1. Vinegar is typically produced in fed batch reactors because
A.a fed batch reactor can be used to maintain low acetic acid concentrations
B.a fed batch reactor can be used to maintain low ethanol concentrations
C.acetic acid bacteria tend to ferment at high ethanol concentrations
D.all of the above

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2.  For the recovery of citric acid after fermentation, Ca(OH)2 is added to the slurry to
A.precipitate calcium carbonate
B.precipitate calcium citrate
C.precipitate calcium phosphate
D.precipitate calcium sulphate

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3. Which of the following microorganism is used for the production of citric acid?
A.Lactobacillus bulgaricus
B.Saccharomyces cerevisiae
C.Aspergillus niger
D.Streptococcus lactis

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4. Sugar content of the fermentation medium for citric acid is maintained at
A.10-15%
B.15-20%
C.20-25 %
D.25-30 %

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5. Spirit vinegar is produced from
A.fruit juices
B.malted grain
C.ethanol
D.ale

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6. What is the pH of the medium when sucrose is used as substrate for the production of citric acid?
A.3
B.4
C.5
D.6

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7. In liquid surface culture process for the fermentation to produce citric acid,
A.A. niger is used with solid substrate as sweet potato
B.A. niger floats on the surface of solution
C.Fungal mycelium grows through out the solution in a deep tank
D.both (a) and (b)

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