The production and accumulation of carbon monoxide in stored dry grain

Carbon monoxide was identified as a common constituent of head space atmospheres in storage containing dry grain (<13% moisture content (w.b.)). Concentrations exceeded the hygienic standard for workspace atmospheres in most of the stores investigated and interfered with phosphine measurements using an electrochemical sensor. In the laboratory carbon monoxide at 10,000 ppm was observed in wheat (10.8% m.c.) that had been held at about 22°C for 7 years in a sealed glass flask. In the field it was detected in association with stored wheat, oats, paddy and field peas at levels up to 1000 ppm. Carbon monoxide concentrations were consistent with evolution rates from the grain of up to 9 ng per gram of grain per day.