Assessment of Temperature at Recommended Methods of Determining Doneness in Egg Recipes

Introduction: USDA and FDA recommend that egg dishes be cooked to an end-point temperature of 160°F. However, a nationwide survey found that only 5.3% of consumers used a food thermometer when preparing egg dishes.  Reported methods for determining doneness by consumers included: cooking time, firmness of the product, if the product jiggled, color of the dish, or whether an inserted knife or toothpick came out clean. 

Purpose: This study was designed to assess the potential safety of consumers reported methods for determining doneness of egg dishes. 

Methods: After standardizing ingredients and measurements, chess pies, quiche, and breakfast casseroles were prepared and analyzed for doneness. Researchers recorded the time at which the dish reached 160°F, the consistency of the dishes at 160°F, temperature upon completion of the recommended cooking time, and time to “doneness.”  Various methods were used to determine if dishes were fully cooked.

Results: All replications of the chess pie and quiche reached the recommended temperature before the completion of the recommended cooking time but still had a liquid consistency at that temperature.  Upon completion of the recommended cooking time the products were above 160°F, were set (did not “jiggle”), had browned, and both the knife and toothpick came out clean.  The breakfast casserole failed to reach a safe temperature of 160°F within the recommended cooking time and was still liquid.  The dish continued to cook until a safe temperature was reached, averaging another 12 minutes.  At 160°F the casseroles were set, both the knife and toothpick came out clean and they were light brown in color.

Significance: Methods used by consumers to determine doneness of quiche and pies containing eggs appear to be safe. Breakfast casseroles needed to be cooked longer than the recommended time. Although alternate methods work, checking the internal temperature could ensure safe cooking.