Total sulphydryl contentwas determined by a procedure using DTNB
as reagent (Eymard, Baron, & Jacobsen, 2009). In brief, 1-g meat sample
was homogenized in 20 ml of 0.05 M phosphate buffer (pH 7.2) by
using an Ultra Turrax, and 1 ml of the homogenate was mixed with
9 ml of 0.05 M phosphate buffer pH 7.2 containing 0.6 M NaCl, 6 mM
EDTA, and 8 M urea. The mixture was centrifuged, and 3 ml of the
supernate was incubated at 40 °C for 15 min with 0.04 ml of 0.01 M
DTNB solution in 0.05 M sodium acetate. The absorbance was measured
at 412 nm (Shimadzu UV 160A, Kyoto, Japan) and the sulphydryl content
was calculated using a molar extinction coefficient of 13,600 M−1 cm−1.
Results were expressed in nmoles of sulphydryls/mg of protein.