A Comparative Study of Batch Fermentation Performance of ...
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A Comparative Study of Batch Fermentation Performance of A Comparative Study of Batch Fermentation Performance of
Saccharomyces carlsbengensis and Saccharomyces cerevisiae Saccharomyces carlsbengensis and Saccharomyces cerevisiae
based on Kinetic Parameters based on Kinetic Parameters
Luljeta Pinguli University of Tirana, [email protected]
Ilirjan Malollari University of Tirana
Anisa Dhroso University of Tirana
Hasime Manaj University of Tirana
Dhurata Premtis University of Tirana
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Recommended Citation Recommended Citation Pinguli, Luljeta; Malollari, Ilirjan; Dhroso, Anisa; Manaj, Hasime; and Premtis, Dhurata, "A Comparative Study of Batch Fermentation Performance of Saccharomyces carlsbengensis and Saccharomyces cerevisiae based on Kinetic Parameters" (2018). UBT International Conference. 159. https://knowledgecenter.ubt-uni.net/conference/2018/all-events/159
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A Comparative Study of Batch Fermentation Performance
of Saccharomyces carlsbengensis and Saccharomyces
cerevisiae based on Kinetic Parameters
Luljeta Pinguli1, Ilirjan Malollari2, Anisa Dhroso3, Hasime Manaj4, Dhurata Premti5
1,2,3,4,5University of Tirana, Faculty of Natural Sciences, Department of Industrial Chemistry, Tirana , Albania
E-mail: [email protected]
Abstract. Biological systems are very complex regarding their kinetic behavior. There are many models that intend to predict fermentation performance, although Monod equation remains the best model. A detailed investigation of batch fermentation process at room temperature for two different types of yeast Saccharomyces carlsbegensis and Saccharomyces cerevisiae was carried out. Batch fermentation experiments were carried in 1 liter bioreactors, in the same medium, time and fermentation conditions. Kinetic constants were used to compare fermentation performance under similar conditions. Kinetic parameters investigation was done based on growth kinetics, ethanol productivity and substrate consumption (glucose) using computer simulation for different kinetic models. There are some notable differences based on kinetic models. Although two types of yeast strain leave the same remain extract in the end of fermentation, fermentation dynamics
differ from each other. Saccharomyces carlsbengensis has higher ( max and Ks ) kinetic constants compared to Saccharomyces cerevisiae. For both fermentations the best predicting model was Monod, better results give saccharomyces carsbegensis curve.
Keywords: kinetic parameters, model, Sacharomyces carlsbegensis, Saccharomyces cerevisiae, batch fermentation.
1 Introduction
Yeasts have been used by humans to produce foods for thousands of years. Bread,
wine, sake and beer are made with the essential contribution of yeasts, especially from
the species Saccharomyces cerevisiae and Saccharomyces carlsbegensis[1].
Nowadays, modern industries require very large amounts of selected yeasts to obtain
high quality reproducible products and to ensure fast, complete fermentations.
Efficient and profitable factory-scale processes have been developed to produce yeast
biomass. The standard process was empirically optimized to obtain the highest yield
by increasing biomass production and decreasing costs. However in recent years,
several molecular and physiological studies have revealed that yeast undergoes
diverse stressful situations along the biomass production process which can seriously
affect its fermentative capacity and technological performance. Several classic studies
have evaluated the energy, kinetic and yield parameters of the yeast biomass
production process [2],[3]. However, the biochemical and molecular aspects of yeast
adaptation to industrial fermentation conditions have been poorly characterized. In
recent years, a substantial effort has been made to gain insight into yeast responses
during the process. It was believed that fermentation conditions were optimized to
obtain the best performing yeast cells, but now we know that yeast cells endure
several stressful situations that induce multiple intracellular changes and challenge
their technological fitness As a result, these dynamic environmental injuries seriously
affect biomass yield, fermentative capacity, vitality, and cell [4], [5]. This paper
undertakes a study to compare fermentation processes with Sacharomyces
carlsbegensis and Saccharomyces cerevisiae under similar conditions through
evaluations of kinetic parameters.
2 Materials and Methods
There were carried out in parallel in the same conditions batch fermentations in 1 liter bioreactors with two types of yeast strains, bottom brewery yeast strain Saccharomyces carlsbegensis SW 35 and industrial bread yeast Saccharomyces cerevisiae. Cell density used for both parallels were 8% of fermentation medium. Yeast suspensions have almost the same concentration, vitality and generation. After 2 hours in aerobic conditions with moderated stirring, the bioreactors were put in fermentation conditions. There was used different substrate concentration in total 8 parallel trials. As fermentation medium was used beer wort with 16%, 14 %, 12%, 10%, 8%, 7%, 6%, 5% sugar extract. Batch performance was surveyed for up to 48
hours in 200C and at regular intervals of time was taken samples to substrate
concentrations. Tested methods used were standard analyses taken from “Analytica EBC; Methods of Analysis” and “Analytica-EBC Microbiologica” [9], [10]. Kinetic studies based on data gathered from experiment were done based on computer simulation and modeling.
3 Results
Fermentation performance was studied based on substrate consumption curves. Samples were taken into regular intervals until remain extracts remain constant for 24 hours. Figure 1, represent fermentation curves in presence of two yeast strains for different initial substrate concentration batches.
5% 6% 7% 8%
10% 12% 14% 16%
18 16 14 12 10
8
6
4
2
0
0 5 21 24 Fermentation time in hours for S. cerevisiae
5% 6% 7% 8% 10% 12% 14% 16%
18 16 14 12 10
8
6
4
2
0 0 5 10 15 20
Fermentation time in hours for S. carlsbegensis
Fig. 1. Substrate consumption versus fermentation time for different substrate concentration
batches inoculated with two different yeast strains.
Comparing fermentations performances noticed that fermentation with
Saccharomyces cerevisiae is faster for the first hours of fermentation. Final remain
extract in the end of fermentation is proportional to initial wort extract and are almost
the same for parallel batches with different yeast strains.
0.45 S.
0.4
for 0.35
(µ)
0.3
grow
thra
te ce
r
evis
iae
0.15
0.25
Spec
ific
0.2
0.05 0.1
0 0 5 10 15 20 Substrat concentration %
0.4
S.
0.35
f o r
0.3
grow
th ra
te
(µ)c
arlsb
egen
sis
0.25
0.2
0.15
Spe
ci
fic 0.1
0.05
0
0 5 10 15 20 Substrate concentration %
Fig. 2. Substrate concentration (s), versus specific growth rate (µ).
Kinetic constant determination was realised based on linearization curves
Lineweaver-Burk. Figure 3 and 4 represent linearization’s lines. Equations 1-4
represent linearization equations and their values for each figure. 1
Ks
1 1 [1]
max s
max
y 21.05 x 0.921 [2]
max
1 1.0857
[3] 0.921
Ks 21.05 K
s
max 21.05 22.85 [4]
max
7 6 5 4 3 2 1 0
y = 21.05x + 0.921
0 0.05 0.1 1/s 0.15 0.2 0.25
Fig. 3. Lineweaver-Burk linearization for Saccharomyces cerevisiae fermentation.
9 y = 36.917x + 0.6705 8
7
6
1/µ
5
4
3
2
1
0
0 0.05 0.1 0.15 0.2 0.25 1/s
Fig. 4. Lineweaver-Burk linearization for Saccharomyces carlsbegensis fermentation.
Kinetic constants for Saccharomyces carlsbegensis were:
and Ks 55.123
In this paper to compare our experimental model we have used three models. The
well-known Monod model and equations 5 and 6, which represent respectively the
model in a high microbic density and the model wih a varesi from limiting substrate.
max
s [5]
K s x s
max
s [6] K
s
s s 0
max 1.491
1
0.9
cere
sisi
ae 0.8
0.6
0.7
S.
0.5
fo r
( µ ) 0.4
rat
e
0.3
gro
wth
0.2
Spec
if
ic 0.1
0 5 10 15 0
Substrate % (s)
1.2
S.ca
rlsb
egen
sis
1
0.6 0.8
(µ)
for
0.4
rate
grow
th
0.2
Spec
ifi
c
0
0 5 10 15
Substrate % (s)
Fig. 5. Specific growth rate versus substrate concentration for different experimental data’s ( ) Monod model (•••••••••), high density model (
substrate model ( ).
20
20
models
used: ) limiting
4 Conclusions
Study of batch fermentation processes for two different types of yeast strains Saccharomyces carlsbegensis and Saccharomyces cerevisiae gives some results that were confirmed by kinetic parameters also. There were some notable differences based on kinetic models. Although two types of yeast strain leave the same remain
extract in the end of fermentation, fermentation dynamics differ from each other. Saccharomyces cerevisiae ferment faster for the first five hours and later slow down significantly fermentation rate. Brewery yeast has a uniform fermentation rate until
final extract stops. Saccharomyces carlsbengensis has higher ( max and Ks ) kinetic constants compared to Saccharomyces cerevisiae. For both fermentations the best predicting model was Monod, better results give saccharomyces carsbegensis curve.
4 References
1. Reed, G. & Nagodawithana, T. W.: Technology of Yeast Usage in Winemaking. Am. J.
Enol. Vitic., (1988), Vol. 39, No. 1, pp. 83-90. 2. Reed, G. & Nagodawithana, T. W.: Baker's Yeast Production. In: Yeast Technology
(1991), 261-314 3. Beudeker, R.F.; Van Dam H.W.; Van der Plaat, J.B. & Vellenga, K.: Developments in
bakers' yeast production, (1990), 103-146..
4. Blanco, C. A.; Rayo, J. & Giralda, J. M.: Improving industrial full-scale production of
baker's yeast by optimizing aeration control. J.AOAC Int., (2008), Vol. 91, No. 3, pp. 607-
613.
5. Chur, Switzerland. Di Serio, M.; Tesser, R. & Santacesaria, E.: A kinetic and mass transfer
model to simulate the growth of baker's yeast in industrial bioreactors. (2001) Chem. Eng.
J Vol. 82, pp. 347-354.
6. Gibson, B.R.; Lawrence, S.J.; Leclaire, P.R.; Powell, C.D. & Smart, K.A.: Yeast responses
to stresses associated with industrial brewering handling. FEMS Microbiol. Rev., (2007)
Vol 31, No. 5, pp.535-569. 7. Hulse, G.: Yeast Propagation, in Brewing Yeast Fermentation Performance, Second
Edition (ed K. Smart), Blackwell Science, Oxford, UK, (2008), doi:
10.1002/9780470696040.ch23.
8. Maemura, H.; Morimura, S. & Kida K.: Effects of aeration during the cultivation of
pitching yeast on its characteristics during the subsequent fermentation of wort. J Inst
Brew. (1998), Vol. 104, pp. 207–211. 9. Europian Brewing Chemists: (1992). Analytica EBC; Methods of Analysis. 10. Europian Brewing Chemists: Analytica-EBC Microbiologica.