insights of production and downstream processing of two industrially important acids(fermentation technology).

1. 1 . CITRIC ACID
2. LACTIC ACID
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Production and downstream
processing of organic acids.
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MSc II

2. Organic acid
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 Organic acids are organic compounds that possess
acidic properties. One of the most common organic
acids is carboxylic acid, which has the molecular
formula RCOOH. Other common organic acids include
sulfonic acid and alcohol
 Organic acids can be used to manufacture a variety of
products.
 If we look at our food industry, citric acid is a type of
organic acid found in products such as sodas and
canned tomatoes.
 Acetic acid is a very well known organic acid used to
make vinegar. They are also used in pharmaceutical
production, leather tanning, and the manufacture of
other organic chemicals.

3. Introduction - Citric acid
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 Molecular formula C6H8O7
 Citric acid produced by fermentation and suitable
pH is around 3-6

4. Citric acid
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Citric acid is widely used in the food industry as an
acidulant and flavouring agent in beverages,
confectionery and other foods in leavening systems
for baked goods.
As a food constituent, its use is unrestricted
because it has GRAS status.
This organic acid also has many non-food
applications.
They include roles in maintaining metals in
solution for electroplating, as a cleaning and
‘pickling’ agent for metals, and as a replacement for
polyphosphates in the detergent industry, along
with several pharmaceutical uses.

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Until the 1920s citric acid was mainly prepared
from lemon juice, but in 1923 Pfizer began
operating a fermentation- based process in the
USA.
The production organism was the filamentous
fungus Aspergillus niger, an obligate aerobe,
which was grown in surface culture on a medium
of sucrose and mineral salts
Since the late 1940s, submerged fermentations
have become the principal mode of production.
Many microorganisms, including filamentous
fungi, yeasts and bacteria, can be used to produce
this primary metabolite.

6. CITRIC ACID BIOSYNTHESIS
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 The metabolic pathways involved in citric acid
biosynthesis are the Embden–Meyerhof–Parnas
(EMP) pathway and the TCA cycle.
 A. niger also operates the pentose phosphate pathway,
which can compete with glycolysis for carbon units.
 But in order to accumulate citrate, its onward
metabolism (continuation of the cycle) must be
blocked.
 This is achieved by inhibiting aconitase, the enzyme
catalysing the next step in the TCA cycle.
 Inhibition is accomplished by removal of iron, an
activator of aconitase

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 Consequently, during citrate accumulation, the TCA
cycle is largely inoperative beyond citrate formation
 Hence the importance of the anaplerotic routes of
oxaloacetate formation.

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11. FERMENTATION PROCESSES USED IN
CITRIC
ACID PRODUCTION
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1. Surface and solid-substrate fermentations
2. Submerged processes

12. Surface and solid-substrate fermentations
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 These methods use simple technology and have
low energy cost, but are more labour intensive.
 Liquid surface methods involve placing the
sterilized medium, usually containing molasses
plus various salts, into shallow (5–20 cm deep)
aluminium or stainless steel trays stacked in an
aseptic room.
 The trays are inoculated by spraying with A. niger
spores, either a spore suspension or dry spores.
 Solid-state fermentation processes for citric acid
production are small-scale operations.

13. Submerged processes
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 More than 80% of the worldwide supply of citric acid is
produced using submerged batch fermentation in stirred tanks
or larger airlift fermenters.
 These fermentations mostly use beet or cane molasses as the
carbon source.
 Unlike surface methods, vegetative inocula, rather than
spores, are normally used.
 These fermentations are highly aerated and maintained at
30°C.
 For the initial growth phase, the pH starts at 5–7, but must
then be kept below 2
 Overall yields of 0.7–0.9 g citrate per gram glucose can be
attained in these submerged fermentations with productivities
of up to 18.0kg/m3 per day.
 Smaller volumes of citric acid are also produced using yeasts
such as Candida guilliermondii and Yarrowia (formerly

14. CITRIC ACID RECOVERY
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 First step is the removal of fungal mycelium from the
culture medium.
 Further polishing filtration may be necessary to
remove residual mycelia and precipitated oxalate.
 The resulting clarified solution is heated and lime
(CaO) is added to form a precipitate of calcium citrate.
 This is separated by filtration and treated with
sulphuric acid to generate citric acid and a precipitate
of calcium sulphate (gypsum).
 Following filtration, the dilute citric acid solution is
decolorized with activated carbon and evaporated to
produce crystals of citric acid.
 These crystals are recovered by centrifugation, then
dried and packaged.
 Alternate recovery methods used are solvent
extraction, ion-pair extraction and electrodialysis.

15. Lactic acid
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 Lactic acid is with the formula CH3CH(OH)CO2H. In its
solid state, It is a white and water-soluble. In its liquid
state, it is clear. It is produced both naturally and
synthetically.
 Lactic acid is primarily used in the food industry, where
30000 tonnes are incorporated into food each year to act as
a preservative, an acidulant, or in the preparation of dough
conditioners.
 Its salts are also used in other industries, for example,
antimony lactate is used as a mordant in dyeing and sodium
lactate has applications as a plasticizer and corrosion
inhibitor.
 Lactic acid is produced in 20000–100000L anaerobic
fermentations using Lactobacillus delbruckii or other
homolactic bacteria such as L. bulgaricus

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 The media normally contain a complex nitrogen
source and vitamin supplements, along with up
to 12% (w/v) sucrose or glucose as a carbon and
energy source.
 These carbohydrates are metabolized to pyruvate
via the EMP pathway, which is then converted to
l (+) lactate by l-lactate dehydrogenase.
 Lactic acid fermentations are operated at 45–
60°C with a pH of 5–6. They last for 4–6 days
and can achieve yields of over 90% based on
sugar supplied

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18. Recovery
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 It is very challenging to recover pure lactic acid
from medium
 Recently great amount of research work is being
carried out regarding downstream processing of
lactic acid but success rate is very low.
 To recover and purify the L-lactic acid produced
from the microbial fermentation media
economically and efficiently, ion exchange
chromatography is used among the variety of
downstream operations.
 Nanofiltration and microfiltration membrane
 Desalting electrodialysis

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Source -V HÁBOVÁ, K MELZOCH and RYCHTERA {Modern
Method of Lactic Acid Recovery

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 Out of various processes the comparative studies
showed that:
 Two stage electrodialysis is a suitable and efficient
technique for the recovery of lactate ions from the
pretreated fermentation broth and the subsequent
conversion into lacticacid with respect to
environmental aspects

21. References
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 Belén Max1; José Manuel Salgado , BIOTECHNOLOGICAL
PRODUCTION OF CITRIC ACID, Brazilian Journal of Microbiology
(2010) 41: 862-875
 H V., M K., R M. (2004): Modern method of lactic acid
recovery from fermentation broth. Czech J. Food Sci., 22: 87–
94.
 Tayyba Ghaffar , Muhammad Irshad ,*, Zahid Anwar, Tahir
Aqilb,Zubia Zulifqar, Asma Tariq , Muhammad Kamran , Nudrat
Ehsan . Recent trends in lactic acid biotechnology: A brief
review on production to purification , 11 March
2014,Accepted 15 March 2014,Available online 13 April ,Journal of
Radiation Research and Applied ,Sciences journal homepage: http:
/ /www.elsevier.com/locate/jrras.
 Industrial Microbiology: An Introduction( Michael J.
Waites)

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Thank you!!!
For your attention
Thought of wise—
“All power is within you; you can do anything and everything.”
-SWAMI VIVEKANANDA

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 Dr A.P.J Abdul Kalam