1. A batch of poorly processed dry cherries contains 500 µg/kg of OTA. Approximately 90% is retained in the husks, and of what is left in the green beans 75% is destroyed during roasting. All of the remaining OTA is brewed into the cup. How much OTA is present in one litre of coffee made with 50g of the ground coffee?
2. Calculate the quantity of OTA (in micrograms) to be found in each of the following beverages:
- 100 ml of coffee made from 1g of soluble coffee containing 10 ppb OTA
- 100 ml of coffee made from 5g of roast and ground coffee containing 5ppb of OTA
- 100 ml of wine containing 2ppb of OTA
3. A European coffee importer has arranged to carry out sampling and analysis for OTA of an incoming container with 18 tonnes of green coffee in bags. The sampling plan calls for 3 composite samples to be taken of 1.25 kg each. The 3 samples are analysed for OTA and the following results are obtained:
- 6.2 ppb
- 8.7 ppb
- OTA not detected
The method of OTA analysis utilised is based on HPLC and has a detection limit of 0.1 ng/g. The buyer's contract had specified that the green coffee should contain less than 10 µg/kg OTA on arrival at the buyer's warehouse. Determine whether the coffee shipment would be acceptable or not.
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