No, it is not safe to store leftovers on the counter overnight. Leaving food at room temperature for an extended period allows bacteria to grow and multiply, increasing the risk of foodborne illnesses.

When cooked food is left out at room temperature, the "danger zone" temperature range of 40°F to 140°F (4°C to 60°C) is reached, which is where bacteria can thrive. In this temperature range, bacteria can double in number every 20 minutes.

Perishable foods such as cooked meat, poultry, seafood, dairy products, and cooked vegetables should be refrigerated within two hours of being cooked or removed from the oven. If the room temperature is above 90°F (32°C), the food should be refrigerated within one hour.

Here are a few examples to illustrate the importance of refrigerating leftovers promptly:

1. Cooked chicken: If you roast a chicken for dinner and leave the leftovers on the counter overnight, bacteria like Salmonella or Campylobacter can multiply rapidly. Consuming this chicken the next day without proper refrigeration can lead to food poisoning.

2. Rice: Cooked rice is particularly prone to bacterial growth due to its moisture content. Leaving cooked rice at room temperature overnight can allow Bacillus cereus, a bacteria commonly found in rice, to multiply and produce toxins that cause food poisoning.

3. Dairy products: Leaving dairy-based leftovers like milk, yogurt, or cheese on the counter overnight can promote the growth of harmful bacteria such as Staphylococcus aureus or E. coli. These bacteria can cause severe foodborne illnesses.

It is crucial to follow proper food safety guidelines to prevent foodborne illnesses. If you have leftovers, cool them quickly and store them in airtight containers in the refrigerator within the recommended timeframe. This helps maintain food quality and reduces the risk of foodborne illnesses.

References:

1. United States Department of Agriculture (USDA) Food Safety and Inspection Service: "Danger Zone". Available online: https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/danger-zone

2. Food and Drug Administration (FDA): "Refrigeration and Food Safety". Available online: https://www.fda.gov/food/buy-store-serve-safe-food/refrigeration-and-food-safety