title: The effect of different atmospheric conditions on the changes in myoglobin and colour of refrigerated Eastern little tuna (Euthynnus affinis) muscle.
abstract: BACKGROUND
  Oxidation of myoglobin is responsible for the undesirable appearance and loss in acceptability of fish and fish products. The retardation of such a change by a modification of the surrounding atmosphere would be a means to maintain the quality of fish during the refrigerated storage.
  
  
  RESULTS
  The changes in oxymyoglobin and metmyoglobin from dark muscle of Eastern little tuna (Euthynnus affinis) as affected by different atmospheric systems (closed system, opened system and flushed oxygen system) were determined. A saturated oxygen atmosphere more likely weakened the haem-globin complex, especially as the exposure time increased. Autoxidation of the oxy form proceeded rapidly in the presence of oxygen with the concomitant formation of the met form. When the oxygen was excluded, oxidation of oxymyoglobin was retarded. With flushed oxygen and increasing exposure time, conformational changes of globin occurred, mainly associated with protein oxidation. Generally, oxymyoglobin was more susceptible to oxidation and conformational change than did metmyoglobin. After keeping the samples at 4 °C for 3 days, dark muscle of tuna fillet kept in vacuum packaging had a slight decrease in redness and it was still acceptable. The fillets stored in exposed air or packed in 100% O(2) atmosphere turned brown, most likely due to myoglobin oxidation.
  
  
  CONCLUSIONS
  The oxygen level of the packaging atmosphere had a profound impact on myoglobin alteration, which was governed by the forms of myoglobin.
authors.affiliation: Department of Food Technology, Faculty of Agro-Industry Prince of Songkla University, Hat Yai, Songkhla, Thailand.
authors.forename: Yaowapa
authors.initials: Y
authors.lastname: Thiansilakul
authors.forename: Soottawat
authors.initials: S
authors.lastname: Benjakul
authors.forename: Mark P
authors.initials: MP
authors.lastname: Richards
mesh_terms: D000818:Animals; D004044:Dietary Proteins; D029941:Fish Proteins / Q000737:chemistry*; D005519:Food Preservation / Q000379:methods*; D019156:Indian Ocean; D007700:Kinetics; D008786:Metmyoglobin / Q000032:analysis; D018482:Muscle, Skeletal / Q000737:chemistry; D009211:Myoglobin / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D010084:Oxidation-Reduction; D010100:Oxygen / Q000009:adverse effects; D010858:Pigmentation; D011487:Protein Conformation; D011786:Quality Control; D017747:Seafood / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013785:Thailand; D014413:Tuna
chemical_list: D004044:Dietary Proteins; D029941:Fish Proteins; D009211:Myoglobin; C017595:oxymyoglobin; D008786:Metmyoglobin; D010100:Oxygen