Are vegetables losing nutritional value?

Considering some 'fresh' fruit and vegetables picked up in the supermarket can actually be months off the tree or out of the ground, we look at the science to see if it’s really such a big deal, and how you can ensure the most bang for your buck when it comes to the nutritional value of your fruit and vegetables

Many of us are not aware of how fruit and vegetables come to sit on the supermarket shelf. An apple on the supermarket shelf bursting with freshness may have actually been picked ‘green mature’ and stored months ago. Or a bright yellow, perfectly ripened banana actually came off the tree green and hard before transportation.

The science is not actually new. In order to provide ‘fresh’ fruit and vegetables to the supermarket shelves, a little magic has to happen. Basically, advanced cold storage – predominately using a technology called SmartFresh in Australia – allows for some fruit and vegetables to be picked and stored for a lengthy period of time while retaining qualities such as taste, texture, smell, size, colour, absence of deterioration and lack of blemishes.

Why do they do it?

To give supermarkets (one of the bigger movers of pre-ripe food) their due, it all comes down to meeting customer demand. Consumers generally don’t buy ugly fruit and vegetables, even when there is nothing wrong with it. We want to pay low prices, and we like to pick up several pieces before making our selection (so the one we ultimately pick needs to be able to withstand a bit of handling). We also like to eat as many fruit and veg varieties as we can get our hands on all year round.

Essentially, convenience shopping and ‘just picked from a local grower at the peak of its readiness and packed and delivered’ isn’t going to happen.

Do we need to be worried?

The science of picking, storing and ripening fruits and vegetables is a precise and well researched and monitored one. Postharvest and food safety expert from Sydney University, Robyn McConchie, says she fully supports SmartFresh technology that put fruit to ‘sleep’, and consumers need not worry they are missing out.

Essentially some fruit and vegetables can be picked ‘green mature,’ put to sleep and then be woken up months later and allowed to ripen naturally using food-grade ethylene, a man-made copy of the hormone naturally released in the ripening process. It’s a process that has been safely used for decades.

Robyn says the process means there's hardly any metabolism going on (during storage), including the amount of sugars, starch, vitamin and polyphenol – essentially they all remain pretty close to the level of when they were actually put into storage.

She says ‘storage organ’ vegetables such as carrots and potatoes had low metabolisms and can be stored for a long time, provided you use the right temperature.

Leafy greens on the other hand are highly perishable and won’t stand up to the same treatment however – but fear not, it would be apparent in the drooping leaves.

It’s actually what you do with your fruit and vegetables that makes the most difference.

Interestingly, it’s what we do with our produce that makes more difference to the level of nutrients and vitamins retained in our fresh food.

If you want to get the most bang for your buck nutrients wise, choosing fruit and vegetables with good colour and undamaged condition (for example, look out for wilting greens) is a good start, as is steering clear of the pre- or partly prepared fruit and vegetables in the fresh section.

Cutting and shredding can expose many plant chemicals to oxygen in the air, which dramatically decreases the antioxidant levels.  So that pre made salad or pre-chopped roast vegetable pack is not as nutritional a choice as making it yourself (though pragmatically speaking, a premade salad is better for you than skipping the vegetables all together!)

How you handle and store the fruit and veg you bring home is also key, and the CSIRO has published a handy and comprehensive guide to storing fruit and vegetables.

Some vitamins and minerals are water soluble and sensitive to heat and air, so food preparation is also part of the equation. Vegetables lose 50 percent of their nutrients when boiled, but only 15 percent when steamed, making it a better choice. Copper cooking utensils destroy Vitamin C, so give them a miss when cooking fruit or vegetables if you are being nutrient conscious.

And last but not least – remember when it comes to fruit and vegetables, the best thing to do with them is consume and enjoy them!