The Kitchen Scientist

Could Salt Make Coffee Taste Better?

We asked cookbook author and molecular biologist Nik Sharma. The answer depends on a lot—including your genetics.

August 16, 2020
Photo by James Ransom

If you're like us, every time you hear about a kitchen hack—whether it's advice from grandma or trending on TikTok—you wonder: But does it actually work? In The Kitchen Scientist, we're asking author Nik Sharma (whose new book, The Flavor Equation, comes out in October!) to put it to the test.


Of the five basic tastes, I find bitterness to be the most interesting—not only from an ingredient perspective but also looking at our behavior in response. In most recipes, we usually try to avoid tasting bitterness, and, as cooks, we’ve developed various ways in the kitchen to make the taste more palatable by trying to reduce it, cover it up, or remove it entirely.

There are, however, some bitter foods that we’ve learned to like, such as alcohol, tea, cocoa, and, of course, coffee, one of the most popular bitter beverages in the world. There’s a common theme throughout these four ingredients: They’re stimulants. We appreciate the bitter taste in these foods because the stimulant activity—working on our brain and nervous system to make us more alert—acts as a reward. Our brains learn that drinking a cup of coffee provides positive reinforcement in the form of its stimulant activity.

Coffee contains a variety of different taste and aroma molecules. Some are naturally present in the raw green beans, and others develop after roasting. Of these substances, caffeine is one of the most well known that not only tastes bitter, but also acts as a stimulant. In addition, caffeine is both a water- and fat-soluble molecule. Because of this, it can easily travel through the body (in the blood and through the membranes of cells), acting on the central nervous system and keeping us alert.

Join The Conversation

Top Comment:
“Marissa - we were taught that, weren’t we? Seeing that “Nik Sharma is a molecular biologist...” one would hope that he knew what he was talking about...Yep, he does. Alcohol is a stimulant, with depressive properties. So two-faced! 😉 ”
— Phatgal
Comment

Genetics also plays a role in our perception of bitterness. Those of us with certain genetic sequence variations are more sensitive to bitter foods and will avoid them whenever possible.

However, with coffee, things get even more interesting. Based on a 2018 study, people who were more sensitive to caffeine, due to those genetic variations, actually consumed more coffee but lower amounts of tea. There could be a few reasons for this, one of which might be the strong reward stimulus elicited by caffeine, a learned positive effect that gets reinforced with every sip of coffee. While some teas contain caffeine (present in a smaller amount than in coffee), another stimulant called theophylline is also present; in comparison, theophylline is weaker at inhibiting the enzyme cyclic AMP phosphodiesterase, which caffeine acts on. (Note: There are other stimulants in tea, like theobromine, and the concentration of these stimulants varies by the type of tea. Tea additionally contains L-theanine, an amino acid with a relaxing effect and umami taste.)

There are various ways people try to reduce the bitterness in coffee. Think: stirring in milk or creamer; a sweetener, such as sugar; even butter. These mix-ins dial down coffee’s bitterness, to whatever levels we are comfortable with. (I drink mine with a big splash of milk.) You can also temper the bitterness in coffee by using cold-brew methods, since caffeine’s solubility in water decreases with temperature.

Another ingredient that’s reported to mask the bitterness of coffee is salt, added either while brewing the ground beans or directly to the finished product.

How does salt influence bitterness in coffee? One way is by decreasing caffeine’s solubility. Hence, adding salt during brewing potentially turns down the bitterness. Another way this effect can occur is by activating the salt receptors on the tongue; salty tastes at any concentration are known to suppress bitter tastes.


The Experiment

To test how salt affects coffee, I brewed four different batches. For the first one, I used a cold-brew method: salted ground coffee, steeped in cold water for two days (about ¼ teaspoon of salt for every ¼ cup of ground coffee). For the second batch, I brewed salted ground coffee with hot water (with the same ratio of salt to coffee). Then I compared the results to a cold-brew batch without any salt and a hot-water batch without any salt.


The Results

The cold brew, both with and without salt, had the least bitter taste, while the ones brewed with hot water tasted totally bitter. (Disclaimer: I don’t like bitter foods that much, though I’ve never been tested for any genetic predispositions around bitterness.) I did not find the coffee to be noticeably salty.

When I asked a few friends to repeat my experiment, they came back with mixed results. Two of them found that salt minimized bitterness in both cold and hot brews, while another found no difference.

So, what’s the final verdict? The effect of salt on bitterness really depends on a lot of variables: the type and concentration of coffee, the temperature of water used, the amount of salt added, and also genetics. Will I add salt to my coffee down the line? In all likelihood, yes, especially if I can’t get my hands on any milk or creamer (caffeine can bind the proteins present in milk).

Try it out, see what you think, and report back in the comments.

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Nik Sharma is a molecular biologist turned cookbook author and food photographer who writes a monthly column for Serious Eats and the San Francisco Chronicle and is a contributor to the New York Times. His first cookbook, Season: Big Flavors, Beautiful Food, was a finalist for a James Beard Foundation award and an International Association of Culinary Professionals award. Nik resides in Los Angeles, California and writes the award-winning blog, A Brown Table. Nik's new book, The Flavor Equation will be released in October 2020.

84 Comments

Marla K. November 10, 2020
I don't bother salting my cold brew, as that method of brewing tends to remove almost all of the bitterness.

Hot coffee is another story. I use an Aeropress and salt the grounds before I pour in the water. I find that salting the coffee makes it taste fuller and rounder and all around more pleasant. On the few occasions when I've forgotten to salt, I notice the difference. It's very subtle, but noticeable.
 
Steve N. September 14, 2020
We have always sprinkled a little salt in the ground coffee while making it. Never have bitter coffee...
 
Tin L. September 13, 2020
Fresh coffee isn't bitter..
 
Warren M. September 18, 2020
I've got to disagree, and I own a coffeehouse. Bitterness depends on the grind, temperature, agitation and time of contact between coffee and water. Some bitterness is a positive point in a cup of coffee, but not so much that your mouth puckers. And then there are some of the coffees, particularly some of the African ones that have an acidity which is unusual and some people interpret as bitter or unpleasant..
 
Mary E. September 13, 2020
This recommendation has completely changed my pleasure in drinking coffee. Just a little salt in the mug before I brew my morning cup gives my coffee a much smoother and less bitter taste. Thank you.
 
tastysweet September 13, 2020
Good morning Mary E. As I sit here having my morning brew, I read your comment. I would make a recommendation that you use just a a very small pinch in your grounds before you brew. It’s like we salt our pasta water so it can permeate the pasta. You can’t salt after pasta after. I mean you can, but it doesn’t work the same.
Have a sunny morning. We have rain. Project day.
 
M September 9, 2020
I'm not surprised that the salt question wasn't answered by the test. There are so many sources of bitterness in coffee. It depends on your bean, how you roast it, and how you extract it. I would assume that the source of the bitterness would then effect whether or not salt helps. Is this bitterness from over-extracted grind? Oily, dark-roasted coffee that has had the bean's bitterness dialed to 11? A bean has a particular flavour you find more bitter than other beans? I'd like to hear about taking a particular bean, roasting it to different levels, brewing it different methods, and recording how salt affects things.

Personally, I prefer adding coffee to my salt than salt to my coffee. Coffee salt is great.
 
tastysweet September 9, 2020
I am not sure we have to go to such lengths for this article. I really don't care why the salt works for me, it just does. Being doing for over 55 years, Though thanks for your input.
 
Marsha S. September 13, 2020
Me too.
 
M September 15, 2020
If you don't care about why salt works for you, then perhaps a kitchen science column that sets out to scientifically test the impact of salt on coffee isn't for you.
 
tastysweet September 15, 2020
By golly, I think you are right. ☀️
 
Cindy W. September 6, 2020
Could someone tell me what brand of coffee you use? Plain old Folgers, Maxwell House or some expensive brand of coffees? Thanks in advance Cindy
 
Aaron M. September 6, 2020
I buy from a local coffee shop that does their own roasting. I tend to choose medium and light roast coffees from them and haven’t needed to add anything.
 
tastysweet September 6, 2020
Everyone has their preferred coffee. I personally have been ordering Peets coffee since 1985, when we first tasted it at my sisters home in CA. I’ve been using it since then. I have a subscription service which now gives free shipping. We like the French Roast in both the K cups and fresh beans.
 
sreastland September 3, 2020
Perhaps the kind of salt used is also a factor. I’ve always added a little pinch of fleur de sel to hot chocolate so decided to try it. I used a small pinch in my palm press and enjoyed the cup. Not something I would do with all roasts but a useful tip. Thx for sharing.
 
Teresa15 September 3, 2020
I add salt to the coffee grounds before I start brewing. If it tastes salty you’re definitely adding way to much. I find just a little pinch is enough to taste the difference, for me at least.
 
tastysweet September 3, 2020
AgreedTeresa15
 
Barbara September 1, 2020
Thanks, Nik,
I'd like to hear your take on adding chicory to coffee. I love the Now Orleans French Market Coffee with Chicory, but it's tough to find where I live. But I have been able to purchase ground chicory and have experimented with adding it to my coffee grounds. I find that it makes the coffee smoother (I.e. removes some of the bitterness) without diluting the richness. Maybe you can tell me why. Please?
 
Ms6Black August 31, 2020
TikTok? Why would anyone care shout the nonsense floating around there?

Other than spiders and worms (which have never come out of any strawberries I’ve rinsed off before), what kind of bugs are expected to be in strawberries?! Were you advised to intentionally put a any specific kind of bug ‘in’ strawberries for the salt water rinse testing?
 
Kristen S. August 31, 2020
I added 1/4 teaspoon of salt to my coffee grounds before brewing (pour over style). I do think the coffee is a bit smoother, but darn, it tastes salty, and I like salt! I drink my coffee with warm milk added.
 
tastysweet August 31, 2020
You may have over salted the grind. I use kosher salt and only use a very small scant pinch.
Try that next time.
 
Frank C. August 30, 2020
I brewEd my favorite go to Bustelo and tried the using Himalayan Pink Salt. I used a teaspoon of salt to 1/4 or so cup of coffee grinds and about 10 cups of hot water. I found the cup easier to drink, no bitterness and smooth. Will have my wife try to see what she thinks. We have never used salt in coffee. Will use less salt next time as I learned in here if I could taste it, I probably used to much. Thanks
 
tastysweet August 30, 2020
It so happens, my mom always added a bit of salt to the grind when making coffee. Now I’m talking about the 1950’s. And as a result, I do as well.
 
Frank C. August 30, 2020
I brewed my favorite go to Bustelo and by far am I a coffee connoisseur but the salt worked in managing the bitterness and made it a lot smoother which I like. I used a teaspoon of Himalayan Sea Salt to ten cups of water and 1/4 cup or so of coffee grinds. I think I will have to perfect this by adding less salt as I let red from the other comments on here because I can taste it but I think I’m on the right path to a perfect cup. Will have my wife try it and see what she thinks. If anyone has any ideas as to what I could be doing different please share. Thank you
 
JillKir August 30, 2020
What a useless piece. Comes to no conclusions at all about the effects of adding salt to cold brew or hot. Bitterness in each were the same, with or without the salt added.
 
catalinalacruz August 30, 2020
Too bad so many of the comments here center on whether coffee is a stimulant or a depressant (people love to debate), when really this article is about the effect of salt added to coffee. That's what I would like to hear about. Did the salt make a difference for you or not?
 
Aaron M. August 30, 2020
I’ve read through the comments and most center around adding things to make their favorite dark roast smoother and less bitter. Salt, baking soda and cinnamon cone to mind. What if the problem is the coffee itself? Maybe people are doctoring a bad brew or the wrong one for them? Switching to a light roast where you taste less of the process and more of the bean itself might be the solution. Coffees from Costa Rica, Mexico, Ethiopia, Kenya, Sulawesi and Hawaii have very different flavor profiles. Until you burn them down until the best descriptor is how dark they are.
 
Mindy S. August 30, 2020
Alcohol is a depressant NOT a stimulant
 
Carol C. August 30, 2020
Actually alcohol, per my doctor and many other medical experts, is a stimulant!
 
Ginger52 September 13, 2020
Yes agreed. Stimulant!
 
Warren M. September 18, 2020
From my Psychopharmacology courses: Alcohol is a depressant, but it affects the inhibitory centers first, at lower blood levels than it affects the excitatory centers. This leads to a perceived stimulant effect at low to moderate levels.

Individual variation also shows in some people who show more aroused physical or emotional response than others even with great intoxication.
 
patricia G. August 30, 2020
Salt tamps down the Perception of bitterness and acidity. You can use it modulate flavor in many interesting ways, not just in coffee. Try a tiny amount in hot chocolate. Next time you make a vinaigrette, pay attention to the way salt balances (smooths the acidity) of the vinegar in the dressing.
 
Christine August 30, 2020
Yes, first thing I thought of was putting salt on grapefruit. And, the Southern habit of using vinegar on slow-cooked greens such as collards, while not salt it does cut the bitterness. Of course there is a fair amount of salt and fat in the greens if made in the traditional manner.
 
Jayne M. August 30, 2020
Folks, skip the salt and replace with baking soda (which is sodium bicarbonate). A light dusting across your coffee grounds, 1/4 tsp should do it. Smoothest cuppa you'll have had...
You're welcome...
 
tastysweet August 30, 2020
Jayne, I have never heard of that one. Have you tried the salt? I have used a sprinkling of salt to ground beans for eternity😉.
Might try yours just to see.
 
Jayne M. August 30, 2020
It's my father's trick. He has been doing it for decades and now my sister and I carry that same tradition. I have only used the salt trick when having a lousy cup of diner coffee. I add a scant amount to the actual cup of joe before drinking...does the best it can to make it palatable. Please try and let me know if you taste the difference. Be well...
 
NoSugar20 October 11, 2020
I've been using the baking soda trick for a while now and have found quite a difference in taste. I not only enjoy the flavor of my favorite brew, my stomach handles the coffee much better than it had been....as an aside, and a plus!