Sophie Lin
The Effect of Sunlight, Time, and Salt Concentration
on the Rate of Fermentation of Kimchi
I)
Introduction
A) Background
Kimchi is a delicacy of the Korean culture, a fermented mixture of
Chinese cabbage, radishes, red pepper, garlic and ginger. It is very important to
learn the most effective conditions for Kimchi fermentation that will help
companies to produce Kimchi at the best quality. Fermentation is furthermore an
important process to learn about. In today’s world, there is an immense market of
products that use fermentation to alter the appearance and/or flavor of foods and
beverages such as beer, buttermilk, cheese, wine, vinegar and yogurt.
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Western world: yogurt, sourdough breads, sauerkraut, cucumber pickles and
olives
Middle East: pickled vegetables
Korea: kimchi (fermented mixture of Chinese cabbage, radishes, red pepper,
garlic and ginger)
Russia: kefir
Egypt: laban rayab and laban zeer (fermented milks), kishk (fermented cereal and
milk mixture)
Nigeria: gari (fermented cassava)
South Africa : magou (fermented maize porridge)
Thailand : nham (fermented fresh pork)
Philippines : balao balao (fermented rice and shrimp mixture)
B) Goals
My goal for this experiment is to see a steady trend of the rate of
fermentation of water though time, and a significant difference of the results
between different variables.
C) General Expectations and Models
If cabbage is contained in no sunlight conditions with more salt, the lower
pH of the liquid excreted from the cabbage.
D) Variables
1) Constant Variables
(a) Amount of cabbage in the bag
(b) Type of Salt
(c) The type of Ziploc bag
2) Independent Variables
(a) Time
(b) Sunlight (Temperature)
(c) Salt Concentration
3) Dependant Variables
(a) The pH level of the water excreted from the Kimchi (acidity)
(b) The rate of fermentation
II)
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Materials
16 Small Ziploc bags
2 large Ziploc bags
Chopped cabbage
Scale
Noniodized salt
Electronic pH measurer
III) Method and Procedures
1) Separate chopped cabbage in sixteen bags of 35 grams of cabbage in Ziploc bags
2) Separate the sixteen bags into two groups, label half of them WINDOW and half
of the CUPBOARD
3) Label the WINDOW bags, A to H
4) In bags A, B, C, and D, add 5 grams of salt to each bag
5) In bags E, F, G, and H, add 15 grams of salt to each bag
6) Make all of the WINDOW bags airtight
7) Label the CUPBOARD bags, A to H
8) In bags A, B, C, and D, add 5 grams of salt to each bag
9) In bags E, F, G, and H, add 15 grams of salt to each bag
10) Place the CUPBOARD bags in two large Ziploc bags, to conceal the air (four
small bags in each big bag)
11) Make the bags airtight
12) Place WINDOW bags on window sill
13) Place the CUPBOARD bags in two large Ziploc bags, to conceal the air (four
small bags in each big bag)
14) Make the bags airtight
15) Place CUPBOARD bags in a CUPBOARD
16) After one day, measure all the ph level of the each bag of cabbage by:
a. Placing the electronic ph measurer in the liquid of the kimchi
b. Rinsing the measurer in distilled water after each use
c. Writing the results on a table
17) Measure the ph level of every single kimchi bag each day at regular intervals for
two weeks
18) Graph Data
19) DO NOT EAT
IV)
V)
Expectations
Results
A) Qualitative Observations
B) Quantitative Observations
C) Data Processing and Analysis
VI)
Discussion
VII) Appendix I: Scientific Terminology
 pH pH is a measure of the concentration of hydrogens ions (= H+) (= protons) in a
solution
 Fermentation an acid produced by glucose-burning cells when these cells have an insufficient
supply of oxygen The scientific meaning of fermentation is the energy-yielding
anaerobic metabolism of a nutrients, such as sugars, without oxidation. Fermentation
converts these nutrients mainly into lactic acid, acetic acid, and ethanol.
 Lactic Acid Bacteria A large group of beneficial bacteria that have similar properties and all
produce lactic acid as an end product of the fermentation process. They are widespread in nature and
are also found in our digestive systems. Lactic acid bacteria have been used to ferment foods for at
least 4000 years eg yoghurt, cheese... They may also be responsible for food spoilage.
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Lactic Acid Fermentation- A type of fermentation carried out by lactic acid bacteria
in which sugar (eg lactose, glucose, pentose) are converted either entirely (or almost
entirely) to lactic acid (homolactic fermentation) or to a mixture of lactic acid and
other products (heterolactic fermentation).
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Anaerobic microorganisms-Their survival does not depend on the availability of
oxygen
Actobacillus Plantarum -in the late stage, this could affect the ripening of kimchi.
L. Brevis- in the late stage, which could affect the ripening of kimchi.
Streptococcus faecalis- actively grows in the early stage of fermentation
Leuconostoc mesenteroides- actively grows in the early stage of kimchi
fermentation, thereby producing lactic acid and carbon dioxide which could acidify
kimchi and create an anaerobic state to suppress the growth of aerobes.
Pediococcus pentosaceus- in the late stage, which could affect the ripening of
kimchi.
Acid-A solution that has an excess of H+ ions. It comes from the Latin word acidus
that means "sharp". (As time passes, our kimchi became more acidic)
Bacteria- Beneficial bacteria found in food after fermentation are capable of
producing so many enzymes necessary for the building up and breaking down of
organic compounds
Base-A substance that yields hydroxyl ions when dissolved in water.
NAD+ is nicotinamide adenine dinucleotide.-It serves as an intracellular oxidizing
agent (a.k.a., electron acceptor).
NADH:
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NADH is reduced NAD+.
NADH serves as means by which cells transfer reducing power around (a reducing
power intermediate) similar in concept to the way cells employ ATP as an energy
intermediate.
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VIII) Appendix II: Key Concepts, Models, "Big Ideas"
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Lactic acid fermentation produces no gas, which is unusual among fermenation
pathways.
 Lactic acid is an acid and therefore sour to the taste.
Fermentation, the process
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Anaerobic byproduct production:
o Fermentation includes all metabolic processes that do at least three* of the
following:
 release energy from a sugar or other organic compound
 do not require molecular oxygen
 do not require an electron transport system
 use an organic compound as the final electron acceptor.
The BIG idea
Bacteria such as lactic acid bacteria produce ATP without the presence of oxygen by
fermentation. The by product of the fermentation contributes to the taste of a food. Some
bacteria help change the flavor and appearance of food and suppresses the growth of
other non-helpful bacteria which could grow under such conditions..
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/pH.html
http://www.mansfield.ohiostate.edu/~sabedon/biol1095.htm#substrate_level_phosphorylation