經一氧化碳氣體處理之鮪肉在冰藏及凍藏過程中品質的變化   全文下載

Quality Changes during Iced and Frozen Storage of Tuna Flesh Treated with Carbon Monoxide Gas

將大目鮪魚肉片（8 × 6 × 2 cm）先經一氧化碳（CO）氣體處理5天之後，再與對照肉於0°C下冰藏7天或於-20°C下凍藏6個月，探討鮪魚肉片之表層（表面2mm厚）、中層（表面下2~4 mm厚）及深層（表面下4~ 6mm厚）各部位的氧化型肌紅蛋白比例（metMb%）、色澤及CO殘存量之變化。結果顯示CO氣體處理肉在冰藏7天的過程中，其表、中、深層部位的metMb%有略微上升之現象，但均維持在10%以下；但對照肉之中、深層部位的metMb%於冰藏前即高達50%，且明顯較表層部位之40%為高，但三者在冰藏過程中均呈微幅之增加。鮪肉的Hunter L，a，b值顯示，不論表、中、深層部位，CO氣體處理肉的+a值明顯較對照肉為高。鮪肉中的CO殘存量會在冰藏中急速下降，中、深層部位在冰藏7天後無法檢出CO的殘存量。至於CO氣體處理肉在凍藏6個月的過程中，metMb%幾乎維持定值，而對照肉之metMb%則在凍藏中逐漸上升，可高達40 ~ 60%，+a值則在凍藏中由11下降至5。鮪肉之表層及中層部位的CO殘存量在凍藏初期有下降之現象，其後則維持定值，深層部位的CO殘存量在凍藏中無明顯之變化。 The bigeye tuna steaks (ca. 8 × 6 ×2 em), after being treated with carbon monoxide (CO) gas for 5 days, were stored together with the untreated control fish steaks under two different conditions, in ice at 0°C for 7 days and frozen stored at -20°C for 6 months. For each storage condition, the changes in metmyoglobin formation (metMb% ), color appearance and CO residue in the surface layer (2 mm thick), the middle layer (2~4 mm from surface) and the inner layer (4~6 mm from surface) of the CO gas-treated and the control were measured and compared. The results revealed that, during the 7-day ice storage period, the metMb% values in the three layers of the CO gas-treated tuna steak increased gradually, but all remained below 10%. For the control, the metMb% in the middle and inner layers were as high as 50% before storage, obviously being higher than that of the surface layer, but increased only slowly in all three layers throughout the iced storage. In views of the measured tristimulus color values (Hunter L, a and b) among the three layers of tuna steaks, the +a value of the CO gas-treated steak was lower than that of the control. The amount of the CO residue in the CO gas-treated steak decreased drastically during iced storage and became undetectable in both the middle and the inner layers after 7 days of storage. In the case of frozen storage at -20°C for 6 months, the values of metMb% and Hunter a for CO gas-treated steak remained almost constant, whereas the value of metMb% of control increased gradually up to 40-60% while the +a value decreased from 11 to 5. The CO residue in the surface and middle layers decreased during the early stage of the six-month freezing storage followed by no apparent change. There was no apparent variation in CO residue in the inner layer of tuna steak throughout the frozen storage."

The bigeye tuna steaks (ca. 8 × 6 ×2 em), after being treated with carbon monoxide (CO) gas for 5 days, were stored together with the untreated control fish steaks under two different conditions, in ice at 0°C for 7 days and frozen stored at -20°C for 6 months. For each storage condition, the changes in metmyoglobin formation (metMb% ), color appearance and CO residue in the surface layer (2 mm thick), the middle layer (2~4 mm from surface) and the inner layer (4~6 mm from surface) of the CO gas-treated and the control were measured and compared. The results revealed that, during the 7-day ice storage period, the metMb% values in the three layers of the CO gas-treated tuna steak increased gradually, but all remained below 10%. For the control, the metMb% in the middle and inner layers were as high as 50% before storage, obviously being higher than that of the surface layer, but increased only slowly in all three layers throughout the iced storage. In views of the measured tristimulus color values (Hunter L, a and b) among the three layers of tuna steaks, the +a value of the CO gas-treated steak was lower than that of the control. The amount of the CO residue in the CO gas-treated steak decreased drastically during iced storage and became undetectable in both the middle and the inner layers after 7 days of storage. In the case of frozen storage at -20°C for 6 months, the values of metMb% and Hunter a for CO gas-treated steak remained almost constant, whereas the value of metMb% of control increased gradually up to 40-60% while the +a value decreased from 11 to 5. The CO residue in the surface and middle layers decreased during the early stage of the six-month freezing storage followed by no apparent change. There was no apparent variation in CO residue in the inner layer of tuna steak throughout the frozen storage.