Understanding the Risks: Cooked vs. Raw Scallops
The safety of scallops is largely dependent on how they are prepared. When cooked thoroughly, most pathogens are eliminated, making them a very safe food. The primary risks are associated with eating them raw or undercooked.
The Dangers of Eating Raw Scallops
Consuming raw or improperly handled scallops can expose you to harmful bacteria, particularly Vibrio parahaemolyticus, which is naturally present in certain coastal waters. Unlike parasites, which can be killed by freezing, bacteria like Vibrio are only eliminated by thorough cooking. A Vibrio infection can cause gastroenteritis symptoms such as diarrhea, cramps, nausea, and vomiting, and can be more serious for individuals with pre-existing conditions.
Beyond bacterial risks, scallops can concentrate marine toxins produced during harmful algal blooms, commonly known as "red tides". These toxins are not destroyed by cooking and can lead to several types of shellfish poisoning, including:
- Diarrhetic Shellfish Poisoning (DSP): Causes digestive issues that usually resolve within a few days.
- Paralytic Shellfish Poisoning (PSP): A severe, potentially fatal illness affecting the nervous system.
- Amnesic Shellfish Poisoning (ASP): A rare but serious illness that can cause memory loss and neurological problems.
The Importance of Sourcing and Freshness
The most critical factor in mitigating these risks is sourcing. You should only consider eating raw scallops, such as in sashimi or crudo, if you can absolutely guarantee their provenance from a trusted and reputable supplier. This supplier should be able to verify that the scallops were harvested from safe, unpolluted waters and handled correctly throughout the supply chain. For everyone else, and for all supermarket scallops, cooking is the only way to ensure safety.
How to spot fresh, safe scallops:
- Smell: Fresh scallops have a mild, sweet, and oceanic aroma. A strong, fishy, or ammonia-like odor indicates spoilage.
- Color: The flesh should be creamy off-white, beige, or pale pink. A yellow, gray, or darkened appearance is a sign of age or improper storage.
- Texture: The meat should be firm and resilient to the touch, not slimy or mushy.
- Moisture: Avoid scallops swimming in liquid, which can be a sign of poor handling or chemical treatments.
'Wet' vs. 'Dry' Scallops
When shopping for scallops, you may encounter the terms "wet" and "dry." This distinction is crucial for both taste and safety.
Comparison of Scallop Types
| Feature | 'Dry' Scallops | 'Wet' Scallops |
|---|---|---|
| Processing | Untreated; not soaked in water or chemicals. | Soaked in a phosphate solution (e.g., sodium tripolyphosphate) to absorb water. |
| Flavor | Naturally sweet, rich, and concentrated. | Diluted flavor with a potentially soapy or chemical aftertaste. |
| Texture | Firm and will caramelize beautifully when seared. | Waterlogged, steams rather than sears, resulting in a rubbery texture. |
| Weight | Accurate to the actual scallop meat. | Artificially inflated, meaning you pay for absorbed water. |
| Safety | Safer when sourced from a trusted provider. | Chemical treatment and extended shelf life introduce additional variables. |
For the best results and taste, always choose "dry" scallops. For those with compromised immune systems, it is best to avoid raw or undercooked shellfish altogether.
Proper Handling and Cooking to Prevent Illness
Once you have purchased high-quality scallops, proper handling is key to a safe meal. Seafood is a time-temperature controlled for safety (TCS) food and must be kept properly chilled.
How to safely prepare scallops
- Storage: Keep fresh scallops in the refrigerator in an airtight container at 40°F (4°C) or below and cook them within one to two days of purchase. Frozen scallops should be thawed slowly in the refrigerator.
- Rinse and Pat Dry: Rinse the scallops briefly under cold water to remove any sand or grit. Pat them thoroughly dry with a paper towel before cooking to ensure a proper sear.
- Cooking: The most reliable way to kill harmful bacteria is by cooking them until they are opaque throughout. The time will vary depending on size, but pan-searing, grilling, or broiling until they are no longer translucent is the standard. Avoid overcooking, which can make them rubbery.
- Cross-Contamination: Keep raw scallops and their juices separate from cooked food and other raw produce. Wash your hands, utensils, and cutting surfaces thoroughly after handling raw seafood.
Heavy Metals: Are They a Concern in Scallops?
Like all marine life, scallops can accumulate heavy metals from their environment, including mercury and cadmium. However, the good news is that scallops are low on the food chain and generally contain very low levels of mercury compared to larger predatory fish like tuna. The FDA and EPA list scallops as a "best choice" for consumption, recommending 2–3 servings per week, including for pregnant and nursing individuals. While some studies note they can be high in cadmium depending on location, the nutritional benefits typically outweigh the risks for most people.
Conclusion: Your Safest Bet is Proper Preparation
Overall, scallops are a delicious and nutritious addition to your diet when approached with common-sense food safety practices. For the average consumer, the safest way to enjoy scallops is to purchase them cooked or to cook them thoroughly at home. Raw consumption should be reserved for scenarios where you can verify the scallops came from a reputable, sanitary source, preferably a "day-boat" or "diver" scallop that was handled with care. By prioritizing freshness, proper handling, and sufficient cooking, you can enjoy this versatile seafood with confidence.
For more information on the dangers of raw seafood consumption, visit the Centers for Disease Control and Prevention's seafood safety page at https://wwwnc.cdc.gov/travel/page/fish-poisoning-ciguatera-scombroid.
