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Manufacturing of Citric Acid in Pakistan

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

 

Applications:

•    Flavour enhancers for fruits, berries and other ingredients used in the manufacture of foods and 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 the flavour 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, algaecide formulations, dyeing of fabrics, etc.

 Manufacturing process: The most important commercial source of Citric acid is the mycological fermentation of carbohydrates (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 hydrolysate obtained from corn, potato or wheat starch. Citric acid is manufactured by the following processes:

a)    By fermentation of cane or beet molasses either by surface fermentation or submerged fermentation. 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 of either sucrose or dextrose. The fermentation medium is then aerated continuously by bubbling air 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 raw material used, are introduced to the mash to produce pre-purified solution of Citric acid. After the recovery of pre-purified CA solution, the vats are refilled with nutrients to repeat the process. Recovery of Citric acid from broth is to be done carefully for maximum yield. The solids are filtered from the solution and the isolated solution is then treated with activated carbon, cation and anion exchange resins to recover purified Citric acid. The anion exchange resins 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 as the largest importer and China as the largest exporter. It may also be noted that almost half of the 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 and detergent market. New growth will also be seen in industrial applications such as plasticizers and green cement. In Europe, the Citric acid manufacturers have been under pressure due to tough competition from Chinese suppliers. In Asia, other than China, consumption is highest in India, Indonesia, Thailand and the Republic of Korea. World wide growth is expected to remain at 6-7% per year over the next few years. The general perception that production capacity has been more then demand may not hold any longer as growth in demand coupled with closure of some European plants may level out excess capacity in the next year or two. In the global market Europe, USA, China and others hold 35%, 33%, 20% & 12% share respectively. Food & beverages, pharmaceuticals, detergents, metal cleaning, textile dyes, cosmetics and others have 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 through imports, mainly from China. The import figures, as shown in table below, show the rise in demand. It is also evident that the unit prices of Citric acid are also on the rise. It makes a good case for putting up an investment in Pakistan to industrially manufacture Citric acid for local consumption as well as exports. The domestic market is already protected enough as Citric acid (2918.1400) attracts custom duty on import at the rate of 10% advance. Furthermore the by-products of the Citric acid manufacturing process can be used in cattle feed, fertilizer and other industrial applications.

 

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

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