Glazes induced degradation of tea catechins | Hacker News Reader

Glazes induced degradation of tea catechins

nature.com

32 pointsgeox23 comments

They fired the glaze powder onto the sample tiles, as one would do with one’s ceramic vessels - then pulverized the resulting glazed tile back into a colored powder before mixing it with the tea, to improve its reactivity?

I appreciate that the point of this work must be to identify which degradation products to be on the look out for in the first place, not to suggest the rate at which they might form under actual use. Still, in the real-life applications the authors are worried about, surely the fused glaze is doing some degree of work to physically bind its constituents in place.

Maybe the key takeaway for real life is to not stir your tea so vigorously that you scratch chunks off your mug. Never assume that other people do or do not do something that you might find odd.

No one is scratching fused silica and alumina off their mug with a stainless steel spoon.

You can certainly chip it off, but that's a different mechanism of action.

I think you are totally correct but now I'm stuck trying to find if anyone really knows about the formation of scratch marks inside a mug. Is it really the metal from the spoon depositing on the mug?

this seems plausible, as there are often darker marks left on white ceramics from spoons.

> Is it really the metal from the spoon depositing on the mug?

Probably, it's additive for sure, you can remove them quite easily: https://www.reddit.com/r/CleaningTips/comments/11z7get/thoug...

Set glazing basically is glass, you wan't scratch that very easily

Here's the safety data sheet of the product:

https://www.barkeepersfriend.com/wp-content/uploads/2014/12/...

Here are the ingredients:

Feldspar

Sodium dodecyl benzene sulfonate

Oxalic acid

Long ago I worked in a restaurant. One day the manager ordered new silverware and we were told to inspect and throw the others away. I was stuck by how much different the forks and spoons were. The forks were shorter by a noticeable length and bent in a different direction. The spoons had obvious wear marks on the bottom and the shape was thin and deformed.

Yes, it is scratched off metal (you see it also on bathroom tiles if you use a bathroom wiper with aluminum frame for cleaning the shower tiles) or from using cast aluminum pans with machined bottom on glass ceramic cooktops (you get little aluminum deposits on the glass).

It is reversible and you can "wipe" it off using acid and abrasives but it's tedious as the metal adheres really good to the ceramic.

It may also help to let the tea sit for less than 6h at 80°C.

True, true. I throw away the tea and eat the mug.

Has anyone looked into the plastic lining on the inside of disposable coffee cups? I feel there could be significant health implications, both in terms of scale and toxicity...

Yes, it is typically BPA or BPB and I believe makes the cup hard / impossible to recycle.

Not sure standard food wax can substitute due to temperature issues; perhaps a shellac would be better.

The PE lined coffee cups are recycled in the UK, and there is a mandatory cup takeback scheme coming in over the next couple of years to help increase recycling rates.

https://www.jamescropper.com/about/innovation/coffee-cup-rec...

https://www.valpak.co.uk/case-study/national-cup-recycling-s...

> There are five facilities in the UK that are able to accept polyethylene lined paper cups for recycling and together have the capacity to recycle all the cups consumed in the UK annually.

Yes: it's bad

https://pubmed.ncbi.nlm.nih.gov/33091697/

Gotta use unglazed Yixing purple clay teapots if you're serious about tea!

Came here to say the same thing. Unfortunately, they're not too easy to find, often expensive, and somewhat fragile. Mine didn't survive a recent move, and I haven't yet found an affordable replacement.

So, uhh, is that a good thing or a bad thing?

I suppose it’s a mechanism by which tea might taste different depending on the cup. Which is by itself interesting

My read is that certain teapots destroy some of the beneficial nutrients in green tea

Yeah exactly, it's not just taste. While bitter, catechins are the antioxidants that give green tea its cancer-fighting power. So your tea may taste less bitter, but you're getting less benefit. Generally though if your green tea is too bitter you should reduce heat.

translation: "the cups we use can change how our tea tastes"...

"... bring new impacts on daily tea drinking and long-term human health-related issues ..." this seems like reaching since nothing in the article talks about human effects at all? Way to make the paper sound more than it is? Ig Nobel Prize candidate? :-p

Catechins might be useful.

I think the paper leaves discussion of catechins’ benefits outside its scope, and given the incentives and limitations in academic publishing I am most often willing to show such…breathlessness? in introductions? some sympathy. As I read on to evaluate the technical and investigative and scientific merit.

On catechins, To put it very very carefully:

In the scientific literature there are presented indications that catechins have a range of biological effects, and some are said to be beneficial.

Catechins are antioxidants. I’ve been surprised in recent years to find that antioxidants really do seem to serve an important role. Have learned this when navigating a critical period of health isses – I assure you that this has been a time with absolutely no leeway for chasing placebo effects or self-delusion. There’s much mumbo-jumbo on antioxidants. There’s also a bunch of clear scientific results on their benefits, which were in my view obscured by the mumbo-jumbo.

—

Healthline often has a decent summary of literature; I don’t know at all how solid their page on the catechin EGCG: https://www.healthline.com/nutrition/egcg-epigallocatechin-g...

Google Scholar seems to have interesting papers on catechins: https://scholar.google.com/scholar?q=catechins&btnG=Search&a...

as well as EGCG, currently the best known / most discussed catechin as far as I know: https://scholar.google.com/scholar?hl=en&as_sdt=7%2C39&q=egc...

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