The small laboratory at the Jejuri spice store tests moisture and bacteria in the dried spices we store for two exporters. Exporters ask how we know our numbers can be trusted; this note is the answer.
Once a year, in November, the laboratory takes part in an external proficiency scheme for food microbiology. The scheme sends the same samples to many laboratories and scores each result. At Jejuri a result is accepted if its score lies between -3 and +3. Anything outside that stops us reporting that test until we have found out why.
There is no scheme for spice moisture, so twice a year we split six samples with the exporters' own laboratories and compare. This interlaboratory check passes if the results agree within half a percentage point.
The moisture balance is checked every morning with a certified weight and calibrated every year by an outside firm. The incubators are checked twice a day with a reference thermometer, and their readings go on the sheet on each door.
Results of the scheme and the comparisons are shown to either exporter's auditors on request.
A copy of each year's results is filed with the laboratory's equipment records, and the laboratory supervisor writes a short note on anything unusual for the store manager.