Citric acid is used as a flavoring agent in soft drinks, fruit juices, and many
ID: 303418 • Letter: C
Question
Citric acid is used as a flavoring agent in soft drinks, fruit juices, and many other foods. Worldwide, the market for citric acid is valued at hundreds of millions of dollars per year. Commercial production uses the mold Aspergillus niger, which metabolizes sucrose under carefully controlled conditions.
(a) The yield of citric acid is strongly dependent on the concentration of FeCl3 in the culture medium,. Why does the yield decrease when the concentration of Fe3+ is above or below the optimal value of 0.5 mg/L?
(b) Write the sequence of reactions by which A. niger synthesizes citric acid from sucrose. Write an equation for the overall reaction.
(c) Does the commercial process require the culture medium to be aerated—that is, is this a fermentation or an aerobic process? Explain.
Explanation / Answer
B)
GLUCOSE > FRUCTOSE 6- PHOSPHATE > FRUCTOSE 1,6-DIPHOSPHATE > PYRUVIC CoA > CITRIC ACID and this citric acid now enters into Kreb Cycle.
Answer C) Yes aeration is required for the production of citric acid.This is a fermentation process and aeration has a detrimental effect on fermentation also.High aeration results in high amount of foam. The air provide oxygen and control the temperature of fermentation.Aeration increases fermentation process.This production can be categorized into 3 ways:
1) surface fermentation
2)submerged fermentation
3)solid state fermentation