將黃鰭鮪魚肉片(8x5x2cm)在4℃之密封袋內以99.5%一氧化碳(CO)氣體處理5天，同時進行對照實驗，探討鮪肉在CO處理過程中肉片之表層(表面2mrn厚)、中層。表面下2～4mm厚)、深層 (表面下4～6mm厚)各部位之色澤、氧化型肌紅蛋白比例(metMb%)、揮發性鹼態氮(VBN)及CO殘存量等之變化。結果發現CO處理肉之Hunter +a值在處理4hr之後即較對照肉為高，而L值與+b值的差異則不明顯；至於鮪肉中之metMb%，處理肉之表層部位與對照肉無明顯差異，但處理肉之中層部位及深層部位則明顯低於對照肉。處理肉與對照肉之VBN在冷藏5天的過程中均維持在20mg/100g以下。分析鮪肉中之CO殘存量時，表層部位在24hr內增加最快，但需要96hr才能達到最高，中、深層部位則在48hr內快速增加，在48hr以後即大致維持一個定值，且其殘存量僅及表層部位的一半。

The yellowfin tuna steaks (ca. 8x5x2 cm) sealed in a package and treated with 99.5% carbon monoxide (CO) gas at 4℃ for 5 days were compared with the control steaks without CO gas treatment stored at same condition. The surface layer (2 mm thick), middle layer (2～4 mm from surface) and inner layer (4～6 mm from surface) were separately cut from the fish　steak. For each layer, the Hunter's color value (L, a, b), metmyoglobin formation (metMb%), volatile basic nitrogen (VBN) and CO residue were measured and compared.
The results revealed that Hunter +a value of tuna steaks treated with CO gas for 4 hr increased higher than that of the control steak for all three layers. However the values of L and +b between the CO gas-treated steak and the control steak differed slightly. The metMb% in the surface layer showed no significant difference with or without the CO treatment whereas the metMb% in the middle and inner layers of CO gas-treated steak were apparently lower than that of the control steak. The VBN of the steaks remained below 20 mg/100 g during the 5-day chilling storage regardless of CO gas treatment.
The amount of CO residue in the surface layer increased rapidly in 24 hr of the treatment and consequently reached the highest value at 96 hr, while those in the middle and inner layers increased quickly in 48 hr. The CO residue in the inner layer remained constant after 48hr of treatment at a value about a half as high as thatin the surface layer.