L 5. Use of Carbon Monoxide for Color Retention in Fish

The use of carbon monoxide (CO) applied either as a single gas or a component in ‘tasteless smoke’ (TS) is increasing in both domestic and international fish commerce in the United States. Following initial investigations in the early 1960’s with modified atmospheric packaging and the traditional knowledge of fish smoking, commercial interest submitted petitions for regulatory recognition of this practice in 1999. A controversial decision by the U.S. Food and Drug Administration suggested recognition as a generally recognized as safe (GRAS) procedure with required labeling to distinguish treated products. This controversy continues and has extended to recent approvals for red meats. This situation parallels similar controversy in Europe where certain nations desire continued use of CO for meats (Norway), yet the EU does not currently recognize use of CO treatments for seafood. Commercial interests are divided. While there is a definite growing market for CO treated products based on product appeal and convenience, processors debate due to concerns for preserving, enhancing, and masking of inferior products. This is countered by support for a processing method that now allows use of freezing which can reduce potential product quality and safety problems that are more common in fresh fish commerce, i.e., discoloration and elevated histamines, respectively. A primary concern is increasing competition from frozen products that can retain colors vs. traditional fresh products with natural colors denoting freshness and value per color grades. Likewise, for certain histamine-prone species, color retention could mask potential scombrotoxic products, and some adverse opinions question the safety of CO treated foods. Science is rapidly evolving to better direct regulatory and commercial decisions. Although recent human feeding trials have demonstrated that CO treated fish do not pose a health threat, elevated histamine levels are possible in certain thermally abused CO treated species that are otherwise apparently fresh. Commercial applications have expanded beyond the initial applications with tunas to numerous species from both wild and cultured sources. Abusive use both in terms of discolored product and enhancing inferior product is possible. Attempts to develop measures to detect CO treatments have been questionable for both the quantity of residual gases in tissue or the utility of color standards. Current work is focusing on examining the effect CO and TS has on various quality and safety factors of different fish species as well as elucidating what occurs on the molecular level with different fish muscle components. This work intends to develop rapid and improved methods for CO detection in fish muscle. Commercial Development Processing methods to influence and retain color in fish muscle have been used probable since the first cavemen placed a piece of fish near a smoking fire. Although they had no understanding for the cause of the color change, product appeal encouraged continued use. Eventually the smoking techniques evolved to applications of cold smoke as a culinary art to impart colors without fully cooking the muscle. With the introduction of reduced oxygen packaging (ROP) and modified atmospheric packaging (MAP) during the 1960’s, it became more obvious that product exposure to gas blends with carbon monoxide (CO) yielded favorable color development and retention. Patents began to appear in the late 1970’s for specific applications of CO to impart color in meats, poultry and fish (Woodruff et al. 1985). Use of filtered smoke to concentrate the favorable components and CO were patented in the 1990’s (Yamaoka et al. 1996). The most meaningful patent, in terms of fish applications, was issued to Kowalski (1999) for use of ‘tasteless smoke’ for color retention in frozen seafood. The success of this seafood patent encouraged more recent issues for CO applications to red meats, including ground beef (Shaklai, 2001). Today CO is being applied to variety of seafood as a single gas with variable concentrations depending on product type and thickness, as a component in filtered or ‘tasteless’ smoke, and more recently as so-called artificial-filtered smoke based on gas blends to exemplify ‘tasteless smoke’. Commercial use is expanding primarily with fish from either traditional harvests or culture operations in most seafood producing nation’s about the world. The primary market driving this trend is based in the United States due to particular market acceptance, regulatory allowances, and the necessities for frozen products. The modes for application include 1) passive introduction in gassed enclosures or packaging, 2) active additions with pressurized chambers, and 3) post-harvest euthanasia of cultured fish. Despite some commercial efforts to develop processing and product standards through licensing and trade associations, market competition is attracting less experienced and less controlled applications. Although there are no obvious objections in the retail sectors, some wholesale competition with certain fresh fish is mounting efforts to eliminate these frozen CO entries or require sterner labeling. Market demand appears to be increasing with no objections to the atypical, or in some cases, ‘plastic’ colorations in certain fish, but public Innovative handling and processing K 1 TAFT 2003 25 opinion could be alerted by pending publicity to question the concept of ‘CO treated’ food. In the near future, public response could influence commercial practice and regulatory status.