Question

Which is the specific spoilage organism in fresh fish ?

• A. Shewanella
• B. Shigella
• C. Staphylococcus
• D. Aeromonas

Hint:

Shewanella putrefaciens is the classic Specific Spoilage Organism (SSO) of chilled marine fish. It produces hydrogen sulfide ($\text{H}_2\text{S}$) and reduces TMAO to TMA, which causes the spoiled fish odor.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
While many bacteria are present on fish skin and gills, only a few species actively drive the spoilage process under specific storage conditions.
These are referred to as Specific Spoilage Organisms (SSOs).
Detailed Explanation:
- {Shewanella putrefaciens (1) is the primary Specific Spoilage Organism (SSO) of fresh marine fish stored under aerobic iced conditions.
It is a psychrotrophic bacterium that reduces trimethylamine oxide (TMAO) to volatile trimethylamine (TMA), producing the characteristic "fishy" spoiled odor.
It also produces hydrogen sulfide ($\text{H}_2\text{S}$), causing off-odors and off-flavors.
- Shigella (2) and Staphylococcus (3) are human pathogens associated with fecal contamination and poor hygiene, not with the natural spoilage of fresh fish.
- Aeromonas (4) can be found in freshwater fish, but it is not the primary specific spoilage organism associated with iced fresh marine fish.

Step 2: Final Answer:
The specific spoilage organism in iced fresh fish is Shewanella.