Canned vs. Dried

Many canned food containers are lined with a very thin layer of plastic to prevent the metal can from contaminating the food. However, more often than not these plastic linings contain Bisphenol-A (BPA), associated with a number of concerning health problems which I covered in a previous post.

I decided to do some research and ask some of the main UK supermarkets and organic companies whether their food cans contain BPA and these were the results:

BPA Cans

As you can see BPA is pretty much used in most cans, whilst remaining within the EU prescribed limits. Suma helpfully pointed me towards the Ethical Shopping guide to tinned tomatoes that further enlightens us on the topic:

Toxic tin linings & Toxic BPA alternatives
Bisphenol A (BPA) is an endocrine-disrupting chemical, meaning that is has potentially deleterious effects on reproduction and brain development. It is primarily used in the production of polycarbonate plastics and epoxy resins, which have many uses, from CDs and medical devices to impact-resistant safety equipment and dental sealants.[6] The concern for many consumers around BPA is its role in food cans, bottle tops and jar lids, and the potential leakage of BPA into the food and drink later ingested by humans. In 2015 the European Food Safety Authority (EFSA) published the results of a re-evaluation of BPA carried out by one of its expert panels. This review found that BPA “poses no heath risks to consumers because current exposure to the chemical is too low to cause harm.”[7]
However, the EFSA also significantly lowered the estimated safe level (tolerable daily intake or TDI) to 4 micrograms per kilogram of body weight, although this is temporary pending the outcome of a long-term study into the pre- and postnatal effects of BPA exposure. The EFSA’s study found that public exposure to BPA is “well below” the new TDI of 4µg/kg of body weight per day, with the highest estimated exposure being 3-5 times lower than the new TDI. Dietary exposure is highest among infants and toddlers, given their higher food consumption per kilo of bodyweight, but this is still more than 4 times below the new TDI. A person would have to ingest more than 400µg of BPA per kg of body weight per day to cause adverse kidney and liver effects. However, the EFSA said that effects of BPA on the reproductive, nervous, immune, metabolic and cardiovascular systems, as well as in the development of cancer “are not considered likely at present but they could not be excluded.”
However, choosing BPA-free packaging does not necessarily mean consumers are avoiding potentially harmful chemicals. A recent study by a consortium of North American non-profit organisations tested 192 cans from a range of companies and found four coating types besides BPA in use: acrylic resins, oleoresin, polyester resins and polyvinyl chloride (PVC) copolymers.[8] The report described these as “regrettable substitute[s]” several of these are known or potential carcinogens, including PVC and polystyrene: “We know very little about the additives used in these compounds to give them the properties that make them stable and effective can linings. Our research does demonstrate that there are multiple formulations of most of these compounds, but there is no way to determine the specific chemicals used or how they are produced … the lack of safety data and unknown additives mean we have no reliable data attesting to the safety of [several of] these compounds.”

Canned vs. Dried: What is more energy efficient?

I also had a second motive for contacting all these companies. I wanted to find out what is more energy intensive: soaking dried pulses overnight and then boiling them for an hour (or more!) at home, or buying them ready canned? It turns out all companies use more or less the same process: The pulses are imported in their dried form, in some cases dehydrated again and then boiled until soft. After being canned they go through another heat process at a very high temperature to sterilise and finish off the cooking process. (Note: Plastic lined BPA cans containing food are heated above 100 degrees.)

It is clear that buying the dried pulses, soaking them overnight and then boiling them up for an hour or more is far less energy intensive and healthier than canned pulses:

Essentially it’s up to you to judge whether you care or don’t care about the potential threat a small amount of BPA has on your health. For some brands you can look out for the “BPA-free” symbol, although we know worryingly little about the substitute materials used.
Best option for health & environment: buy the products fresh or dried, or alternatively in glass jars to avoid plastic.

5 thoughts on “Canned vs. Dried

  1. Dried versus canned is such useful information. I was wondering the other day myself about the production process of my canned chickpeas for the hummus i make every week. I certainly don’t like the idea them being boiled in a can that leakes God knows what chemicals. Also with the dramatic increase in infertility, young people should be extra vigilant. You certainly have convinced me to lay off canned food (as if I didn’t know), but your research is compelling. Great idea re. Making a bulk and then deep freezing. I have gone to town today and bought myself a brand new pressure cooker!!

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  2. Hey Ush,
    thanks so much for sharing your research with us! Ive always wondered if TetraPak is really plastic free -isnt it lined with plastic too? Also, “paper” coffee cups as the sustainable to-go option -arent they also lined with plastic?

    I’ve never taken much to freezing things, I think because I dont really know: do the nutrients die, how long the food is still edible, how to de-freeze healthily, what to package frozen food in…

    If you have any knowleadge on this I’d be happy to hear it, otherwise i’ll do the research and share it here!

    Love,
    Maria

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    1. Hey girl, yeah good point about TetraPak – they are in fact also lined with plastic but not with BPA plastic and are recyclable. But it turns out it takes a lot of energy to actually take them apart in the recycling facility, so worth avoiding. The best option for packaging is obviously always glass. Here’s an interesting blog: https://treadingmyownpath.com/2014/09/11/why-tetra-paks-arent-green-even-though-theyre-recyclable/

      As to coffee cups – no they were never a go to option really. They’re a huge issues in cities like London, although more and more people here are switching to reusable coffee cups here I’ve noticed. Coffee cups are lined with plastic and our generic recycling facilities are unable to break them down and so hundreds of thousands of cups go to landfill or incineration in Britain daily.. Here’s a BBC article about it http://www.bbc.co.uk/news/magazine-36882799

      Freezing Food: Although I don’t do it often I don’t think it’s such a big deal. When I freeze I use glass containers or paper bags. You’ll need to do more research on the science behind keeping the nutrients though! Johanna wrote an interesting blog about it and says that freezing fresh peas for 2 years retains the nutrients more than than letting them sit at room temperature for 7 days. She also talks of the energy cost of freezing: https://utopia.de/ratgeber/tiefkuehlkost-konservendose-was-ist-besser/

      Let us know if you find out something new 🙂
      xx

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  3. Why dont we try and make our own Passata – Tomatosauce from fresh tomatos and herbs this summer, and store it in sterilized glasses, or even freeze it?

    This recipe looks awesome:

    https://www.bbcgoodfood.com/recipes/817646/tomato-passata

    Also, here is a detailed description of how to cook dried beans and freeze them:

    https://www.kitchentreaty.com/how-to-cook-dried-beans-and-freeze-them-for-later/

    Gaby, heres a “recipe” how to freeze your chickpeas…apparently they should keep for one year!

    https://toriavey.com/how-to/how-to-soak-and-cook-chickpeas/

    xxxx

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  4. Surprised me, but this food can be frozen:

    • OPENED WINE: 6 months
    Can’t finish the whole bottle? Freeze leftover wine in ice cube trays and transfer to freezer bags. Great for cooking, in sauces, stews and the like.

    • BUTTER: 6-12 months (salted lasts longer)
    Butter freezes well, so stash a stick or two in the freezer (leave in the original wrapping and place in a freezer bag) and you’ll always have some on hand when you need it. You can also make your own butter, made with cream from a glass-jar (plastic free!): http://www.stuff.co.nz/life-style/food-wine/recipes/8450863/How-to-make-your-own-butter

    • MILK: 3 months
    If you’re constantly running out, freeze a backup supply in an airtight container. Thaw in the fridge and stir well before using — the texture may be a little grainy, but it’s fine for cooking and usually okay for drinking.

    • NUTS – INCLUDING PECANS, ALMONDS, WALNUTS: 1 -2 years
    Thanks to their high oil content, nuts are especially prone to going rancid. Freeze them and they’ll stay fresher longer.

    • FRESH HERBS – INCLUDING BASIL, CILANTRO, PARSLEY: 6 months
    Most recipes call for only a sprig of herbs, but you have to buy the whole bunch. Freeze what you don’t use in ice cube trays, covered with a bit of water, and then transfer to freezer bags.

    • MAPLE SYRUP (100% PURE): keeps indefinitely
    Sure, it’s more expensive than the imitation stuff. But pure maple syrup keeps forever in the freezer — so you’ll never have to waste a delicious drop.

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