In each treatment, 10 g frozen flesh was ground with 25 mL
of ice-cold extraction buffer and 0.5 g polyvinylpolypyrrolidone
(PVP, Sigma Chemicals) with a tissue grinder Kinematica (Crl-6010,
Kriens-LU, Switzerland). For PPO and CAT assays, the extraction
buffer was 50 mM sodium phosphate (pH 7.8). For POD, 100 mM
sodium phosphate buffer (pH 6.4) was used. The homogenate was
centrifuged at 27,000 × g for 50 min at 4 ◦C and the resulting supernatants
were used directly for assay.