Science Questions

Foods lose nutrients during transport?

Tue, 11th Feb 2014

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Alice Danger asked:

Are there foods that are not worth buying as they loose too many nutrients over a long commute?


Chris -   Marie-Ann quickly, a question from Alice Danger (What a lovely name).  ďI'm interested in the loss of nutrients over the long commute.  What things are not worth getting Ė what things if you can't have them fresh are not worth getting at all?Ē

Marie-Ann -   Salad vegetables actually.  Anything with a leafy, dark green leaf looses certainly things like vitamin C within 24 hours of picking.  So, you really need to be looking carefully anything that's too old.  There's been a paper recently that found that even fat soluble vitamins which we thought would stay for a while actually breakdown after 4 months, that's in sweet potatoes.  So, itís really looking carefully again where things come from and seasonality, so some things in season.  Then itís likely to be fresher and better for you.

Ginny -   So, what about eating fish?  Is that better or worse than meat or vegetarians?

Marie-Ann -   Itís the same answer.  It depends on how itís fished.  So, Marine (c) Ken Hammond

" alt="Workers harvest catfish from the Delta Pride Catfish farms in Mississippi." />Council Certified fish is fished in such a way that it should protect fish stocks and allow regeneration within the oceans.  Itís again, transportation involved there as well because we are land loft in Cambridge so itís not that easy unless we have freshwater fish.

Ginny -   What about refrigeration because I guess, fish goes off quite quickly, so you have to keep it quite well-refrigerated?  So, does that make it worse?

David -   Well, itís often frozen, isnít it?  So, that's expensive on the refrigeration side.

Ginny -   Is freezing things worse than keeping them refrigerated?

David -   Well, itís a good question.  It takes a lot of energy to freeze stuff.  The temperature is much lower so you have a lot more leakage of cold.  On the other hand, refrigeration in supermarkets is often or almost always has a lid or a door.  So, that's a lot better from that point of view.

Chris -   And if you look at keeping an animal alive, then that's got a carbon footprint associated with it too rather than it just being in a freezer.  So, how does that work out?

David -   Well, then you got to keep the water clean and cool and all that...

Chris -   But equally, not just fish but meat in general.  You know, itís easy to condemn a fish when itís got a lot of meat in it, but the meat is not respiring.  Itís not contributing carbon dioxide to the planet.  Itís not eating food and belching out methane because itís in a fridge.  Whereas if you kept it as a live animal sustainably farmed, it is, isnít it?  

David -   If you could take the animal straight from the farm to your plate then you would miss out the whole refrigeration component wouldn't you?  This would be rather difficult to do that.

Ginny -   But also, freezers can be positive and that they reduce food wastes.  So, when I cook too much dinner, I freeze some of it and have it another night.  So, there's pluses and minuses I guess.

Marie-Ann -   Yes, because it is one very good way of decreasing food waste, freezing any food that you see is getting up these by date.  I keep my butter frozen because it doesnít go often go rancid that way.


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