Characteristics of Reaction between Carbon Monoxide Gas and Myoglobin in Tuna Flesh
CHAU-JEN CHOW*, SUE-MEI LIU AND MEI-LIN TSAI
National Kaohsiung Institute of Marine Technology, Kaohsiung, Taiwan, R. O. C.
Abstract
In order to understand the characteristics of the reaction between carbon monoxide (CO) gas and myoglobin (Mb) in tuna flesh, yellowfin tuna steaks (thickness 1.5～2.0 cm) were treated with CO gas. After treatment, the absorption spectrum of the Mb and the penetration of CO gas into the tuna flesh were analyzed.
The specific spectrum of MbCO within the visible range was observed after bubbling CO gas directly into Mb extracts for 10 seconds. However, characteristic MbCO spectrum was not found for the Mb extracts from the tuna steaks treated with CO gas for 30 minutes. Neither was it found for the extracts from tuna steaks treated with CO for 120 hours. The penetration of CO gas into the tuna flesh was very slow. It took about 1～4 hours for CO to penetrate to 2 to 4 mm under the surface. The penetration time to reach 4 to 6 mm under the surface was about 8 hours.
The Mb extracts from tuna flesh treated with CO gas had higher absorbance at 570 nm than at 580 nm. This characteristic could be used to determine whether a sample had been treated with CO gas.
Key words: tuna, carbon monoxide, absorption spectrum, qualitative analysis