1. Ethanol Fermentation vs. Yeast-to-Sugar Ratio
Anastasia Frances Frederica, Danilo Pena, Michelle K. Garnadi, Syed Emir Pasha, Temitope Blessing Pecku
ChE 264 Project Oral Presentation
November 11th, 2015

2. Introduction
Objective: Learn and understand the Effects of Yeast-to-Sugar Ratio on Ethanol Production
Significance: Optimal Fermentation Performance
As the title suggests, the objective of our group’s project is to observe the effects of yeast-sugar ratio on ethanol production.However, what is the significance of our project. Well, have you every considered alcohol industries. In general, industries want to earn profits and by doing so, it is to produce beer at the least amount of time possible especially if there is only a few brewing pots available. By reducing the time it takes to brew the perfect alcohol beverage, more can be produced. Therefore, our investigation aims to obtain the optimal fermentation performance.

3. Theory-Yeast Life Cycle
Before we can begin the experiment, it was important to understand the mechanisms behind yeast growth. Hopefully, with these information, we can use create reasonable parameters as well as verify the theories to our experimental data. Therefore, I would like to begin introducing everyone the life cycle of the yeast.
Georgiou, G. (2015).BME 339 Web Notes #3. UT Austin

4. Theory Growth Factors of Yeast Anaerobic Process (Absence of Oxygen)pH
Substrate (Oxygen and Sugar) Amount
Initial Cell Amount
Alcohol Production Rate (Bottleneck Hypothesis)
Temperature
Yeast Nutrients
Anaerobic Process (Absence of Oxygen)
GLUCOSE ENERGY CO ALCOHOL

5. Parameters Kept Constant
Temperature
No nutrients vs nutrients pH
Substrate amount
Yeast strain

6. Previous and Ongoing Work
Instructions given in brewing beer at home
2 packets (23.0g) of yeast
5 gallon bottle
3-4 lb of sugar extract

7. Procedure-Apparatus
Half Gallon Bottle
Hydrometer
Boiling Container

8. Approach-Procedure Boil ½ Gallon of Water
Combine Sugar and Yeast Solutions in Sterilized Container
Take Gravity Measurement of Container + Content
Take Density Measurement Every 7 and 10 Days
Data Analysis and Result Report
Use ¾ of Boiled water to dissolve Sugar
Use ¼ of Boiled water to Hydrate Yeast
Cool Sugar-Solution to Room Temperature

9. Safety-Waste Stream Plan
Water: Non Hazardous Effluent Discharge
Disposal: Sewer System
Alcohol Waste: Organic Waste (Ethanol <24%)
Spent Yeast: Solid Waste
Disposal: Solid Waste Disposal

10. Safety-Worst Case Accident Plan
Hot Water Spills/Burns
Response
Run Cool Water Over Burns
Precaution
Use of Heat Resistant Gloves
Team Assistance During Lifting

11. Data Collection and Sample Calculations
Hydrometer
Data Collected: Specific Gravity
Attenuation
Conversion of Sugars into Alcohol
Attenuation =
100 % * (OG - FG) / (OG - 1)
OG is Original Gravity
FG is Final Gravity

12. Sample Calculations (cont.)
Alcohol by Volume (ABV)
% EtOH =
 (  ( 1.05  x  ( OG – FG )  )  / FG  )  / 0.79  x  100
1.05 g — Amount of CO2 Produced for Every Gram of Ethanol Produced
0.79 g/mL  — Density of Ethanol Alcohol

13. Results and Discussion
Trial
Description
1-4
Manipulated Yeast-to-Sugar Ratio
5-6
Manipulated Yeast-to-Sugar Ratio using data from optimal Trial 1
7-8
Used optimal Yeast-to-Sugar Ratio with two different yeast strains
9-10
Added nutrients to optimal Trial 1 conditions 11
Repeat Experiment of Trial 1

14. Results and Discussion
Increasing trend that will eventually reach steadystate

15. Results and Discussion
Time it takes to reach steady state

16. Results and Discussion
Reaction limited vs growth limited

17. Results and Discussion
conversion

18. Results and Discussion
Effects of sugar on a constant yeast and constant volume system
conversion

19. Results and Discussion
conversion

20. Results and Discussion
conversion

21. Error Analysis-Possible Errors
Varying Temperatures
Inaccurate Weight Scale
Improper Fermenter Sealing
Sample Contamination
graduated cylinder, 1400 mL
+/- 0.5 mL
thermometer, 110°C
+/- 0.2 K
balance, analytical 150 g
+/ g

22. Problems Encountered Yeast on Container Walls
Undesired Aerobic Respiration
Varying Fermentation Temperature
Too High or Too Low
Will test yeast/sugar ratios with different strains of yeast
Will add yeast nutrient to see how this effects ethanol production

23. Conclusion
Yeast-to-sugar-to-volume ratio is a dependent factor when ethanol production is to be scaled up
Bottleneck hypothesis was observed in experimental data where optimal yeast to sugar ratio was obtained.
Nutrient effect is minimal due to high alcohol production rate

24. Conclusion (Cont’d)
Ethanol production is directly proportional to yeast -to-sugar ratio up until a maximum
Ethanol kills yeast eventually by alcohol poisoning
all yeast is killed at approximately 8% alcohol
Takes 2 to 3 weeks to reach steady state for Safale and Gold’s Yeast but shorter for other yeast

25. Future Work/Recommendations
Obtain the nutrient trend using the Safale-US or Gold’s Brewer Yeast
More research into bakers yeast and how it can be used in beer brewing without altering taste
Use more complex/ appropriate sugars
Perform experiment on a larger scale
Measure alcohol content using other types of techniques i.e. gas chromatography
Have more consistent experimental procedure

27. Appendices-HAZOP Protocol
Gauge Temperature with
Thermometer
High Temperature
Kills Yeast, Stops Fermentation
Low Temperature
Reduces Fermentation Rate
High mixing
Kills Yeast, Stops
Fermentation
Gauge Temperature with
Thermometer
Avoid Container
Movement
during Experiments