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1. CITRIC ACID
1.
PRODUCT CHARACTERISTICS
Chemical formula
Appearance
Storage
(CH2COOH)2C(OH)COOH
Citric acid is in the form of white or translucent solid.
Stored under dry ambient conditions in well closed containers
Crystalline anhydrous Citric acid can be stored in dry form without
difficulty, although highly humid conditions and elevated temperatures
should be avoided to prevent caking.
Indian Standard Specification
Characteristics
Citric acid, % by weight (as monohydrate)
min.
Sulphate (as SO4), % by wt. Max
Halides (as Cl) ppm, by wt. max.
Sulphated ash (% by wt. max.)
Heavy metals (as Pb) ppm, by wt. max.)
Iron (Fe) ppm, by wt. max.
Oxalate (as C2H2O4) wt. % max.
Water, % by wt. max.
Readily carbonizable substance
Arsenic, ppm by wt max.
2.
Grade 1
99.7
Grade 2
99.5
0.002
5
10
0.01
0.10
5
10
1
0.005
to pass the test
8.8
to pass the to pass the test
test
1
1
PRODUCT APPLICATIONS
The food and pharmaceutical industries utilise Citric acid extensively because of its high
solubility, pleasant sour taste, very low toxicity, ready assimilability.
Citric acid also finds application in some cosmetic preparations and in metal and
chemical cleaning, electropickling and copper plating,secondary oil recovery and other
industrial uses.
There are three popular variety of Citric acid, namely Monohydrate Citric acid,
Anhydrate citric acid and Sodium citrate.
Food
Candy: Citric acid is added to enhance the flavours of fruit, berries and other ingredients
used in the manufacture of candy. Citric acid, when added to the candy batch during the
cooking process (a procedure known as "doctoring" the batch), causes conversion to
simple sugars which would not crystallise readily.
Desserts: In the manufacture of Gelatin desserts, careful control of pH is important, as the
setting qualities of the gelatin are a function of pH. Citric acid not only permits pH
adjustment to the optimum (3.0 to 3.5) but adds flavour and refreshing properties that
account for its popularity and wide use. The solubility and non toxic qualities of Citric
acid are also important in this application.
Jellies, Jams and preserves: Citric acid serves to adjust the pH of jellies, jams or preserve
mixtures to the optimum range, where pectin can act most effectively. Certain foods
would not naturally contain sufficient acids to give the proper pH. The use of Citric acid
also gives the desired degree of flavour, which are important to jellies. After the jelly
juice-pectic sugar mixture is cooked and concentrated, Citric acid is added. Many
processors use juice concentrates as a starting point and add Citric acid and other
ingredients directly to the concentrates.
Soft drinks and syrups: Since Citric acid occurs naturally in fruits, it is the preferred
acidulant for carbonated and still beverages. Citric acid adds refreshing properties to the
drink, often duplicating natural fruit products. It acts as a preservative in syrups and the
finished beverage and aids in obtaining the desired bouquet by modifying the sweet
flavours. It sequesters harmful metals which cause haze and accelerates deterioration of
colour and flavour.
The amount of Citric acid added to soft drinks depends upon the flavour and the
particular end uses intended. Some syrup flavours, such as grape or orange, contain as
little as 0.5 OZ of Citric acid per gallon of syrup, whereas the Citric content of certain
mixers may be as high as 4 OZ per gallon. Sufficient Citric acid should be added to give
a final pH of 2.5 to 4.5.
Anhydrous Citric acid is generally used as a 50% solution prepared by dissolving 2
kilograms of anhydrous Citric acid in enough water to make 5 litres of final solution.
Soft drink tablets: Tablets containing Citric acid, an alkaline salt, a sweetening agent and
various flavours have been placed on the market, which effervesce when dissolved in
water. Carbonation of the water solution is caused by the release of carbon dioxide when
Citric acid reacts with a metal bicarbonate.
Fruit and vegetable juices: In general, lower pH value exert a protective effect on fruit
juice pigment. Strawberry fountain syrup in particular is colour stabilized by Citric acid.
The natural flavours of grape and other fruit juices are greatly enhanced by the tartness
which Citric acid gives. The lower pH increase the resistance to spoilage.
Frozen fruits: Citric acid is used for two purposes in the processing of fruits for frozen
packs. First, since lye peeling operations are common, it is important after a thorough
water washing to neutralise the residual lye by dipping fruits or vegetables in 1 to 2%
Citric acid solutions. Since residual alkali destroys natural ascorbic acid, it is extremely
important that the last traces be neutralised. The Citric acid further stabilises Ascorbic
acid by lowering the pH to inactivate the oxidative enzymes present. In addition, the
Citric acid retards destruction of Ascorbic acid by binding harmful metal contaminants.
Citric acid in addition to D-erythorbic acid (D-araboascorbic acid) or sodium-Derythorbate, when added to products such as peaches, apricots, plums, pears and cherries
protects the fruit from undesirable colour and flavour changes due to oxidation. Citric
acid complexes contain metals which accelerate oxidation. The net result is that
discolouration is retarded and flavours and natural vitamins are protected.
Pharmaceuticals:
The citrate ion is rapidly and almost completely oxidised, less than 1% being excreted
unchanged in the urine. Intravenous injection shortens the coagulation time of the blood,
but in vitro the citrate ion acts as an anticoagulant.
The free acid is employed in pharmaceuticals preparations as an acidulant and to enhance
the flavour of syrups, solutions and elixirs.
With Sodium bicarbonate, Citric acid is used in many effervescent powders and tablets to
liberate carbon dioxide on the addition of water in the large scale manufacture of these
tablets and powders.
Citric acid salt such as sodium citrate and potassium citrates are also used in the mixture.
The free acid may also be employed as an acidulant in mild astringent preparations.
Many of the salts are important pharmaceuticals.
Illustrative list of Formulations using citrates
S.No.
1.
2.
3.
4.
5.
6.
7.
8.
Type of Formulations
Antianaemic iron tonic
Antianaemic liver vitamin tonic
Vitamin amino acid tonic
Liver tonic
Antipyretic analgesic mixture
Cough syrup
Cold, cough and fever remedy
Anti dysentry anti syrup diarrhoeal
Citrates used
Ferric ammonium citrate
Choline dihydrogen citrate
Choline dihydrogen citrate
Choline dihydrogen citrate
Potassium citrate
Sodium citrate
Citric acid
Caffeine citrate Piperazin citrate
Diethyl carbamazin citrate
Ferrous calcium citrate
9.
Antiestogens ie, a fertility
Clomiphene dihydrogen citrate inducer
Cosmetics:Hair Rinses and setting fluids: Citric acid rinses have enjoyed wide popularity for many
years. Hair rinsed with a small quantity of the Citric acid in water becomes lustrous. In
addition, Citric acid added to a solution of dextrin and glycerol with ammonium chloride,
hydrogen sulphide and potassium hydroxide to pH 10, makes a hair setting fluid that has
excellent holding opportunities.
Lotions: Citric acid has been suggested for use in astringent lotions, to treat oily skin
having large pores and in bleaching lotions where a mild acid is preferred to adjust pH
and to acts as a sequestrant.
Other industrial applications:
Many of the industrial applications of Citric acid are based not only upon its acidic
properties, but also upon its powerful sequestering action with various transient metals,
such as iron, copper, nickel, cobalt, chromium and manganese.
Metal cleaning: Before the layers of rust, scale and tarnish can be removed efficiently
from metals, the grease, dirt and oil must be eliminated by precleaning. Most oil and
grease removal is accomplished with organic solvents, emulsions, or alkali systems. The
Citric acid dip follows to remove tarnish and rust and produces a shiny surface.
Certain aluminium brightener formulations also contain Citric acid, as do general metal
cleaners and polishes for home use. Citric acid is the product of choice for home use
because it is non toxic and completely safe. Citric acid, in combination as a paste or
powder to copper surfaces, produces a brilliant shine.
Rust and scale removal: Citric acid and Ammonium citrate has been used for rust and
scale removal for many years.
Ammonical Citric acid solutions in addition to their efficient cleaning action, offer the
desired advantage of being nontoxic. Personnel are not exposed to the hazards,
customarily experienced with other compounds.
Chemical cleaning: Modern high pressure steam generators contain various sections
fabricated from austenitic materials which required monochloride containing Citric acids
for cleaning. Citric acid also serves to clean atomic reactors and chemical process
equipment.
The ammoniated Citric acid is also used for the removal of boiler oxides.
Electro pickling: Citric acid at levels of 0.1% is extremely effective in the electropickling
of copper and its alloys. This process is generally accomplished in the presence of
aqueous solutions of ferric salts. Citric acid in combination with these salts removes
scale, produces a bright, smooth, natural surface and prevents discolouration. Citric acid
enjoys use in alkaline anodic pickling and when combined with sulphuric acid in pickling
processes, contributes greatly to the stability of the pickling solution.
Copper plating: The addition of Citric acid to copper cyanide plating solutions increases
both cathode and anode efficiency and yields smooth, lustrous, light and streak free
surfaces. The desirable effect on citrate ion in copper plating baths include a bright
surface, a smooth copper deposit in a short period, reduced effect of impurities and
greater efficiency in plating on stainless steel magnesium, zinc, lead and aluminium.
Secondary oil recovery: Citric acid a powerful sequestering agent, keeps iron in solution
and prevents injection rates from decreasing as a result of iron plugged conditions, When
a previously plugged well is cleaned, Citric acid prevents replugging.
Tanning: Citric acid as a component of the tanning liquors does not cause undesirable
smelling of the hide. The use of Citric acid to adjust the pH of tanning liquors has been
recommended as it is the acid, whose properties must closely approach those of the
mixture of acids naturally present in tanning materials.
Bottle washing compounds: In hard water areas, the use of caustic bottle washing
compounds results in insoluble residues on bottles and equipment. Citric acid is used to
prevent the formation of hard water scale.
Printing: Citric acid acts as a stabiliser in diazo-sensitised materials used to make diazo
paper. The most important function of this stabiliser is to prevent the "precoupling" of
diazo and coupler while the product is still on the shelf.
Miscellaneous: Citric acid is the starting point in the manufacture of various esters and of
the citrates of sodium, ammonium, bismuth, calcium. ferric iron, lithium, magnesium,
manganese, potassium and strontium.
Citric acid is also used in floor cements, linoleum, inks, silvering compounds and algicide
formulations as well as in the dyeing of fabrics, in the stablization of peroxides and in the
processes for removal of contamination of radioactive isotopes.
New applications
Pesticide formulations:
The Scientists tentatively suggest that the inclusion in
pesticide formulations of a chemical like Citric acid would help lower insecticide
resistance in insects.
Food preservation:
fish.
Citric acid and Potassium sorbate as additives in ice to preserve
The Food and Drug Administration of USA has approved recently the use of ice
containing 0.2% Citric acid and 0.05% potassium sorbate for the preservation of whole
fish. Two additives should be both of food grade.
Insecticides:-The scientists at the Central Food Technological Research Institute, Mysore
studied the effect of feeding Citric acid to houseflies and their resistance to insecticides.
The insecticides studied were, Permethrin, Malathion, Bromophos and Lindane.
Citric acid controls morphine loss from poppy:Scientists trying to prevent loss of Morphine from the fresh latex of poppy plants have
found that Citric acid helps them in the task. The Morphine content of poppy latex
declines on contact with air and sunlight and researchers are trying to identify chemicals
that when sprayed on plants can prevent this loss. They attribute the loss to activation of
the enzyme
peroxidase.
Studies by scientists at the Acharya Narendra Dev University of Agriculture and
Technology, at Faizabad in Uttar Pradesh, show that Citric acid is the most effective
agent. Others that stem morphine loss are potassium sulphate, zinc sulphate and calcium
carbonate, Ethelating agents such as Citric acid, tartaric acid and ascorbic acid inhibit
deterioration of the latex when sprayed along with sodium chloride.
3.
IMPORTS
Around 7000 tonnes per annum
4.
EXPORT DETAILS
Small quantity
Anti dumping duty
The Government notified that the anti dumping duty on Citric Acid should not exceed the
difference between the export price and landed value of Rs.58,925 per tonne.The
preliminary duty was recommended on October 20, 1998 and notified on November 24,
1998 This had effect up to and inclusive of May 23,1999.
5.
INDIAN MANUFACTURERS
*
*
*
Citric India Ltd., Maharashtra
Citurgia Bio Chemicals Ltd., Mumbai
Bharat Starch Industries Ltd.,Baroda (reported to be not in operation)
6.
DEMAND SUPPLY TRENDS
Indian demand level
Around 12,000 tonnes per annum
Growth rate in demand
8 to 9% per annum
7.
MANUFACTURING PROCESS
The most important commercial source of Citric acid is the mycological fermentation of
carbohydrates (such as cane molasses). Citrus fruit and pine apples are also used.
Citric acid is manufactured by the following processes.
1.
By fermentation of molasses either by surface fermentation or submerged
fermentation
2.
Recovery from lemon juice and pine apple waste
Deep fermentation is the main commercial route to manufacture Citric acid.
The fermentation medium which consists of dextrose or sucrose is aerated continuously
by bubbling air through it.
Citric acid can also be produced from corn sugar using submerged culture fermentation.
Other process include liquid surface fermentation where a mixture based on beet or cane
molasses is fermented in shallow Aluminium pans.
Solid state fermentation uses moist estimated to be 80 of worldwide capacity.
Technology development
Improving the efficiency of the conventional Citric acid fermentation process:Strathelyde and Glasgow Universities in Scotland carried out joint research for the
manufacture of Citric acid. The conventional Citric acid process is based on fermentation
of sucrose solution by the fungus Aspergillus Niger.
Commercial process is carried out in giant fermentation vats using batch production.
Sucrose solution is pumped into the vat, where fungus spores are added and allowed to
grow and then Citric acid is collected and the vat is refilled with nutrient to repeat the
process.
Recovery of Citric acid:Anion exchange resin like DOWEX 66 can be used to recover Citric acid from
fermentation broth by operating at a pH below the first ionization constant, followed by
elution with an alkaline solution.
Basee and Sirkas have used a hollow fiber non dispersive extraction, made of
hydrophobic polypropylene (250 microns id and 290 microns od) for extracting Citric
acid with trioctylamine, dissolved in MIBK; Back extraction is done with NaOH.
The Cahn method:
An unusual method of Citric acid production was advocated by F.J. Cahn in 1934 and
reported by W.L.Owen and also by Prescott and Dunn.
The Cahn process utilised blackstrap molasses as the source of fermentable sugar and
sugarcane bagasse as an inert material for the suspension of the mould mycelia. The
fermentation was carried out in shallow trays with false bottoms of iron screens and the
impregnated bagasse which contained 15.3 parts bagasse, 63.7 parts added water and 21.0
parts molasses, was spread as a layer 40 mm thick resting on the screen. No forced
aeration was necessary, as sufficient draught was created by the heat of oxidation. The
fermentation was completed in less than 4 days and the yield of acid on molasses was
about 19% (i.e. about 38% of fermentable sugars).
This process has not been used commercially but with certain modifications it could
probably have been utilised where small scale production is envisaged in cane sugar
countries, provided the steam and water consumption are brought down to more
reasonable figures.
8.
GLOBAL SCENARIO
Global demand
7,04,000 tonnes per annum
Global Citric acid consumption is estimated to be 80% of worldwide capacity.
In developed countries, 65% of Citric acid consumption is in food and beverages and
20% in household detergents.
Estimated global growth rate in demand: 4 to 5% per annum
Global major players
Plant capacity (100% anhydrous)
Company
Location
Jungbunzlauer
Archer Daniels
Midland
Perhofen,Austria
Southport
NC,US
Ringaskiddy,
Co Cork, Ireland
Tienen, Belgium
Eddyville, Iowa,US
Dayton, Ohio, US
Hoffmann-La Roche
Cargill
Tate & Lyle
Global market pattern
Europe
35%
Capacity in `000 tonnes per
annum
136
98
45
90
72.6
60
US
China
Others
33%
20%
12%
Global consumption pattern
Food and beverages
Pharmaceuticals
Detergents
Metal cleaning solutions
Textile dyes
Cosmetics
Others
9.
60%
12%
12%
6%
5%
3%
2%
RECOMMENDATIONS
Considering the fact that Citric acid can be produced from cane molasses by fermentation
process, the project has excellent relevance to Tamil Nadu in view of the large
availability of Molasses in the state.
Recommended capacity
15000 tonnes per annum
Estimated project cost
Rs.50 crores