GENERAL BIOLOGY I
Laboratory Activity: FERMENTATION
Fermentation is the anaerobic oxidation of sugars to form ethanol or ethyl alcohol. On the other hand,
aerobic oxidation of sugars will produce acetic acid. Wine preparation is not limited only to the fermentation of
sugar cane. It can also be done to any kind of fruit that may be in season during the performance of the experiment,
as long as the amount of sugar is adjusted to provide enough, substrate for the production of alcohol.
Yeast (Saccharomyces cerevisiae), is a fungi that produces the enzyme to hasten the anaerobic/aerobic
oxidation of the sugar. Brewer’s yeast is more preferred that Baker’s yeast but the latter is used in the experiment
due to economic considerations, and the availability of the material.
OBJECTIVES:
At the end of the experiment, the student will know how to:
1. Prepare wine from indigenous materials.
2. Utilize different type of fruits to produce acetic acid or vinegar.
EQUIPMENT AND MATERIALS:
1. 2 Fermentation jars
2. Cheese (cotton) cloth (as strainer)
3. Measuring cups
4. Yeast
5. Fruits
6. Brown sugar/white sugar
7. Thermometer
PROCEDURE:
8. Cooking Pot for Pasteurization
9. 2L Distilled Water
10. Knife
11. Cutting Board
12. Bowl
13. Stirring Rod/ Spatula
A. Wine Preparation
1. Wash and peel ripe (or slightly overripe) fruits.
2. Crush or grate the peeled fruits to extract the juice.
3. Alternatively, use blender to fully extract the juice of the fruit.
4. Dilute the crushed fruit extract with the proportion, 1 cup of water to 1 cup of the juice.
5. Add 1 cup of sugar to every 4 cups of the diluted juice. Mix thoroughly and pasteurize through heat
over a low flame for 30 minutes. Alternatively, add more sugar to give variation on the flavor of wine.
Note: With higher sugar concentration, the longer the fermentation process.
6. Cool and pour the mixture into a bottle (fermenting container) three-fourths (3/4) full.
7. Add ½ teaspoon of dry yeast to every litter of the mixture.
8. Stopper with a cork, fitted with a U-tube in which the other end is dipped in a test tube filled with
Calcium hydroxide solution.
9. Alternatively, use condom to stopper the mouth of the fermenting jar. This will allow you to monitor
the amount of CO2 gas produced during the fermentation.
10. Allow the mixture to ferment for three to four weeks or until no more bubbles are formed, or until the
latex balloon stopped inflating.
11. After fermentation, strain and pasteurize the prepared wine at 65℃ for 30 minutes.
12. If impurities are observed, let the particulate settle and decant in a suitable sterilized container and
pasteurize
13. Alternatively, to make the wine clear, add a well-beaten egg white to every 12 cups of the mixture,
then pasteurize.
14. Let the wine cool down. Stopper tightly and label.
B. Vinegar Preparation
1. Alcoholic Fermentation
a. Dissolve one (1) part of sugar to eight (8) parts of the fruit juice extract.
b. Filter through cheese cloth and pasteurize for 20 minutes.
c. Cool to room temperature and pour into the fermentation bottle, ¾ full.
d. Add 1 teaspoonful of yeast to every 1-liter bottle.
e. Protect the fermenting mass from dust by covering the mouth of the bottle with clean cloth.
f. Allow to ferment for 4-7 days or until an appreciable characteristic odor is observed.
2. Oxidation of Alcohol
a. Add one (1) part mother vinegar to eight (8) parts of the alcoholic solution prepared above.
b. Filter and set aside for two (2) weeks or until the desired acidity is obtained.
c. Pasteurize.
EVALUATION
Wine Preparation
Guide Questions:
1. What type of respiration is employed in the process of wine making?
2. How is alcohol produced through this process? Specify the reaction process by writing the complete and
balanced chemical equation.
3. Yeast (Saccharomyces cerevisiae) has been used for food and beverage preparation for hundreds of years.
Explain the importance and the mechanism of these microorganism in producing such products.
4. Observe the change in appearance of the solution. What do you think is the reason behind this change in
appearance along the process of fermentation?
5. How about the odor and texture? Explain how the fermentation process affects the change in odor and
texture of the solution.
6. Is there any change on the pH Level of the solution? Explain what causes this change in pH level of the
solution.
Observations:
PARAMETERS
Color/Appearance of the
Solution
Odor
Texture
pH Level
OBSERVATIONS
Initial
Final
Vinegar Preparation
Guide Questions:
1. What type of respiration is employed in the process of vinegar making?
2. Specify what compound is produced in this reaction by writing the complete and balanced chemical
equation of this process.
3. The mechanism in the production of vinegar is quite different with that of the wine production using
microorganisms. Give an explanation on the mechanism on how these microorganisms enhance the
reaction thereby producing the desired products.
4. Observe the change in appearance of the solution. What do you think is the reason behind this change in
appearance along the process of fermentation?
5. How about the odor and texture? Explain how the fermentation process affects the change in odor and
texture of the solution.
6. Is there any change on the pH Level of the solution? Explain what causes this change in pH level of the
solution. Take note of the pH level for 4 (four) observation periods with 3 replicates.
7. Use Analysis of Variance (ANOVA) specifically Completely Randomized Design at 5% significance
level, as Statistical Analysis for the comparison of the pH Level for each of the observation periods.
8. Is their significance difference between the observation periods? Show your Table of Means and give a
graphical illustration of the result. Discuss the result of the experiment.
9. What is the implication of these result?
10. Include documentations in the appendices for the methods and results.
Observations:
OBSERVATIONS
PARAMETERS
1
2
3
4
Color/Appearance
of the Solution
Odor
Texture
R1
R2
R3
R1
R2
R3
R1
R2
R3
R1
R2
R3
pH Level
Summary, Conclusion and Recommendations:
.
*Use extra sheet for your lab results.
*Use only long sized bond paper for your outputs.
INDIVIDUAL PERFORMANCE EVALUATION
Group Member
Names
Name of Rater
Asst. Surgeon:
Workload Contribution(s)
Rating
A–
B–
C–
D–
E–
TOTAL –
Chief Surgeon:
* Rating of Group Members to be accomplished by the Chief Surgeon.
* Rating of the Chief Surgeon to be accomplished by anyone of the Assistant Surgeon.
* Refer to the attached Rubric for the pointing of the members.
* Adjust/Add rows if necessary.
RUBRIC IN LABORATORY ACTIVITY FOR GENERAL BIOLOGY
Criteria
(A)
Set-up and
Equipment
Care
(B)
Following
Procedure
(C)
Data
Collection
(D)
Safety
(E)
Clean-up
1
Set-up of equipment
is not accurate,
help is required
with several major
details
Many necessary
supplies must
found in mid-lab
2
Set-up of equipment
is generally
workable with
several details that
need refinement
Some necessary
supplies must be
searched out
3
Set-up of equipment
is generally
accurate with 1 or
2 small details that
need refinement
All necessary
supplies on hand
4
All equipment
accurately placed
All necessary
supplies on hand
Demonstrates good
knowledge of the
Demonstrates sound
Lacks the appropriate
lab procedures
knowledge of lab
Demonstrates
knowledge of the
Will ask peers for
procedures
general knowledge
lab procedures
help with
Will discuss with
of lab procedures
Often requires help
problems in lab
peers to solve
Requires help from
from the teacher to
procedures
problems in
teacher with some
even complete
Works to follow each
procedures
steps in procedures
basic procedures
step before
Carefully follows
moving on to the
each step
next step
Measurements are
incomplete,
inaccurate and
imprecise
Observations are
incomplete or not
included
Symbols, units and
significant figures
are not included
Measurements are
somewhat
inaccurate and
very imprecise
Observations are
incomplete or
recorded in a
confusing way
There are 3 or more
minor errors using
symbols, units and
significant digits
or 2 major errors
Measurements are
Measurements are
accurate with
mostly accurate
reasonable
Observations are
precision
generally complete Observations are
Work is organized
thorough
Only 2 or 3 minor
Work is generally
errors using
neat and organized
symbols, units and Includes symbols,
significant digits
units and
significant digits
Proper safety
precautions are
consistently
missed
Needs to be
reminded often
during the lab
Proper safety
precautions are
often missed
Needs to be
reminded more
than once during
the lab
Proper safety
precautions are
generally used
May need to be
reminded once
during the lab
Proper safety
procedures are
consistently used
Uses general
reminders of safe
practices
independently
Proper clean-up
procedures
generally used
May need some help
on occasion to
complete tasks
Station generally left
clean
Consistently uses
proper clean-up
procedures
Station generally
neat and clean
Proper clean-up
Needs to be
procedures are
reminded more
seldom used
than once during
Often requires help
the lab to use
to complete cleanproper clean-up
up
procedures
3 or more items left
1 or 2 items left at
at station or station
station or not
not cleaned
cleaned
5
All equipment
accurately placed
All necessary
supplies on hand
Very neat and
organized
Demonstrates very
good knowledge
of the lab
procedures
Gladly helps other
students to follow
procedures
Thoroughly and
carefully follows
each step before
moving on to next
step
Measurements are
both accurate and
precise
Observations are
very thorough and
may recognize
possible errors in
data collection
Work is neat and
organized
Includes appropriate
symbols, units and
significant digits
Proper safety
precautions are
consistently used
Consistently thinks
ahead to ensure
safety
Will often help other
students to
conduct labs safely
Consistently uses
proper clean-up
procedures
Often will help other
students to
complete tasks
properly
Station always left
neat and clean