As a coffee professional, I often see customers torn between their love for a morning brew and the discomfort it causes. In the Australian specialty coffee scene, we often prize high acidity that "sparkle" or fruitiness in a cup. However, for the sensitive stomach, that same quality can be a recipe for disaster.

The Science: What is Actually Happening?

To solve the problem, we must identify the trigger. When we talk about "acid" in coffee, we are usually talking about Chlorogenic Acids (CGAs).

While CGAs provide antioxidants, they degrade into harsh compounds that irritate the stomach lining. Furthermore, high caffeine levels stimulate gastric acid secretion. To fix this, we need to manipulate three variables: Origin, Roast, and Brew.

1. The Bean Origin: Altitude Matters

In the coffee world, altitude is everything.

• High Altitude (1,500m+): Beans grown high up (like in Kenya or Ethiopia) ripen slowly. This creates complex, acidic, fruit-forward flavours. Avoid these.

• Low Altitude (Below 1,200m): Beans grown lower down ripen faster. They naturally develop lower acidity and milder, nuttier profiles.

The Expert’s Selection

If you are buying single-origin beans from your local roaster, look for these specific regions: 

The Roast Profile: Darker is Smoother

This is the most critical rule for sensitive stomachs: The darker the roast, the lower the acid.

During the roasting process, heat breaks down Chlorogenic Acids. A light roast retains most of these acids (which is why they taste "bright" or "lemony"). A dark roast burns them off.

• The Sweet Spot: Look for a roast developed past the "second crack."

• Visual Cue: The beans should be dark brown and might have a slight sheen of oil on the surface.

Pro Tip: In Australia, many specialty cafes serve "Light" or "Filter" roasts for their black coffee. Always ask the barista for their "Espresso Blend" or a darker roast, even if you are drinking it black.

3. Extraction: The Cold Brew Method

If you want to eliminate up to 67% of the acid chemically, you must switch to Cold Brew.

Hot water extracts oils and acids rapidly. Cold water extracts flavour compounds slowly but leaves the harsh acids behind.

The Expert’s Recipe for Australian Cold Brew:

1. The Grind: Ask your roaster for a "Course Grind" (texture of rock salt).

2. The Ratio: 1 part coffee to 8 parts water (by weight).

3. The Method: Steep in ambient temperature water (filtered is best) for 12 to 18 hours.

4. The Finish: Filter twice. Once through a sieve, once through paper.

Decoding the Label: What to Buy

Marketing jargon can be confusing. When browsing shelves in an Australian supermarket or roastery, use this decoder to ensure you pick a stomach-friendly bag.

Top Recommendations 

Based on bean composition and roast profiles, these are solid choices readily available in Australia:

• Vittoria Mountain Grown: Despite the name, this is a darker roast style typical of traditional Italian-Australian coffee. It is heavy on body and low on sharp acids.

• Campos Superior: This is the quintessential Aussie cafe blend. It uses South American beans as a base, providing a balanced, chocolatey cup that is rarely sharp.

• Jasper Coffee (Fairtrade): Look for their "Midnight" or Indian blends. They are excellent at sourcing low-acid, shade-grown coffees.

If you have dialed in your beans and roast but still struggle, look at your milk. A Piccolo Latte or Macchiato is often better than a Long Black because the proteins in the milk bind to the remaining acids, neutralising them before they hit your stomach.

Relatable article for more knowledge: IS COFFEE ACIDIC?