optimal productivity for a given fermentation system.
Development of fermentation models:
The computer can be used to develop mathematical models of fermentation processes. These models in turn will be useful to have a better control over fermentation systems with high productivity in a cost-effective manner.
Measuring Brix in Fermentation
How often do you measure Brix during fermentation when making wine? Is there a starting point or standard schedule to measure or does this come with experience?
Like most everything in winemaking, the glib answer is, “It depends.” The real answer, however, is much more complex and as you intimate, experience can play a large part in fine-tuning your sugar-measuring schedule during fermentation.
During the alcoholic fermentation process, yeast cells convert the sugar in grapes (or other fruit) into ethyl alcohol and carbon dioxide. Typical starting degrees Brix would be around 25 for a typical red wine (or 1.106 specific gravity). Interestingly, the fermentation is considered complete on the Brix scale only when the fermentation drops to -1.0 this is because alcohol is less dense than water and will cause the negative reading when all the sugar is gone. Specific gravity (SG) is a little more intuitive as “dry” is considered anything below 0.995.
During fermentation, winemakers measure the density of the fermenting juice in order to get an idea as to how quickly the sugar is disappearing and how much sugar remains. I would argue that the rapidity with which the sugar is consumed (and the density is lowered) is almost as important as the level of sugar itself the speed of a fermentation can give a winemaker important insight into how it is unfolding. Usually a 1–3 °Brix drop per day for whites and no more than 4 °Brix drop per day for reds is what I like to see. What happens when a fermentation goes from 25 to 10 °Brix too quickly? It means that the fermentation is probably hotter than it should be (fermentation gives off heat), which might cause the yeast cells to become stressed. Stressed yeast cells have a harder time completing a fermentation and can cause off-odors like ethyl acetate and fusel oils, which at certain concentrations become undesirable. Also, as alcohol levels increase, the yeast cell walls become increasingly permeable and sensitive to alcohol itself. A high fermentation temperature exacerbates this and can contribute to a stuck or sluggish fermentation.
However, let’s return to your original question. In my cellar experience, I would say that the most basic “standard” sampling schedule is twice a day — once in the morning and again 12 hours later. I recommend measuring sugar more often if you believe you will have a rapid fermentation. Conversely, measuring once a day is acceptable if you are in the first 24–36 hours of the fermentation this is the “lag phase” when sugar isn’t measurably being consumed but the yeast cells are rapidly multiplying and getting ready to start performing. Measuring once a day is also acceptable if your fermentation is in its last 1–2 degrees Brix or approaching 0.995 SG, unless you suspect a sluggish fermentation. Then I would measure more often in order to get a handle on how quickly things may be coming to a halt. At that point I would start deploying anti-stuck fermentation tactics like adding yeast hulls and making sure the temperature stays between 75–80 °F (24–27 °C). Yeast sometimes need a little warmth to complete a fermentation while on the opposite end of the spectrum, excessive heat at the end of fermentation can exacerbate alcohol permeability and hasten cell death.
As you can see, you can follow the natural curve of the fermentation and match your measurements to how quickly your fermentation is progressing. This is where the experience comes in. If you know your Zinfandel is a runaway fermenter (and many are), you may want to measure more often during the lag phase to know right when the yeast cells start to “take off.” Then you’ll have an idea of when you might want to put extra temperature control to tame those wild horses. When in doubt, measure Brix twice a day and at the height of fermentation, if you can, do three. That way you’ll always have a handle on where your fermentation might or might not go.
The powder result pattern is a quick start which then slows down quickly, probably as the powder clumped together. The average speed for the powder experiment was 13 cm3 every 10 seconds. If you compare the 3 results, you can clearly see how the chips are, by far the slowest reaction while the powder is the fastest during the first 30 seconds. The granules seem to have a more steady production of gas while the powder had a very quick start and then slowed down. The reason why the chips were so slow was because it had a very small surface area to volume ratio.&hellip
Cellular Respiration: Yeast Fermentation Questions
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2. In the presence of oxygen, how many ATP molecules are generated by the breakdown of one glucose molecule?
Ans: 36 ATP (Although total 38 ATP is formed in aerobic oxidation of glucose, but 2ATP is utilized in the beginning of glycolysis)
3. Describe the path oxygen takes as it travels from the air to your cells.
Ans: Oxygen is taken up along with air during breathing, which enters from nose and then respiratory track i.e. pharynx, trachea, bronchi. Thereafter oxygen enters to the lungs where it passively diffused from the alveoli into the blood and get attached to hemoglobin of RBC (red blood cells). It is then transported to the body where it gets released and passively diffuses into a cell to be used in cellular respiration.
4. If the demand for energy outstrips the oxygen available in your muscle cells, what process begins?
Ans: Anaerobic respiration will be going to take place in muscle cells due to deficiency of oxygen for production of energy.
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Fermentation Lab Report
tation lab report Lab Exercise 7 The Effect of Temperature on the Rate of Carbon Dioxide Production in Saccharomyces I. Student Objectives 1. The student will use this lab exercise as the basis for writing a scientific method report. 2.
The student will understand how the rates of chemical reactions are affected by temperature. 3. The student will understand the overall fermentation reaction by yeast, starting with glucose as an energy source. 4. The student will understand how to measure fermentation rate.
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II. Introduction The student is to use this lab exercise as the foundation for writing a scientific method report.The instructions for writing the report are found in the addendum section of the lab manual. The purpose of the experiment is to test the effect of five different temperatures on the rate of carbon dioxide production in yeast. The experiment is an example of alcoholic fermentation that is characteristic of yeast.
The original energy source of glucose is in the form of molasses in the lab. The carbon dioxide that is measured is in the form of gas bubbles, seen in fermentation tubes. The overall chemical equation is the Gay-Lussac Equation, which states that: Glucose + water produces ethanol + carbon dioxide + ATP.This fermentation reaction is anaerobic, taking place without the presence of oxygen. It is an ancient method of alcoholic fermentation, using yeast, and produces a small amount of energy in the form of ATP.
A hypothesis is typically referred to as “an educated guess”. The student is expected to generate a hypothesis for this lab experiment, test it, and then report if the hypothesis has been accepted or rejected, and why. Yeast is an example of a sac fungus, and is eukaryotic and unicellular. The rates of chemical reactions will increase with increasing temperatures, up to a certain point.When living organisms are used in chemical reactions, such as yeast, an added variable becomes important to consider.
That variable is the presence of enzymes in the yeast. Enzymes are proteins that function in optimal environmental conditions. The conditions include heat, pH and salinity. Different enzymes function best in different environments. Sometimes, the temperature of an environment becomes too hot, and the action of the enzymes becomes unsustainable.
As enzymes are dependent on their protein shape remaining unaltered, if anything should break chemical bonds to change the protein’s conformation, that protein becomes denatured.A denatured protein is one with an altered shape, and that means it cannot function as it was originally designed. The fermentation rate in this experiment is measured in ml/min. It is the rate of carbon dioxide production that is measured over time spent in a water bath. Carbon dioxide is a gas, and the lab has no direct method of gas measure.
Thus, an indirect method must be used. Water will substitute for the gas measure’s mark at the conclusion of the experiment, and the amount of water in milliliters will serve as an indirect method of fermentation rate.As this experiment is to be used for a scientific method report, the student must answer and cite the appropriate references for the following questions, as the Introduction of the report is written: 1. When one refers to the temperature of a system, what does this mean? 2. How are chemical reactions, especially their rates, influenced by temperature? 3. Give various examples of the effect of temperature on biological systems.
4. What is yeast? 5. What is the overall fermentation reaction by yeast, starting with glucose as an energy source? 6. What is an enzyme? 7.How are enzymes and the reaction rates they control influenced by temperature? 8. How can fermentation rate by measured? 9.
What is the hypothesis of the effect of temperature on the rate of carbon dioxide production? III. Materials and Methods Students work in groups of four for the experiment, but each student writes his own scientific method report. The Title of the report is the title of this experiment. The student obtains the names of the lab partners, includes those names on the Title page of the report, and identifies the report as written by a specific student.Specific students identify their reports by putting their name in a different font, color, or in boldface type on the Title page. All lab materials are in the refrigerator, or on the carts set out in the lab.
The water baths are set up on the lab counters. They are labeled with the appropriate temperatures. Obtain 5 fermentation tubes and label them with the following temperatures: 250 C, 35 0 C, 450 C, 55 0 C, and 65 0 C. The first temperature is equivalent to room temperature. The remaining four temperatures are set up in four water baths in the lab.
Put group initials on each of the 5 tubes. Use the red wax pencils. Add 30 ml of yeast + sugar culture to each of the 5 tubes. Be sure and swirl the flask first to suspend any cells that may have settled out of solution over time. The yeast culture contains glucose, in the form of molasses.
The brand of molasses used is called “Grandma’s Molasses”, a common retail product found in grocery stores. The yeast is common baker’s yeast, “Fleischmann’s rapid rise”, a common retail product found in grocery stores. It is important to note the expiration date of the yeast packets, found on the back.Three packets of yeast have been added to the glucose mixture. This is equivalent to a cell concentration of approximately 450,000 cells/cm3.
This absolutely insures there will be enough yeast, and that the reaction will proceed rapidly. Place each tube in a water bath at the appropriate temperature, and record the START time. Allow to ferment (form gas bubbles) until ? of the closed end of the tube has been filled with carbon dioxide. In the case of slow or non-reactions, keep in water bath as long as possible, leaving enough time to complete the following sections.When ? of the closed end of the tube has been filled with gas, mark the level with a red marking pencil, and record the END time.
Calculate the difference between start and end times, noting how much time each fermentation tube remained in the water baths. Pour out the yeast solution, fill the closed end of the tube with water to the mark, pour into a graduated cylinder, and record the volume in milliliters. The rationale is that gas cannot be measured directly in the lab water, however can be measured to the mark, and can serve as an indirect measure of gas production.Calculate the rate of carbon dioxide production by dividing the volume of the gas produced by the time. Dimensions are ml/min.
There are 5 values, one for each of the 5 water bath temperatures. This is the data that should appear on a graph, marked Figure 1. Calculate the temperature co-efficient value of Q10. This is done for four temperature intervals. Start with the two lowest temperatures, 250 and 350 C. The temperature co-efficient is a numerical value that refers to the relative rate of change in carbon dioxide production, over a 100 C change in temperature.
Four temperature intervals are used for calculation purposes because the lowest temperature, corresponding to room temperature, does NOT have a ten degree lower temperature for comparison. The refrigerator is not used in this experiment for any of the temperature variables. The calculation is straight forward: Q10 = Rate at T _________ Rate at T – 100 C The value of T is the temperature of the individual water bath used for comparison. Thus, T – 100 C represents the cooler temperature by 100. An example is: If the carbon dioxide production was 5 ml/min at 250 C, and 10 ml/min at 350 C, thenQ10 = 10 ml/min _________ 5 ml/min = 2 The value of 2 is interpreted to mean that the rate of carbon dioxide production was twice as fast (it had doubled) as the temperature rose by 100 C, when these two particular temperatures were compared.
The values of the temperature co-efficient can be graphed, or presented in histogram format, as the student prefers. IV. Results and Interpretation A continuous graph summarizing the effect of temperature on carbon dioxide production should be presented in the report as Figure 1.The graph can be roughly drawn in the lab exercise, and used later for reference. Temperature of water bath is the independent variable, and should be presented along the x-axis.
The carbon dioxide rate of production is the dependent variable, and is graphed along the y-axis. A graph for Figure 1 is presented. Graph the five variables, and write out the conclusions based on the data in the graph. Sarah, Please insert one of the Kendall/hunt graphs here for the students. Thank you. Please label it Figure 1.
I guess we had better give the students an entire page for this graph + their conclusions, under it.So the size of the graph should take up, say ? of the page size, with enough room under the graph for them to write down their conclusions. The second graph should be used to display the Q10 data. The data can be presented in graph form, or the student may choose to display it in histogram form. Either way is acceptable.
This is Figure 2. Write out the conclusions of the data below the graph. The water bath temperature intervals (in 100 C differences) represent the independent variables, and will be graphed along the x-axis. Remember there are four of them.The numerical values of Q10 represent the dependent variables, and are graphed along the y-axis.
Sarah, please insert the 2nd graph at this point, labeled Figure 2, same instructions as above. V. Application and Conclusions 1. What is the hypothesis of this experiment? 2. Which water bath represented the control in this experiment and why? 3.
Was the hypothesis accepted or rejected? 4. Why or why not? VI. Instructor’s Guide Have the students arrange into groups of three or four to conduct this experiment. Five students in a group are too many. Two is really too few.
The lab should already have the yeast available in packet form – 3 packets per lab. This is a lot of yeast – the reactions will proceed rapidly, as long as the water bath temperatures are constantly monitored. Usually, the gas production will be completed within 45 minutes of the start time. The sugar (molasses) solution should already be made up and kept in the refrigerator until the lab begins. At least 1 liter per lab of a 2. 5% glucose solution is used.
Stir bars are highly desirable to keep the molasses from settling to the bottom of the beaker, and to swirl the yeast, once it is added.The lab instructor should add the yeast five to 10 minutes before the students are instructed to add the solution to the fermentation tubes. Each student group should use 5 fermentation tubes, and at least 1 100 ml. graduated cylinder. The groups should also have 1 10ml. graduated cylinder to measure very small amounts of gas production.
Red wax marking pencils should be provided. Five water baths are needed for this lab to work. One of them does not even need to be turned on, as it represents the control, room temperature.The other four need to be watched carefully. Once the temperatures are set properly, it is important to keep them that way.
If the temperature of any one of them starts shifting too much, it will skew the results. Answers to the questions: 1. the hypothesis should be something along these lines: If temperature of water bath rises, the rate of carbon dioxide production in yeast will also rise, up to a point. Yeast is a living eukaryotic cell, and contains enzymes, as the chemical reaction of alcoholic fermentation is characteristic of it.It is possible that at the highest temperature, the chemical bonds of the enzymes might start breaking, and the enzymes would not work as well. Thus, at the highest temp.
, the rate may fall. Their graph should reflect that. The water bath, especially at the highest temp. , has to be maintained constantly. If that temp drops, even a little bit, for even as much as 5 minutes, it will skew these results.
2. room temp – no heat added 3. the hypothesis should be accepted. 4. b/c of effect of rising temperature on chem. Rxns, and presence of enzymes in yeast.
Among the most compelling features of fermentation is the potential to use diverse and malleable feedstocks, such as leveraging existing agricultural sidestreams for economic and sustainability advantages.
The current state of feedstocks for fermentation
Feedstocks provide the nutrients — the basic building blocks of life — to support microorganisms’ growth during fermentation. Much of the resiliency and adaptability of fermentation derives from its innate malleability with regard to these feedstock raw material inputs.
At the same time, feedstocks are a major cost driver for most fermentation processes. Thus, a great deal of optimization is possible in engineering industrial-scale production schemes to use unconventional feedstocks, including potential sidestreams from other industries. This presents potential gains for both economic viability and sustainability.
At present, the majority of fermentation relies on fairly standardized, refined, sugar-based feedstocks. These have a long history of validated use in both food and industrial biotechnology fermentation processes. To reach mass commercialization, cheaper and more sustainable substrates must become widely available. Additional research is needed to move beyond this paradigm and empower fermentation companies to leverage more diverse inputs.
The challenges for optimizing fermentation feedstocks
Due to the sheer volume of raw materials required, feedstock is a key input cost in the fermentation process, regardless of the microbe or downstream processing techniques. Furthermore, shipping costs for feedstocks are high relative to the cost of the feedstock itself.
While these are not notable bottlenecks for current uses of fermentation because sugar feedstocks are sufficiently cheap, of high enough quality, and in large enough supply, growing demand for fermentation will result in substantially increased needs for traditional feedstocks.
Growing demand for fermentation is an opportunity to diversify.
Ultimately, this growing demand may become problematic but also represents an opportunity to diversify.
Alternative feedstocks remain highly inconsistent and poorly characterized. There are concerns around the food safety and regulatory issues that may arise given the use of a lower grade, unconventional input such as an agricultural sidestream.
A shift toward these more diverse feedstocks would be easier if widely-adopted ingredient standards were established and trustworthy, with comprehensive characterization methods easily available. There is a need not just for technological solutions but also market-based solutions in the form of marketplaces, exchange platforms, brokers, and services that can facilitate matching ingredient buyers and sellers. This would include easily ordering R&D quantities and simple comparisons between different suppliers and products.
The future of better feedstocks
An increasing number of companies and researchers are capitalizing on the potential to convert waste products or agro-industrial byproducts into high-quality protein biomass. Nature’s Fynd produces protein from extremophile fungi isolated from a thermal spring in Yellowstone National Park.
These fungi exhibit wide metabolic flexibility and therefore can use diverse feedstocks. 3F Bio and Mycorena in Sweden also position themselves as leaders in sustainable feedstock use. Other startups, including Air Protein, leverage gaseous feedstocks, deriving energy from chemical reactions involving hydrogen, methane, or carbon dioxide gas.
Building a global bioeconomy
Feedstock optimization should be considered in the context of global shifts in demand across many biological raw materials. The rise in demand for fermentation feedstocks is driven by a wholesale shift toward a bioeconomy model of production. This bioeconomy could potentially leverage microbial platforms for manufacturing not just food and pharma products but also green chemical products, biopolymers, and fuels that have historically been dominated by petrochemical-based production.
With this perspective, it is possible to engage in more strategic decision-making regarding the location of new fermentation facilities, placing them near abundant low-cost feedstock sources.
Feedstocks should also be examined across all alternative protein production platforms, including plant-based and cultivated. All these production modalities currently require slightly different feedstocks as primary inputs, and strategic forecasting of raw material demands across all sectors informs better decision-making regarding processing, sourcing, and formulation.
The industry’s ability to nimbly tap into diverse, unconventional feedstocks will also be bolstered by the adoption of globally recognized standards and the development of novel characterization technologies. These will give purchasers confidence in the quality and performance of the feedstock material they buy. These standards will also equip them with the predictive capacity to adapt their process as needed to suit a given lot, even if it is from a source or of a composition they have not routinely used in the past.