Is eating frozen and jarred food more eco friendly?

[tardisjumper]

I realise it is a complex area and a complete first world problem, but we are quite careful to eat British and seasonally with some small exceptions (citrus for example). However, as always happens towards the end of January I feel if I will go mad if I so much as see another swede!

I have always assumed that jarred, tinned and frozen food has a lower carbon footprint. However I can only find literature claiming that frozen food increases the demand for freezers which increases carbon footprint, but I kind of feel that view is not seeing the wood for the trees.

So, it buying tinned artichokes that were probably canned in season, better than buying an out of season fresh one (Sainsburys is selling them this week)? What about jars of passata vs 'fresh' tomatoes?

interesting conundrum! difficult to estimate but let's see...

assuming that up to the point of harvest both types are equal carbon footprint (this is flawed if specific varieties are grown for canning which are more or less water-hungry)

flash-freezing involves energy as does blanching for canning. prep of fresh veg for sale may just involve water, probably a lot of it.

transport of canned veg vs fresh is slightly heavier but no refrigeration required and more can be carried per vehicle due to packing density

tomatoes preserved as passata involves a whole cooking stage and use of new or recycled jars, labelling, high temp washing, sterilising etc. Buying fresh toms out of season may not come off much worse but if you had the storage space you could make your own passata when toms are in season and cheap, and your domestic-level jar reuse might be lower impact than the factory process.

freezing raw veg is definitely an ongoing use of energy and as you can get UK green veg locally in season all year probably not a sustainable choice. freezing soft fruit, batch-prepared meals and home-made stock is probably the best use of the freeze followed by meat/fish bought in bulk to cut down on shopping miles.

Tricky one. An out of season fresh vegetable mostly incurs its carbon 'cost' from transport. The further it has travelled and the more lavishly... air-freight massively wore than sea-freight... the higher the cost. Any kind of packaging is instantly creating carbon emissions because of the initial production of the glass, tin, cardboard, plastic etc. Then there's the factory process of putting the product into the packaging. Then storage and transport to final destination. And if you're trucking glass jars of tin-cans around... very heavy things... you can't put as big a volume on a truck as you could, say, loose artichokes. Frozen food, by definition, involves big powerful freezers running from harvest to consumption... lots of electricity going to waste there.

I think loose, outdoor-grown fruit and veg that has travelled by ship/truck is still a better carbon footprint than anything in a packet therefore. Outdoor-grown rather than electricity-guzzling hothouses. Shipping and trucking is a very carbon-efficient way of getting something from A-B. So a Spanish broccoli or a French cauli that has been on the road for a day or two only, spent a few days in a coolstore and then ended up on the shelf in minimal or zero packaging is better than packaged alternatives..

"more can be carried per vehicle due to packing density "

There are axle weight restrictions on HGVS so whilst you may be able to get 22 pallets of loose apples on a vehicle you might only get 14 pallets of denser canned apples before you hit the same weight restriction.

ah I knew there was a flaw, thanks cog

"out of season fresh veg" to me means forced in artificial heating and lighting.

"in season a day's road move away" is certainly better

The other thing I was thinking is that supermarkets have a massive turnover of fruit and veg they have to dump as it goes off. Plus it is transported in chillers. Also, how do you kow that it is transported canned? Ie do olives from spain get canned on site or when they get here? Or do they go to another site entirely?

AND some people I know who do buy locally etc, often shop every day which involves 4-5 40 minute round trip car journeys a week. However, i can top up my veg intake with these frozen and jarred ones with a fortnightly supermarket delivery. We walk in the veg stall at the weekends for fresh stuff.

I did chutney and preserve every veg I could get my hands on over the summer, but it is nowhere near enough for all our requirements as we live in a small flat and I have nowhere to store it.

So basically, I am asking is the waste issue with fresh fruit and veg a big enough factor to make it less efficient than preserved stuff?

There's actually plenty of fresh veg at the moment that is coming in from southern Europe. Dutch stuff, be careful, because their climate is similar to ours so the peppers and tomatoes etc. are going to be glasshouse. French and Spanish brassicas are outdoor. Spanish courgettes and a few other things are grown in plastic 'tunnels' with no extra heat. More robust things like outdoor-grown Mexican avos, RSA grapes or NZ kiwifruit get here on refrigerated ships... which are amazingly carbon friendly means of transport - better than trucks, even. The things to avoid are the delicate, short shelf-life stuff from very far away because the only way to get that here in one piece is by air.

oh also, how do you knwo that home preservation is more efficient. I recycle jars etc, but I have a massive electricity bill as I cook so much. How do I know that the amount of electricity I would use to simmer passata for an hour or so is less than a factory doign it on a bigger and thus potentially more efficient scale?

Plus tin cans are on average 25% recycled material across Europe. Not ideal but not that bad either.

"The other thing I was thinking is that supermarkets have a massive turnover of fruit and veg they have to dump as it goes off"

Supermarkets dump next to nothing. They can't afford to. In fact, store managers are given waste targets and have to stay under them or they are in big trouble. Too much thrown away or reduced for quick sale means their stock-control has failed and reflects badly on those responsible.

Few things are transported canned to be sold loose. Cans are just too expensive and too pricey to be used and disposed of. Bulk transport is often much cheaper, disposable or re-usable packaging

Re the electricity usage. If the food you are buying is mostly unprocessed and unpackaged then its carbon footprint up to you is practically zero. You are using more electricity to turn that raw food into edible means and so on, but that is still a far lower impact than that of industrial food production ... factories, trucks, packaging, storage and all that I talked about earlier.

meals... not means :)

I don't know that your electricity use is more or less efficient than the factory process. I didn't offer any comparative carbon-per-kg-of-asparagus figures at all.

If your objective is price then you should buy tins etc.

If your objective is the impact on the planet then you need to know the resource consumption of the growers, factories, transporters and supermarkets. You would then be able to make a more knowledgable choice of whether you then delegate the cost of the production to them or bear it yourself.

I would really like it if food packaging told me the country of origin and the greenhouse / open field conditions, the freight method and whether the packaging is virgin or recycled. might be so much info it would be better as a QR code which could take me to the she's website. Technically not difficult with the amount of business intelligence the big shops keep but would it win them any custom? perhaps not.