Espresso Crema: Simple in Appearance Yet Worth Deep Investigation!

Some coffee enthusiasts have consulted FrontStreet Coffee about espresso extraction issues. Many of them have encountered situations where espresso extraction doesn't produce golden crema or the crema is thin. For espresso coffee, that golden coffee crema is its soul, so FrontStreet Coffee will analyze what reasons might cause the lack of crema during coffee extraction.

Normally extracted espresso should have black espresso liquid topped with a layer of golden coffee crema about 1/3 thick, with a cream-like effect when shaken and noticeable adherence to the cup walls.

However, if coffee extraction produces no crema, this indicates that something has gone wrong in some stage - it could be a problem with the coffee beans, the machine, or more likely, the parameters and operation.

What Factors Affect Crema?

a. Freshness of coffee beans

Because crema is formed by oils from coffee encapsulating carbon dioxide, we can also judge the freshness of coffee beans by the amount of crema - the more crema, the fresher the coffee beans.

b. Roast level of coffee beans

Similarly, under the same freshness conditions, more crema indicates a darker roast level of the coffee beans.

c. Extraction degree of coffee beans

The darker the crema, the more dissolved substances from coffee have entered the coffee liquid.

d. Coffee bean varieties

Different coffee species produce different characteristics, which also affects the amount of crema produced. Currently, it's known that Robusta coffee species produces more crema than Arabica coffee species. Therefore, when designing FrontStreet Coffee's classic espresso blend beans, the roaster added about 10% Robusta coffee beans to the original "Manba formula" to produce denser crema in espresso. This not only enhanced the coffee's body and caramelized aroma but also provided prerequisite conditions for latte art due to the golden crema.

e. Coffee machine pressure

The reason espresso machines can extract rich golden crema mainly relies on 9-bar pressure extraction. The greater the pressure, the richer the coffee crema will be.

Possible Reasons for Lack of Crema

FrontStreet Coffee has summarized some possible reasons for everyone's reference:

① Coffee beans are roasted too light

Coffee beans on the market are generally divided into those for pour-over drip coffee and those for espresso machines. The former mainly consists of single-origin beans with lighter roasts. The latter mainly consists of blend (formula) beans, as well as SOE (Single Origin Espresso) beans, which are generally roasted darker.

Generally, darker roasted coffee beans will produce richer crema. Using pour-over single-origin beans for espresso will result in thinner crema, so everyone should pay attention when purchasing.

② Coffee beans are no longer fresh

If the espresso extraction state is normal, then it's very likely that the coffee beans are no longer fresh. Espresso machine extraction is actually quite particular. overly fresh coffee beans will produce unstable crema when extracting espresso, with large bubbles that break down quickly; stale coffee beans will have no crema.

Generally, the degassing period for espresso beans is about 7-10 days, meaning only after the seventh day from the roasting date will the coffee beans' extraction state begin to stabilize. The best-before period for espresso beans is about 60 days. After two months, espresso beans basically have no aroma or flavor, and the amount of crema will be greatly reduced. (This only applies under normal storage conditions; FrontStreet Coffee has not tested nitrogen preservation.)

③ The coffee machine's pressure is insufficient

This problem is more common in home coffee machines. Typically, we can extract rich crema because the coffee machine's 9-bar pressure extracts the essence from the coffee puck. However, some small espresso machines don't have stable 9-bar extraction pressure, thus cannot produce rich crema.

④ Coffee grind is too coarse

In this situation, crema will also not be rich. This situation is very easy to confirm - the extraction process shows very fast coffee liquid flow rate, accompanied by channeling that causes spray jets, and the coffee crema will appear light in color and thin. The espresso taste will also be rather weak. Everyone can use 20 seconds as a judgment standard - if you extract twice the amount of coffee liquid as the coffee grounds within 20 seconds, it's very likely that the coffee grind is too coarse.

The extraction process is a mess

⑤ Water temperature is too low

Many modern coffee machines now have manual water temperature adjustment functions. The general water temperature for extracting espresso is around 93°C. Too low a temperature might also result in no crema appearing.

Another situation more common with home coffee machines is that it may take 10 minutes or longer from startup to complete heating. Extracting espresso before heating is complete is likely due to water temperature not being reached, resulting in no coffee crema, and the coffee taste will also tend toward sharp acidity.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473