Equations for spectrophotometric determination of relative concentrations of myoglobin derivatives in aqueous tuna meat extracts

► The %metMb in tuna extract was estimated using equations derived from horse Mb. ► The results showing different %metMb were obtained with the different equations. ► This discrepancy was due to difference in absorption spectra of horse and tuna Mb. ► New set of equations derived from absorption spectra of tuna Mb was established.