An official website of the United States government.

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Consumption Risks and Consumer Perceptions of Muscle Foods Treated with Carbon Monoxide or Filtered Smoke

Kristinsson, Hordur; Balaban, Murat; Otwell, Walter
University of Florida
Start date
End date
  1. Investigate the level of carbon monoxide absorption in humans after consumption of raw, partially and fully cooked fish and meat products subjected to different CO and FS treatments, and connecting the uptake to CO level in the muscle products.
  2. Investigate consumer acceptance and preference of raw, partially and fully cooked fish and meat products subjected to different carbon monoxide and filtered smoke treatments, and correlate to color and level of CO in products
More information
NON-TECHNICAL SUMMARY: Treatment of muscle foods with carbon monoxide (CO) and filtered smoke (FS), containing CO, to stabilize color is a recent processing method. These processes are highly controversial due to concerns that CO/FS treated products could mask underlying safety problems and mislead consumers. Preliminary work by our group has indicated a significant preference for products treated with CO or FS over untreated products. One of the risks associated with consuming CO/FS treated products is the uptake of CO into the human body. CO is a highly toxic gas that can lead to adverse physiological effects even at very low concentrations. Our preliminary work shows that CO is taken up into the body even at low consumption and CO product levels. CO/FS processing is practiced widely even though scientific understanding on the effect on product safety is still limited. However, with more research leading to recommendations of proper processing and controls, these processes could become a valuable addition for muscle food processors. This proposal addresses two concerns with CO/FS processing which have not yet been scientifically documented: (a) the consumption risk of consuming products containing carbon monoxide, and (b) the consumer acceptability/preference for treated products. This work is expected to produce very important unbiased scientifically based opinions and information which we will communicate to industry, government and the public for them to responsibly and correctly make use of this new emerging technology with public safety as the highest priority.

APPROACH: We will perform a comprehensive study to assess how different CO/FS processing methods of muscle foods will affect CO uptake into humans and relate this to the type of muscle food consumed, level of food consumed, food preparation method, and CO level in the food. We will also perform a comprehensive sensory study on the same products subjected to CO uptake trials, to obtain an understanding on consumer reactions to treated products. We will investigate two different muscle sources. Beef will be the land animal muscle of choice, as it is the most consumed muscle products in the US and has acquired recent approval for CO treatment. Yellowfin tuna will the fish species of choice as it is the top imported fish species processed with CO and FS. We will subject beef and tuna to different CO/FS treatment to obtain different levels of CO binding and thus varying CO concentrations as well as varying levels of redness. After treatment, the samples will be measured for their carbon monoxide concentration using a gas chromatography instrument with an FID detector. Samples will also be analyzed for color using a color machine vision system (CMVS). For the consumption studies adult subjects (age 18-60) with no history of respiratory, cardiovascular or gastrointestinal disease will be used as test subjects. The subject will either ingest 150 or 300 grams of meat or fish. We will evaluate the effect of different levels of cooking on the products. Expired air from the subject will be measured for CO concentration. There is a direct relationship between blood CO and expired air CO. In addition, heart rate and heart rate variability as well as ventilation (i.e. respiratory frequency), known to change with hypoxemia, will be monitored. We will conduct a study to obtain information on consumer visual acceptability of the treated and untreated fish/meat samples. The results from the sensory trials will be correlated with sample color and CO concentration data.

PROGRESS: 2006/09 TO 2008/08
OUTPUTS: (1) Experiments were performed to develop several new rapid qualitative and quantitative detection techniques which can be used by industry, regulatory agencies and academia to determine (a) if products have been treated with gas blends containing carbon monoxide (CO) and commercial filtered wood smokes (FWS) containing (also containing CO) and (b) how much products had been treated. (2) Experiments were performed to understand the penetration and location of CO in tissues during and after treatment. (3) Experiments were performed to assess consumer perception of different muscle products treated with CO and FWS at different levels and times. (4) Groundwork was laid for experiments on consumer consumption risk of treated fish products (uptake of CO on consumption), which were planned for year 3 of this project (funding pending). Outcomes of the research during this period were presented to a wide audience (academia, industry and government representatives) by disseminating results via research publications, presentations at conferences and by demonstrations
PARTICIPANTS: Students: Lihua Huo, Stefan Crynen, Yavuz Yagiz, David Mantilla, Nineveh Ludlow and Puh Siriporn Faculty: Hordur G. Kristinsson, W. Steven Otwell, Murat Balaban, Frank A. Chapman, Sivakumar Raghavan
TARGET AUDIENCES: Food science researchers, governmental agencies, fish and meat processing companies

IMPACT: 2006/09 TO 2008/08
(1) Simple spectrophotometric methods were developed to determine presence of CO in muscle based on the fact that heme proteins and their derivatives have characteristic absorption spectra. With a one-wavelength spectrophotometric method, any heme protein extraction which exhibit a maximum peak wavelength at 415 nm or above can be determined as CO treated. With a two-wavelength spectrophotometric method, after addition of a reducing reagent, a two pigment mixture is produced and absorbance of the pigment is measured. The spectra developed can be used to calculate the percentage of COHb/Mb in muscle.
(2) An accurate quantitative gas chromatographic method was improved and developed to determine CO levels in muscle. Many different extraction procedures were explored. For example, liberating CO directly from the mixture of muscle and buffer was more effective than releasing CO from a solution of Hb/Mb extracted from the muscle homogenate. It was determined that there was a significant difference between various CO liberating methods. It was determined that a liberation solution containing 5% sulfuric acid could release CO from the muscle more effectively than all other liberation methods tested. An excellent correlation was found between the simple two wavelength spectrophotmetric method and the GC method. However, it was determined that it's important to combine both methods together if the intention is to determine both the total CO amount and CO binding status in muscle.
(3) Fate of CO during treatment and following storage of CO treated samples was investigated in detail. The effect of external factors, such as CO concentration, and various internal factors, e.g. Hb concentration, Hb oxidation status, pH, ionic strength, lipid content, on the CO penetration rate and CO amount in muscle was studied. It was found that CO could penetrate the first muscle layer after only 15 min treatment. As CO treatment time progressed, CO amount in each layer of the muscle increased significantly in a manner which was greatly influenced by external and internal factors.
(4) Consumer testing was conducted on products treated with filtered wood smoke (FS), artificial filtered smoke (AS) and industrial CO at different application levels and in fresh and frozen state. Color analysis confirmed effectiveness of the different applications on the preservation of color properties and appearance. Increased red color stability of all three treatments was especially noticeable after frozen storage. Industrial CO led to the highest increase in redness. FS and AS treatments were not significantly different in terms of color. Consumers had a clear preference for all treated products compared to untreated products. For some species industrial CO was preferred over FS and AS. This preference was based on visual appeal of the treated products. No significant differences could be found based on odor and appearance between filtered smoke and artificial smoke treated samples. The results are expected to help regulate products treated with various forms of gases and smokes containing carbon monoxide, and also provide important insight into consumer perception of treated products.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
View this project
Project number
Accession number
Risk Assessment, Management, and Communication
Food Preparation and Handling
Natural Toxins