Question

In brine pickles during the curing process the presence of Aerobacter is characterized by the production of ‐‐‐‐‐‐ .

• A. Hydrogen
• B. Carbon dioxide
• C. Carbon dioxide and hydrogen
• D. Sulphur dioxide and Carbon dioxide

Hint:

Coliforms and Aerobacter are "Gas Kings" in food spoilage. Unlike LAB (which mostly produce just $CO_2$ if heterofermentative), these enteric bacteria produce both $CO_2$ and $H_2$.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question concerns the fermentation biology of vegetable pickling. Aerobacter (now mostly classified as Enterobacter) is a group of coliform-like bacteria that can interfere with the early stages of fermentation.

Step 2: Detailed Explanation:

• Fermentation Phases: A proper brine fermentation should be dominated by Lactic Acid Bacteria (LAB). However, in the very early stage (before the pH drops), various "contaminant" bacteria like Aerobacter can grow.

• Metabolism: Aerobacter species are facultative anaerobes that perform "Mixed Acid Fermentation" or "Butanediol Fermentation."

• Gas Production: A hallmark of their metabolism is the production of significant amounts of gas. They possess the enzyme complex "Formate Hydrogen Lyase," which breaks down formic acid into equal parts of Carbon dioxide ($CO_2$) and Hydrogen ($H_2$).

• Pickle Defects: This gas production can lead to "bloaters" (hollow pickles) or bubbling in the brine jars, which is undesirable. Successful pickling requires a rapid drop in pH to inhibit these gas-producers.

Step 3: Final Answer:
The growth of Aerobacter in pickles produces a mixture of $CO_2$ and $H_2$.