Restaurant operators can take a few precautions to keep diners safe from scombroid poisoning and reduce methylmercury exposure. Obtaining fresh and high-quality seafood is the first step toward safe fish and shellfish service. To avoid scombroid poisoning, restaurant operators must only procure fish and shellfish from contracted and licensed vendors who take strict safety precautions to ensure that seafood is caught, processed, stored and transported properly. This ensures that the seafood is commercially and legally harvested from designated areas. It also has the advantage of being traceable back to its source during food poisoning investigations.
The following step will be to develop Standard Purchase Specifications (SPS) for all types of fish, shellfish and other seafood served. Such efforts will ensure that seafood is obtained in accordance with the safety and quality specifications outlined in the purchase specifications. Receiving is another critical stage that affects the safety of fish and shellfish. The restaurant operator must work with the seafood vendor to develop a delivery schedule that allows the receiving clerk enough time to inspect and store the seafood in a timely manner.
Receiving clerks must also be trained to ensure that the fish is fresh and delivered in sanitary conditions and at a safe minimum temperature. Accept those that arrive at temperature of 41 degrees Fahrenheit or lower unless otherwise stated. Reject fish that arrive in melted ice or that have cloudy and sunken eyes, cracked and dull skin, loose scales, and white gills, as these are signs of rotting. Once the batch of fish is accepted, it must be refrigerated to 35 degrees Fahrenheit or lower to avoid bacterial spoilage. Inadequate inspection and delays in refrigerating seafood may occur due to a lack of time, putting the seafood's quality and safety at risk.
If more than one customer reports having suffered scombroid poisoning restaurant owners must discard the suspected batch of fish to prevent further incidents, consult with the seafood supplier and notify public health authorities. Of note, Pesticides and other toxic substances that commonly accumulate in the skin and fatty parts of fish are also a concern and must be removed while cleaning the fish. The only way to avoid scombroid poisoning is to handle it safely from catch to service.
As far as methylmercury poisoning is concerned, it has no cure. Worse, mercury binds to protein in fish and cannot be neutralized by high-temperature cooking. To reduce the customer exposure to methylmercury, restaurant operators can replace high-mercury-level fish in the menu with low-mercury-level fish such as Salmon, Anchovies, Flounder, Sardines, Sole, Herring, and Catfish, without compromising menu balance. Crabs, prawns, and lobster are also good choices for restaurant operators to serve because they contain less mercury than fish, which is especially important when serving seafood platters.
Another option for restaurant operators to reduce methylmercury exposure is to procure farm-raised fish from a reputable and licensed dealer. The amount of methylmercury in farm-raised fish varies depending on the type of fish and the environment in which they are raised. The majority of farmed fish, including Catfish, Tilapia and Salmon, have low or very low mercury levels. Farm-raised fish have lower mercury levels than wild-caught fish because they are fed on corn, soybean and fishmeal and raised in a controlled environment.
It is imperative to note that some fish, such as anchovies and sardines, are always caught wild and are not typically farm raised, restaurant operators can base their fish purchasing decisions on this fact. Another significant finding from research studies is that methylmercury levels are higher in saltwater fish (sea and ocean) than in freshwater fish (lakes and rivers). This is due to the fact that sunlight can break down methylmercury in fresh water, making it less toxic, but it cannot penetrate the depths of saltwater and thus cannot break it down. Another good practice is to procure smaller, shorter-lived and non-predatory fish because they have had less time to accumulate mercury in their body tissue and thus have lower mercury levels. Methylmercury levels are known to be higher in predator fish that feed on other fish.
From nutrition standpoint, it is worth noting that small fish also have good omega-3 profile and have low saturated fats making them a good alternative to larger fish. Salmon, Tilapia, Anchovies and Sardines are examples of such fish. In contrast, most farmed fish contain higher levels of antibiotics, herbicides, pesticides, PCBs, and dioxins than wild-caught fish. It is, however, dependent on where and how fish are farmed. The national government's regulations on fish farming and feed have resulted in significant reduction in contamination levels.
When it comes to labelling fish, shellfish and other seafood for methylmercury, regulatory agencies face challenges because it has both benefits and drawbacks. Labeling is expected to educate the public about the dangers of methylmercury in seafood and assist consumers in making informed decisions, but it is also expected to reduce fish consumption and harm the aquaculture industry.
People who consume high-mercury fish are more likely to develop mercury poisoning over time. They must educate themselves on safe fish consumption and seek professional advice. It is best to keep blood methylmercury levels below 5.0 mcg per litre to avoid health complications. For this, experts recommend two to three servings per week of fish with methylmercury levels less than 0.1 ppm, one serving of fish with mercury levels greater than 0.1 but less than 0.3 ppm per week, and 2-3 servings of fish with levels greater than 0.3 but less than 0.4 ppm per month. Avoid eating fish with methylmercury levels of 0.4 ppm or higher.
Given their public health responsibilities, restaurant owners and operators must keep fish dinners safe by preventing scombroid poisoning and reducing customer exposure to methylmercury. After all, promoting healthy eating is one of their social responsibilities.
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About Dhruv Kishore Bole
MBA - Hotel Management | Preventive Controls Qualified Individual (PCQI)
ISO 9001: 2015 (QMS) | FSSC 22000 V5 (FSMS) | cGMP | HACCP
Lean Six Sigma | Train The Trainer | Revenue Management | CGSP
Food Handler | FOSTAC | OHSMS
Dhruv Kishore Bole is a hospitality and food safety specialist with qualifications in hotel management, food safety and quality management system. He has extensive experience spanning over twelve years in operational and training roles. His expertise centers on hospitality operation, food and beverage services and food safety. He has attended numerous workshops and conferences on customer service, leadership and food safety and quality and is certified by Food Safety and Standards Authority of India in food safety competencies. He is currently offering services in the capacity of Faculty, Food & Beverage service at State Institute of Hotel Management, Siddhpur, India. He is an empanelled trainer with Hero Mindmine and IL&FS Skills. He is a member of Quality Council of India and an instructor and proctor with ServSafe for India region.
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Editor’s Note
According to the Western Cape Government website, the Tygerberg Poisons Information Centre reports an increase in seafood poisoning calls to their centre in autumn (March to May). In South Africa, red tides usually occur in late summer and autumn. They posit that the high occurrence of scombroid poisoning at this time could be linked to the uniquely South African tradition of serving pickled fish on Good Friday, which usually occurs during March/April over Easter. With an increase in demand for fish over this time, there is an associated likelihood of cold chain issues between vendors, or as a result of poor temperature control from the consumer, due to a lack of refrigeration.
The site also states that the Cape yellowtail (which is an example of a red-muscled fish) is usually the culprit when it comes to scombroid poisoning in South Africa.
https://www.westerncape.gov.za/news/beware-seafood-poisoning
Recommended reading:
Fish and Fishery Products Hazards and Control Guidance
https://www.fda.gov/media/80637/download
Watch out for more information coming soon on legislation relating to fish and seafood.
