Earlier this year, when a salmonella outbreak affected more than 100 people, eyebrows collectively raised at the cause. Not meat, not fish, not cheese - the salmonella was linked to pre-packaged lettuce, of all things. And while, at the time, Produce Marketing Association technology manager Richard Bennett said that trying to eradicate salmonella would be "like trying to eradicate oxygen" - futile, because it's everywhere - the take-home message was that we just aren't washing our fruit and veg properly. In the case of lettuce, in particular, with its deep crevices, bacteria can harbour within the spaces and grow freely, totally invisible to the naked eye.
So how do you wash your strawberries and potatoes 'properly', then?
The first step, says Dr Lisa Szabo, CEO NSW Food Authority, is to ensure you yourself have good personal hygiene habits. "It's no good washing a piece of fruit with a dirty hand - and I see it all the time," she says.
Before preparing any food, wash hands with soap and water (there's no need for anti-bacterial soap, plain old-fashioned soap is fine) and dry thoroughly. "Most fruit and veg needs to be washed before use," says Dr Szabo. "Wash with cool tap water immediately before eating - if you wash it then store it in the crisper, the water can actually lead to more contamination and bacteria."
How about pre-bagged lettuce or spinach that claims to be washed already? "These can be used without further washing," she says, "but if you want to be extra cautious, rinse them again."
A common mistake Cathy Moir, senior food microbiologist at the CSIRO, sees is people preparing fruit and veg on the same chopping board as raw meat. "Even if you've washed your rocket and tomatoes, if you're slicing them on the same surface as you've chopped raw meat - and you're not cooking the vegetables any further - you'll expose yourself to the risk of salmonella and E. coli." Ideally, she says, we'd all use separate chopping boards for fruit and veg, and meat, all the time.
For fruit and veg with hard skins, try using a hard-bristled brush to wash away excess dirt. Don't be tempted to simply peel away the skin on your carrots, potatoes and pumpkin - the skin contains excellent sources of nutrients that shouldn't be discarded. Simply wash with water, scrub with a hard-bristled brush, and rinse again, says Moir. Something that should be discarded? Any bruised or damaged areas you find in your fruit and veg. "Bacteria can grow very easily in these areas," says Dr Szabo. "Clean the knife when finished to avoid contaminating other food."
When it comes to storage, Moir urges consumers to ensure that that visibly dirty fruits or vegetables - say, a whole lettuce, roots and all - are not in contact with fruits or vegetables that will be eaten without further washing, peeling or cooking – like an apple - as the dirt may contaminate the clean fruit.
If all this sounds like too much hard work, rest assured that the risk of becoming sick from fruit and veg is still very, very small. However, there is a risk.
"With any fresh produce," says Moir, "there's the risk of pathogens and bacteria. But you have to keep in mind that it's very remote, especially here in Australia where we have very good growing conditions and excellent standards for food hygiene. Things do happen, and there can be outbreaks, but in the majority of circumstances, we don't need to be concerned."
The dirty dozen?
You've probably heard of the "clean 15" and the "dirty dozen" - nicknames given to the fruit and veg that supposedly contain the lowest and highest levels of pesticides. The lists, released every year, might have given you pause when buying grapes (consistently on the "dirty" list) or licence to eat more avocados (always "clean"). But since the research comes from the Environmental Working Group, based in the US, is it relevant to us here in Australia? Do we need to be particularly vigilant when washing "dirty" fruits like strawberries, apples and peaches?
According to Food Standards Australia New Zealand (FSANZ), no. For starters, we have different growing conditions, with different herbicides and pesticides, says Lorraine Haase of FSANZ. Here, we also set very strict limits on residue limits, as well as the minimum time between spraying a crop and harvesting, to minimise impact, she adds. Besides all this, there are annual checks on the pesticide residue levels found in produce - not just by FSANZ, but also by the Department of Agriculture and Water Services, which releases the National Residue Study. The 2013-2014 study showed 100 per cent compliance for all 167 samples of honey, 99.2 per cent compliance for 6137 samples of grains and 99.5 per cent compliance for 1087 samples of horticulture. Haase says that the produce on the "dirty" and "clean" lists should be treated like any other - simply wash, dry and eat.