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