Transcript CITRIC ACID PRODUCTION

INDUSTRIAL PRODUCTION OF
CITRIC ACID
Presented by:
Priya S.Pokale
M.Sc.I (semII)
CONTENTS:
Introduction
Applications
Microorganism
Medium
used
requirements
Recovery
References
INDUSTRIAL PRODUCTION OF CITRIC ACID

Introduction:

Citric acid is a weak organic acid.

it is a natural preservative and is also used to add an acidic, or sour ,
taste to foods and soft drinks and cakes.

Citric acid exists in greater than trace amounts in a variety of fruits and
vegetables, most notably citrus fruits, lemons and limes.

It is the product of fermentation of numerous organisms. However,
certain strains of fungus A.niger produce commercially high yield of
citric acid.

Applications of Citric Acid:
o
Acidulant in food, confectionary, and beverage (75%)
o
Pharmaceutical (10%), e.g. soluble aspirin preparation
o
industrial (15%): complexes with metals such as iron and copper
to be stabilizer of oil and fats.
A typical citric acid plant consist of four areas:

1.
Media preparation
2.
Reactor design
3.
broth separation
4.
Product recovery
Microorganism:
Citric
Aspergillus niger.
acid production is mixed growth associated, mainly take place
under nitrogen and phosphate limitation after growth has ceased.
Medium
-
requirements for high production
Carbon source: molasses or sugar solution.
Na-ferrocyanide is added to reduce Iron (1.3 ppm) and manganese
(<0.1ppm).
-
High dissolved oxygen concentration
-
High sugar concentration
-
pH<2
-
30 oC.
Invertase
Figure :Biosynthesis of
citric acid from sucrose
by A. niger.
hexokinase
phosphofructokinase
pyruvate carboxylase
aconitase
citrate synthase
malate dehydrogenase.
succinic
dehydrogenase
isocitrate
dehydrogenase
a-ketoglutarate
dehydrogenase
Bioreactor:
5-25X106
Aeration
batch or fed-batch (100m3)
A. niger spores/L may be introduced to the fermentor.
is provided to the fermenter by air sparging (0.1-0.4 vvm)
Temperature
is controlled by cooling coil.
Agitation:
50-100rpm to avoid shear damage on molds.
Fed-batch
is used to reduce substrate inhibition and prolong the
production phase one or two days after growth cessation.
Volumetric
yield: 130 kg/m3

Advantages and disadvantages of submerged
fermentation over surface fermentation:
Advantages:
•lower
total investment costs
•higher
yields of citric acid
•improved
•Reduced
•reduced
•lower
fermentation time
floor space requirements
labor costs
•simpler
•easier
process control
operations and
maintenance of aseptic conditions on an industrial scale.

Disadvantages:
o
expenses for equipment are higher
o
consumption of electrical energy is higher and
o
the process is very sensitive to short interruptions or breakdowns in
aeration and vulnerable to infections, which result not only in losses of
yield, but also in a total breakdown of respective batches.

Separation:
The
biomass is separated by filtration.
The
liquid is transferred to recovery process:
-Separation of citric acid from the liquid:
Precipitation: calcium hydroxide is added to obtain calcium citrate
tetrahydrate → wash the precipitate→ dissolve it with dilute sulfuric
acid, yield citric acid and calcium sulfate precipitate → bleach and
crystallization → anhydrous or monohydrate citric acid.
Fig. Schematic diagram of the production and purification of citric acid from
molasses by A. niger
References:
K.
Shetty, G.Paliyath, Anthony Pometto, Robert E. Levin, Food
biotechnology, by Taylor & Francis Group, LLC,2006, p-369-413.
Michael
J. Waites, Neil L. Morgan, John S. Rockey, Industrial Microbiology:
An Introduction, Gary Higton School of Applied Science, South Bank
University, London, UK,P-157-158.