Experiment: Coffee Sensitivity To Salt & Carbonate

I’ve done something of a partial experiment on coffee brewing chemistry.

I think we all know that the water used changes foods, drinks, beer making, and more. There are places with horrible drinking water (a place outside Phoenix Arizona comes to mind… very hard water with a dirty rocks flavor…) and they often have bad coffee too. BUT run the water through a purification process and you can get good coffee.

Well, I had some “less than stellar” coffee bought because it was cheap at Bargain Market Discount Grocery (or whatever…) and I was taking my time about getting through it. Along the way, I bought a supply of better coffee (Folgers I think…) that’s leaving faster. I’ve resorted to using the ‘less stellar’ coffee for DIY Mocha. Realize just how “less than stellar” it must be if Folgers beats it… But put it in the Italian stove top mini-pot espresso maker, mixed with excess chocolate & milk, and it’s not bad.

But before I got there, I was trying to choke down a cup one morning and there, on the dresser in front of me, was a salt shaker. Left over from a snack the night before. I remembered folks in my old home town who would put salt in their beer. And I vaguely remembered one guy salting his coffee cup… Just a sprinkle or so, not much.

I gave it a try. Coffee was much improved. A good long sprinkle gave me… salty coffee that was not so good. What I learned from that was that coffee is sensitive to salt, and just a tiny bit can shift the flavor a LOT. BUT, it does improve bad coffee.

This morning, I had a bit of water with bicarbonate of soda left in it (from an unfortunate incident involving taco sauce to excess in chicken quesadillas the night before ;-) This gave me the bright idea of seeing if it would cut back the acidity of coffee in the first cup of the day. Off to the kitchen…

Well, it certainly does. MAYBE there was 1/8 to 1/4 tsp of bicarbonate in the whole cup of water ( not the ‘official’ 6 oz. coffee makers lie cup, and not the 8 ounce actual size of a cup, but the 16 ounce mug of coffee I make first thing, that’s about 15 ounces after the drip grinds drink their fill…) But it DID have a dramatic effect on the coffee.

No bite. No acidity. Damn near no flavor at all to speak of other than a vaguely “coffee was here” reminder.

So, OK, I’m onto something, but it will take a lot more care in the testing to ‘get it right’. I’m probably looking at something like a match head size bit of carbonate in a mug to really cut back the “strength” of it, and about 1/2 that of salt to make it more interesting. We’re talking tiny amounts for significant flavor shifts.

Then there’s that whole ‘tuning it to the particulars of local water and coffee brand’. So no, I’m not able to give a recipe or directions on fixing bad coffee. But I can point a way…

IF the coffee is just too acidic and brash, a little bit of baking soda, barely a touch. If the coffee is a bit dull and also harsh, a little salt can lift it, barely a 1/2 shake. And, IF your local water is alkaline or not that great, it is highly likely that some bottled water or a water filter will improve your morning brew a lot.

So now I’m off to finish my cup of “almost has flavor” coffee and try again using the harsh acidic coffee and a lot less bicarbonate. I’m pretty sure none of this will change the caffeine levels, so I’m likely to end up a bit hyper by the time dinner rolls around ;-)

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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10 Responses to Experiment: Coffee Sensitivity To Salt & Carbonate

  1. Sandy McClintock says:

    Very interesting observation.
    We rely on rainwater collected from the roof connected to an underground concrete tank.
    A friend turned up one day with a $15 CCP pH meter and we were both astonished to see a reading of 10.4 pH. Since this reading I have checked that this was correct – yes.
    A big container of ‘pool acid’ (HCl) brought the 30,000 US Gallons down to about pH 7.8.
    The dishwasher is producing better results and the coffee is good ;)
    Who would have guessed concrete would have had such a long-lasting effect.

  2. Clay Marley says:

    Ever try shaving a match head into your coffee? (Seen a few years ago on the Expanse). Some think the potassium or phosphorus may improve the flavor. Others think it was a means to reduce your libido. ;)

  3. jim2 says:

    Sodium sulfate will react with the calcium in the water to create an insoluble CaSO4 precipitate. The particles created may be fine or course depending on solution conditions, but I suppose some could be added to the water in the coffee maker and the filter would probably catch it. It would just be a matter of determining how much was enough.

  4. jim2 says:

    On second thought, sodium sulfate in the coffee pot is a bad idea. It could cause gypsum scale in it. The water would have to be treated outside of the coffee maker.

  5. philjourdan says:

    Egg shells to settle the grounds and a pinch of salt to smooth out bad coffee. Back in the day when Keurig was a German name and not a product, and you wanted espresso (my grandfather would drink nothing else), that is what you did. His espresso was more like coffee syrup than coffee. But it had the kick of a mule and was very good. With a pinch of salt.

  6. Peter says:

    For your youtube browsing, a video by James Hoffmann, a rather well known coffee connoisseur, about salt in coffee, along with an experiment and some explanations. Enjoy!

  7. H.R. says:

    We use filtered water. The coffee you buy is the coffee you get. Stale coffee tastes like crap. Good coffees taste great!

    As an added bonus, we never have to do the occasional vinegar cleanout routine to get rid of the deposits that build up in the feed lines.

    Or… you could just switch to lead plumbing and a lead-lined coffee pot. Your coffee will taste sweeter and after a couple of years, you won’t give a rat’s @$$ what it tastes like 😜

    BTW, I heartily endorse a Folgers coffee roast aptly named Black Silk. Yum!

  8. E.M.Smith says:


    Well THAT saved me a lot of time!

    Nice to know I’m not alone on a fools errand and that it is something known to work.

  9. E.M.Smith says:


    Yeah, concrete (cement in it really) is VERY alkaline. Essentially lime with CaSi and sometimes CaS04.


    Um, no, never heard of it before. I’d be reluctant due to the various and low purity things in it (including ground glass in some…)


    I see that NaSO4 is available in small amounts food grade. Interesting idea…


    OMG I remember somebody who did that. An aunt or uncle… I was maybe 4 or 5 at the time and the idea of left over egg on the shells made me a bit, er, um, well I left the room…

    Now I’m thinking “I have egg shells. Give ’em a rinse and into the funnel with the coffee grounds?… ”

    I get the feeling I’m ploughing well ploughed ground…


    I’ll look for it.

    The Spouse only drinks bottled water, so I think I’ll try a cup with some of ‘her’ water supply ;-)

  10. Gail Combs says:

    When I cold brew green tea (Gun Powder loose.) I add 1/8 teaspoon of bicarb to ‘smooth’ out the taste after I remove the tea leaves. I gave up putting sugar in my tea and found using a better brand of tea plus the bicarb made the tea much more drinkable.

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