Characteristics of myoglobin and haemoglobin-mediated lipid oxidation in washed mince from bighead carp (Hypophthalmichthys nobilis)

Myoglobin (Mb) and haemoglobin (Hb) accounted for 61% and 39% of the total haem-protein in bighead carp (Hypophthalmichthys nobilis) dark muscle, respectively. Molecular weight of Mb and monomeric-Hb was ∼16 kDa. Haemin loss from metHb was more rapid, compared to metMb (pH 6.0, 4 °C). Pro-oxidative activities of oxyMb/Hb and metMb/Hb were examined in washed mince during 9 days of iced storage (pH 6.0). Soret measurements suggested the existence of holoMb throughout storage. For Hb, weakening of haem–globin linkage was observed, especially for metHb which had undetectable Soret after 3 days of storage. Loss of redness was more rapid and extensive in washed mince containing Hb, compared to Mb. During storage, Hb induced larger amounts of peroxides, thiobarbituric acid-reactive substances and hexanal than did Mb (p < 0.05), especially for met-form. Thus, Hb had lower haemin affinity and was a stronger pro-oxidant than Mb.