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.