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I have grown up in a country where milk is stored in a steel container in the fridge at home. That’s what makes me wonder why milk is not sold that way?

Nowadays the steel container single wall is cheap anyway. Given the fact that steel is infinitely recyclable, I would think it is far cheaper than single-use disposable plastic or even reusable glass. Is there any scientific reason like bacteria formation when stored in steel? Or corrosion due to an acidic nature?

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  • $\begingroup$ I don't see a reason it would be connected to chemistry of steel. It's just heavy and difficult to process. $\endgroup$
    – Mithoron
    Jun 4 at 14:26
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    $\begingroup$ There is no such thing as "food grade" stainless. There are stainless steels traditionally used in the food industry , primarily 316 and 304. $\endgroup$ Jun 4 at 15:16
  • $\begingroup$ PE-coated cartons are designed to be recyclable, and I suspect that the environmental impact of people who don't offer those for recycling is lower than the environmental impact of putting stainless steel into rubbish dumps. Bulk transport of milk is done in stainless steel tanks. $\endgroup$ Jun 4 at 17:08
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    $\begingroup$ This question probably makes more sense if you live in a country where bottle recycling is a regular feature $\endgroup$
    – Valorum
    Jun 4 at 18:10
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    $\begingroup$ Your country doing it one way does not mean that it is the best way. Even before reading the Answers, my first thoughts were, "steel is expensive and heavy compared to plastic and paper. (Heck, in Canada, milk is sold in thin plastic bags!!! $\endgroup$
    – RonJohn
    Jun 4 at 23:45
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I believe it is cost. According to 1, food-grade stainless steel works well as a container for milk.

However, the article also says that the wholesale cost of a 0.568 L (19.2 fluid ounce) glass milk bottle in Great Britain was 0.35 £ ($0.50) in 2020.

By contrast, I searched a few wholesale sites, and the least expensive staineless steel water bottle I could find in that size (20 oz.) was $3.19 in quantities >2000[2]. [US cost.]

On the other hand, stainless steel does have a longer lifetime than glass, which reduces the effective cost. But that would only apply if customers actually returned the bottles, which many don't; and the deposit doesn't make up for the cost of the stainless steel container.

References

  1. Tomasz Błażejewski, Stuart RJ Walker, Rukayya Ibrahim Muazu, Rachael H Rothman, Reimagining the milk supply chain: Reusable vessels for bulk delivery, Sustainable Production and Consumption, Volume 27, 2021, DOI: 10.1016/j.spc.2021.02.030.
  2. https://www.silkletter.com/venture-20-oz-stainless-steel-sports-bottle.html
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    $\begingroup$ Also, plastic is lighter and reduces transport costs. If you ship it far enough, a plastic bottle will save more than its own cost compared to the steel one. This is also an argument for plastic over glass which used to be common. Finally, the recycling of steel is not free. $\endgroup$
    – badjohn
    Jun 4 at 5:01
  • $\begingroup$ @badjohn The article I linked addresses those issues in a lot of detail; though it concerns wholesale, rather than retail, delivery of milk. $\endgroup$
    – theorist
    Jun 4 at 5:03
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    $\begingroup$ Sorry, I didn't follow the links and just read your text. For the benefit of other lazy readers, it might be nice to mention them. $\endgroup$
    – badjohn
    Jun 4 at 5:05
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    $\begingroup$ There are other types of milk containers, like cardboard (with a very thin plastic (polyethylene) coating on the inside) - for instance, used for the majority of milk products where I live. It has started to be recycled here (not just incinerated). Plastic-coated paper $\endgroup$ Jun 4 at 13:40
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    $\begingroup$ The other advantage of plastic or glass over steel is that it's transparent - One of the first signs the milk is starting to go bad is curdled lumps clinging to the side of the bottle. With steel, you might not notice that until it starts to smell or the lumps are solid enough to pour out, by which point the milk has already been partly bad for a few days. (Cardboard containers have the same problem, with the added drawback that they don't seal very well and are thus more likely to spoil quickly.) $\endgroup$ Jun 4 at 14:08
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Any steel container is going to quickly show wear and dents in it. If you use one thin enough to be cost and weight effective, even more so.

Milk is one of those products that has to look clean and fresh on the shelf. A dented can isn't going to work well in this situation.

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  • $\begingroup$ That's a really good point. The analysis I cited was for commercial deliveries, where customers are concerned more about practicality than presentation. Retail is an entirely different ballgame. $\endgroup$
    – theorist
    Jun 4 at 23:12
  • $\begingroup$ A dented bottle is also probably not going to get deposit back. We have to be responsible with the bottle and return it in acceptable condition to get full deposit back. This way we can keep bottle in circulation for long and eliminate single use waste. $\endgroup$
    – user43325
    Jun 5 at 22:28
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Polyethylene-coated cartons are designed to be recyclable, and I suspect that the environmental impact of people who don't offer those for recycling is lower than the environmental impact of putting stainless steel into rubbish dumps.

Glass is very recyclable, but there are additional transport costs associated with the weight and volume overheads of glass containers compared to PE-coated card, and broken glass is more dangerous than broken card.

Milk has a limited use time because there will be bacteria in it, regardless of the packaging used to contain it. Milk which has been filtered to remove (some) bacteria is available (e.g. sold as Cravendale, but even that has a limited lifetime). UHT milk is perhaps not the same product as normal milk, depending on what it's going to be used for.

Bulk transport of milk is done in stainless steel tanks which are cleaned between uses: the re-use of a milk-tanker is pretty-much guaranteed.

Overall, it is cheaper to use PE-coated cartons than any other package for small volumes of milk.

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