Question

Swelling of moist macaroni is caused due to the presence of ………

• A. E. coli
• B. L. cremoris
• C. S. aureus
• D. Enterobacter cloacae

Hint:

Package swelling = Gas. Gas producers = Yeasts, Coliforms (Enterobacter), or Clostridia. In pasta, Enterobacter is a frequent culprit.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
Macaroni and pasta are usually dry products. However, "moist" or fresh macaroni can support microbial growth. The question asks for the specific bacterium responsible for gas production that leads to the "swelling" of the product or its packaging.

Step 2: Detailed Explanation:

• Gas-Producing Bacteria: Swelling in food packages is almost always caused by microorganisms that ferment sugars and release gases like $CO_2$ and $H_2$.

• Enterobacter cloacae: This is a Gram-negative, facultatively anaerobic rod. It is a coliform and a prolific gas producer. In the moist, carbohydrate-rich environment of fresh macaroni, it can rapidly ferment residual sugars, leading to significant gas accumulation and package distension.

• Other Options:
- E. coli (A): Also a gas producer, but E. cloacae is specifically noted in food microbiology texts as a common spoilage agent for moist cereal products.
- S. aureus (C): Does not typically produce large amounts of gas; it is a pathogen that produces heat-stable toxins without necessarily changing the appearance of the food.
- L. cremoris (B): A lactic acid bacterium used in dairy; it produces acid, but homofermentative strains do not produce gas.

Step 3: Final Answer:
Enterobacter cloacae is the organism responsible for the swelling of moist macaroni.