Written by Claire Duncumb
Have you ever wondered if it is safe to eat the rest of the loaf of bread if you spot a few bits of mould on one slice? Or, do you really need to wash your packaged salad leaves before adding to your salad? Read on for answers to these food safety conundrums and more.

If only one slice of bread has mould on it, can I still eat the rest of the loaf?

Throwing away an entire loaf of bread just because there is mould on one piece might seem wasteful, but it is the right thing to do!  When you see mould spots on a slice of bread they are in fact colonies of spores that can spread through the air and contaminate the rest of the loaf. Breads that have a higher moisture content such as whole grain bread, fruit bread and bagels, will mould faster than drier breads like white bread and sourdough. Mould grows best in dark and warm conditions so it’s a good idea to store your bread in your fridge or freezer, particularly during the warmer months of the year. 

What about cheese?  Can I still eat cheese if there is mould on it?

Hard cheese - Mould generally cannot penetrate deep into a hard cheese so you can still use the rest of the cheese.  Cut off at least a few centimetres around and below the mould spot. 

Cheese made with mould e.g. blue cheese, brie - Discard soft cheeses such as brie and Camembert if they contain moulds that are not a part of the manufacturing process. 

Soft cheese e.g. cottage or cream cheese - Throw away soft cheeses where mould is present.  Soft cheeses have a high moisture content and can be contaminated below the surface of the cheese.

If one grape or strawberry is mouldy should I throw the rest of the fruit away?

If it’s just one or two mouldy grapes or strawberries, throw those away and take a good look at the rest of the fruit and make sure to wash the fruit. It’s usually fine to eat the remaining fruit, however you can’t guarantee that it hasn't come into contact with mould spores. You should always avoid eating fruit that is actively growing mould.

Generally, for firm fruits and vegetables with low moisture content like carrots, capsicums, you can trim off mould spots as it is difficult for mould to penetrate dense and hard vegetables. Soft fruits and vegetables with a high moisture content (cucumbers, peaches) can be contaminated below the surface so it's best to throw these away or add to the compost bin.

Is it safe to eat a potato if there are green spots on it?

Before cooking your potatoes always remove any green spots or damaged parts of the potato as the green indicates chlorophyll buildup, which signals the presence of solanine, a harmful toxin that cannot be destroyed by cooking. Also, do not eat potatoes that taste bitter and remember to store potatoes in a cool, dry and dark spot.

I’ve heard that you shouldn’t eat leftover rice.  Is that true?

Bacillus cereus is a type of bacterium that is often present in starchy foods such as rice. Bacillus cereus can make you unwell, causing symptoms such as nausea, vomiting and diarrhoea. Illness from this bacteria usually occurs between 1 to 6 hours after eating contaminated food.   

It’s important not to leave cooked rice at room temperature to cool. Instead, make sure you keep the rice hot (above 60 degree Celsius) or immediately cool the rice and store it in the fridge. It is perfectly safe to reheat one-day-old rice, but you should only re-heat once and if the rice was cooled and refrigerated within an hour of cooking.

Is it safe to eat a hamburger if the meat patty looks pink in the middle?

You should not eat a meat patty, hamburger or meatballs if the meat looks pink on the inside and you suspect that the meat is undercooked. Mincing meat can cause any bugs that are on the surface of the cut of meat to be distributed throughout the mince, so only searing the surface of the hamburger patty or meatball might not kill all the bugs that are present. To ensure your hamburger patty or meatballs are safe to eat, always cook mince thoroughly all the way through.

Is the three second rule true?

Unfortunately no ... but it is a good excuse to encourage your toddler to finish eating the sandwich that they dropped on the floor! Food can be contaminated by bacteria from the ground within milliseconds - so if you can’t wash it after it’s been dropped, you’re probably best to throw it out.

Do I really need to wash my fruit and vegetables?

It’s always a good idea to wash your fruits and vegetables under cool running water before eating. For bagged lettuce, coleslaw and spinach that claims to be pre-washed, you can use without further washing, or give them a rinse if you prefer. Also, ignore any messages to use soaps or detergents to wash your fruit and veg - just stick to water.

Is it safe to drink raw milk?

Raw unpasturised milk (and raw milk products) may contain harmful microorganisms such as Campylobacter, Listeria and E. coli, which can cause severe diarrhoea and vomiting as well as more serious complications such as kidney problems and paralysis. In New Zealand there have been cases of illness outbreaks caused by consuming raw milk. Pregnant women, children, babies, the elderly and those with compromised immune systems are at greatest risk and it is recommended that these groups do not consume raw milk.

If you have any other food safety questions, get in touch with us via our email contact@foodtruths.org.