The dangers of BBQs, buffets and take-out leftovers

Primrose Freestone, a senior lecturer in clinical biology at the University of Leicester in the US, said she rarely eats out "because the risk of food poisoning increases when food is taken outside".

“Eating outdoors attracts flies, ants, and other pests that can transmit dangerous bacteria like E. coli, salmonella, and listeria to food,” says Freestone.

Eating at barbecues and picnics with prepared foods can also create conditions for germs to grow and potentially cause food poisoning.

The same is true for buffets. She emphasizes the “two-hour service” rule, which means food is not safe to eat within two hours of being left out if it is not covered or kept refrigerated.

"Buffets are often set up before you arrive, so it's hard to know if the trays of meat, seafood, salads, desserts, and fruit will be left out within two hours of your meal," she says.

The two-hour limit also applies to take-out leftovers, as they're often past this time frame by the time you put them in the fridge. Plus, leftovers can spread bacteria from touching utensils.

Even for hot buffets, Freestone's general rule is to avoid "lukewarm" dishes, as bacteria thrive in the so-called "danger zone" between 5-60°C.

Furthermore, the buffet-style arrangement leaves uncovered meals vulnerable to contamination from other diners' coughs and sneezes; hands, hair.

One food she will never touch is raw oysters and packaged salad mixes. “Oysters are filter feeders, meaning they eat particulate matter floating in the water and can collect germs like Vibrio and norovirus in their tissues,” she says.

According to the Centers for Disease Control and Prevention (CDC), 80,000 people get sick with Vibrio enteritis (marine cholera) and 100 die from it in the United States each year. Oysters containing Vibrio will not smell, taste, or look any different than normal, so the only way to kill the bacteria is to thoroughly cook the shellfish. With packaged salads, she recommends washing them before use and eating them as soon as possible after purchase.

Freestone also offers a "list of dos and don'ts" for cooking. The first is to regularly check expiration dates, throw away items with bulging packaging, and not eat foods that look or smell different.

“I never use the same cutting board for raw and cooked food. Washing your hands before and after handling food should be second nature,” she says.

However, her number one "never do" is reheating cooked rice, as it often contains bacillus cereus, a toxin-producing bacteria that can cause vomiting and diarrhea.

"If rice is left to cool at room temperature, the spores will develop into bacteria, and the number will increase rapidly because rice is a good Bacillus culture medium when left overnight. Although the bacilli cells are destroyed when cooked, the spores still survive," warned the American microbiologist.