From shrivelled carrots to limp lettuce, there's nothing nice about having a fridge full of food that's gone off. So how can you avoid this major source of household food waste?
Each year 4.2 million tonnes of food waste goes to landfill in Australia and over half of this comes from households. Not only is this a waste of water and energy used to grow the food, but it produces methane, which is a more powerful greenhouse gas than CO2.
Experts say saving food waste can do more for the environment than switching off the lights.
And then there's the cost to your wallet.The average household throws away around $2,000 worth of food each year, according to a 2013 survey of 1,600 Victorian households. Nearly two thirds of the food thrown away could have been eaten.
The problem is not just related to what we buy and what we do with it when we get home, but how we shop, plan and cook in our busy lives.
"It's complicated. It's not an easy thing to avoid food waste in our modern world because of our lifestyle," said Amanda Kane, who manages the NSW EPA's Love Food Hate Waste program.
It turns out that fruit and vegies are among the top products wasted by households. And part of the challenge is that each product has its own individual needs when it comes to keeping fresh.
Still, understanding the different physiological needs of the fruit and vegies can help.
Storage hacks for your fruit and vegies
By and large once you pick something it starts to die a slow death. So, if you can't eat it immediately, the trick is to keep it alive as long as possible.
"All these products are still alive and are still respiring, like we are," said post-harvest physiologist Dr Jenny Ekman of Applied Horticultural Research. "Like us they breathe in oxygen and breathe out carbon dioxide."
Salad leaves respire a lot, and along with a lot of other green vegetables are best stored in the fridge. Low temperatures will slow down respiration and help keep the bacteria and fungi at bay.
Vegetables like this also need to be in a humid environment to stay crisp, but if they get too wet they can get attacked by microbes and you'll end up with a rotten slimy mess.
So, avoid washing vegies before you store them in the fridge — wait until you're ready to use them. And watch out for condensation in the fridge, which tends to occur when you open and close the door a lot, causing temperature fluctuations.
Keeping produce in the crisper should help protect it, but even here, the cold air can suck moisture out of vegies, so it's best to keep them in something like a plastic bag.
The plastic bags that loose salad leaves come in can be good for storage, says Dr Ekman because they allow the produce to breathe. But you need to keep greens cool and transfer them to the fridge as soon as you get home.
"Don't leave them sitting in the back of the car when it's hot," she said.
As the bag heats up the greens will respire faster and you'll have to transfer them to a fresh container if condensation builds up. But make sure your containers are not airtight or vacuum-sealed as the vegies will suffocate and are more likely to go off.
Both cucumbers and beans also need to be kept in the fridge. They generally prefer warmer temperatures and will easily go slimy and rotten from the chill, so eat them as soon as you can.
If you buy a cucumber tightly wrapped in plastic, it will last longer if you don't take it out, as the plastic forms a "second skin" that prevents moisture loss without causing condensation, said Dr Ekman.
Carrots — especially those that have been polished clean — lose a lot of moisture and can easily shrivel, so keep them in a container in the fridge too, and cut off any green bits.
Some fruit including strawberries, citrus and grapes, which are not likely to get any sweeter after they are picked, should be kept in the fridge.
If you don't like using plastic bags, there are special plastic containers that have vents in them and a small raised shelf in the base. These ensure your produce can breathe and prevent it from sitting in a puddle of water.
According to Dr Ekman, these containers can really help extend the fridge life of blueberries, strawberries, asparagus, and leafy salad vegetables.
And what about stopping mushrooms from getting sticky and slimy?
Keep them in the brown paper bag you buy them in — this helps absorb excess moisture to prevent bacteria attack. You can put this paper bag in an unsealed plastic bag in the fridge to keep the mushrooms from drying out.
What not to put in the fridge
While the fridge is useful for keeping many things fresh, cold storage can come at a cost.
"Everything is a compromise," said Hannah James, post-harvest physiologist with AgroFresh. "If you're keeping it cool you may not develop flavour."
Fruits that go soft and sweet when they ripen are generally best kept in a bowl on the bench, at least until they are ripe.
This includes stone fruit, pears, apple and kiwifruit — but also tomatoes and avocado — yes, these last two are technically fruit.
If you put them in the fridge, the cold will interrupt their ripening and end up affecting their taste, texture and colour.
This applies to many other fruits as well.
Another reason to keep ripening fruit out of the fridge is that most emit ethylene gas, which can cause problems for other produce. For example, the gas can turn carrots bitter and cause cucumbers to spoil.
If you keep fruit together in a bowl on the bench, they can trigger each other to ripen, so make sure lots of air can circulate around the fruit to help disperse the ethylene.
On the other hand, you might want to harness the power of ethylene.
"You can ripen avocadoes and tomatoes by putting them in your fruit bowl with [ripening] bananas," said Dr James.
But watch out for any rotten fruit and remove them from the bowl or the rot will spread.
And, said Dr James, having flowers next to a fruit bowl is also a no-no, because ethylene will make petals drop.
Not sure where to store? Ask yourself where it was grown
If in doubt about whether a fruit should go in the fridge, think about the climate that it was grown in, said Dr Ekman.
For example, tropical fruits like bananas, mangoes and pineapples are sensitive to chilling injuries in the fridge, so keep them in the fruit bowl.
To find out the optimum conditions for storing different produce, try this handy little tool.
Potatoes, onions and garlic should also be kept out of the fridge crisper as humidity will make them sprout. And the cold will cause potatoes to turn sweet, which means your chips will burn at a lower temperature.
Keep these root crops in a cupboard with good ventilation to keep them dry — make sure they don't stay in a sweaty plastic bag.
Potatoes will go toxic if they're exposed to light. It's easy to spot an off potato as light causes the production of chlorophyll, which turns the potato green. Unfortunately, you can't just cut the green bits off because the toxin is elsewhere in the spud.
Sweet potatoes, on the other hand, aren't so sensitive to the light and do not produce any toxins.
Plastic can help keep food fresh
If you buy vegies in plastic packaging, the chances are it is best to store them in this packaging at home. Some packaging even has storage instructions on it.
"Generally the packaging things come in will keep it fresher for longer," said Ms Kane from the Love Food Hate Waste program.
Plastic packaging is all part of a system where fruit and vegies are grown on big farms that ship produce long distances to supply supermarkets with everything we want all year round.
Food producers use plastic because it's lightweight, cheap, transparent and flexible. It can bundle up produce together and stop it from being knocked about. And it can be engineered to allow the right amount of gas and moisture flow, slow down respiration and ripening, and inhibit bacteria or condensation.
Dr Ekman points to the resealable plastic containers that herbs are sold in at the supermarket.
"Single-use plastics are a dreadful thing, but the plastic punnets for herbs are very effective for keeping herbs," she said.
Simon Lockrey of RMIT University's School of Design says cucumbers wrapped in plastic last 22 days instead of just a few, which makes the packaging "really good bang for buck".
Dr Lockrey argues this packaging has a small environmental cost compared to the food that would be wasted if it wasn't used. And if we want to do away with plastic packaging, we need to grow food closer to where it is consumed, he adds.
"A lot of these cucumbers are grown in centralised farming contexts. We're not growing them close to cities. If you want to get them there and keep them in saleable condition you've got to put them in plastic," he said.
"With our current system, if you get rid of plastic packaging you'll be driving a worse issue, which is food waste."
But plastic has an environmental cost, so there are things you can do.
How to cut down your plastic use
Some people avoid plastic packaging and reduce food waste buy growing their own vegies and picking them as needed, at least for things like herbs, leafy greens, beans and cucumbers that are hard to store.
Buying locally grown fruit and vegies in season — perhaps from farmers markets — can be another way to get fresher food that lasts longer.
There are also many plastic-free methods you can use to store produce in the fridge such as using moist paper towels, brown paper bags, or cloth wrapped around the produce or covering glass or stainless steel containers.
The idea is to keep the produce humid. The trick is making sure that any absorbent material doesn't suck moisture out of the produce, and doesn't make the produce wet.