The respiration rate (RR) of mushroom (Agaricus bisporus Lange, strain X25) under air follows Arrhenius' law with an apparent activation energy of 43 400 J mol(-1) corresponding to a Q(10) of 2.9 between 10 and 20 degrees C. Oxygen from 20 to 1 kPa did not affect RR at temperatures ranging from 5 to 20 degrees C, confirming previous studies. The initial RR of mushroom (same cultivar, flush, growing conditions) measured 24 h after harvesting can vary from 1 to 2 mmol O-2 kg(-1) h(-1) at 10 degrees C. The apparent K-m value was below 0.1 kPa at 10 degrees C, and could not be estimated more accurately due to instrumental limitations. Decrease in dry matter of modified atmosphere-packed mushrooms matched the theoretical carbon consumption calculated from the constant respiration rate. Glucose and glycogen were rapidly catabolized, whereas mannitol consumption began 3 and 8 days after harvest at 20 and 10 degrees C, respectively. It was concluded that no extension of mushroom shelf life was attainable through modified atmosphere packaging. Controlling RH within the package is likely to be more effective. (C) 1999 Elsevier Science B.V. All rights reserved.