Question

A good product of citric acid is :

• A. Aspergillus
• B. Pseudomonas
• C. Clostridium
• D. Saccharomyces

Answer 1

The correct option is A Aspergillus

Citric acid is used for a multitude of purposes around the world, most obviously as a food & drink additive (E330) for flavouring or as a preservative but also for purposes as diverse as soaps & detergents, hair dying, explosives, industrial pipe cleaning, photography and many more. The ability of A. niger to make citric acid was originally identified in 1917 by James Currie and industrial-level production began two years later by Pfizer. Up to that point when citric acid was needed citrus fruit juices were employed. The process of citric acid production by A. niger:

• In this production technique, which is still the major industrial route to citric acid used today, cultures of Aspergillus niger are fed on sucrose or glucose-containing medium to produce citric acid. The source of sugar is corn steep liquor, molasses, hydrolyzed corn starch or other inexpensive sugary solutions. After the mould is filtered out of the resulting solution, citric acid is isolated by precipitating it with lime (calcium hydroxide) to yield calcium citrate salt, from which citric acid is regenerated by treatment with sulfuric acid.

So, the correct answer is 'Aspergillus'.