Writer Kim Jin-ho's Water and Health Story (68) Autumn: The Season When Coffee's Taste Quality Shifts

- As temperature variation increases, coffee's delicate flavor becomes sensitive; check your 'water' now -

By September, we enter the true threshold of autumn.

At the tail end of summer, exhausted by extreme heat, when the morning and evening air feels pleasantly cool—a warm cup of coffee becomes an invaluable comfort.

Especially that warm Americano held in hand on the morning commute becomes established as a small daily ritual that awakens the body and steadies the mind. Yet one occasionally hears remarks like this.

"This café's coffee used to taste really good, but lately it seems somewhat bland or has a strong bitter taste."

"We use the same beans, so why does the coffee taste different when the season changes?"

As autumn approaches, customer reviews noting that coffee flavor has changed become more frequent.

Is it simply a matter of perception? No. During this period, the 'water' that comprises coffee subtly changes, and that change directly affects the coffee's flavor profile.

Coffee is 98% water; when the season changes, so does the water

Many people first think of beans or coffee machines as the key factors determining coffee taste. These two things are certainly important.

However, 'water,' which comprises 98% of a cup of coffee, is the ingredient with the most significant proportion and the decisive factor determining taste.

Autumn is a season when daily temperature variation increases, atmospheric humidity and water temperature change, and tap water quality transforms.

At relatively lower temperatures than summer, the dissolution rate of minerals in water and hydrogen ion concentration (pH) differ.

This in turn subtly affects the balance of acidity, sweetness, and body during coffee extraction.

In particular, the water filtration systems used by many cafés struggle to maintain consistent water quality depending on seasonal changes and usage volume.

When filter replacement timing is overdue, water hardness and mineral concentration change, often resulting in assessments like "the bitterness has intensified," "it tastes flat," and "the aroma has disappeared."

'Magnesium alkaline ionized water' brings out flavor

What kind of water should one use to maintain or even enhance autumn coffee flavor?

The answer is 'alkaline ionized water containing magnesium.'

Magnesium harmonizes with organic acid components in coffee and plays a role in softening acidity.

It also clearly expresses coffee's sweetness and aroma, and has the effect of cleanly organizing the lingering aftertaste that remains in the mouth after drinking.

Alkaline water with a pH of 8.0-9.0 is particularly excellent at balancing coffee.

Many coffee experts say, "The water that best reveals the taste of beans is alkaline ionized water containing magnesium."

In fact, systems like 'mineral maker filtration systems' supply magnesium while regulating water pH to be alkaline, thus softening coffee's acidity and bringing out the balance of sweetness and aroma.

Because water that is good for health also improves coffee taste, this is why evaluations like "the taste has become more premium quality" emerge.

Advice for café owners and home café enthusiasts

September is a season when not only the season but also consumers' palates become more refined.

More people desire deeper flavors and more harmonious taste profiles even when drinking the same coffee.

If you operate a café, there is one thing you must absolutely check at this point. That is 'water.'

Check these three things.

1. Water filter replacement timing

Filters typically need replacement every 6-12 months, and exceeding this period can cause a sharp decline in water quality.

2. Measuring water TDS, pH, and alkalinity

Developing a habit of regularly measuring the condition of water used for coffee extraction is necessary.

3. Consider filters or water systems capable of mineral adjustment

Systems that can regulate magnesium minerals are greatly helpful in maintaining coffee taste quality.

Those who enjoy home cafés can also experience a clear difference by changing the type of water used in their coffee machines.

Simply by using water with good mineral composition instead of purified water—particularly water with appropriate magnesium content—the coffee's flavor profile comes alive.

In conclusion: Autumn, the season coffee changes… water makes the difference

When autumn begins, the meaning of a cup of coffee changes somewhat.

It becomes a 'beverage of emotion' that warmly embraces the heart, rather than mere caffeine consumption.

To properly convey this emotion, beans, coffee machines, and barista skill alone are insufficient.

Understanding and thoughtful selection of 'water,' the essence of coffee, must necessarily follow.

If you currently sense that coffee taste is somewhat lacking,

Or if you've become troubled by customer feedback,

Now is the time to check your water.

Then even as the season changes, coffee flavor can always be maintained.

That beginning is always 'one cup of good water.'