2.4. Protein oxidation
The oxidation of myofibrillar proteins was evaluated by assessing
both the loss of natural tryptophan fluorescence and the emission
of fluorescence by protein oxidation products (FP) in the
emulsions using fluorescence spectroscopy (Giessauf et al., 1995;
Heinonen et al., 1998).
Samples (100 lL for tryptophan fluorescence, 250 lL for FP)
were dissolved in phosphate buffer (5 mL) and dispensed in a 4-
mL quartz spectrofluorometer cell. Emission spectra of tryptophan
were recorded from 300 to 400 nm with the excitation wavelength
established at 283 nm (LS 55 Perkin Elmer luminescence spectrometer).
Emission spectra of FP were recorded from 400 to 500 nm
with the excitation wavelength set at 350 nm. In both measurements,
excitation and emission slit widths we