Pesticide residue in fruit and vegetables

Does spending more on organic produce guarantee you'll avoid pesticide residues? We tested grapes from supermarkets, greengrocers and farmers' markets to find out.
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04.Shopping for the most nutritious fruit and vegetables

is organic food really betterThere are a mind-boggling array of factors affecting the freshness, nutrition and taste of your food.

Most fruit and veggies are 70-90% water, and once harvested immediately start losing moisture and degrading in quality and nutritional value. So the less time between harvest and plate there is, the better.

Although time since harvest is important, there are other factors influencing quality, including the particular variety, soil health, growing methods (fertilisers high in nitrogen can reduce vitamin C levels), changes in temperature and humidity during transport, and storage methods.

As well:

  • The nutrient content and taste is optimised if produce is picked ripe.
  • Bruising leads to a loss of nutrients, so produce should be gently handled. Handpicking is less likely to damage produce than mechanical.
  • Soft or leafy fruit and veg have high levels of water-soluble C vitamins that are unstable, so the fresher they are when you eat them, the better. Shrivelling and yellowing is a sign of ageing and moisture loss.
  • Minerals and antioxidants such as carotenoids (which give tomatoes their red colour) are more stable than water-soluble vitamins, as are the nutrients in root veggies, so time since harvest is less crucial.

apples can be kept in cold storage for more than a year

Birthday apples

Birthday apple is a term for apples that are one year old before they hit the stores. Most apples are harvested between February and April, so it’s standard for them to be placed in a controlled atmosphere storage straight off the tree and distributed gradually throughout the year.

The combination of reduced oxygen levels and temperature, plus an increase in carbon dioxide, stops the apple’s production of ethylene, effectively putting it to “sleep”. Once removed from cold storage, the apples “wake up” and start ripening again.

Exact conditions in the rooms are set according to the apple variety, but incorrect storage can cause flavour loss or a brown core. Storage has little effect on apple nutrients; the way the fruit is treated before and after storage is more important.

“People may not like the idea of cold storage, but would they prefer to eat Australian apples all year or to eat imported apples?” asks Colin Gray from the NSW Chamber of Fruit & Vegetable Industries.

How is early-picked fruit ripened?

In order to get fruits to market without damage, they’re usually picked before ripening, transported and then exposed to ethylene gas.

Ethylene occurs naturally in fruit and veg and naturally triggers the ripening process. Fruits such as bananas, tomatoes, avocados, apples, mangoes, pears and peaches continue to ripen after harvest as they produce their own ethylene.

There doesn’t appear to be any evidence that exposure to ethylene is harmful to crops, but if crops are picked too early they may not ripen completely. They can reach full colour, but not necessarily full nutrition.

Other fruit such as raspberries, cherries, grapes, lemons, oranges, pineapples and strawberries don’t ripen after harvest, but oranges and lemons can be made to look less green by exposure to ethylene gas.

With a structure similar to ethylene, 1-methylcyclopropene (1-MCP) is used to block the fruits and veggies’ ethylene receptors, slowing the ripening. It’s used in cold storage and controlled atmosphere for tomatoes, pears, plums, avocados and kiwifruit.


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