Category: Food

How Can a Tin of Beetroot Last for Three Years Without Going Bad?

By Jack Mercer – Rabbit Hole Fisherman

Leave a fresh beetroot in the kitchen long enough and it will eventually be
fit for the compost. Put it through a cannery, however, and it can spend years
in a cupboard without refrigeration. The explanation takes us from a French
inventor working more than 200 years ago to some surprisingly sophisticated
food science. And it turns out that the vinegar in your beetroot is doing more
than making your sandwiches taste better.

In This Story

There’s a peculiar sort of archaeology that takes place in the average
Australian pantry. Somewhere behind the pasta, the half-used packets of rice
and the bottle of sauce nobody particularly likes, you find a tin of beetroot
that appears to have been purchased during a previous era of your household’s
history.

Perhaps it was intended for a barbecue. Perhaps somebody was going through a
phase of making proper hamburgers, the Australian kind with beetroot and an egg
threatening to slide out the side.

Either way, the tin has been forgotten.

You turn it over, look at the date and discover that the manufacturer expected
it to last considerably longer than you remembered.

The beetroot was harvested, cooked, packed and sealed years ago. Yet,
assuming the food was properly processed and the can has remained intact and
appropriately stored, it may still be perfectly suitable for lunch.

Fresh beetroot is considerably less accommodating. It can survive for a while
under good storage conditions, but leave it long enough and moisture loss,
microbial growth and the vegetable’s own biological processes will eventually
take their toll.

The canned version has somehow escaped most of that trouble.

To understand how, it’s worth meeting a Frenchman who was trying to solve much
the same problem before anyone had a satisfactory explanation for why food
spoiled.

The man who preserved food before we understood germs

Nicolas Appert was a French confectioner and food preserver who spent years
experimenting with ways to stop food deteriorating. His work attracted the
attention of a government with a practical problem: armies and navies needed
provisions that could survive long journeys without becoming inedible.

In 1810, Appert published his findings in a book describing methods for
preserving animal and vegetable foods.

His approach involved putting food into containers, sealing them and heating
them. He worked with glass vessels, not the familiar supermarket tins that
would become widespread later.

The remarkable part is the timing.

Louis Pasteur’s work explaining the role of microorganisms in fermentation and
spoilage was still decades away. Appert had discovered a practical preservation
method without knowing precisely what was happening to the microscopic
organisms responsible for much of the deterioration.

He knew that the method worked, even if the science behind it remained
incomplete.

The method was far from perfect by modern standards, and early preservation
systems had limitations that later research would expose. Nevertheless, Appert
had helped establish the principles on which an enormous food industry would
eventually be built.

Within the same year, the English inventor Peter Durand received a patent for
food preservation using tin-plated iron containers. Metal cans gradually became
a practical alternative to glass, particularly for transporting provisions.

Two centuries later, a supermarket tin of beetroot owes something to both men.

What Appert couldn’t have explained is that heating food under controlled
conditions can destroy or inactivate microorganisms, while a properly sealed
container helps prevent fresh contamination.

Modern canneries have spent generations refining that process. The temperatures,
heating times, container designs and food formulations are all carefully
considered, because getting the balance wrong can produce anything from
unpleasantly mushy vegetables to a serious food-safety problem.

What happens to a beetroot in a cannery?

Imagine the beetroot arriving from the farm. It carries soil, has a tough outer
skin and looks very little like the neat red cubes that eventually appear on a
supermarket shelf.

Commercial preparation generally involves cleaning, trimming, cooking or other
preparation, and cutting the beetroot into the form required for the finished
product. The details vary between factories and products, and the order of
operations isn’t identical everywhere.

The prepared vegetable is packed with its liquid, and the food and container
undergo a validated preservation process.

That word, validated, matters. Food processors need evidence that the chosen
treatment will control the relevant microorganisms under the conditions in
which the food will be sold and stored.

Heating a vegetable until it is tender enough for dinner is one thing.
Producing a container of food that can remain safe on a supermarket shelf for
an extended period is another.

The seal is just as important as the heat treatment. A properly processed
product could be contaminated again if microorganisms were able to enter
through a faulty container.

Once sealed and processed correctly, the contents are protected from the
ordinary environmental contamination that helps make fresh food deteriorate.

There is a catch, though. Different foods require different treatment, and the
distinction has a great deal to do with acidity.

The vinegar has a second job

Australian beetroot has a long association with vinegar and sweetness. For
anyone who grew up eating beetroot on hamburgers or beside a plate of cold
meat, the sharp, sweet liquid is as familiar as the vegetable itself.

Look at the ingredients of a typical canned beetroot product and you may find
beetroot, water, sugar, salt and an acid such as acetic acid.

Acetic acid is the principal acid in vinegar. It contributes the tangy taste,
but it also changes the environment in which microorganisms would have to
survive and grow.

Food scientists measure acidity using the pH scale. A lower pH indicates
greater acidity, and one particularly important dividing line in food
preservation is pH 4.6.

The number matters because of Clostridium botulinum, a bacterium capable of
producing an extremely dangerous toxin under suitable conditions.

Its spores are unusually resistant to heat. In low-acid foods, simply boiling
the contents at ordinary atmospheric pressure cannot be relied upon to control
them.

Properly acidified foods, with an equilibrium pH of 4.6 or below, help prevent
the growth and toxin production of this organism when they are also properly
processed and sealed. The required processing method still depends on the
complete product and its formulation.

This is why a can of beetroot in an acidic liquid and a can of plain sweetcorn
may need quite different preservation processes.

Corn is generally a low-acid food. Commercial processors must account for that
when determining the necessary heat treatment, which may involve temperatures
above the boiling point of water under ordinary atmospheric pressure.

Acidified beetroot can be processed under different conditions, provided its
acidity and other safety requirements are properly controlled.

That distinction is also why recipes for preserving vegetables at home cannot
safely be improvised by guessing how much vinegar to add or how long to boil a
jar.

In a commercial cannery, the process must be designed around the actual food
being packed.

And what about the sugar?

It certainly contributes to the flavour. At high enough concentrations, sugar
can also help preserve food by reducing the water available for microorganisms
to use. Jam is a familiar example.

But the sugar content of ordinary canned beetroot shouldn’t be assumed to
provide that sort of protection on its own. The same applies to salt. Both
ingredients can influence the finished product, but their presence doesn’t
remove the need for an appropriate preservation process.

For a food that looks so uncomplicated on the plate, quite a lot depends on
getting the chemistry right.

Why doesn’t it turn into red porridge?

There is another puzzle here, especially for anyone who has ever left vegetables
boiling on the stove while distracted by something more interesting.

Heat softens vegetables. Too much heat can leave them barely recognisable.

Yet canned beetroot usually emerges in reasonably distinct slices or cubes,
soft enough to eat but firm enough to hold together.

Plant tissue gets much of its structure from cell walls and the substances that
help bind cells together, including pectin. Cooking alters those structures,
which is why a raw beetroot feels so different from a cooked one.

Food processors must balance the treatment needed for safety against the texture
customers expect. The balance varies with the vegetable, its size, its
preparation and the product’s formulation.

Some processed vegetables use permitted firming agents to help preserve their
texture. Others rely on the natural properties of the vegetable and the way it
is processed.

A glance at the ingredients can help establish which applies to a particular
product.

Beetroot is also rather generous with its colour. The red liquid that stains
your fingers, the chopping board and occasionally your shirt contains pigments
called betalains, which give the vegetable much of its characteristic
appearance.

These pigments can move into the surrounding liquid and are affected by
processing conditions, including heat and acidity.

So the liquid in the can isn’t simply a flavouring mixture that happens to be
red. Some of that colour has come from the beetroot itself.

It also explains why the vegetable and the liquid may change in appearance over
time without that change necessarily indicating spoilage.

Is the old beetroot still nutritious?

The common assumption that fresh vegetables must always be nutritionally
superior to canned ones doesn’t survive much scrutiny.

There are differences, certainly, but they depend on the vegetable, the nutrient
and what happens to the food between harvest and consumption.

Heat-sensitive vitamins can be reduced during processing. Vitamin C is one
example, although the extent of any loss depends on the conditions involved.

Minerals are generally more stable under heat, while some water-soluble nutrients
may move from the vegetable into its packing liquid.

Fresh produce has its own complications. Nutrient levels can change during
transport, storage and cooking, particularly when vegetables spend extended
periods between harvest and the dinner table.

Canning also has a substantial practical advantage: it makes vegetables
available when fresh produce is expensive, out of season or inconvenient to
prepare.

None of that means a three-year-old tin contains precisely the same nutrients as
it did when it left the factory. Some components may deteriorate during storage,
and flavour, texture and colour can change.

Food safety and eating quality follow different clocks.

A properly preserved product may remain microbiologically safe after its flavour
or appearance has begun to decline.

The date on the container helps consumers understand the manufacturer’s
expectations, although there are some subtleties to Australian date-labelling
rules.

The date on the bottom isn’t always an expiry date

Australian food labels distinguish between best-before and use-by dates.

A best-before date generally concerns the period during which food is expected
to retain its quality, assuming appropriate storage. A product can sometimes
remain safe and suitable after that date, although its quality may have
declined.

A use-by date has a different meaning. Food carrying one should not be eaten
after that date.

Some shelf-stable foods with a shelf life of two years or more are exempt from
mandatory date marking under the Food Standards Code, although manufacturers
may still choose to provide one.

The condition of the can matters independently of any printed date.

A container that is swollen, leaking, badly rusted or damaged around a seam may
no longer be safe. Serious damage can compromise the barrier that protects the
food from contamination.

Nor is it wise to rely on a sniff or a tentative taste to determine whether
suspicious canned food is safe. Some dangerous contamination cannot be
reliably identified that way.

The sensible approach is to follow the manufacturer’s instructions and discard
cans showing warning signs.

Once a can is opened, its long shelf life is over. The contents are exposed to
the environment and need appropriate refrigeration and handling, just like
other perishable foods.

The technology that kept the beetroot stable for years depended on the food
remaining in its correctly processed, sealed container.

A familiar name from North Brisbane

For Queensland readers, Golden Circle provides a local connection to the
history of food preservation.

Its cannery opened at Northgate in North Brisbane in 1947, at a time when
processing locally grown fruit and vegetables was a substantial part of the
state’s manufacturing economy.

The Northgate factory continues operating, and Kraft Heinz says it now produces
over 150,000 tonnes a year of canned pineapple, fruit juices and cordials.

Golden Circle’s history is a reminder that the ordinary canned foods we keep in
our cupboards come from an industry requiring considerable engineering, technical
knowledge and agricultural organisation.

There is a separate story to be told about how Australian food manufacturing has
changed. For the moment, though, the tin of beetroot offers enough to think
about without following it all the way through the international food trade.

The next time you find an old tin

Appert’s early experiments required an extraordinary amount of patience. He had
to work out which combinations of heating, sealing and storage actually kept
food from spoiling, long before microbiologists could explain the results.

Today, a commercial processor can measure acidity, specify heating conditions,
test seals and validate a preservation process using knowledge that would have
been unavailable to him.

The result is so commonplace that most of us scarcely notice it.

We buy beetroot, put it in the cupboard and forget about it until the next
barbecue.

The tin might have been sitting there for three years, but the real question
isn’t how the beetroot has managed to survive for so long.

It’s how much work went into making sure it could.

Your “GREEK-STYLE” Feta May Not Be Greek. And It May Not Be Feta Either.

By Jack Mercer – Rabbit Hole Fisherman

There are two little words on supermarket cheese packets that most of us barely notice: “Greek style”. They look like marketing copy, but they do more than that. They quietly tell you what kind of cheese you’re actually buying, and where the argument over names, origin and identity begins.

In This Story

Next time you buy feta, don’t put it straight into the trolley. Pick up two packets and turn them over. One might be genuine Greek Feta PDO, made in Greece from sheep’s milk, perhaps with some goat’s milk added. The almost identical-looking block beside it might be Australian-made from cow’s milk.

Both are white and are salty. Both crumble over a salad. They both sit in the same supermarket fridge and, to most of us, both look like feta. But look at the front of the Australian packet and you may find two easily overlooked words: Greek style.

That word “style” is doing a surprising amount of work. It can separate a cheese made in Greece under rules governing its origin, milk and production from an Australian cheese inspired by it but made thousands of kilometres away, often from the milk of a different animal. And there’s another oddity: some Australian packets don’t even spell feta the same way. They call it fetta.

None of this is accidental. Behind one of the most ordinary cheeses in the supermarket is an argument involving Greek farmers, Australian cheesemakers, European food law and international trade negotiations. At the centre of it all is a deceptively simple question: who owns the word “feta”?

To answer that, we first need to understand what feta actually is.

Feta isn’t just a recipe

There is a fundamental difference between saying this cheese is made like feta and saying this cheese is Feta PDO. Within the European Union, feta is registered as a Protected Designation of Origin, or PDO, a status given to foods whose identity is tied to where they come from. Champagne is the obvious comparison. You can make excellent sparkling wine in Tasmania, South Australia or Victoria, but that doesn’t make it Champagne.

Under the European PDO rules, Feta has its own geographical and production requirements. It must be produced in specified areas of Greece, and the milk must come from sheep and goats of breeds traditionally raised in those areas and adapted to local conditions. Genuine Feta PDO can be made entirely from sheep’s milk or from sheep’s milk with goat’s milk added. What you won’t find in genuine Greek Feta PDO is cow’s milk.

The European Commission’s description of Feta PDO links the cheese to Greece’s landscape. Much of the country was historically poorly suited to widespread cattle farming, while sheep and goats could thrive in mountainous, hot and dry conditions. The animals graze on local vegetation, and that combination of breed, feed, environment and traditional cheesemaking became part of the argument that feta belongs to Greece.

Which makes a visit to an Australian supermarket rather revealing.

Turn the packet over

At the time of writing, Coles sells a Greek Feta PDO made in Greece. Read the ingredients and the first two are pasteurised sheep’s milk and pasteurised goat’s milk. Now pick up an Australian-made Greek-style fetta.

Riverina Dairy’s Greek Style Fetta is made in Australia from milk from its own farm at Corowa in New South Wales. Its first ingredient? Pasteurised cow’s milk. It also contains cream, salt, calcium chloride, rennet and cultures. Woolworths’ own Greek Style Fetta is also Australian-made and lists pasteurised cow’s milk as its principal ingredient.

There is nothing inherently wrong with that. These are cheeses made in the feta tradition rather than as Feta PDO. But it explains why two blocks of white cheese that appear to be doing exactly the same job can taste and feel quite different. They’re not necessarily made from the same animal’s milk in the first place.

Why does the milk matter?

Cow’s milk, sheep’s milk and goat’s milk aren’t interchangeable raw materials. Their composition differs, and that affects cheesemaking, texture and flavour. Traditional Feta PDO gets much of its character from sheep’s milk, with goat’s milk sometimes contributing to the blend. The European Commission describes genuine feta as salty and slightly acidic, and notes the slightly peppery character associated with the milk used to make it.

An Australian producer using cow’s milk is starting somewhere else. That doesn’t automatically make the resulting cheese inferior. In fact, some people may prefer the smoother or milder result. Riverina Dairy, for example, deliberately adds cream to its cow’s-milk Greek-style fetta and describes the result as having a smooth, creamy mouthfeel alongside the salty tang and crumbly texture consumers expect from this style of cheese.

So when two fetas taste different, it may not simply be that one manufacturer makes “better feta”. You may actually be comparing cheeses made from different milks.

Then there is the brine

The liquid surrounding feta can look like little more than salty packaging water. It isn’t. In traditional feta production, brine is part of making and maturing the cheese.

After the milk is coagulated, the curd is placed into moulds and allowed to drain without pressure. The cheese is removed, cut and salted. Ripening then takes place in stages. During the first stage, brine is added and the cheese is held under controlled temperature and humidity. It then continues maturing under refrigeration. Under the PDO production process described by the European Commission, the total maturation period is at least two months.

That helps explain why feta isn’t simply “white cheese in salty water”. The salt, moisture, cultures, milk and maturation are all involved in producing the cheese we eventually crumble onto dinner.

And that leads to the really contentious part.

Who gets to use the word “Feta”?

For years, Australia and the European Union have disagreed over geographical indications, the names associated with products from particular places. For Australian consumers this can sound like an obscure trade negotiation happening somewhere in Brussels or Canberra. It isn’t. It reaches directly into the supermarket fridge.

Australia and the EU concluded negotiations on a free-trade agreement on 24 March 2026. As part of the negotiated outcome, Australia agreed to protect hundreds of European geographical indications. One of them is Feta.

But Australian feta makers weren’t simply forgotten. The Australian Government says existing producers with a continuous history of making and labelling feta will be able to continue using the term under a grandfathering arrangement once the agreement takes effect. To qualify as a prior user, producers will need to demonstrate continuous, good-faith use for at least five years before the agreement enters into force.

There is an important qualification here. As of October 2026, the Australia-EU agreement has not yet entered into force. Negotiations are finished, but legal checking, signature, parliamentary processes and ratification still have to occur. DFAT says signature is expected in late 2026 or early 2027, followed by the necessary domestic processes.

So this isn’t merely a historical argument. Australia is in the middle of changing the rules.

Which brings us back to “Greek-style”

Those two little words suddenly make considerably more sense. A cheese can borrow the characteristics we associate with Greek feta without claiming to be a Greek product. And the spelling “fetta” gives Australian producers another way of distinguishing their product in the marketplace.

But the most useful distinction for the person standing in front of the supermarket fridge isn’t really the spelling. It’s the ingredient list and country of origin. Pick up the Coles Greek Feta PDO and you’re looking at cheese made in Greece from sheep’s milk and goat’s milk. Pick up Riverina Dairy Greek Style Fetta and you’re looking at an Australian cheese made principally from cow’s milk, with added cream.

They may sit centimetres apart. They may both crumble beautifully over the same salad. And they may both be delicious. But they are not the same cheese.

And perhaps that is what makes the word “style” so useful. Most of us probably walk past it without noticing. Once you know what it means, it tells quite a story.

How Do They Get the Pits Out of Olives, and Why Do They Sometimes Miss One?

By Jack Mercer – Rabbit Hole Fisherman

Pitted olives are produced by machines capable of processing thousands of olives a minute. They are remarkably good at it, but not perfect, which explains why the occasional stone survives and why “pitted” should never be taken to mean “guaranteed stone-free”.

In This Story

There is a particular sound that anyone who regularly eats pitted olives never wants to hear.

Crunch.

You have bought a tub of pitted Kalamata olives from the supermarket. You eat one, then another, then perhaps another dozen, and every one of them is exactly as promised: no stones.

That is precisely why the next one can cause trouble. After enough perfectly pitted olives, you stop treating them as fruit that once contained a hard stone and start treating them as something that doesn’t. You bite down normally — until, one day, you find the exception.

The first thought is usually not about olive-processing technology. It is more likely to be: Was that the stone or was that my tooth?

It’s easy at that point to be furious with the manufacturer or supermarket. You bought pitted olives, so surely finding a pit inside one means somebody has made a serious mistake.

The answer isn’t quite that simple.

Take a close look at the packaging and you may find a warning that seems almost absurd:

May contain pits or pit fragments.

Coles is particularly direct about it. Its pitted Kalamata olives are described as mechanically pitted, followed by a warning that an occasional pit or pit fragment may remain and that consumers should take care to avoid dental injury.

It raises an obvious question: how can we build machinery capable of removing stones from olives at industrial scale, yet still end up with the occasional one in the packet?

The answer begins with the olive itself.

Take a look at the next pitted olive you eat

Before putting it in your mouth, turn it over. A pitted olive carries the evidence of what has happened to it, with an opening where machinery has passed through the fruit and removed the hard stone that once occupied its centre.

It’s easy to imagine some fantastically sophisticated process going on inside an olive factory, but the basic idea is quite mechanical. The difficult part is doing it very, very quickly.

An olive is a drupe, the same broad type of fruit as a cherry or plum, with soft flesh on the outside and a hard stone within it.

The International Olive Council identifies the relationship between the two as one of the important characteristics of a table olive. A flesh-to-stone ratio of 5:1 is considered acceptable, and the stone should ideally separate readily from the flesh. Size, shape, skin and stage of ripeness also vary between olives and varieties.

In other words, an olive-processing machine isn’t handling ball bearings. It’s handling fruit.

Inside the pitting machine

A 2025 engineering study from the University of Seville gives us a remarkably detailed look at how commercial olive-pitting machinery works.

The olives first enter a feeder, where they are separated and carried individually in compartments towards the pitting mechanism. At the critical moment, the fruit meets a stone-detaching mechanism fitted with awls. Through a combination of rotary and linear movement, the machine pierces the olive and separates the stone from the flesh.

Then it has to do exactly the same thing to the next olive, and the one after that.

Modern machines described by the researchers can process 2,500 to 3,000 olives every minute, depending on the variety. At the upper end, that’s 50 olives every second.

Think about what the machine is being asked to do in that fraction of a second. Each olive has to arrive correctly, sit correctly in the carrier and meet the pitting mechanism in the right orientation. The stone has to come away from the flesh, the olive has to survive the process in saleable condition, and everything has to be ready for another piece of fruit about one-fiftieth of a second later.

It works most of the time, but occasionally an olive doesn’t cooperate.

The olive that gets through

This is where the explanation for that unexpected crunch becomes clearer.

Engineers who study these machines have identified several things that can go wrong. Two olives can enter together, fruit can break during feeding or a blockage can leave a carrier empty. More importantly for anyone eating the finished product, an olive can enter the pitting mechanism incorrectly oriented.

Researchers call one particular form of this the “boat error”. Instead of meeting the pitting mechanism in the intended orientation, the olive is pierced off-axis. The result can be damaged flesh, a stone that isn’t properly removed, or fragments of the stone left embedded in the olive.

Seen in that context, the supermarket warning doesn’t seem quite so strange. A machine may do its job successfully thousands of times while somewhere in that stream of irregular pieces of fruit, one olive behaves differently.

The next challenge is catching it before it reaches the consumer.

Finding the mistakes is an engineering problem of its own

Olive processors have quality-control methods specifically aimed at finding pitting failures. One traditional method described in the engineering research sounds wonderfully simple: flotation tanks can be used as part of destructive sampling to identify pitting defects.

The limitation is that sampling is not the same thing as examining every olive, which is one reason researchers are now experimenting with computer vision.

Cameras can watch olives as they travel through the machinery while software analyses their size and orientation. In the 2025 University of Seville study, 97 per cent of the Gordal olives analysed were correctly aligned before pitting, while 1.1 per cent showed critical misorientation.

Those figures need some context. The study involved Gordal olives rather than Kalamata olives, so they should not be applied to every olive-processing line. What they demonstrate is the problem engineers are trying to solve.

A companion 2025 study goes further, examining how machine vision might help identify the off-axis orientation that can lead to pulp damage and stone splinters.

Nor should a processing defect rate be confused with the number of stones consumers actually find in supermarket olives. There are quality-control processes between pitting and the finished product, and the research does not establish that one olive in every hundred bought at a supermarket will contain a stone.

If anything, everyday experience suggests how effective the entire process usually is. You can eat pitted olives for weeks or months without encountering a whole stone, which is also why the one that slips through can catch you completely unprepared.

The stone isn’t the only thing being removed

There is another part of the olive’s journey that is easy to overlook: you couldn’t simply pick most olives from a tree and serve them in a bowl.

Fresh olives contain oleuropein, which contributes much of their intense bitterness. Before they become the olives we recognise as food, that bitterness has to be reduced through processing.

Depending on the style, this can involve brining, repeated washing, fermentation or alkaline treatment. The methods vary enormously between countries, traditions and types of olive. Kalamata olives are commonly prepared as naturally ripened black olives and are often processed in brine.

By the time we encounter an olive in the supermarket, the agricultural product has already been through a surprisingly long transformation. Perhaps that is also why the word pitted carries more certainty in our minds than it should.

We tend to see it as a description of what the olive is. From a processing point of view, it makes more sense to think of it as a description of what has been done to the olive: it has been mechanically pitted.

The process is astonishingly fast and remarkably reliable, but it is not infallible.

So should we actually be careful eating pitted olives?

Yes — although there is no reason to be frightened of them or suspicious of every olive in the bowl. It simply makes sense to remain aware that a stone is possible.

This isn’t advice dreamt up by nervous lawyers. Australian supermarket packaging explicitly acknowledges the possibility. Coles warns that mechanically pitted olives may contain an occasional pit or fragments and specifically mentions the risk of dental injury.

Once you’ve seen how the machinery works, that warning makes much more sense. The extraordinary thing isn’t really that a stone occasionally survives; it’s that a machine can take a soft, irregular piece of fruit, remove a hard object buried inside it, leave the surrounding flesh largely intact and repeat the operation as many as 3,000 times in a minute, hour after hour.

Almost every olive we eat gives us good reason to trust that process.

Then comes the rogue one.

Crunch.

And suddenly you remember what used to be inside it.