How to Tell If Shrimp Has Gone Bad

When shrimp spoils, its bright, translucent color can turn dull, yellowish, or cloudy; its texture can become soft and slimy; and it may develop a sharp, ammonia-like odor. Fresh shrimp should have a mild, briny smell, a shiny shell, and firm flesh. An ammonia-like odor can indicate that shrimp has been held at an improper temperature. The odor may persist after cooking and can become more noticeable. To assess shrimp, consider its smell, color, and texture together.

What Signs Should You Look for When Shrimp Has Spoiled?
Check several signs together:

• A sharp, unpleasant, ammonia-like odor.
• Color that has changed from bright and translucent to dull, yellowish, or cloudy.
• Flesh that has become soft and slimy rather than firm and elastic.
• Shell and flesh that separate easily; on fresh shrimp, the shell clings tightly to the flesh.
• A head that has turned black or darkened; this area spoils faster than the rest.

What Mistakes Should You Avoid When Storing Shrimp?
Common storage mistakes can make shrimp spoil sooner:

• Keeping raw shrimp in the refrigerator for more than 1–2 days.
• Leaving cooked shrimp at room temperature for more than 2 hours, or more than 1 hour above 32°C / 90°F.
• Thawing frozen shrimp on the counter at room temperature.
• Trying to mask even a slight ammonia-like odor with plenty of garlic and lemon. Shrimp with this odor should not be cooked.
• Leaving shrimp in the liquid released as it thaws, which can create conditions favorable to bacterial growth.

Why Does Shrimp Develop an Ammonia-Like Odor?
Some naturally occurring compounds in seafood can be broken down by bacteria as a product spoils, forming sharp-smelling substances similar to ammonia. This process is offered as an explanation for why spoiled shrimp and other shellfish can smell sharper than freshwater fish. This odor may be noticed earlier and more clearly in shrimp than in some other foods. Someone who clearly recognizes this odor once can identify a questionable product much more quickly on a later shopping trip.

Are Spoilage Signs the Same in Raw and Cooked Shrimp?
Color and texture are commonly used to check raw shrimp, while odor is described as the most reliable indicator for cooked shrimp. Mild spoilage odors may go unnoticed during cooking and become more noticeable when the shrimp is reheated. Store cooked shrimp as carefully as raw shrimp and use it within a reasonable time. When cooking a large batch, cool the shrimp quickly and divide it among separate containers.

Assess shrimp by considering changes in smell, color, and texture together. A mild briny smell is normal, while a sharp ammonia-like odor is a strong sign of spoilage. If you are unsure, discard the shrimp without cooking it. Returning shrimp to cold storage promptly after shopping is the single most important step in preserving its freshness.