The Effect of Yeast and Temperature on the Alcohol Content of Zea Maize

after Fermentation

Madeline LaBelle—Warren Mott High SchoolKeara Miley—Lake Shore High School

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Background

• Petroleum oil supplies are being depleted • They are being used up rapidly• A sufficient alternative is needed• Biofuel can be used instead–Made from renewable biomass resources– Safe and environment friendly

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Background

• Biofuel emits 51% less greenhouse gases than fossil fuel– More efficient methods of production• Due to new technologies

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Background

• Biofuel is made from the fermentation of plant matter

• Fermentation is the process in which yeast and enzymes break down sugars and convert them into alcohol

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Background

• Alcohol content is directly related to how well a material can be used as a biofuel– The higher the better

• The higher the alcohol content, the hotter is burns and the better it is for a car’s engine

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Background

• Cars have combustion engines• How a combustion engine works– Increase in pressure from combustion expands the

cylinder– Pushes piston and causes crankshaft to turn

• The hotter a material burns, the more combustion– More efficient

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Background

• Different types of biofuel– Corn ethanol– Cane ethanol– Cellulosic ethanol

• Cane ethanol is most efficient• Corn ethanol is the most common in America– Corn is the most abundant source here– No import taxes

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Background

• Two different corn ethanol production processes– Dry milling– Wet milling

• Dry milling is the most common• Wet milling is more extensive but produces

more byproducts

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Dry Milling

• Kernels ground up, enzymes and water added– Called mash– Enzymes break down starches into sugar

• Mash heated to reduce bacteria• Mash is cooled and yeast added– Fermentation starts

• When fermentation finished, it is distilled– Distillation separates substances

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Wet Milling

• Kernels soaked and the middle is removed– Used to produce corn oil

• Starch and gluten separated– Gluten used for animal feed

• Water and enzymes added to ferment– Remaining starch used to make corn syrup

• Mixture distilled and sent to oil companies

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Terminology

• Zea maize– Corn

• Saccharomyces cerevisiae– Type of yeast

• Hydrometer– Tool used to measure alcohol content of a material

• DOE– Design of experiment

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Purpose

• To find a way to make corn ethanol more efficient by increasing the alcohol content– Different temperatures during fermentation– Different amounts of yeast added to the mixture

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Problem Statement

What amount of Saccharomyces cerevisiae and what temperature during fermentation would yield the highest alcohol concentration in Zea maize?

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Hypothesis

Out of all amounts of Saccharomyces cerevisiae (1, 2, and 3 grams) and temperatures (22, 25, and 28 °C), 3 grams of yeast at a temperature of 22 °C will yield the highest concentration of alcohol in fermented corn.

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Data Measured

• Dependent variable– The alcohol content of the fermented corn (%)

• Independent variables– The amount of yeast (grams)– Temperature during fermentation (°C)

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Materials

• Active dry yeast (Saccharomyces cerevisiae)

• 21 half-bushels of corn• 21 emptied two liter

bottles• Scale• Funnel • Balloons

• Blender• Hydrometer• Mesh colander• Incubator (set at 22, 25,

and 28 °C)

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Blender

Mesh Colander

2 Liter Bottle

Balloon

Scale

Active Dry Yeast

Corn

Funnel Graduated Cylinder

Hydrometer

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Procedure

• Blend corn mixture together and measure alcohol content with hydrometer

• Add yeast to mixture (amount dependent on trial)

• Pour mixture into a 2 Liter bottle with the funnel

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• Place bottle in incubator (temperature dependent on trial)

• After four days, remove the corn mixture and measure alcohol content with hydrometer

• Subtract second alcohol measurement from the first

Procedure

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• Record the value in the table• Repeat for each combination of temperature

and amount of yeast

Procedure

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Procedure Video

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Data

High and Low Values

Temperature (°C) Amount of Yeast (g)

- Standard + - Standard +

22 25 28 1 2 3

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DataDesign of Experiment Data

Order Run Result Order Run Result Order Run Result

1 Standard 6 1 Standard 6 1 Standard 6

2 + + 7 2 + + 7 2 + + 8

3 - - 5 3 - - 5 3 - - 6

4 Standard 6 4 Standard 5 4 Standard 8

5 + - 8 5 + - 7 5 + - 8

6 - + 5 6 - + 5 6 - + 6

7 Standard 7 7 Standard 6 7 Standard 6

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DataStandard Trials

6 6 7 6 5 6 6 6 6

0 1 2 3 4 5 6 7 8 90

1

2

3

4

5

6

7

8

Trial

Alc

ohol

Con

tent

(%)

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Data

RunsFirst DOE Second DOE Third DOE Average

Temperature (°C)

Amount of Yeast (g)

+ + 7 7 8 7.33

- + 5 5 6 5.33

+ - 8 7 8 7.67

- - 5 5 6 5.33

Grand Average: 6.145

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Observations

Date Observation

Oct 22 9 standard trials are set up. Corn and yeast blends are consistent.

Oct 26 Corn and yeast blend produced CO2 which can be seen by the balloon inflating.

Oct 29 All (+,-) trials produced CO2 and the balloons inflated.

Nov 2 Only 3 (+,+) trials produced CO2. The balloon on the Trial 2 bottle did not inflate resulting in a redo of this trial.

Nov 6 All (-,-) trials produced CO2 and the balloons inflated.

Nov 10 All (-,+) trials produced CO2 and the balloons inflated.

Nov 13 Trial 17 (-,+) blend seemed more separated than the rest, but still produced CO2 and stayed consistent with rest of trials.

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Data Analysis and Interpretation

• A Two Factor DOE was used– Temperature (°C)– Amount of yeast (g)

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What is a DOE?

• DOE stands for a Design of Experiment• DOE measures the individual effects and

combined effects of different factors• Appropriate for this experiment because two

different factors were manipulated at two levels

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Data Analysis and Interpretation

• The effect of temperature on the alcohol content of fermented corn was 2.17 units

• As temperature increased, the alcohol content increased by 2.17 units

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Data Analysis and Interpretation

-1 10

2

4

6

8

10

6.5 6.33

Amount of Yeast (g)

Alc

ohol

Con

tent

(%)

• The effect of the amount of yeast on the alcohol content of fermented corn was -0.17 units

• As the amount of yeast increased, the alcohol content decreased by 0.17 units

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Data Analysis and Interpretation

-1 10

2

4

6

8

10

7.677.33

5.33 5.33

Amount of Yeast (g)

Alc

ohol

Con

tent

(%)

• The effect of temperature and yeast has an effect of

-0.17 units• There may be an

interaction between the two effects because the slopes are not parallel

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Determining Significance

• Any effect that is greater than two times the range of standards is deemed significant

• None of the variables were considered significant in this experiment

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Conclusion

• The hypothesis was rejected• Neither temperature during fermentation or

amount of yeast had a significant effect on the alcohol content of corn after fermentation

• These results of this experiment agree with current work in this field

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Why Did These Results Occur?

• The amount of yeast had no effect because yeast can only convert the sugars that are present in the mixture and after these sugars are converted can do no more

• Temperature will only speed up the process

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What Will Have an Effect?

• The only factor that will have a significant effect on the amount of alcohol in a material is the amount of sugar in a material

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Sources of Error and Weakness

• Incubator temperatures fluctuated slightly• Yeast was left in water to rehydrate for longer

than necessary• Balloon did not always inflate with carbon

dioxide during fermentation

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Recap

• An alternative fuel source is needed to replace fossil fuels– Biofuels (ethanol)• Made from fermented plant matter

• High alcohol content is directly related to how well a biofuel can be used

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Recap

• What amount of yeast and at what temperature during fermentation will yield the greatest alcohol content?

• The hypothesis was that 22 °C and 3 grams of yeast would yield the highest alcohol content– Hypothesis was rejected

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Recap

• Corn, water, and yeast were blended and poured into a two liter bottle with a balloon placed around the mouth

• The bottle was placed into an incubator to ferment

• Alcohol content was taken using a hydrometer

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Recap

• A two factor DOE was used– Temperature (°C)– Yeast (g)

• Neither variable had a significant effect – Yeast can only convert the sugars that are present– Temperature speeds up the process

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Real World Applications

• This information can be used by the fuel industry by saving time, money and resources used during the production of biofuel

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Further Research

• Rerun the experiment using different materials such as sugar cane, beats, or switch grass. Experimenting with different plants could help find an abundant source that would be more efficient

• Use and compare different types of yeast

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Acknowledgements

• Skip Walker – Works at local brewery

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Works Cited• "Biofuel Info." Information about Biofuel, What Is Biofuel,

Renewable Energy Solutions, Ethanol Uses. Biofuel Watch, 2010. Web. 18 Sept. 2012. <http://www.biofuelwatch.org/>.

• Curry, Jim. "Yeast and Fermentation." MGreisMeyer. Dukes of Ale BJCP Preparation Course, 19 Apr. 2009. Web. 18 Sept. 2012. <http://www.mgriesmeyer.com/doatest/bjcp/yeastAndFermentation.pdf>.

• "Dry Mill Ethanol Production." Ethanol Info. N.p., n.d. Web. 12 Oct. 2012. <http://people.hws.edu/environmentalstudies/Ethanol%20Info/Dry%20Mill.html>.

LaBelle -- Miley

Works Cited• "Fermentation: World of Microbiology and

Immunolgy." Fermentation. Ed. Brenda Wilmoth Learner. N.p.: n.p., n.d. N. pag.Gale Virtual Reference Library. Web. 9 Sept. 2012. <http://go.galegroup.com/ps/retrieve >.

• Janson, Lee W. Brew Chem 101: [the Basics of Homebrewing Chemistry]. North Adams, MA: Storey, 1996. Print.

• "Practical and Theoretical Considerations in the Production of High Concentrations of Alcohol by Fermentation." ScienceDirect.com. N.p., n.d. Web. 05 Dec. 2012.

• "Some Interesting Oil Industry Statistics." Oil Industry Statistics from Gibson

• Consulting. N.p., n.d. Web. 05 Dec. 2012.

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LaBelle -- Miley

Works Cited

• Stairs, David. Yeast. Portland, Or.?: D. Stairs, 1999. Print.• "Wet Mill Ethanol Production." Ethanol Info. N.p., n.d. Web.

12 Oct. 2012. <http://people.hws.edu/environmentalstudies/Ethanol%20Info/Wet%20Mill.html>.

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Any Questions?

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