Brewing coffee in titanium: does it impact flavor?

[Dave .]

When backpacking, I use the MSR Mug Mate to brew coffee in the MSR Titan mug. I like to think that I know a little bit about how to make good coffee while on the trail. In the back country, I use the same fresh ground, organic, fair trade, shade grown beans that I use in day to day coffee drinking. This is to say that I have a good baseline to compare the results of my backcountry brews to. And I've always found my backcountry results to be inferior to that of of the day to day stuff that I brew in a French press. The flavor is just flat and lacks the same depth as normal.

I've always wondered why this was the case. One of my suspicions was that brewing the coffee in a titanium mug rather than glass pot did something to the flavor. So, on a whim today, I tried the Mug mate with my normal mug, and…perfect. The coffee tasted fine, just like normal.

So, does anyone know why the titanium mug is having an impact on the flavor of my coffee?

[Roger Caffin]

I do not KNOW, but I have my suspicions.

When you pour boiling water into a glass pot the glass does not take a lot of heat out of the water: it is a fairly good insulator. But when you pour boiling water into a metal container, then you are going to suck heat out of the water rather fast. Even titanium is a far better conductor of heat than glass.

What I do know is that it is the last few degrees of tenmperature which extract a lot of the coffee flavour from the ground beans. That's why an Expresso machine uses really boiling water, at a moderate pressure, to make coffee, and have you noticed the difference?

Fwiiw, I pour boiling water through coffee grounds into a plastic mug: close to glass.

My 2c.

Cheers

[Dave .]

Hi Roger. You know that makes good sense. It's considered bad form to stir your coffee with a metal spoon while brewing it in a French press. took me ages to figure out why this is so. Originally, I assumed it was just an odd tradition. But, no: a metal spoon would act as a heat sink. And, yes, the plunger is metal, but you don't put that in the coffee until it's done brewing.

Good thinking.

Brings me to a question for you though, Roger. How safe is it to drink out of those polypropylene GSI Cascadian Cups that you reviewed? I generally don't like the idea of pouring boiling water into plastic and then drinking it. I'm something of a hardliner on the subject, actually.

But at this point bad coffee is a certainty and health risks are uncertain…

I'm such an addict. Listen to me rationalize…

[Rick Dreher]

As a coffee nerd I'm obliged to chime in.

I don't believe you've conducted the right test. Try drinking the same fresh pot of coffee from the two subject mugs to isolate the material and shape's effect on taste–if any. I'll venture what you're noticing is the effects of the shape, thickness and how the fluid flows on the material, not a material difference in the coffee itself. I've seen coffee tasters "cup" coffee and they always do so by slurping from a spoon, they don't drink from the cup at all.

A parallel is with wine glasses. The bowl's size and shape, the wall thickness and the material (glass vs. crystal) all affect how the wine tastes, and it's not a small difference either. Nothing kills the flavor of a fifty-buck bottle of red faster than drinking from a thick, small restaurant glass.

Brewing temperature certainly has an effect on flavor and extraction, but a fair comparison of brewed-in-the-cup coffee at least requires preheating the glass mug, otherwise the brewing temperature will be a good deal lower due to the heat lost in warming the glass. Nerd note: espresso brewing temperature is the same as coffee–195-205F. The difference is pressure–espresso water is forced through finely ground and tightly packed coffee. Only Turkish-style coffee is actually boiled (high-altitude brewing aside). Stovetop espresso makers are actually small percolators, and they overheat the brew.

A thin-wall Ti cup will start hotter and cool faster than glass and plastic, slower than aluminum and steel. I put a neoprene wrap around mine, which more or less takes care of that problem. A doublewall mug is even better, if heavier.

Is it also possible that bare titanium attracts some coffee component ionically? (I think that's the right term.) Might the oils or some other flavor component be clinging to the metal? Heck if I know. But getting back to the wine glass example, wine clings to crystal bowl walls more and longer than glass, helping concentrate the fragrance and enhancing taste, even after the glass is empty.

I'm betting it's size and shape.

[Nick Gatel]

Well, I don't have your taste or appreciation for coffee. But I found mine tastes a lot better in my double wall Ti cup vs my single wall. So that is my indulgence in life, a double wall cup.

[Roger Caffin]

Hi Dave

> How safe is it to drink out of those polypropylene GSI Cascadian Cups?

My understanding is that polypropylene plastic does not contain any plasticisers of any sort, nor does it contain any other leachable materials. It is not a 'new' plastic, btw. So I cannot see any hazards in this material, and I am not aware of any (properly) reported hazards either. My wife is also a bit of a hard-liner, and she has no qualms either.

---

MSDS:
Stability and Reactivity: The product is stable. Avoid temperatures above 300 degree C (570 F). [Boiling water? Ha!]

Conditions of Instability: No additional remark. [nothing to report]

Incompatibility with Various Substances: Incompatible or reactive with fluorine gas, oxidizing agents (nitric acid and perchloric acid), free halogens, benzene, petroleum ether, gasoline and lubricating oils, and aromatic and chlorinated hydrocarbons. [Er, yeah, right…]

Hazardous Decomposition Products: Hazardous decomposition products are carbon monoxide & carbon dioxide. [no harmful nasties then]

Hazardous Polymerization: no

LD50: Not available.
LC50: Not available. [means no results – good]

Chronic Effects on Humans: CARCINOGENIC EFFECTS: Classified NONE by NTP, NONE by OSHA. 3 (Not classifiable for human.) by IARC.

Other Toxic Effects on Humans: Not considered to be dangerous to humans, according to our database.

---

However, the virtues of good coffee are indisputable.

Cheers

[Roger Caffin]

Hi Rick

> Try drinking the same fresh pot of coffee from the two subject mugs to isolate the
> material and shape's effect on taste–if any.

I think the Q was about the container used for brewing the coffee in, not about distinguishing between different cups. I brew my coffee in my polypropylene cup, with boiling water.
But I have to admit, what I wrote is just my guesstimate after much coffee drinking. No hard facts.

> Is it also possible that bare titanium attracts some coffee component ionically?
> (I think that's the right term.) Might the oils or some other flavor component be
> clinging to the metal? Heck if I know.

Well, they do use titanium these days for surgical implants, so it has to be awfully NON-reactive. If there is a coating on your cup/pot – dunno. Teflon is often used – also non-reactive.

Each to his own…

Cheers

[Rick Dreher]

Hi Roger,

Right, I was just reframing the question to separate out the brewing side from the drinking vessel side. I doubt the ultimate backcountry coffee quality answer lies in hauling a glass mug hiking :-)

I'm confident titanium isn't lending anything to the coffee itself, as you rightly note it's famously nonreactive. My curiosity is whether any coffee components might cling to the cup walls and affect the coffee's taste–alteration through subtraction if you will. Seems unlikely, but I try to keep myself open to surprises. I didn't believe the whole wine glass thing, until I was proven wrong.

If I weren't a junkie I probably wouldn't be on this tangent, but…there it is.

[Sarah Kirkconnell]

Hope you are using organic raised coffee then ;-)

[Dave .]

Roger, thanks for the info on the Cascadian cups.

Rick, interesting idea. Should be easy enough to sort out. I'll brew some coffee in the French press like normal, pour half in the Titan mug and half in my day to day ceramic mug. If it tastes okay out of the Titan mug in this test, that'd be more evidence toward the "titanium as a heat sink" side of things. If it still tastes bad out of the Titan, maybe that does have something to do with other characteristics of the mug.

>>I doubt the ultimate backcountry coffee quality answer lies in hauling a glass mug hiking :-)

If it does require a glass mug, I'm prepared to do what has to be done…

In any case, I'm off to visit my parents this weekend. The brew Foldgers in a Black & Decker wall mount percolator. (Blech!) I got them a French press for Chistmas, but to no avail…

[Rick Dreher]

"If it does require a glass mug, I'm prepared to do what has to be done…"

(Sniff) You've made me very proud today!

[Anton Koliev]

I believe, that you have different taste of coffee boiled in mug, because you are doing this bit wrong.
So far, making coffee in mug are similar to making turkish coffee (Türk kahvesi) in cezve, instead of french press.
1. Try to fine grind your coffee beans instead of coarse milling like for french press.
2. Do not boil it – try to do following instead of boiling:
a. stirr desired amount of sugar into cold water with desired amount of coffee powder until sugar will be dissolved and coffee particles sink.
b. Start heating your mug until water just start boiling
When foam start rising – just remove your pot from fire and drink it.
This way taste will be better!

[Brad Groves]

In the interest of science and the curiosity of a one-time barista I did some informal testing this weekend. Very informal, very small sample size, mind you–I had no tastebuds other than my own for feedback.

Nearly all coffee shops use stainless for their brewed coffee. I've never heard complaints of strange metallic tastes; part of that could be attributed to some build-up of coffee oils. So I decided to brew coffee in several different materials. I wanted the material of the vessel to be the only variable, and so brewed all coffee by pouring 6 fluid ounces of boiling water over 1 tablespoon of (free trade organic) coffee grounds, my normal brew. After letting the grounds steep and settle, I decanted each brew into identical matching coffee cups.

In short, I brewed in titanium, stainless steel, aluminum, glass, and lexan. As much as I slurped, I couldn't detect a significant difference in taste between most of the materials. The lexan brew was ever so slightly… richer, sweeter almost? Sort of more oily?

I could develop this testing further if there's interest. Otherwise, just something to consider. From my findings, it seems like it's the mug itself contributing to the difference in flavor, quite possibly the shape? In reference to the temperature questions, I can say that my recipe for quick-rise yeast bread calls for putting hot tap water into a pyrex bowl–and plan on the pyrex bowl dropping the water temp about 20*F.

[James Mancini]

Most serious espresso brewers will pre-heat the mug before putting the coffee in to avoid that effect, so if you're concerned, splash a little of the boiling water in to the metal cup first, swirl it about for a few seconds, then pour it out and refill with piping hot coffee.

Of course, if your mug isn't insulated, there's no point, as the heat will flee through the metal at an amazing rate.

[cary bertoncini]

tends to make my titanium somewhat coffee flavored

[Rod Lawlor]

To the OP

Are you boiling the water in your titanium mug, or in a pot and pouring it in?

Your description of the coffee tasting 'flat' makes me think you're boiling in the cup. This can leave a flat taste that is corrected when you aerate the water by pouring it into your normal cup.

This theory is somewhat borne out by Brad's testing, where he poured the boiling water into each of the brewing cups, as opposed to boiling in the cup.

[Ben Pearre]

Cool question! Thanks for that! What grinder do you carry?

To Roger’s point: can you monitor the temperature? A cheap digital probe thermometer stuck in every 30 seconds or so might reveal much.

I can’t really tell any difference between different brewing vessels if they’re clean (given the same brew temperature profile). Drinking vessels can affect flavour based on shape. But if you have a few days’ coffee residue in either, then your coffee will taste off. My impression based on not-very-methodical testing is that the main factor is how clean your equipment is, some materials are far easier to clean than others. Glass and ceramic seem to do fine for many days with a good hot-water rinse. Stainless steel seems far harder to clean. I need to test titanium over long periods and see how it compares to SS, but I just received some exciting roasts from my kaffebox subscription, so I don’t want to do the stale-mugs experiment right now ;)

(I wouldn’t bring a full pourover rig into the woods, but I might wonder which bits I could trim off an Aeropress, which can do a great brew (especially if you follow the world aeropress championships), doesn’t seem to pass on as much smell as I’d expect for a few days, although still much heavier than a tea infuser or backpacking plunger… but hey, if you need good coffee…)

A few companies are now making ceramic-lined stainless steel vacuum mugs. I just ordered a Kyocera one; should presumably be easy to clean like ceramic and safe on the trail, but not exactly light. Anyone here know how to do ceramic coating at home? I wonder how all the metals compare for flavour and cleanability. Somehow I like the idea of insisting on drinking my coffee only from a gold-plated-double-walled-titanium mug.

[Geoffrey Lehmann]

 It’s considered bad form to stir your coffee with a metal spoon while brewing it in a French press. took me ages to figure out why this is so. Originally, I assumed it was just an odd tradition. But, no: a metal spoon would act as a heat sink.

I thought the non-metal spoon was to avoid breaking the glass French press.  At least, that’s what the instructions that came with mine advised.

[Mark J]

I’m not sure why, but my coffee and tea always taste better drinking out of my ceramic-lined mug at home than my Snowpeak double wall Ti cup, though never as enjoyable as staring off into mountains and sky enjoying it nevertheless.  I’ve noticed that the Ti cups also stain from tea but washing or scouring doesn’t seem to make any difference in taste.  Maybe it’s all lip-feel of the white ceramic against the lips vs. metal.

As for metal spoons pulling heat while stirring a French press….really?  I can’t imagine 1). having it in contact with the liquid, given its size in relationship to the volume of liquid and the amount of time of that contact having any impact on reducing temp to a discernible degree, and 2). dropping the liquid temp by that amount having any discernible effect on the taste/brewing of the coffee.

I roast my own beans, hand grind, and have been pouring over with a Melita since my college days, which was back in the late ’70s if you must ask.  It’s a rabbit hole one can go down for sure, but for all that is sacred and good, it’s enough to just get up in the morning, measure out some beans, pour boiling water on it (gasp!), add a little cream and wake the f#@k up to a beautiful day and dispense with the intricacies of fine variations and variables; I leave that for my fly fishing!

[Sarah Kirkconnell]

Since this was a dredged up post from 2009…and it’s 2023…I’ll say this: Quit worrying so much you all. It’s just coffee, and a few days of less than stellar brew won’t break your life. I quit caring long ago when it comes to my brew in the morning if I am out and about. I was a barista for 9 years of my life, I have a pro setup at home I use most days…but I literally drink cocoa mix with instant espresso added when camping.

And yes, metal spoons in glass is not the best of ideas….it can lead to breaking. Even with Pyrex it’s an issue. But then again, how many actually carry glass in the backcountry? Even I, the human that owns over 1,000 mason jars, does not even carry glass in her glamping RV.

[BlackHatGuy]

Ha! I’ll be the coffee heretic here. My morning coffee routine: drop a Folger’s coffee bag (like a tea bag) in a cup, pour some hot water over it, dunk the bag 15 times, wait 60 seconds, dunk the bag another 15 times, and I’m done! Coffee tastes fine to me! (Well, for my first cup in the morning, and only my first cup, I then add a tablespoon of MCT oil, mix it up with an immersion blender, then I’m done).

I only drink one cup of caffeinated coffee a day, the rest are decaf, also made with Folger’s coffee bags.

[AK Granola]

Then you have to pack out soggy coffee bags. Instant! It makes the brewed delight so much more delightful when you’re back in civilization.

[BlackHatGuy]

Sorry, I was relating my at-home coffee routine. When backpacking, yes, I use instant as well.

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