Global Aquaculture Issues - 5/2010

Carbon monoxide in tilapia processing

Tuesday,25 May,2010 09:16:25

Carbon monoxide (CO) is a clear, odorless and tasteless gas. Though highly toxic when inhaled, it is present in low levels in animals as a component of normal metabolism. When CO binds to the hemoglobin molecule in red blood cells the result is an indefinite red coloration of meat. Even when the meat is spoiled it will still appear red. Currently in the U.S., it is legal to use CO in case ready meat packaging and to treat tilapia with it. This is a contentious practice and some groups are calling for this practice to be banned as they believe that it has the potential to mislead consumers.  

There are a number of arguments that are being put forth. I believe that the argument that probably has the greatest merit is that certain bacteria can produce toxins that are not destroyed by cooking and that consumers could be made ill by consuming these tainted materials. Of course this is true even if the product has not been treated with CO. Food poisoning in the U.S. is a massive public health problem with estimates of well over 75 million cases per year. There are many causes although it is not likely that CO treated tilapia play much if any role in this (although no one tracks this as far as I know).  

Food additives are regulated jointly in the U.S. by the USFDA and the USDAs Food Safety and Inspection Service. They are defined as any substance that is used to provide a technical effect in foods. This includes affecting the flavor, appeal, preparation and processing, freshness and safety. The use of chemicals to alter the appearance of food products to make them appear more appealing to the consumer is a common practice. 

Processed meats in many parts of the word as well as hamburger are treated with sodium nitrite and/or sodium nitrate to enhance the appearance of the meat. This chemical gives the characteristic red appearance and has the added benefit of inhibiting the growth of certain types of bacteria (CO does not appear to inhibit bacterial growth at all).  Its use is however controversial as it is converted into a carcinogen during cooking. It does not inhibit all bacteria and one could argue that it misleads the consumer into believing that  meat that has been treated with these chemicals are fresher than they really are.

Many processers in China routinely use CO on tilapia immediately prior to and during processing in order to give fillets a bright red color increasing product appeal. Tilapias sold into the local markets in China are not treated with CO. It is not legal in China! Every processor that I have worked with has always told me the same thing. Chinese processing plants are catering to their customers requesting it. When their clients ask for it, it is used. They do not add it as standard operating procedure but only in response to clients requesting it.  

In recent years, there have been accusations leveled that CO is being used by many Chinese processing plants to mislead the consumer by covering up deteriorated product. It is being implied that it is being done as a deliberate effort to deceive consumers. Others point out that this is really no different than any other process that makes a product more appealing to the consumer and that there is no intention to dupe consumers. Many smoking processes rely on CO as a part of the process. 

In my opinion, the pivotal issue here is to what extent CO is actually being used to color tilapia fillets so that the product appears to be purchasable beyond the shelf life of the product. Since the demand for the coloration is being driven by the companies that buy the fish from the plants, it makes little sense that there is any thought about deliberately deceiving consumers. If this were the case then it would be the middlemen that are doing the deceiving, not the processor.  

If one assumes that consumers are incapable of making choices about the freshness of the food that they buy or that unscrupulous sellers of seafood will label product with pull dates that exceed shelf life then perhaps CO and all other materials that are used in food to make it appear more attractive should be banned. Why limit it to CO? All compounds that have the same potential downside should be banned. 

A much wiser solution I would think is to educate consumers. Responsible sellers of seafood should not be selling food that is outdated. Whenever I go into the grocery store to buy seafood, I ask to smell it. If it smells even a little fishy I do not buy it. Rather than pointing fingers at what is in reality a widely accepted practice in many different types of food, it makes more sense to let customers know that odor and pull dates are clues that should be used to judge if a fish is a good buy, not the appearance. I would like to think that there would be some interest in doing this because it is the right thing to do, but I suspect that there would have to be some type of legislative effort. 

Requiring signs stating that fresh fish should rarely smell strongly of fish would do the trick.     

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