Food safety is important to keep in mind when preparing and storing food. However many myths surround best practices. Here are five food safety myths busted.
So it turns out you can thaw out meat and refreeze it. Who knew? Osseous/Flickr, CC BY-SA
This time of year, most fridges are stocked up with food and drinks to share with family and friends. Let’s not make ourselves and our guests sick by getting things wrong when preparing and serving food.
As the weather warms up, so does the environment for micro-organisms in foods, potentially allowing them to multiply faster to hazardous levels. So put the drinks on ice and keep the fridge for the food.
But what are some of those food safety myths we’ve long come to believe that aren’t actually true?
Myth 1: if you’ve defrosted frozen meat or chicken you can’t refreeze it
From a safety point of view, it is fine to refreeze defrosted meat or chicken or any frozen food as long as it was defrosted for no longer than 48 hours in a fridge running at 5°C or below. Some quality may be lost by defrosting then refreezing foods as the cells break down a little and the food can become slightly watery.
Another option is to cook the defrosted food and then divide into small portions and refreeze once it has stopped steaming. Steam in a closed container leads to condensation, which can result in pools of water forming. This, combined with the nutrients in the food, creates the perfect environment for microbial growth. So it’s always best to wait about 30 minutes before refrigerating or freezing hot food.
Plan ahead so food can be defrosted in the fridge, especially with large items such as a frozen turkey or roll of meat. If left on the bench, the external surface could be at room temperature and micro-organisms could be growing rapidly while the centre of the piece is still frozen!
Myth 2: Wash meat before you prepare and/or cook it
It is not a good idea to wash meats and poultry when preparing for cooking. Splashing water that might contain potentially hazardous bacteria around the kitchen can create more of a hazard if those bacteria are splashed onto ready-to-eat foods or food preparation surfaces.
It is, however, a good idea to wash fruits and vegetables before preparing and serving, especially if they’re grown near or in the ground as they may carry some dirt and therefore micro-organisms.
This applies particularly to foods that will be prepared and eaten without further cooking. Consuming foods raw that traditionally have been eaten cooked or otherwise processed to kill pathogenic micro-organisms (potentially deadly to humans) might increase the risk of food poisoning.
Fruit, salad, vegetables and other ready-to-eat foods should be prepared separately, away from raw meat, chicken, seafood and other foods that need cooking.
Myth 3: Hot food should be left out to cool completely before putting it in the fridge
It’s not OK to leave perishable food out for an extended time or overnight before putting it in the fridge.
Micro-organisms can grow rapidly in food at temperatures between 5° and 60°C. Temperature control is the simplest and most effective way of controlling the growth of bacteria. Perishable food should spend as little time as possible in the 5-60°C danger zone. If food is left in the danger zone, be aware it is potentially unsafe to eat.
Hot leftovers, and any other leftovers for that matter, should go into the fridge once they have stopped steaming to reduce condensation, within about 30 minutes.
Large portions of hot food will cool faster if broken down into smaller amounts in shallow containers. It is possible that hot food such as stews or soup left in a bulky container, say a two-litre mixing bowl (versus a shallow tray), in the fridge can take nearly 24 hours to cool to the safe zone of less than 5°C.
Myth 4: If it smells OK, then it’s OK to eat
This is definitely not always true. Spoilage bacteria, yeasts and moulds are the usual culprits for making food smell off or go slimy and these may not make you sick, although it is always advisable not to consume spoiled food.
Pathogenic bacteria can grow in food and not cause any obvious changes to the food, so the best option is to inhibit pathogen growth by refrigerating foods.
Just because something passes the sniff test, doesn’t make it OK. www.shutterstock.com
Myth 5: Oil preserves food so it can be left at room temperature
Adding oil to foods will not necessarily kill bugs lurking in your food. The opposite is true for many products in oil if anaerobic micro-organisms, such as Clostridium botulinum (botulism), are present in the food. A lack of oxygen provides perfect conditions for their growth.
Outbreaks of botulism arising from consumption of vegetables in oil – including garlic, olives, mushrooms, beans and hot peppers – have mostly been attributed to the products not being properly prepared.
Vegetables in oil can be made safely. In 1991, Australian regulations stipulated that this class of product (vegetables in oil) can be safely made if the pH (a measure of acid) is less than 4.6. Foods with a pH below 4.6 do not in general support the growth of food-poisoning bacteria including botulism.
So keep food out of the danger zone to reduce your guests’ risk of getting food poisoning this summer. Check out other food safety tips and resources from CSIRO and the Food Safety Information Council, including testing your food safety knowledge.
Team leader, Microbial and chemical sciences, Food microbiologist and food safety specialist, CSIRO.
This article was originally published on The Conversation on the 28th of December. Read the original article.
2nd February 2016 at 12:22 pm
I’d like more precise details.
“It’s not OK to leave perishable food out for an extended time or overnight before putting it in the fridge”
What if it is put in a sealed container whilst still extremely hot?
Is there any difference between the safe treatment of different types of food (e.g. cooked poultry vs cooked red meat vs stew with tomato/wine vs dairy sauce vs vegetables)?
I don’t want to heat up my fridge (and the planet) unnecessarily!
4th February 2016 at 10:21 am
Hi,
The statement above still holds even if the food is hot, although leaving it on the bench for 30 minutes will cool it enough. Modern fridges are efficient and a medium sized container or two of hot food shouldn’t affect its operation and food should cool down fairly quickly with little temperature impact on other foods in the fridge.
Leaving hot food on the bench for 30 minutes is a rule of thumb that suits a variety of different food types. Acidic food types (such as tomatoes) can inhibit or slow microbial growth but a tomato based stew may contain non-acidic food ingredients (e.g. meat and vegetables), hence the 30 min rule of thumb is the safest recommendation.
Regards,
Ellen
CSIRO Social Media
29th July 2016 at 7:31 am
I would think a stew/casserole/stockpot that has been cooked with lid on for 2 hours or more would be sterile at that point, and could be left out overnight to cool.
5th August 2016 at 9:06 am
Hi Matt,
Unfortunately this is not the case. Any food, substance or material, if re-exposed to the environment after cooking, is not sterile. Cooking food to above 70°C is the best way to destroy many microorganisms that can hurt us. However, there are some bacteria that produce heat resistant spores that can survive many hours of cooking at 100°C (Clostridium botulinum, the bacterium that produces the toxin that causes botulism, being one of them). As the stew cools to the ‘danger zone’ of between 5 and 60°C, these spores will germinate and grow and consumption of the toxin they might produce and/or high numbers of their cells can result in foodborne illness. It’s best to wait for only about 30 minutes before refrigerating hot food. Leaving cooked food out on the bench to cool overnight is potentially unsafe.
Regards,
Ellen
CSIRO Social Media
10th January 2016 at 10:23 pm
Further to my previous question, would it not be better if the supermarkets offered their meat products as a ‘still frozen’ option so the consumer can be sure that it’s only been frozen once ?
17th January 2016 at 11:39 pm
You can ask the supermarket for food still frozen. They will get it for you if they have it. I dislike the “thawed for your convenience” I don’t find it convenient at all!
10th January 2016 at 10:18 pm
So is it safe to buy meat from any of the supermarket chains and freeze it ?
2nd February 2016 at 1:27 pm
That’s the problem with headlines – the headlines contradict, but the details do not. Read the first paragraph where the critical rider is stated that it is only safe provided it remains below 5 degrees C. That condition will be very difficult to meet with a supermarket purchase.
So, in reality, calling it a myth is a mistake because in many commonly arising situations it is actually correct. Too many times people only remember the misinterpreted headline and not the details.
4th February 2016 at 10:19 am
Hi Geoff,
Yes, it is safe to buy meat from the supermarket and freeze it.
Regards,
Ellen
CSIRO Social Media
5th January 2016 at 5:11 pm
http://www.csiro.au/en/Research/Health/Food-safety/Food-handling
Generally speaking, thawed food should not be refrozen. It can be stored safely in the chilling section of the refrigerator for up to 48 hours if it has been thawed properly under controlled conditions in the refrigerator.
contradictive much?
28th July 2016 at 9:18 pm
I don’t find this all that contradictory. The most important part of the instruction is that the food that was frozen and then refrozen was thawed so that it did not heat above 5 degrees C. With this as the primary point the minor contradiction takes the form of an update that clarifies. Since most thawing may occur in less controlled conditions it’s better to not refreeze it but use it. Unless is was well controlled and then it can be refrozen. That seems to sort confusions.
8th November 2017 at 7:52 pm
That article is 2 years old. They learn new things every day.
4th January 2016 at 9:59 pm
And for every expert that agrees with this there is an expert that disagrees ….