Manufacturing of Citric Acid in Pakistan

Citric Acid (C6H8O7) is a weak organic acid and a natural preservative. It was first discoveredby 8th century Islamic alchemist Jaber Ibn Hayyan. Citric acid was first isolated in 1784 by theSwedish chemist Carl Wilhelm Scheele. Industrial scale production started in 1890. Citric acidis naturally found in greater than trace quantities in citrus fruits. Lemons and limes have highconcentration of Citric acid then oranges and tangerines. However, on commercial scale it isproduced out of an industrial fermentation process to be used in a variety of applications. It isin the form of white or translucent solid and bitter in taste. Varieties of Citric acid includeMonohydrate Citric acid, Anhydrite Citric acid and Sodium Citrate. It should be stored underdry ambient conditions in well closed containers as high humidity and elevated temperaturemay result in caking.

 

Applications:

•    Flavour enhancers for fruits, berries and other ingredients used in the manufacture of foodsand candies.•    pH adjuster in the manufacture of gelatine desserts, jellies, jams, etc.•    Acidulent in the manufacture of soft drinks, syrups and carbonated drinks.•    Preservative in processed food and other processed food products.•    Citric acid is employed in pharmaceutical preparations as an acidulent and to enhance theflavour of syrups, solutions and elixirs.•    The Citrate ion is used as anticoagulant for intravenous applications.•    The cosmetic industry uses Citric acid in hair rinses, hair setting fluids, hair lustre,astringent lotions and bleaching lotions.•    Metal cleaning from grease, dirt, oil, rust, etc.•    Aluminium brightener formulations•    Removal of boiler oxides•    Electro pickling of metals•    Electro plating of metals•    Preparation of tanning liquors•    Domestic washing preparations•    Intermediate for many chemical preparations•    Citric acid is used in floor cements, linoleum, inks, silvering compounds, algaecideformulations, dyeing of fabrics, etc.

 Manufacturing process:The most important commercial source of Citric acid is the mycological fermentation ofcarbohydrates (such as beet or cane molasses). Citrus fruits and pineapples are also used.There are processes where Citric acid can be produced from Hydrogenated starch hydrolysateobtained from corn, potato or wheat starch. Citric acid is manufactured by the followingprocesses:

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a)    By fermentation of cane or beet molasses either by surface fermentation or submergedfermentation.b)    Recovery from lemon juice and pine apple waste (less preferred).c)    By fermentation of glucose derived from Hydrogenated starch hydrolysate.

Out of the above, deep fermentation is the main commercial route to manufacture Citric acid.The raw materials are first processed to obtain the fermentation medium which is in the form ofeither sucrose or dextrose. The fermentation medium is then aerated continuously by bubblingair through it. This process is carried out in giant fermentation vats using batch production.Sucrose solution is pumped into the vats where fungus spores are added and allowed to grow.Mutant strains of Aspergillus Niger (fungi), specially selected according to the type of rawmaterial used, are introduced to the mash to produce pre-purified solution of Citric acid. Afterthe recovery of pre-purified CA solution, the vats are refilled with nutrients to repeat theprocess. Recovery of Citric acid from broth is to be done carefully for maximum yield. Thesolids are filtered from the solution and the isolated solution is then treated with activatedcarbon, cation and anion exchange resins to recover purified Citric acid. The anion exchangeresins recover Citric acid by operating at a pH below the first ionization constant.

 

The World Scenario:The trend in world trade of Citric acid indicates an increasing demand of the product.

The above table indicates that there has been rising trend in international trade with USA asthe largest importer and China as the largest exporter. It may also be noted that almost half ofthe import demand is met by China through its exports.In the USA, Citric acid demand is likely to continue growing due to growth in beverage anddetergent market. New growth will also be seen in industrial applications such as plasticizersand green cement. In Europe, the Citric acid manufacturers have been under pressure due totough competition from Chinese suppliers. In Asia, other than China, consumption is highest inIndia, Indonesia, Thailand and the Republic of Korea. World wide growth is expected to remainat 6-7% per year over the next few years. The general perception that production capacity hasbeen more then demand may not hold any longer as growth in demand coupled with closure of

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some European plants may level out excess capacity in the next year or two. In the globalmarket Europe, USA, China and others hold 35%, 33%, 20% & 12% share respectively. Food& beverages, pharmaceuticals, detergents, metal cleaning, textile dyes, cosmetics and othershave 60%, 12%, 12%, 6%, 5%, 3% and 2% share in global consumption respectively.

 

Citric acid in Pakistan:Citric acid is not produced or manufactured in Pakistan. All of its requirements are met throughimports, mainly from China. The import figures, as shown in table below, show the rise indemand. It is also evident that the unit prices of Citric acid are also on the rise. It makes a goodcase for putting up an investment in Pakistan to industrially manufacture Citric acid for localconsumption as well as exports. The domestic market is already protected enough as Citricacid (2918.1400) attracts custom duty on import at the rate of 10% advance. Furthermore theby-products of the Citric acid manufacturing process can be used in cattle feed, fertilizer andother industrial applications.

 

Recommendation:Considering the fact that Citric acid can be produced from cane molasses (available inabundance in Pakistan) by fermentation process, the project has excellent relevance to areasin the vicinity of sugar mills in Punjab and Sindh provinces.

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