Consumer

safefood commissioned a scientific research project, to determine the optimum time for cooking a turkey in an electric fan-assisted oven to make sure that it is both safely and thoroughly cooked while remaining tasty. This work was carried out on unstuffed turkeys and on cavity-stuffed turkeys and included a number of steps as follows:

Cooking trials

A number of birds were roasted in a fan-assisted oven and temperature changes during cooking were measured using thermocouples. The time needed to cook the whole turkey to a temperature high enough to kill any dangerous bacteria present was also recorded. The data collected enabled mathematical equations to be derived giving cooking time instructions according to weight for turkeys cooked in electric fan-assisted electric ovens. This research indicated that the thickest portions of the breast and thigh meat were the slowest parts of the turkey to cook. In the case of the cavity stuffed turkeys, the centre point of the stuffing was the slowest point to cook.

Sensory trials

Sensory experts rated the taste, appearance and texture of the turkeys cooked according to the cooking time instructions developed in the first step. The experts gave sensory evaluation scores of 6 and 7 on a 9 point scale. These scores indicated that the cooking instructions developed as a result of the cooking trial produced better than acceptable quality according to appearance (external and internal appearance of the white and dark meat), flavour and texture.

Microbiological challenge assays

Microbiological challenge assays were undertaken to ensure that the cooking instructions produced cooked turkeys that were microbiologically safe. Sample turkeys were inoculated with a cocktail of five strains of Salmonella and Campylobacter. After cooking no surviving microorganisms were recovered from any of the birds, either stuffed or unstuffed, indicating that the cooking instructions produced microbiologically safe turkey.

Overall the cooking instructions that were developed from the project produced microbiologically safe turkey of more than acceptable sensory quality. The results from this project provide cooking advice for electric fan-assisted ovens based on sound science and led to the following recommendations which will help to ensure that every turkey (large or small), is cooked sufficiently to ensure it is safe, but not overcooked (which can lead to reduced eating quality).

Recommendations

1.  Make sure that the turkey is thoroughly defrosted before cooking. If it is not defrosted it will not cook properly and safely. Once thoroughly defrosted a previously frozen turkey cooks in the same way as a fresh turkey.
2. Think carefully about whether or not to cook stuffing inside the bird, because stuffed turkeys can take a lot longer to cook than unstuffed turkeys. For example, a large (7.5kg) turkey with cavity stuffing took 30% (almost 1½ hours longer) to be properly and safely cooked, than a similar sized or unstuffed bird. Such longer cooking times can impair the quality of the turkey meat. By the time the centre of the stuffing is properly cooked, the meat of the turkey may be dry and overcooked.
3. Get an accurate estimate of the weight of your turkey, and allow for the increase in overall weight related to the addition of stuffing. Make sure to use the weight of the total oven ready bird, including the weight of the added stuffing, in calculating the correct cooking time for your turkey (see below).
4. Calculate how much stuffing to add, and don’t add too much, as this increases the cooking time. A weight of stuffing not greater than 10% of the weight of the unstuffed cleaned bird is usually about right. 
5. Cover the bird with tinfoil during cooking and baste every hour. The use of tinfoil helps cook the bird more evenly and gives a more “juicy” product. The turkey should be basted every hour during cooking (the tinfoil can be removed for the last half hour to finally brown the skin).
6. When cooking unstuffed turkeys in an electric fan-assisted oven, the oven should be preheated to a temperature of 180°C, and the bird cooked at 180°C for- 19 minutes per kg + 124 minutes for all birds of 3.3 kg and above
7. When cooking cavity stuffed turkeys in an electric fan-assisted oven, the oven should be preheated to a temperature of 180°C, and the bird should be cooked at 180°C for – 28 minutes per kg + 110 minutes for all birds of 3.3 kg and above
8. Different ovens have different performance characteristics, so it is very important to check the manufacturer’s handbook to ensure safe and optimum performance.
9. Check that you fully understand and have properly adjusted oven controls to achieve the required cooking temperatures. Even when ovens are correctly adjusted, the presence of other items in the oven, or over-frequent opening and closing of the oven door can make the oven less effective and extra cooking time will be needed.
10. Don’t “rush” to carve the stuffed cooked bird! One way of making sure that the stuffing is properly cooked, without risking overcooking the meat, is to remove the turkey from the oven when the meat is fully cooked, and leave it to rest for half an hour covered in tinfoil at room temperature, before carving. The stuffing continues to cook inside the hot bird during this time, but the meat is not being overcooked.
11. Double-check completeness of cooking. It is always essential that you perform additional checks to ensure the turkey is sufficiently cooked before serving. You should check that there is no pink meat left, the juices run clear when the thickest part of the thigh and breast meat are pierced with a clean fork or skewer and that it is piping hot all the way through. If the bird is stuffed, check that the centre of the stuffing is piping hot as well, before serving.

These recommendations apply to electric fan assisted ovens only. Click here for Guidance on cooking turkeys in gas and other types of ovens.

Download PDF: Cooking the Christmas Turkey: Calculation of safe cooking times for stuffed and unstuffed turkey