If leftover grilled hamburgers were properly handled and refrigerated after a picnic, they can typically remain safe to eat for about 3 to 4 days in the refrigerator. Here are some guidelines to ensure the safety and quality of the leftovers:
Refrigerate promptly: After the picnic, refrigerate the leftover grilled hamburgers within 2 hours of cooking. If the ambient temperature is above 90°F (32°C), the food should be refrigerated within 1 hour.
Store properly: Place the leftover hamburgers in an airtight container or wrap them tightly in plastic wrap or foil. This helps prevent contamination and keeps the burgers from drying out in the fridge.
Label and date: If you plan to store the leftovers for more than a day or two, consider labeling the container with the date when the burgers were cooked or the date by which they should be consumed.
Monitor smell and appearance: Before consuming the leftovers, check their smell and appearance. If the hamburgers show signs of spoilage such as a sour or foul odor, slimy texture, or unusual color, do not eat them, as they may have gone bad.
Reheat properly: When reheating the leftover hamburgers, make sure they reach an internal temperature of 165°F (74°C) to kill any potential bacteria.
Remember that these are general guidelines, and individual factors such as the freshness of the ingredients, the cleanliness of preparation and handling, and the efficiency of your refrigerator can also impact the safety and shelf life of the leftovers. When in doubt, it's always best to err on the side of caution and discard any questionable food items to avoid the risk of foodborne illness.