How to Judge a Good Espresso Shot

You paid good money for your espresso—so why does it taste like burnt rubber or dishwater? Maybe it’s not you. Maybe it’s just bad espresso. But how can you tell the difference between a properly brewed shot and one that’s over-extracted, under-extracted, or just plain wrong?

A good espresso follows clear technical standards: 7g of freshly ground coffee, extracted at around 91°C and 9Bar pressure for roughly 25 seconds, yielding about 30ml of liquid topped with a layer of reddish-brown crema. That’s the baseline. But getting there isn’t easy—and most coffee drinkers have no idea what to look for.

Why Most Espresso Tastes Bad

Many coffee drinkers assume espresso is naturally bitter, thick, or unpleasant. In reality, those off-flavors usually come from poor technique, stale beans, or incorrect equipment settings. If your espresso lacks sweetness, has no crema, or tastes overly sour or burnt, it’s probably been brewed wrong—or with subpar ingredients.

The Science Behind a Proper Espresso Shot

Dr. A. Illy, in his book Espresso Coffee: The Chemistry of Quality (1995), defined a high-quality espresso as follows: 7g of freshly ground coffee, extracted with water at approximately 91°C under 9Bar of pressure for about 25 seconds, producing around 30ml of coffee topped with a reddish-brown crema. These parameters aren’t arbitrary—they reflect the balance needed to achieve ideal extraction yield, flavor clarity, and mouthfeel. Yet despite their apparent simplicity, achieving them consistently requires precision, fresh coffee, and skilled technique.

Key Requirements for a Great Espresso

• Fresh Coffee Beans: Freshness is critical. Even high-quality beans lose aroma and flavour quickly after roasting. For espresso, beans older than seven days post-roast often produce thin, flat shots with poor crema. Store beans in airtight, light-proof containers at cool temperatures and grind right before brewing.
• Properly Ground Coffee: Espresso requires a very fine, consistent grind. Once ground, coffee loses volatile compounds within about an hour. If your barista doesn’t grind beans when you order, your espresso will likely be stale.
• Correct Dosing, Distribution, and Tamping: Use around 7g of coffee per shot. Tamping must be firm, even, and consistent—typically with a force of 30–50 pounds—to ensure uniform water flow. Many shops tamp unevenly or inconsistently, leading to channeling and bitter or sour shots. Dual-shot extraction (pulling two shots at once) often yields better balance and quality than single shots.

What Should Good Espresso Look and Taste Like?

A properly brewed espresso should be around 30ml (1 fluid ounce), extracted in roughly 25 seconds. The crema should be thick, stable, and reddish-brown—indicating proper emulsification of coffee oils and CO₂. The flavours should balance sweetness, acidity, and bitterness, with no single note overpowering. Common flaws include sourness (under-extraction), harsh bitterness (over-extraction), or thin body with no crema (old beans, poor grind, or bad tamping).

Frequently Asked Questions

What is the ideal espresso shot size?

A standard espresso shot is around 30ml (1 fluid ounce), extracted using about 7g of coffee. This volume ensures enough contact time and concentration for proper flavour development.

How long should espresso extraction take?

Extraction should take roughly 25 seconds. Too short (under 20 seconds) often results in sour, under-extracted shots; too long (over 30 seconds) leads to bitter, over-extracted coffee.

What temperature and pressure are best for espresso?

Ideally, espresso is brewed with water at around 91°C and extracted under 9Bar of pressure. These parameters help extract the right balance of flavours without scorching the grounds or causing excessive channeling.

Why is crema important in espresso?

Crema—the reddish-brown foam on top—is a sign of proper extraction. It indicates good emulsification of oils and CO₂, and contributes to texture and aroma. A thin or missing crema often signals stale coffee, incorrect grind, or poor tamping.

Does the type of coffee bean affect espresso quality?

Yes. Espresso relies heavily on roast level, freshness, and bean origin. Freshly roasted, properly stored beans give better crema and more balanced flavour. Stale or poorly stored beans result in flat, bitter, or sour shots.

Can a bad espresso be fixed by adjusting the machine?

Not always. Machine settings matter, but poor-quality or stale beans, bad grind size, and inconsistent tamping are more common culprits. Fixing those fundamentals often improves espresso more than tweaking temperature or pressure alone.

Recommended FrontStreet Blends for Espresso

For reliable espresso performance, try FrontStreet Coffee’s Classic Blend—a well-balanced mix built for milk drinks and straight shots, known for its rich crema and smooth body. If you're after bold flavour without premium pricing, the Black Cocoa Blend offers full-bodied taste and strong crema at a great value, ideal for high-volume cafes. For a more traditional option, the Commercial Blend delivers solid everyday performance with cost-effective results. All three are optimized for espresso extraction. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.