Lactic acid Production (edited by Ayan Santra)

1. lactic acid Production
by Ayan Santra

2. • Lactic acid was the first organic acid produced by fermentation
process carried out in 1880.
• it is a naturally occurring organic acid that can be used in a wide
variety of industries, such as the cosmetic, pharmaceutical, chemical,
food, and, most recently, the medical industries. It can be made by
the fermentation of sugars obtained from renewable resources,

4. biosynthesis

5. microorganisms

6. ferementation
• Lactic acid production is carried in 25-125 klt fermenters. Lactic acid is
quite corrosive, therefore, wooden fermenters are used commercially
rather than metal fermenters. The pH of the fermentation broth is
maintained at 5.5-6.5 by using calcium carbonate.
• As more and more lactic acid is formed it may become toxic to the
organism. Hence, neutralization of accumulated acid is done by the
continuous addition of calcium hydroxide. Generally, the fermentation
duration is 5-10 days. It can also be completed in 72 hours if 12 to
13% of glucose is used in the medium and pH is maintained at 6.3-6.5
by continuous neutralization of the acid formed.

7. • The fermentation broth is gently agitated to keep the uniform
distribution of nutrients and air. Though temperature is generally
maintained at 45-50°C, maintenance of particular range of
temperature depends to some extent on the type of organism
employed. For example Lactobacillus delbrueckii and L.bulgaricus
requires 45-50°C, while L.casei and L.pentosus requires 30°C.
• Theoretically two molecules of lactic acid are produced from one
molecule of glucose. Over 90% of this theoretical yield is actually
attained in practice.

8. harvest
• 1. The fermentation broth is filtered by using porcelain filters to separate the bacterium.
• 2. The filtrate is acidified with sulphuric acid to regenerate lactic acid, to precipitate calcium as calcium sulphate
and is washed.
• 3. The washed filtrate is treated with activated carbon to remove organic impurities.
• 4. Repeated refining and evaporation steps are undertaken to get higher percentage of lactic acid to the extent of
50-60%.
• 5. It is then treated with ferrocyanide to remove heavy metals, if any, like copper.
• 6. It is finally purified by passing through ion exchange resins.

9. uses
• . It is also used to treat the fibers in the textile industries and laundry.
• 4. Calcium lactate is employed as baking powder and as a source of
calcium in pharmaceutical industries.
• 5. Pure lactic acid is used in plastic industry.
• 6. Ethyl lactate is used in preparation of anti-inflammatory drugs.

10. • 8. As a blood coagulant and dietary calcium source.
• 9. In the manufacture of cellophane resins, biodegradable plastics
and some herbicides and pesticides.
• 10. It is used in food industry as acidulent as it has strong odour or
flavour. Ethyl and butyl lactate are used as flavouring ingredients.

11. references
• www.google.com