2. Introduction
● The earliest records of pickles come from India in 2030 BC
● Since then pickles have been used in used in just about every culture
● Pickling was essential in the early days of travel because it was the only way
to preserve food for a long period of time
● Today pickling takes the form closer to an art rather than a science as just
about everything you can think of has been pickled
3. Introduction Cont.
● Pickles are made when a fresh fruit or vegetable is submerged in saltwater
brine until they are unable to spoil
● When the microbes on the surface of the vegetable experience an anaerobic
environment they begin to ferment the glucose of the vegetable
● In this study cucumbers were the chosen vegetable and one batch reactor
with a high dose of glucose and one batch reactor with a low dose of
glucose were made for this study
● The way that pickling progression was measured was by production of
organic acids in the reactor
5. Methods
● First our team had to prepare the brine
● We dissolved 85g of salt into 1L of water in the reactor, then we combined
70g of garlic and 20g of peppercorns into the solution
● In reactor A 8.93g of sugar was added and in reactor B 4.46g of sugar was
added
● Next, 298g of cucumbers were added to each reactor
● An initial measurement was taken from each reactor
6. Methods cont.
● Every day for the next seven days measurements were taken from each
reactor and then the measurements were frozen to stop the microbe activity
in the sample
● Once all of the samples were collected they were taken to the lab to be
tested for acidity content and COD
● The acidity content was measured by doing an acid titration using 0.1 N
NaOH
● The COD was measured by mixing a sample with a COD tube and digesting
them for two hours
● Then taking the absorbance values of each sample for each reactor
7. Acidity Results
● The initial acidity of reactor A is much higher compared to the remainder of
the experiment
● Days 1 through 6 show a general increase in the acid content of the reactor
● A slight decline was recorded between days 3 and 4 but the upward trend
resumed after day 4
● A pause in the acidity of the reactor was recorded between days 3 and 5
8. Acidity Results Cont.
● The acidity in reactor B was found to have an initial increase, then a
decrease after day 2, then another increase, and finally a slight decrease
after day 5
● The two peaks of the acid content were day 2 at 0.022 mol/L and day 5 at
0.023 mol/L
● The acidity before and after the first peak were very similar
● It is unsure whether or not an extension of the experiment would result in
another peak
9. Calculations
● Acidity: Acidity = VA * (N/VS)
Where: VA is volume of base titrant added, in this case NaOH (mL)
N is the normality of the base titrant (Equ/L)
VS is the volume of the sample (mL)
● Sample calculation: A3, A=VA * (N/VS) = 2.9mL * (0.1N/20mL) = 0.0145
mol/L
10. Acidity Discussion
● The data from both of the reactors generally increased, this was expected
because as the microbes fermented the glucose organic acids were
produced
● A0 was calculated with 0.02 N NaOH which may have influenced the high
acidity reading
● Reactor A showed a closer result to what we expected our acidity graph to
look like, which was a linear increase
● The peaks in reactor B were very unexpected
11. Acidity Discussion Cont.
● As the experiment went on an mold was found on the cucumbers in both
reactors
● This mold was more present in the high dosage reactor
● The mold could be the reason for the variation between the data we
obtained and the data we expected
● We also expected the presence of garlic and peppercorn to skew the data
slightly
12. Chemical Oxygen Demand Results
● Found the absorbance values from the spectrophotometer at 600 nm
● Calculated substrate concentration started out at 18.46 g/L and ended at
30.31 g/L for Reactor A (11.85 g/L change)
● There was an increase in concentration up until day 2 which lead to a
decrease for day 3
● The concentration fluctuated over the 7 days
13. Chemical Oxygen Demand Results Cont.
● The substrate concentration began at 16.69 g/L at the beginning and ended
at 26.08 g/L for reactor B (9.39 g/L change)
● The concentration increased over time
● Day 3 and 6 experienced some slight decreases
15. Chemical Oxygen Demand Discussion
● Both reactors illustrate an increase in substrate over the course of 7 days
● This result was not expected and an error in our experimental procedure
was the reason for it
● A set of standard samples (0, 5 and 10 g/L of sucrose) were created with a
concentration of 85 g/L of salt in each
● A standard curve was generated and the concentrations were calculated for
each day’s sample using the equation from the standard curve.
16. Calculations cont.
● COD:
○ Standard curve equation generated: y=0.026x (y=absorbance value and
x= substrate concentration value)
○ Sample calculation: x=0.48/0.026=18.46 g/L
22. Reactor Design
● The biomass for Reactor A
increases at a greater rate than
Reactor B, as expected.
● Reactor A also reaches a greater
final biomass value before tapering
off
● The production of acid shows the
same trend, with Reactor A both
increasing at a faster rate and
reaching a higher value
Reactor A
Reactor B
23. Conclusions
● The experimental results show a lower sugar content actually resulting in a
faster pickling time.
○ B was quicker than A
● The modelling shows the expected results of the reactor with more sugar
having a faster and more complete pickling.
○ A is quicker than B
● This difference could have occured due to the interaction between the sugar
and the high salt content along with the fact that the model does not
consider any substrate utilized from the cucumbers themselves.
24. Conclusions
● Some additional error may have occurred from opening and closing the
bioreactor to take samples
● This opening and closing resulted in a growth of model on top of each of the
reactors
● This mold could have potentially affected both the acidity production and
COD.
● In addition to the mold, the samples taken for COD were not filtered which
resulted in more than the substrate of interest being present
25. Conclusions
● In the future, we could attempt to model the substrate the cucumbers
contribute as well as attempt to quantify any affect the interaction between
the salt and sugar that exist.
● We would also attempt to develop a method for taking samples without
exposing the reactor to as much mold or oxygen.
White mold on
pickle (A)
White mold
floating in
pickle juice (B)
26. References
Mudawaroch, R. E., Setiyono, S., Yusiati, L. M., & Suryanto, E. (2019).
Fermentation Kinetics of Isolate Lactic Acid Bacteria Probiotic BR 12 and BR
17 were Isolated from Broiler Chicken Meat. 6-7. Doi:2019
Avey, Tori. “History in a Jar: The Story of Pickles.” PBS, Public Broadcasting
Service, 3 Sept. 2014, www.pbs.org/food/the-history-kitchen/history-pickles/.
Drapcho, C. 2020. Biological pathways-anaerobic resporation and
fermentation. Unpublished Lecture Notes, BE 4100, Clemson University,
Clemson SC.
