Minerals in Water and Coffee Flavor – Part 2: Citrates and Custom Profiles

If you're new to the topic of water for coffee, first take a look at Part One — it's the foundation: why minerals are important, the difference between chlorides and sulfates, and how to prepare initial Ca, Mg, Na, K concentrates. In Part Two, we assume you already have that context and we're moving forward. I'll be direct: a lot has changed. We've been working on these recipes ourselves for many months, and what you'll find below is what we use today — not what we started with.

What has changed since the first article

Two things, in short. Firstly, we scaled down the concentrations of the concentrates. Most of our solutions are now two or even three times weaker than the "starter" version. It sounds like a step backward, but in practice, it provides much greater dosing precision. It's literally easier to hit the right flavor profile.

Secondly, we introduced citrates. Magnesium citrate, potassium citrate, and sodium citrate. This is an entirely new family of concentrates that were not in the first iteration, and they made the biggest difference in our waters. Citrates work a little differently than classic chlorides or carbonates — they leave the coffee clearer, emphasize sweetness, and are gentler on the buffer than bicarbonates. More on that in a moment.

Citrates — the third axis of flavor

Returning briefly to the basics. In coffee water, we usually operate with two types of anions: chlorides (Cl⁻) and sulfates (SO₄²⁻). The former round out the flavor, providing body and creamy sweetness. The latter sharpen it, boost acidity, and leave the coffee sparkling. Then there are bicarbonates (HCO₃⁻) — the classic KH, a buffer that neutralizes acids.

Citrates (C₆H₅O₇³⁻ ion, salt of citric acid) are a third option. They also act as a buffer — but in a different way than bicarbonates. Citrate buffers more gently and doesn't diminish that lively acidity.

For specialty coffee — especially light-roasted, fruity, floral — this is a game-changer. A Geisha buffered with bicarbonate can lose its jasmine notes. The same Geisha buffered with citrate retains it but gains a smoother finish. From our tests: magnesium citrate in water for fruity coffee gives a juicier effect — berries, peach, melon become more pronounced. Sodium citrate, on the other hand, adds a subtle layer of sweetness that smooths out harshness without suppressing acidity. These are subtle changes, but that's precisely what we're aiming for.

A small practical note: citrates as salts are readily available, safe, and have food-grade status (E331 for sodium, E332 for potassium, E345 for magnesium). If you're buying reagents, only look for food-grade options.

Updated concentrates — full table

Here are all our current concentrates, in one place. The ppm per drop values are calculated for 1 liter of final water (assuming one drop = approx. 0.056 g of solution).

Rows highlighted in the background are new compared to the first part. The ppm/drop column refers to one liter of final water. The abbreviation (KH) means that this citrate primarily contributes to the buffer, not to GH.

Two numbers from this table are worth noting. Firstly: magnesium chloride (position 3) is unequivocally the strongest player in the arsenal. One drop = ~11.6 ppm per liter. That's twice as much as the next in line, magnesium sulfate, and five times more than potassium bicarbonate. Therefore, we use it where we deliberately want to significantly boost sweetness and body, but cautiously.

Secondly: sodium (position 4) is the gentlest tool in the set. One drop = only ~1.1 ppm. That's why it's ideal for fine-tuning subtle balances in light coffees — where another mineral would "overdo it," sodium allows you to add literally a thin sprinkle. This is the opposite of MgCl₂ in every respect.

Old recipes — a starting point, not a goal

In the first article, we presented five recipes inspired by classics: Budapest, Rao/Perger, Sweet Berry, Jasmine Gesha, and Balanced. For completeness — and as a benchmark against which to compare new profiles — we leave them here, but only in the 300 ml version (i.e., the one you most often use at home for a single V60).

NOTE: these recipes assume the old, stronger calibration of concentrates. When switching to the new, weaker concentrations, you'll need to appropriately increase the number of drops — or, better yet, switch entirely to the new profiles below, which are redesigned for the current table.

These are bases. Starting points. Designed as neutral waters for general brewing. Good if you're just starting out or have one coffee you don't want to get into too deeply. But if you already know that your Saturday morning Kenya needs to be maximally juicy, and your Sunday Geisha maximally jasmine-like — bases are not enough. That's why we invented our own profiles.

Five proprietary Coffee Mates profiles

Each of the five profiles below is a targeted tool — water designed to extract a specific flavor from a specific coffee. These are not neutral "all-purpose" bases. These are tunings.

We provide proportions per unit (u) — meaning that "3u" means three drops from a given concentrate. In practice, for 300 ml of water, we usually assume a scale of: 1 unit = 1–2 drops, depending on how intense an effect you want to achieve. Start at the lower end of the scale, try the coffee, add more drops next time.

A small explanation for each profile, because proportions alone are just numbers. SWEET relies on citrates — Mg for juiciness, Na for a subtle sweetness in the finish — with the addition of classic calcium, which provides a little body. The result is water that turns a natural peach note into peach syrup. It works magically with coffees high in citric and malic acid, where you want sweetness to be louder than acidity.

JUICY goes in the opposite direction — this is water for coffees where acidity is the star and you don't want to suppress it. A strong dose of MgCl₂ gives fullness and sweetness, Epsom salt adds a sulfatic "snap" (a sharp, fresh kick), and calcium merely rounds it out. Kenya AA buffered with JUICY smells of blackcurrant and grapefruit, exactly as it should.

FLORAL is our gentlest water — low calcium content, plenty of potassium, mild buffering with citrate. This water does not take the jasmine out of a Geisha. It takes a step back and allows the floral notes to resonate.

CREAMY/CAKE is almost the opposite of FLORAL — calcium dominates, potassium adds sweetness, sodium citrate smooths the finish. For Milky Cake-style coffees, this water acts like adding full-fat milk to espresso — but without the espresso and without the milk. It simply unlocks the creamy side of the coffee.

BODY/CLASSIC is our espresso-water. Lots of calcium, lots of MgCl₂, a little sodium. Heavy, rounded, chocolatey. If you drink Brazilian natural as a shot or make a flat white with washed Colombian — this water enhances chocolate, nuts, and provides heavy body.

Practical notes

Droplet calibration. All ppm values in the tables assume that one drop from your dropper weighs approximately 0.056 g. This is a refined value for standard pharmacy pipettes with a black rubber bulb — but different droppers drip differently. For everyday use — the assumption of 0.056g is sufficiently accurate.

Purity of salts. Do not use industrial salts, pool salts, or "magnesium for cramps" from the pharmacy, as they contain additives.

Storage of concentrates. In sealed dropper bottles, in the refrigerator. If a concentrate looks strange or smells bad — discard it and make a new one. It's not worth risking an entire batch of coffee for five grams of salt.

Scale of effect. Let's be frank: the changes we're talking about are subtle. Better water won't turn a Brazilian coffee into a Geisha. It won't transform over-roasted coffee into light roast. It won't fix poorly brewed coffee. But take two identically brewed coffees and serve one with BODY/CLASSIC, the other with FLORAL. The difference will be such that a person at a cupping will recognize them almost as two different coffees. That is precisely the power we're aiming for.

Summary

Water for specialty coffee is now a full-fledged tool, just like the brewing method, grinder, or water temperature. In the first article, we presented the foundation: calcium, magnesium, sodium, potassium, chlorides versus sulfates, classic Barista Hustle recipes. Here, in the second part, we took a step further.

Citrates have given us a third axis of flavor control — a gentler buffer than bicarbonates, better preserving acidity in light coffees. The five proprietary profiles (SWEET, JUICY, FLORAL, CREAMY, BODY) are our daily tools, each designed for a specific coffee style, ready for you to try in your kitchen.

The most important caveat at the end, for completeness: the world of specialty coffee is changing rapidly, and so are we. What we have described here is the state of things now — our kitchen, our equipment, our coffees. Tomorrow, another variation or experiment might emerge, and then we will write Part Three.