The Effect of Sugar Types on the Rate of Yeast
Fermentation
Abstract
In pairs, the biology class conducted a one-experiment study regarding the effect of
different sugars, as food sources for yeast, on the speed of fermentation. The experiment called
for five test tubes, each with different solutions: DI water-glucose, DI water-yeast, DI wateryeast-glucose, DI water-yeast-Honey and Di water-yeast-Corn. The class hypothesized that
glucose will significantly increase the speed of fermentation of yeast, compared to the other
sugar solutions. Throughout the experiment, the students calculated the amount of CO2 bubbles
every two minutes in order to compare the speed of fermentation between the control group
(water solution) and the experimental groups (sugar solutions). The data gathered during the
experiment exhibited that yeast with glucose, honey and corn food sources will have a faster
speed of fermentation compared to the yeast with water and glucose with water food sources.
Introduction
Fermentation is the pathway following glycolysis, a metabolic process in cellular
respiration in which cells create ATP. Unlike the Krebs cycle, glycolysis and fermentation are
anaerobic processes, meaning that they do not require the presence of oxygen to occur. Types of
fermentation include alcoholic fermentation and lactic acid fermentation. Similarly, both
alcoholic and lactic acid fermentation require pyruvic acid and NADH as reactants (Levine and
Miller, 2010). However, alcoholic fermentation produces ethanol, NAD+, and carbon dioxide,
whereas lactic acid fermentation produces NAD+ and lactic acid. Fermentation is vital for many
organisms, such as yeasts, certain molds, and bacteria, because it allows them to obtain energy
required to carry on life processes. Alcoholic fermentation is especially important for human
beings, as it is used to produce alcoholic beverages, bread, and many other everyday items (AlbaLois, 2010). On the other hand, lactic acid is a waste product of certain bacteria, which is
utilized to create cheese, yogurt, sour cream, and many other important industrial items.
Additionally, humans’ resort to lactic acid fermentation when oxygen is limited. Bacterial
fermentation is also used in the medical industry to create certain antibiotics. Yeast, a singlecelled organism that utilizes sugar as a food source, produces energy substances through the
breakdown of sugar molecules.
Specifically, the type of sugar as source of food, impacts the speed of fermentation in
yeast. In this lab, we will calculate the rate of fermentation in yeast with different solutions of
sugar, such as glucose, honey, and corn with water as a control group. It is important to humans
that yeast uses the best sugar source during fermentation, as it creates industrial items such as
bread, alcohol, and yogurt. If the type of sugar source affects the rate speed of fermentation,
when you add glucose to a yeast solution, it will cause fermentation to occur at a quicker rate.
Materials
5 Respirometers:
Test tubes, 1-mL graduated
Pipettes, aquarium tubing,
flasks, binder clips
Pipette pump
3 5-mL graduated pipettes,
Labeled DI water, yeast, glucose,
honey and corn
Yeast solutions
Glucose solutions
DI water
Honey solutions
Corn solutions
Wax pencil
Water bath
Experiment
First, we got five tubes labeled as 1, 2, 3, 4 and 5 added solutions to each tubes as tubes 1 we
added (4 mL DI water and Glucose solutions), then tube 2 we added (6 mL DI water and 1 mL
yeast), for tube 3 was (1 mL of DI water, 3 mL of yeast and 3 mL Glucose), then tube 4 had (1
mL of DI water, 3 mL yeast and 3 mL of honey), finally tube 5 we added (1 mL of DI water with 3
mL yeast and 3 mL of glucose). Then added a 1 mL flask to each tube then placed the 5 tubes
with flasks in water bath at 30°C for 5 minutes with tubing unclamped, after that we
attached pipette pump to draw the fermentation solution up to 0 mL then closed the
blinder clip we did the same with all other tubes, after that we recorded the initial
reading for each pipette then every two minutes we took the readings we did that for 20
minutes