Get your degree in freezing mince here

With so many freezers full of mince thanks to COVID-19 panic buying, the right way to freeze, thaw, cook and reheat red meat has never been more important.

Beef producers, and all those all the supply chain, are conscious of the detrimental effect a bad experience with beef and lamb in these unusual times could have on the industry longer-term.

They also hasten to point out, for many of the current generation of household managers freezing meat is something new - or at least something they've not thought about since childhood.

The guidelines, however, are not as black and white as one might think.

That's because there is the food safety element, or the science, and then there is the quality, flavour and eating experience element. Over the top of all that is individual needs and plain old commonsense.

The science busts some widely-held beliefs.

Red meat can be frozen for years and it would still be safe to eat. You can refreeze raw meat many times over provided it is defrosted properly - primarily never placed under a temperature higher than 5 degrees Celsius and thawed for less than 48 hours.

But butchers and nutritionists say abiding by just the science is not practical.

The red meat industry's big marketing and research body Meat & Livestock Australia has very clear recommendations on it's Australian Beef The Greatest website.

It says sausages should not be frozen for more than two months; mince and diced beef two to three months; steaks three to four months and roasts up to six months.

MLA says to always cook defrosted beef before refreezing. Meat retailers and nutritionists agree.

From a taste and flavour point of view, that is a no-brainer, they say, but it's also safer given how difficult it is to adhere to the below 5 degrees rule.

Some butchers and chefs expressed distaste at the idea anyone would freeze products other than mince even once.

CSIRO food microbiologist Cathy Moir explained freezing stopped micro-organisms from growing.

There are millions of micro-organisms and the majority on food are spoilage organisms. In the main, they won't make people sick but on occasion pathogenic organisms like e-coli, salmonella and campylobacter grow. These ones are associated with meat and they can be deadly, especially to vulnerable people such as the elderly, pregnant women and those with certain conditions like diabetes.

All are temperature-sensitive. Cooking at a minimum external temperature of 75 degrees will kill them.

That means mince, sausages, steaks and roasts need to reach that temperature all the way through during cooking.

Ms Moir, who is also chair of the Food Safety Information Council, a health promotion charity providing consumer focused food safety information, said from a food safety perspective, meat could theoretically be frozen for any length of time and the differences in storage time recommendations related to quality changes.

Beef cuts contain a high percentage of water. When frozen, tiny ice crystals form within the meat's structure, says MLA. These crystals rupture the fibre of the meat, causing it to leach water when defrosted - effectively drying it out.

All recommendations, however, agree meat should never be defrosted on a kitchen bench; in the fridge for a day is ideal but the MLA site also has microwave defrosting guidelines.

Ms Moir also said it was not a good idea to wash meat.

"Cooking meat kills micro-organisms. 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," she said.

Hot leftovers should go into the fridge immediately - never leave it to cool first.

Ms Moir explained micro-organisms could grow rapidly in food at temperatures between 5 and 60 degrees Celsius.

Temperature control is the simplest and most effective way of controlling the growth of bacteria, she said.

And finally, the 'sniff test' has no scientific basis.

Pathogenic bacteria can grow in food and not cause any obvious changes to the food.

If in doubt, throw it out.