Insufficient heat treatment of eggs due to following cooking instructions in the labels

Purpose: The demand for ready-to-eat, prepared meals has risen over the years. Following a recipe is a reason pointed by some consumers for not monitoring doneness during cooking. Our aim was to investigate the inactivation of Salmonella in products with eggs during cooking according to instructions in labels/recipes. Methods & Materials: We have chosen a very popular and traditional Portuguese dish made with salted codfish, fried potatoes and eggs – “Bacalhau À Brás”. We bought in a supermarket three packages of a frozen, precooked dish of “Bacalhau à Brás”, all belonging to the same production lot. The package contained a 300 g meal, with the codfish and fried potatoes already precooked, being the consumer responsible to add one raw egg in the end of the recipe. In the package, the cooking instructions are provided: “Conditions of use/preparation: Without defrosting, place the stew in a non-stick frying pan, then place the potatoes over the top and let them cook on a low heat so that it defrosts completely. Add a beaten egg, slowly wrapped for about 2 minutes so that the egg is sufficiently cooked. Garnish with whole olives or slices and chopped fresh parsley.” These instructions were followed in the laboratory where a domestic food preparation was mimicked. Eggs contaminated with different levels of Salmonella were used. Results: The 2 min at low temperature after the addition of the raw egg, as indicated in the package of the pre-cooked dish tested, was not enough to complete inactivate Salmonella. The risk for Salmonella survival and recovery of injured cells increases with the initial level of contamination. Conclusion: Recipes where raw eggs are added by the consumers at home might constitute a safety issue due to failure in proper inactivation of Salmonella as the manufacturer's instructions might not be specific enough to guarantee sufficient time and temperature, which may lead to the survival of Salmonella. This study highlights the need to provide scientifically-based information on food labels to increase food safety.