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Questions and Answers
What process is used to recover free gluconic acid from calcium gluconate?
Which materials serve as the neutralising agent in the production of calcium gluconate?
How is sodium gluconate primarily manufactured?
What role does activated carbon play in the production processes described?
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What is the purpose of adding sulphuric acid in the process of obtaining gluconic acid?
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What is the primary method of fermentation used when paraffins are involved?
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Which fungal strain is commonly used for citric acid production?
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What is a necessary condition for obtaining high yields of citric acid during fermentation?
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How long does the fermentation process for citric acid typically last?
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What factor significantly varies depending on the strain of A. niger used?
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What is the optimal pH maintained during citric acid fermentation?
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Which of the following nutrients is essential for the fermentation process of A. niger?
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How is citric acid extracted after fermentation?
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Which microorganism is primarily responsible for the commercial production of citric acid?
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What is the significant characteristic of citric acid in terms of its chemical structure?
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What happens to citric acid when it is heated to around 175°C?
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What method can lead to the accumulation of citric acid during its production?
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Which of the following acids is NOT produced from citric acid when heated to high temperatures?
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Which factor is NOT essential for the production of citric acid through fermentation?
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What is the annual production of citric acid by fermentation approximately?
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Which of the following is a NOT a potential product of the citric acid cycle?
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What is the primary reason Na or KCO3 is added during the process?
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Which acid crystallises when using CaCO3, making it unsuitable for use?
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What industrial applications are primarily associated with fumaric acid?
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What method is most widely accepted for gluconic acid production?
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Which enzyme plays a critical role in converting glucose to gluconic acid?
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What byproduct is generated during the conversion of glucose to gluconic acid?
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Which fungi are known to produce gluconic acid?
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What is glucono--lactone further hydrolysed to produce?
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What is one of the main advantages of solid-state fermentation (SSF)?
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Which microorganism is responsible for producing amylase in SSF?
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Which of the following best describes submerged fermentation (SmF)?
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What is a common disadvantage of solid-state fermentation?
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Which substance can induce the production of ß-galactosidase in submerged fermentation?
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What is one of the reasons SSF is advantageous for certain molds?
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What is a key requirement for submerged fermentation to yield higher enzyme production?
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What is a disadvantage of using submerged fermentation (SmF)?
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Study Notes
Production of Organic Acids and Enzymes
- Organic acids with microbial production include citric, lactic, and gluconic acids, among others.
- Citric acid is produced via fermentation with an annual output of about 1.5 million tonnes.
Citric Acid
- It is a weak organic acid crucial in the TCA cycle (Krebs cycle) as its conjugate base, citrate.
- Citric acid crystallizes as a tribasic acid and loses water at 130°C, with decomposition resulting in itaconic acid at 175°C.
- Accumulation occurs through mutation of organisms or by inhibiting certain metabolic pathways under controlled environmental conditions such as pH and temperature.
Fermentation for Citric Acid Production
- Key fungal strains include Aspergillus niger, which is the most commercially utilized due to its high yield and stability.
- Fermentation media should be slightly deficient in phosphates and certain trace metals to enhance citric acid production.
- Surface fermentation: Involves growing cultures on the media's surface, traditionally using rice bran or shallow pans.
- Submerged fermentation: Involves using acid-resistant fermenters; pH is maintained with Na or KCO3 to avoid crystallization.
Fumaric Acid Production
- Utilized in the polymer industry for resin manufacturing and can be converted to maleic acid.
- The substrates and fermentation conditions must be optimized for efficient fumaric acid yield.
Gluconic Acid
- A mild, non-toxic organic acid produced through fermentation using glucose oxidase or by microbial processes, primarily via Aspergillus species.
- Formation involves the oxidation of β-D-glucose, leading to glucono-δ-lactone, which is further hydrolyzed to gluconic acid.
- Recovery methods include crystallization of calcium gluconate and ion exchange processes for sodium gluconate.
Enzyme Production
- Enzymes can be produced through solid-state fermentation (SSF) or submerged fermentation (SmF).
- SSF uses semi-solid substrates, which can yield high concentrations of enzymes but requires more space and labor.
- Key enzymes such as amylase, lactase, and protease are produced by various fungi like A. niger and A. oryzae.
Advantages and Disadvantages of Fermentation Methods
- SSF Advantages: Low investment, high yield due to substrate concentration, and natural growth conditions for molds.
- SSF Disadvantages: Greater space requirement, higher labor, and risk of contamination.
- SmF Methodology: Involves sophisticated fermentation equipment similar to antibiotic production for consistent enzyme yields.
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Description
This quiz covers the production of organic acids such as citric, gluconic, and fumaric acids, along with various enzymes produced by microorganisms. It focuses on the applications and processes involved in food biotechnology as taught in CUBT402 at Chinhoyi University of Technology. Test your knowledge on this fascinating topic!
