Fall 2020 Kinetics project

1. Yeast fermentation from
glucose and panela
David Bahamon
Wesley Cagle
Alyssa Knight

2. What is panela?
● Unrefined sugar.
● Origin: Asia, Africa, and Latin America.
● Application: Food industry.
Grinding Clarification Evaporation
Sugar
cane
Molding
Panela
Figure 1. Panela.
Source: https://bit.ly/37kg6NI.
Figure 1. Panela production process.
Adapted from: Mesias et al., 2020

3. Yeast
Saccharomyces cerevisiae or “sugar-eating
fungus”
Yeast cells digest sugars to obtain energy for
growth
In ethanol production, yeast are responsible
for fermenting sugars into ethanol Figure 2. Yeast sample.

4. Ethanol
● Ethanol is a growth associated
product of yeast during
fermentation under anaerobic
conditions.
● Ethanol is found in many products
including cleaning supplies, paints,
fuels, and food.
● Many industries will continue to
require ethanol so demand and
production will likely continue to
rise.
Figure 3. U.S. Ethanol Production
Source: https://www.eia.gov/todayinenergy/detail.php?id=32152

5. Objective
● The objective of this project is to
compare the fermentation process
by yeast using glucose and panela
as substrate.
● Finding cheaper or higher yielding
substrates for ethanol production
would be valuable due to increasing
use and demand.
Figure 4. Bioethanol Production Process
Source: https://bit.ly/39FHto7

6. Methodology
Culture: yeast
(Saccharomyces
cerevisiae)
Substrate (10 g/L):
1. Glucose
2. Panela
Time: 5 days Phase 1: aerobic respiration Phase 2: fermentation
Figure 5. Yeast bioreactors
Source: Own.

7. Methodology
Filtration
Drying
(105°Cx24h)
Digestion
Sample
Filtrate
(soluble)Residue
TSS COD
COD (g/L) = 18.36 * Absorbance
R2 = 0.94
Figure 6. COD determination
Source: Own
Weighing
Absorbance
reading
Figure 6. Process for sample analysis.
Adapted from: Drapcho, 2020.

8. Methodology
Product: Ethanol
Method of measure:
specific gravity via a
hydrometer
Figure 7. Use of the hydrometer.
Source: Left: https://bit.ly/36jVB4g. Right: own

9. Model
Monod model:
Biomass:
Substrate:
Product
(ethanol):
Software: Excel/Forward Finite Differences (FFD).

10. Model
Table 1. Parameters used to model yeast biomass, substrate and ethanol produced.
*Source: Ahmad et al., 2011.

11. Biomass and ethanol yield
Aerobic respiration
Fermentation
Ethanol:
Source: Drapcho, 2020

12. Results: Phase 1
(aerobic respiration)
Figure 8. Biomass concentration in the
reactors over first 2 days of aerobic growth.
Source: Own.
Figure 9. Substrate COD in the reactors
over first 2 days of aerobic growth.
Source: Own.
Biomass yield (COD basis):
● Glucose: 1.35
● Panela: 0.67

13. Results: Phase 2 (fermentation)
Figure 10. Biomass concentration in the reactors
after changing to anaerobic conditions.
Source: Own.
Figure 11. Substrate COD in the reactors
after changing to anaerobic conditions.
Source: Own.

14. Figure 12. Reactor modeling of Biomass and
Substrate concentrations using FFD.
Source: Own.
Figure 13. Reactor modeling of Biomass,
Ethanol, and Substrate concentrations under
Anaerobic conditions.
Source: Own.
Results: Model
Phase 1: aerobic respiration Phase 2: fermentation
Ethanol yield:
0.058 g ethanol/g substrate

15. Conclusions
● Experimental results
○ Our data for phase 1 showed an increase in biomass and a decrease in substrate.
○ Our data for phase 2 did not show an increase in biomass or indicate substrate utilization.
○ There wasn’t measurable ethanol production.
● Modeling
○ Our aerobic phase model follows our data closely and indicated both biomass increase and
substrate concentration decrease as expected.
○ The fermentation phase model shows expected results which we did not replicate as we did
not see significant biomass growth, substrate utilization, or measurable ethanol production
during this phase.
● Recommendations
○ Control carefully the pH until the initial value is stable.
○ Conduct analytical analysis by triplicate.

16. References
Ahmad, F., Jameel, A. T., Kamarudin, M. H., & Mel, M. (2011). Study of growth kinetic
and modeling of ethanol production by Saccharomyces cerevisae. African journal
of Biotechnology, 10(81), 18842-18846.
Drapcho, C. 2020. Unpublished Laboratory Notes, BE 4101, Clemson University,
Clemson SC.
Ethanol (Ethyl Alcohol). https://www.chemicalsafetyfacts.org/ethanol/
Mesias, M., Delgado-Andrade, C., Gómez-Narváez, F., Contreras-Calderón, J., &
Morales, F. J. (2020). Formation of Acrylamide and other Heat-Induced Compounds
during Panela Production. Foods, 9(4), 531.

17. Questions?

18. Supplemental slides

19. Experimental data
Time
(days)
Biomass (g/L) Substrate COD (g/L) pH
Glucose Panela Glucose Panela Glucose Panela
0 0.03 0.03 10.5 10.3 6.5 6.49
1 0.95 0.77 6.8 7.7 2.75 2.72
2 1.18 1.03 9.3 8.2 3.63 3.59
2 - - 10.4 10.5 - -
3 1.36 1.27 10.3 10.7 3.63 3.59
3 - - - - 6.7 6.7
4 0.81 1.15 10.4 10.5 8.32 8.21
5 0.91 1.21 10.4 10.6 8.48 8.47
Table 2. Experimental results.

20. Biomass and ethanol yields
Aerobic respiration Glucose Panela
Theoretical YB (g COD/g COD) 0.498
Experimental YB (g COD/g COD) 1.314 0.605
Fermentation
Theoretical YB (g/g) 0.078
Model YB (g/g) 0.132
Theoretical YP (g/g) 0.330
Model YP (g/g) 0.058