The Lacto-Fermentation of Sunchokes
Materials, Procedure, and an Informal Peek at Who is Living in There
Purpose
The purpose of this project was to facilitate the anaerobic fermentation of Helianthus tuberosus tubers using a traditional salt-brine method as a selective media to encourage the growth of extant Lactobacillus spp.
Materials
For this experiment, the following materials were assembled: 1 gallon jug, 1 airlock, 1 rubber stopper of a size corresponding to the jug opening, 11 tsp of non-iodized salt, 11 tsp table sugar, 1 gallon distilled water, 2 tsp pickling spice, enough sunchoke roots to fill the container, and StarSan sanitizing solution.
Procedure
First, the airlock, rubber stopper, and glass jug were placed into the StarSan sanitizing solution using directions on the bottle and were left to soak.
From the garden, enough Helianthus tuberosus tubers to fill the jug were gathered (this was done by sight estimate). The tubers were washed and put aside. The gallon jug was rinsed and the spout was covered with plastic wrap. The tubers were coarsely chopped and added into the bottle with the pickling spices. The brine was then made by mixing 11 tsp of un-iodized salt and 11 tsp of sugar to 1 gallon of distilled water (this was done twice at half amounts in a measuring cup). The salt/sugar brine was poured over the tubers until the brine reached the top of the bottle neck. The rubber stopper and airlock were then removed from the sanitizing solution, rinsed, and affixed to the gallon bottle. The airlock was filled with distilled water to the mark. The bottle was then left for a period of three weeks.
After three weeks, a gram stain was taken of the broth and the microorganisms were identified in accordance with their Gram (+/-) status, shape, and growth habit. The broth was grown on a blood agar plate under high CO2 conditions using a candle in a sealed glass jar. A pH value was determined. The tubers were then consumed and casually evaluated for flavor and aroma.
Results
Discussion
The gram stain taken of the broth returned a positive result on the dominant microorganism in solution. The microorganisms were rod-shaped and formed short chains. The gram-positive result, cell morphology, and short chain growth habits were consistent with that of Lactobacillus spp[1]. The positive growth exhibiting both alpha-hemolytic and γ-hemolytic activity on blood agar under high CO2 conditions were also consistent with habits of Lactobacillus spp.[2] However, species determination was not possible given a lack of comparative PCR standards and the sheer number of Lactobacillus species (there are reported to be upwards of fifty Lactobacillus species)[3].
Works Cited
[1] http://wineserver.ucdavis.edu/industry/enology/winemicro/winebacteria/lactobacillus_plantarum.html
[2] http://wineserver.ucdavis.edu/industry/enology/winemicro/winebacteria/lactobacillus_jensenii.html
[3] https://microbewiki.kenyon.edu/index.php/Lactobacillus_acidophilus
