Citric acid Production - Dr. S. Sivasankara Narayani

1. Y5E02 BIOPROCESS
TECHNOLOGY – Unit
IV
Citric acid Prduction
Dr. S. SIVASANKARA NARAYANI
ASSISTANT PROFESSOR
DEPARTMENT OF MICROBIOLOGY
AYYA NADAR JANAKI AMMAL COLLEGE
SIVAKASI
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2. Intro
• Citric acid (2-hydroxy-1,2,3- propane tri carboxylic acid) is the most important
commercial product, which is found in almost all plant & animal tissues.
• Citric acid is the most important organic acid produced in tonnage and is
extensively used in food and pharmaceutical industries.
• Citric acid is a weak organic acid found in citrus fruits(lemon).
• It is good ,natural preservative and is also used to add an acidic taste to food and
soft drinks.
• More than million tonnes are produced every year by fermentation
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3. History
• The discovery of citric acid has been credited to the 8th century Muslim alchemist
Jabir Ibn Hayyan (Geber).
• Citric acid was first isolated in 1784 by the Swedish chemist carl Wilhelm Scheele,
who crystallize it from lemon juice.
• Industrial scale citric acid production began in 1890 based on the Italian citrus fruit
industry.
• In 1893, C. Wehmer discovered penicillin mold could produce citric acid from sugar.
• However, microbial production of citric acid did not become industrially important
until world war I disrupted Italian citrus exports.
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4. PRODUCTION TECHNIQUES AND RAW MATERIALS
Classified raw materials used for citric acid production in to two groups:
(i) with a low ash content from which the cations could be removed by standard
procedures (e.g. cane or beet sugar, dextrose syrups and crystallized dextrose);
(ii) (ii) raw materials with a high ash content and high amounts of other non sugar
substances (e.g. cane and beet molasses, crude unfiltered starch hydro-lysates).
Several attempts have been made to produce citric acid using molasses, which is preferred
due its low cost and high sugar content (40-55%).
The composition of molasses depends on various factors, e.g. the kind of beet and cane,
methods of cultivation of crops and fertilizers and pesticides applied during cultivation,
conditions of storage and handling (e.g. transport, temperature variations), production
procedures, etc..
beet molasses is preferred due to its lower content of trace metals.
Generally, cane molasses contains calcium magnesium, manganese, iron and zinc, which
have a retarding effect on the synthesis of citric acid.
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5. FERMENTATION TYPES
• surface fermentation
• submerged fermentation
• solid state fermentation
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6. Note
Surface Fermentation
• In the surface techniques, the
microorganisms are cultivated on the
surface of a liquid or solid substrate.
• These techniques are very
complicated and rarely used in
industry. A. niger forms a mycelium
layer on the liquid surface of the
aluminum or stainless steel trays
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7. Note
• Submerged fermentation is a method
of manufacturing biomolecules in
which enzymes and other reactive
compounds are submerged in a liquid
such as alcohol, oil or a nutrient broth.
• Submerged Fermentation
(SmF)/Liquid Fermentation (LF) SmF
utilizes free-flowing liquid substrates,
such as molasses and broths
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8. Note
• Solid-State Fermentation (SSF)
• involves the growth of microorganisms on
moist solid particles, in situations in which
the spaces between the particles contain a
continuous gas phase and a minimum of
visible water.
• Although droplets of water may be present
between the particles, and there may be thin
films of water at the particle surface, the inter-
particle water phase is discontinuous and
most of the inter- particle space is filled by the
gas phase.
• The majority of the water in the system is
absorbed within the moist solid-particles the
more general term “solid-substrate
fermentation” is used to denote any type of
fermentation process that involves solids,
including suspensions of solid particles in a
continuous liquid phase and even trickling
filters
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14. Factors affecting citric acid Production
• Nitrogen source pH Aeration Trace elements Temperature
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17. Clarification
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sivasan91@gmail.com
sivasan_sf549@anjaconline.org

18. Questions to think
• What are the steps involved in the citric acid production?
• What is submerged fermentation?
• What is solid state fermentation?
• Role of calcium oxide?
• Pointout the use of citric acid
• What is surface fermentation?
• Organisms involved in the citric acid production
• Term refer to the study of oenology
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