Concentration of Carbon Monoxide in Commercial Fish Flesh and in Fish Flesh Exposed to Carbon Monoxide Gas for Color Fixing

Abstract

A survey of the concentration of carbon monoxide (CO) in flesh from a variety of fish was conducted to see whether fish which had been exposed to CO gas could be detected. CO in fish flesh was obtained by head-space gas chromatography and determined after conversion of CO to methane with a methanizer. Concentrations of CO ranged from 3 to 12jg/kg fish flesh, showing a narrow range in each species of fish except tilapia (Tilapia mossambica). CO was high in the red-flesh fish and low in the white-flesh fish. CO in sliced tilapia (a species of white-flesh fish), however, ranged from 7 to 957jg/kg. In tilapia, a high concentration of CO was observed in a sample in which the blood-colored parts of the slice were bright red, whereas the CO concentration was low in a sample in which the blood-colored parts were dark brown. The CO concentration in sliced tilapia containing Big CO/kg increased to 234jg/kg when the slice was exposed to CO gas. The blood-colored parts of the slice became bright red after the exposure. CO in the homogenate prepared from the CO-exposed sample decreased to less than 50jg/kg within 4 days on storage in a refrigerator (5C). The concentration of CO in the control increased slightly during this period. Among 19 commercial samples of tilapia, CO slightly increased in 5 samples containing about 10jig CO/kg and decreased in 14 samples containing more than 50 jig CO/kg when the homogenate was kept at 5C for 2 days. The blood-colored parts of the former group containing lower concentrations of CO were dark brown and those of the latter group containing higher concentrations of CO were bright red. The latter group of tilapia was suspected to have been exposed to CO gas.

Color stability of frozen whole tilapia exposed to pre‐mortem treatment with carbon monoxide

“…Currently, a variety of methods are available for CO detection in food materials. These include spectrophotometric27, 28 and gas chromatographic methods 29, 30. In our present study, we used GC equipped with a flame ionization detector for quantifying CO in tilapia fillets.…”

Use of “filtered smoke” and carbon monoxide with fish

“…The retention time and peak area were compared with those obtained with the calibration CO gas. The detection limit of this method was 2 mg of CO/kg fish flesh (Ishiwata et al, 1996). It has been reported that the CO content in tuna can exactly and reproducibly be determined by using this method.…”

“…In contrast, the heme proteins (Mb and Hb) cause the red muscle colour found in tuna and other darkfleshed fish species. The bright red colour of tuna muscle is an economical important factor due to preference by consumers who consider red muscle colour as an indicator of freshness (Ishiwata et al, 1996). in respect of the colour.…”

“…These papers (Abe et al, 1994;Takeda et al, 1995;Miyazaki et al, 1997;Chow et al, 1997Chow et al, , 1998aChow et al, , 1998bHsieh et al, 1998;Yoshida and Hori, 1998) deal mainly with the determination of CO in fish and were unfortunately mostly written in Japanese or Chinese. Also the probably most often applied method for CO determination originated from that time (Ishiwata et al, 1996). For determination of CO in fish flesh this was homogenised with water under ice cooling.…”

Was hat Thunfisch mit Kohlenmonoxid zu tun?

“…Im Chemischen und Veterinäruntersuchungsamt Karlsruhe wird der Nachweis von Kohlenmonoxid in Lebensmitteln mit einem Gaschromatographen mit Nickelkatalysator [1][2][3] durchgeführt.…”