How does the structure of sugar affect the rate of fermentation?

Background Information:

Living things need to obtain energy in order to sustain their presence by performing their vital activities. For most of the vital activities energy is a must have concept. Cellular respiration is an example fort he process of obtaining energy in the form of ATP (Adenosine Triphosphate)There are two main processes to obtain energy by respiration. They are classified as Aerobic and Anaerobic respiration which are distincted by the use of oxygen.

Anaerobic respiration also stated as fermentation is the process to obtain ATP without the use of Oxygen. The process where yeast converts sugar into ethyl alcohol and carbondioxide is called ethyl alcohol fermentation. This is a result of the absence of oxygen for yeast to convert the organic substance (sugar) into cellular energy. This is considered an anaerobic process.

Yeast, as a member of the fungi family is neither an animal nor a plant,it is an eukaryotic micro organism. In ethyl alcohol fermentation sugar fungi form of yeast is used. The conversion of sugar into carbon dioxide and alcohol provides energy for the yeast cells. Glucose, sucrose, lactose and fructose are the sugars that are often used to perform experiments and observe the process of fermentation.

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Glucose is a type of sugar and a subcategory of the monosaccharides. It’s molecular formula is C6H12O6 . Sucrose is a subcategory of disaccharides as a combination of glucose and fructose. It’s molecular formula is C12H22O11. Lactose is another disaccharide derived from glucose and galactose with molecular formula C12H22O11 which makes it an isomer of sucrose. Fructose is a monosaccharide that is also known as fruit sugar and mostly bonds with glucose to form sucrose. It’s molecular formula is also C6H12O6.

The overall process of ethyl alcohol fermentation is the conversion of sugar into CO2 and alcohol (CH3CH2OH). The reaction is shown for glucose is as shown below ;

The simplicity of the chemical reaction is not preserved in reality and the products are far more complex that it is shown in the reaction. Sugar is also incorporated into other unmentioned products such as yeast biomass,acids and glycerol. This fermentation which was done using glucose as sugar was an example for the fermentation of a monosaccharide. Even though the process does dffer slightly,the amount of the released carbon dioxide and alcohol does change through monosaccharides and disaccharides.

The first step of alcoholic fermentation is the cleavage of glycosidic bonds between glucose and fructose by the enzyme invertase. Then glucose molecules are broken down into two pyruvate molecules by glycolysis. Thus as shown in the reaction above,glycolysis causes the reduction of NAD+ to NADH,ADP is converted into ATP and water molecules via substrate-level phosphorylation.

In the background researches of the previous experiments, it was estimated that different sugars would release different amounts of CO2. Glucose was expected to produce more carbon dioxide than other types of sugar because of it’s 6-Carbon structure. Sucrose was expected to be the runner up producer of carbon dioxide after Glucose because of it’s formation by the combination of glucose and fructose. It has also been considered that the attachment of a 5-Carbon sugar to a 6-Carbon sugar would limit the production of CO2. Fructose was not considered to have a major importance in the experiment but it was estimated that it would evolve some carbon dioxide. The smallest expectation was made on lactose because of it’s complex structure and the absence of enzymes that can break down galactose.

As the results, it was seen that in adequate amount of time both glucose and sucrose reached the maximum amount of CO2 release however sucrose reached it faster. Fructose produced a small amount of CO2 where lactose produced almost none.

Therefore it was stated that the structural differences between different types of sugar effects the CO2 release rate during the fermentation process of yeast.

Aim: To investigate the different fermentation rates of different sugars by measuring the CO2 release.

Research Question: How does the structure of sugar affect the rate of fermentation?

Variables:

Independent Variable	Type of sugar	Glucose,Fructose and Lactose were used.
Dependent Variable	Rate of ethyl alcohol fermentation	It depended on the structure of the sugar used.
Controlled Variable	Temperature	It was done in room temperature (38-40 ºC).
	Amount of sugar	The amount of sugar was kept constant at 5 mg.

(Table 1)

Hypothesis:

If the structural complexity of the sugar increases,the rate of ethyl alcohol fermentation increases.

Material & Method

1. Materials

• 100 ml pure water (x4)
• 5 mg yeast (x4)
• 5 mg Fructose
• 5 mg Lactose
• 5 mg Glucose
• 100 ml beakers (x4, %5)
• 500 ml beaker
• Tube (x4)
• Syrnge (x4)
• Vernier competer inference
• Logger pro
• Vernier CO2 Gas sensor
• 250 mL respiration chamber
• Thermometer
• Heater
• Beral pipettes

2. Method

I. 5 mg of Fructose, Glucose and Lactose was measured separately.

II. Measured sugars were put into separated beakers.

III. 500 ml ofpure water was heated until it reached 38-40ºC and kept constant.

IV. 5 mg of yeast was put into tubes.

V. 25 ml of pure water was put into tubes which were filled with yeast (x4)

VI. Filled tubes were put into the pre-heated 500 ml beaker for 10 minutes.

VII. 2 ml of yeast solution was measured each tube using the syringes.

VIII. All of the solutions were added in to the chamber separately and CO2 sensor was put on the chamber.

IX. Amount of C02 release was calculated for each beaker.

X. All steps were repeated for 5 trials.

3. Design

Data Table (Raw Data):

Fructose
Time	Carbon Diocide Release
	Trial 1	Trial 2	Trial 3	Trial 4	Trial 5	Mean Average
0 s.	0	0	0	0	0	0
20 s.	0	0	0	0	0	0
40 s.	821	830	825	820	820	823. 2
60 s.	877	883	873	875	879	877. 4
80 s.	921	918	920	925	922	921. 2
100 s.	959	957	960	962	958	959. 2
120 s.	981	985	980	982	980	981. 6
140 s.	994	999	993	992	995	994. 6
160 s.	1006	1004	1003	1007	1000	1004
180 s.	1009	1011	1007	1005	1010	1008. 4
200 s.	1016	1019	1014	1017	1015	1016. 2
220 s.	1018	1023	1020	1017	1019	1019. 4
240 s.	1022	1025	1027	1025	1020	1023. 8

(Table 2)

Glucose
Time	Carbon Dioxide Release
	Trial 1	Trial 2	Trial 3	Trial 4	Trial 5	Mean Average
0 s.	0	0	0	0	0	0
20 s.	0	0	0	0	0	0
40 s.	1873	1870	1876	1875	1871	1873
60 s.	2113	2110	2114	2012	2015	2072. 8
80 s.	2313	2315	2310	2311	2314	2312. 6
100 s.	2443	2440	2445	2442	2443	2442. 6
120 s.	2563	2560	2566	2562	2564	2563
140 s.	2651	2652	2556	2550	2555	2592. 8
160 s.	2745	2744	2746	2743	2748	2745. 2
180 s.	2800	2800	2802	2805	2801	2801. 6
200 s.	2839	2840	2842	2835	2841	2839. 4
220 s.	2870	2872	2868	2873	2869	2870. 4
240 s.	2893	2895	2891	2890	2896	2893

(Table 3)

Lactose
Time	Carbon Dioxide Release
	Trial 1	Trial 2	Trial 3	Trial 4	Trial 5	Mean Average
0 s.	0	0	0	0	0	0
20 s.	0	0	0	0	0	0
40 s.	679	680	677	681	680	679. 4
60 s.	744	745	743	748	745	745
80 s.	804	805	803	800	808	804
100 s.	851	855	848	850	852	851. 2
120 s.	895	900	897	890	892	894. 8
140 s.	922	925	917	930	920	922. 8
160 s.	943	940	945	946	941	943
180 s.	961	960	956	967	959	960. 6
200 s.	976	980	970	966	981	974. 6
220 s.	983	985	980	988	979	983
240 s.	994	990	992	995	989	992

(Table 4)

Water
Time	Carbon Dioxide Release
	Trial 1	Trial 2	Trial 3	Trial 4	Trial 5	Mean Average
0 s.	0	0	0	0	0	0
20 s.	0	0	0	0	0	0
40 s.	757	756	758	750	760	756. 2
60 s.	876	877	880	873	875	876. 2
80 s.	970	973	967	977	963	970
100 s.	1022	1024	1020	1027	1017	1022
120 s.	1054	1055	1060	1052	1057	1055. 6
140 s.	1082	1080	1095	1079	1083	1083. 8
160 s.	1109	1109	1111	1107	1109	1109
180 s.	1124	1127	1120	1131	1125	1125. 4
200 s.	1131	1134	1131	1130	1137	1132. 6
220 s.	1143	1140	1145	1147	1141	1143. 2
240 s.	1154	1155	1150	1156	1155	1154

(Table 5)

Average Table (Processing Data):

Fructose
Time	CO2 Release
0	0
20	0
40	823. 2
60	877. 4
80	921. 2
100	959. 2
120	981. 6
140	994. 6
160	1004
180	1008. 4
200	1016. 2
220	1019. 4
240	1023. 8

Glucose
Time	CO2 Release
0	0
20	0
40	1873
60	2072. 8
80	2312. 6
100	2442. 6
120	2563
140	2592. 8
160	2745. 2
180	2801. 6
200	2839. 4
220	2870. 4
240	2893

Lactose
Time	CO2 Release
0	0
20	0
40	679. 4
60	745
80	804
100	851. 2
120	894. 8
140	922. 8
160	943
180	960. 6
200	974. 6
220	983
240	992

Water
Time	CO2 Release
0	0
20	0
40	756. 2
60	876. 2
80	970
100	1022
120	1055. 6
140	1083. 8
160	1109
180	1125. 4
200	1132. 6
220	1143. 2
240	1154

Calculation: The calculations for calculating the fermentation rate should be done using the formula (Final CO2 release-Initial CO2 release)(ppm)/Time(min). The calculations for the experiment is as following,

• Fructose: (1023. 8-0)/4= 255,95
• Glucose: (2893-0)/4=723,25
• Lactose: (992-0)/4=248
• Water: (1154-0)/4=288,5

Graphs

(Graph 1) Shows that the Final CO2 release of yeast with Fructose is 1023.

(Graph 2) Shows that the Final CO2 release of yeast with Glucose is 2893.

(Graph 3) Shows that the Final CO2 release of yeast with Lactose is 992.

(Graph 4) Shows that the Final CO2 release of yeast with water is 1154.

Conclusion and Evaluation

Conclusion

As it has been seen in the light of the datas taken during the experiment our hypothesis has been proven to be wrong. Because even though Glucose was a monosaccharide it’s fermentation rate has been measured higher than the Fructose who is a disaccharide. The complex structure of Frutose didn’t cause the fermentation rate to be higher. Thus the hypothesis haven’t been proven to be correct.

The information in the background information has led us to assume that the rate of the more complex sugar would be higher because the number of bonds was higher. But the principle monosaccharide Glucose had the highest fermentation rate n 4 minutes followed by the disaacharide Fructose.

The slowest fermentation rate was measured from the solution which consisted of only yeast and pure water. It was already estimated because Ethyl Alcohol Fermentation is focused on producing energy for yeast. But in the lacking of an energy providing substance such as sugar,enery can not be produced.

Thus,we can conclude our experiment by stating that the structural complexity of sugars affect the rate of ethyl alcohol fermentation however it is not the only factor that affects the rate when different types of sugars are used. The type of bonds is also an effective factor on the rate of ethyl alcohol fermentation.

Limitations:

Limitations	Sütun1
Deficiency on Temperature	While heating the 500ml beaker to 38ºC,it was a struggle to try to keep the
temperature around 39ºC and it may have affected the rate of
fermentation bacause it may have affected the solublity of the sugars in yeast solution.
Cleaning the Chamber	Cleaning of the chamber in switching between trials and
different sugars has also been a struggle because it couldn’t be
cleaned totally. Hence this may have affected the fermentation
rate because of the mixture of sugars.
Minimum value of syringe	The operation done by the syringe was a little value
but the it’s minimum value was hard to read.

Improvement

The lack of controlling during the heating of the 500 mL beaker caused a uncertainty of the datas of the experiment. We could have used a more precise heater and quickly used it in the solutions. The largest uncertainties were caused by person-based uncertanities. For example if more time was spent or some tools were used in cleaning the respiration chamber the datas of the experiment could have been more accurate. . One of the other limitations during the experiment was that the use of the syringe was hard because of it’s form.

If the stated limitations were decreased to minimum,the datas could have been more precise and accurate.

References

• BiologyMad A-Level Biology. 02 Mar. 2009
• Cohn, Don. (1999) Science in the Real World, Microbes in Action; How Long Will I Be Blue? Universityof Missouri
• Brazillian archives of biology technology. vol. 51 no. 3 Curitiba May/June 2008