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Comment by horeszko | Hacker News Reader

>"But in the 20th century, TCE was used for many purposes, including making decaffeinated coffee" ...

This is exactly the reason I never touched decaf coffee until I found Swiss water process (SWP) decaf. It never made sense to me to use hydrocarbon solvents in a food application

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> It never made sense to me to use hydrocarbon solvents in a food application

I get your point, but isn't this kind of a broad statement? After all, ethanol is a hydrocarbon solvent, and it's been used in food applications for a long time.

Ethanol is also a horrible toxin, it just happens to be common enough in nature that our bodies, and animal bodies as well, have had hundreds of thousands of years to evolve some mitigations against.

Interestingly -- when it comes to toxicology it is not the substance that determines the poison but the dose. Water is still a toxin, we just have evolved ways to handle up to a certain amount of water per day before water poisoning takes hold. Everything is a toxin, we just have it in our bodies to handle some of it.

Wouldn't there be another word for this effect? It's not that water per se is toxic, is that eventually if you have a lot, your body "overflows". Being toxic is not an intrinsic property of the element, but is being derived by its quantity.

I would say water is a solvent rather than a toxin. The water we consume is just not pure water and has lots of minerals in it already diluting the solvency (?is this a real word) of the water. Truly pure water will strip the minerals right out of your hair: https://www.businessinsider.com/super-kamiokande-neutrino-de...

I would say that's not completely accurate either at a biological level. For example, if a neurotoxin merely disables sodium channels temporarily, that's different from a neurotoxin that somehow permanently disrupts or damages neurons (I believe some heavy metals work that way?). In the case of permanent damage, there is essentially almost no "safe dose", although I guess very small amounts will be negligible compared to background cell death. But you essentially want as little as possible, which is different from water, that goes from therapeutic to toxic at extreme amounts. (Not sure how TCE toxicity works)

Ethanol is only a "horrible toxin" if it's consumed in amounts that would be nearly or certainly lethal for any other solvent (save water). Human gut bacteria do not produce trichloroethylene.

As organic solvents go, ethanol is one of the safest — but it's too flammable for dry cleaners.

Ethanol is not a hydrocarbon, nor is TCE. By definition, a hydrocarbon is composed of carbon and hydrogen. Ethanol contains oxygen, while TCE contains chlorine.

Ethanol is technically an alcohol hydrocarbon, if we're getting into the weeds on semantics.

What is an "alcohol hydrocarbon"? Alcohol isn't a hydrocarbon. As already pointed out a hydrocarbon is comprised entirely of hydrogen and carbon.

Alcohol hydrocarbons are hydrocarbons with an alcohol group attached (see the diagram at https://en.wikipedia.org/wiki/Hydroxy_group) The simplest would be methanol, from methane. Any organic chemist would know what you meant, although it's not really correct terminology. IIRC the hydrocarbon would be called an 'alkyl group'.

Thank you to share abuot SWP. I didn't know about it. This page explains how it works: https://www.haymancoffee.com/blogs/coffee-blog/how-is-coffee...

At this point, it looks like the solvent thing is probably overstated (in highly developed/regulated countries)). This page has info about the history of different solvents: https://www.coffeereview.com/coffee-reference/coffee-categor...

I thought the SWP involved supercritical carbon dioxide, but apparently it just involves solubility tricks and sacrificial beans, and CO2 is the new, new method.

It's volatile enough that it won't be present in the final product.

Volatile doesn’t mean harmful byproducts can’t be left behind, though.

Halogenated solvents should definitely be avoided at all costs but I'm generally not too concerned about how hexanes are used to extract cooking oil, for example.

Why not? I don’t know much about the topic, but I’ve wondered about it.

You can also look for Mountain Water Process (MWP), which is basically the exact same process, but from coffee sourced in South America.

I'm very curious about SWP. How does it taste compared to good light roasted single origins?

Based on some light reading just now:

- SWP is a means of treating green coffee beans pre-roast. They can be roasted any which way afterwards.

- Any type of bean can be treated this way.

- The process is pretty specific in targeting just caffeine. In removing caffeine though, the total dissolved solubles in the end coffee will be lower for the same amount of beans. Probably a lessor body unless you use more.

Interested to hear from someone who has tried it.

I roast my own coffee beans. I usually get decaf SWP beans from Sweet Marias. https://www.sweetmarias.com/green-coffee/decaf.html The decaf SWP beans start out a different color of green bordering on tan compared to the light green of regular "green" coffee beans. Its not just the starting color, they roast differently too. Coffee beans crack during roasting - there is a first crack and then if you want it dark there is a second crack. The sound is usually pronounced. With the SWP beans the crack sound is more of a poof. Apparently SWP changes the structure of the beans, possibly introducing cracks or holes. The roasted beans seem drier and duller brown in color, less mahogany, less shiny. Its hard to know what the flavor impact of SWP was b/c I haven't tried the same beans before they were made decaf. It could just be my own prejudice or lack of skill in roasting but I would say on average the decaf coffee turns out 5-10% worse in quality.

In practice, it's far easier to find good single-origin roasts than to find good decaf options. I've actually never been able to find anything lighter than medium roast in SWP -- not sure if that's for some functional or taste reason, or just because it's a sliver of a sliver of the market.

I am very sensitive to caffeine and recently switched to decaf only after drinking coffee daily for 20+ years. I drink mainly Mountain Water Processed coffee, which is the same thing but from coffee sourced in South America. It is roasted by a local roaster in Minneapolis. I honestly can't tell the difference between the decaf and regular (except for the lack of caffeine).

Also, SWP or MWP coffee removes nearly all caffeine unlike the more heavily processed versions.

Which Minneapolis roaster? I'm local

UP Coffee Roasters / UP Cafe

Chlorinated hydrocarbons are generally the ones you want to really watch out for.

Coffee can also be decaffeinated by supercritical carbon dioxide, which was the first process I learned about (as an intro to supercritical fluids in a thermodynamics course).

Would hexane be another example?

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