Production of Organic Acid by Fermentation

BACKGROUND

Organic Acid

Organic acid is abundant in nature, and since ancient times, people have utilised them in their natural forms. Since ancient times, people have prepared food using fermentation techniques that result in the formation of acetic and lactic acid.

When it was discovered that acids were the primary by-product of well-known fermentation processes, industrial production using the microbiological method was initiated.

Chemical synthesis innovations during the first half of the 20th century provided new manufacturing processes that were economically viable and superseded many fermentation processes. The scenario altered in the 1990s as a result of further biotechnology advancements, environmental challenges, and vertical integration of the maize processing and fermentation industries, which greatly improved the economics of the biological method.

Microorganisms create a vast number of organic acids that have current or future uses. Some of the acids whose microbial production has been patented include citric, itaconic, lactic, malic, tartaric, gluconic, mevalonic, salicylic, gibberellic, diaminopimelic, and propionic acids.

The primary organic acid now produced by fermentation is citric acid. The first record of citric acid dates back to W. Scheele in 1784, who separated calcium citrate from lemon juice and used sulphuric acid to produce liquid citric acid.

The first chemical synthesis of citric acid from 1,3 dichloroacetone produced from glycerol took place in 1880 by Grimoux and Adam. Libieg initially proposed that citric acid is actually a three carboxylic acid in 1838.

The first person to notice citric acid as a byproduct of calcium oxalate produced by a culture of Penicillium glaucum fermenting sugar was Wehmer in 1893. He was inspired to patent the method for producing citric acid as a result of this fermentation. The first industrial fermentation employing an open-tray system was constructed on this premise in 1894. Ten years later, the factory was shut down because the fermentation process was deemed to be too prolonged and frequently contaminated.

The production of organic acids covered here includes those that are produced commercially.

REQUIREMENTS

• Aspergillus niger culture
• Potato dextrose agar medium
• Sterile distilled water
• Test tubes
• Erlenmeyer flasks
• Funnel
• Whatman filter paper
• Calcium hydroxide [Ca(OH)2]
• Sulfuric acid
• Activated Charcoal
• Vacuum evaporator
• Phenolphthalein indicator
• 0.1M NaOH

PROCEDURE

1. The Aspergillus niger culture grow on the PDA medium for 3-5 days.
2. Take loopful A. niger spores, add to the 10 ml sterile distilled water.
3. prepare fermentation medium as follows: Sucrose/ glucose – 10gm/L, (NH₄)₂SO₄ – 2.2gm/L, K₂HPO₄ – 1gm/L, MgSO₄.7H₂O – 0.05gm/L, Methanol/ Ethanol – 1-5%.^[1][3]
4. Autoclave the fermentation medium, after sterilization add 1-2 ml A. niger spore inoculum to it by aseptically.
5. Incubate it at 30˚C for 3-4 days in shaking condition.
6. Filter the medium to separate the mycelia of A. niger.
7. Add Ca(OH)₂ gradually to the filtrate to make it slurry, it become calcium citrate.^[2]
8. Filter the calcium citrate, discard the filtrate and take the calcium citrate cake treat with the sulfuric acid to precipitate the calcium, again filter the solution.^[1]
9. Collect the filtrate, add activated charcoal to remove residual impurities.
10. Filter the solution and collect the filtrate.
11. The filtrate is then concentrated in vacuum evaporator to crystallized the citric acid.^[2]
12. Estimate the citric acid by titration with help of phenolphthalein indicator against 0.1M NaOH.

CONCLUSION

The production of the organic acid by fermentation experiment was conducted successfully; we produced citric acid by using A. niger culture and purified it by using the precipitation method, and the concentration of citric acid was estimated by the titration method.

REFERENCES

1. https://gcwgandhinagar.com/econtent/document/1587535005Unit%20III%20Microbial%20production%20of%20organic%20acids.pdf
2. Marin Berovic and Matic Legisa, “Citric acid production”, BIOTECHNOLOGY ANNUAL REVIEW, Vol 13, 2007.
3. Y.D. HANG, B.S. LUH, and E.E. WOODAMS, “Microbial Production of Citric Acid by Solid State Fermentation of Kiwifruit Peel”, JOURNAL OF FOOD SCIENCE, Vol. 52, 1987.
4. F. Sanchez-Riera, “PRODUCTION OF ORGANIC ACIDS”, Bio-Technical Resources, Vol. V.
5. M.T. Liong and N.P. Shah, “Production of organic acids from fermentation of mannitol, fructooligosaccharide and inulin by a cholesterol removing Lactobacillus acidophilus strain”, Journal of Applied Microbiology, 2005.
6. Michael Sauer, Danilo Porro, Diethard Mattanovich and Paola Branduardi, “Microbial production of organic acids:expanding the markets”, Trends in Biotechnology, Vol 26 (2), 2008.
7. Zsolt Zalan, Jaroslav Hudacek, Jiri Stetina, Jana Chumchalova, Anna Halasz, “Production of organic acids by Lactobacillus strains in three different media”, Eur Food Res Technol, 2010.

Also read:

• To Study the Cultural Characteristics of Microorganisms
• Biochemical Tests for Staphylococcus
• Strain improvement of the industrially important isolate A. niger using EtBr for higher yield of the product
• Alcohol Fermentation using different substrates and its downstream processing
• Fermentation process of alcohol production
• Preparation of Baker’s Yeast from molasses
• Determination of Growth curve of yeast and compute growth rate & growth yield
• Determination of TDP & TDT of E.coli for designing of a sterilizer

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