Fermented Plan Juice procedure

1. Fermented Plant
Juice (FPJ)
Experiment
Michael and Amanda
May 2021

2. Intro
● Fermented plant juice has potential to be a more sustainable and
cheaper alternative to traditional hydroponic nutrient solutions
○ Available plant waste can be used
● Research question: Does the extract produced by the fermented
plant juice (FPJ) method contain a higher nutrient content than
extract produced by the fermentation of plant material only?
● Hypothesis: There is a significant difference between the
nutritional content of fermented plant extracts made using the
FPJ method (with sugar) and a non-sugar fermentation.
● Null Hypothesis: There is no significant difference between the
nutritional content of fermented plant extracts made using the
FPJ method (with sugar) and a non-sugar fermentation.

3. Experimental Setup
● Treatment Variables: Ratio of
swiss chard to comfrey to sugar
● Response Variables: pH,
nutrient content, bacterial
growth
● Sample Size: 3 treatments in
duplicate and 1 control (7
samples total)
● Experiment Duration: 7 days

4. Methods & Procedure
● Plant material acquired from Farm Girl Deliveries in Six Mile, SC
○ Sustainable practices: no pesticides/herbicides, permaculture, natural fertilizers only
● Swiss chard leaves not fit to be sold and comfrey leaves collected
○ About twice as much comfrey collected (by volume)
● Three treatments (in duplicate) and one control
○ 60 g swiss chard : 120 g comfrey : 180 g brown sugar
○ 90 g swiss chard : 90 g comfrey : 180 g brown sugar
○ 30 g swiss chard : 150 g comfrey : 180 g brown sugar
○ 60 g swiss chard : 120 g comfrey : 0 g brown sugar (control)
○ 7 samples in total

5. Methods & Procedure
● Plant material treated with brief blending
○ Material weighed out and appropriate amount
portioned into each ~1.4L bottle
● Sugar weighed and added to each bottle,
then shaken until evenly distributed
● Bottle sealed and left to ferment for 7 days
○ Liquid formed within an hour
Before and after shaking the
ingredients together
Plant material after being blended

6. Methods & Procedure
● Visually observed at day 7
● Passed through strainer until 75mL* collected
○ Liquid tested for pH, TDS, temp
● Diluted to 150mL with water
○ Liquid tested for pH, TDS, temp
● 1.5 mL of each diluted sample was collected
○ 100 microlitres of each treatment plated
○ Plates incubated
● Remaining volume of each sample was sent to
Clemson Ag Services Lab
*25mL of the control were collected
Straining/collecting the FPJ on Day 7
1.5 mL aliquots for plating/LAMP

7. Observations
● White mold growth in all vessels
○ Control → mold throughout
○ Treatments → mold only on top
○ No black mold was observed
● Control produced less liquid and had fouler smell
● Difference in color/clarity of control
Treatment 3 (mold on top)
Control (mold throughout)
Mold inside bottle
Diluted FPJ samples (last bag is control)

8. Results - Water quality parameters
● ~75 mL extract produced from each treatment, only ~25 mL from control
● To get 150 mL sample volume (req. for analysis), 75 mL water added to treatment
samples, 125 mL water added to control sample
Treatment Averages
Control (60:120:0) 1 (60:120:180) 2 (90:90:180) 3 (30:150:180)
Before dilution
pH 7.43 6.68 6.32 6.64
Liquid Temp. (deg F) 70.3 70.6 71.4 70.6
TDS (ppm) 6952 745.5 765.5 752
After dilution
pH 7.03 6.94 6.59 6.90
Liquid Temp. (deg F) 70.8 71.3 71.1 71.2
TDS (ppm) 1597 N/A N/A N/A
Table below: Water quality parameters before and after dilution

9. Results - Nutrient Content
N (%) P (%) K (%) Ca (%) Mg (%) S (%)
Zn
(ppm)
Cu
(ppm)
Mn
(ppm)
Fe
(ppm)
Na
(ppm)
Comfrey 3.49 0.53 4.7 1.43 0.65 0.59 45 5 59 93 13966
Swiss Chard 3.33 0.51 6.47 1.54 0.23 0.22 37 10 59 179 278
Treatment chard:comfrey:sugar
P
(ppm)
K
(ppm)
Ca
(ppm)
Mg
(ppm)
Zn
(ppm)
Cu
(ppm)
Mn
(ppm)
Fe
(ppm)
S
(ppm)
Na
(ppm)
1 60:120:180 12553 183964 6052 9697 84.0 33.2 55.7 282 7305 15668
2 90:90:180 14147 185655 5214 11498 89.5 31.1 63.5 155 11274 22742
3 30:150:180 13911 206943 9516 8369 82.6 36.2 51.6 153 5482 11810
Control 60:120:0 9112 103097 7771 5793 55.4 35.3 59.4 112 4847 7861
Fermented Plant Juice Extract
Plant Tissue Samples

10. Results - Plating with MacConkey Agar
● FPJ samples were plated and incubated at ~35 ℃ for ~48 hours
● MacConkey Agar is selective (for gram- bacteria) & differential
(distinguishes lactose-fermenting bacteria)
○ Lac+ coliforms include E. coli, Enterobacter, etc.
○ Lac- coliforms include Salmonella, Shigella, etc
● Coliform bacteria → ferment lactose (pink), used to indicate sanitary
quality (other pathogenic organisms may be present)
Left: ~24 hours of incubation Right: ~48 hours of incubation
Above: Reference photos

11. Uninoculated
Control (60:120:0)
no sugar Trt 2B (90:90:180)
Trt 2A (90:90:180)
Trt 3B (30:150:180)
Trt 1B (60:120:180)
Trt 1A (60:120:180) Trt 3A (30:150:180)
Treatment 1 Treatment 2 Treatment 3
No visible
growth

12. Discussion and Conclusions
● Fermentations done by FPJ method (with sugar) contained a different microbial
community than the control (no sugar)
○ Addition of sugar promotes bacterial growth
● Mold growth occurred during fermentation
○ Possibly due to...
■ Vessel was not air tight
■ Too much air space in vessel
■ Plant material not being submerged in liquid (exposed to air)
■ Warm temperature (room was 68.2 F)
● Fermentations done by FPJ method (with sugar) had higher nutrient
concentrations than the control (no sugar)
End