Espresso – it is intriguing isn’t it? Espresso is essentially a brewing method and the name of a beverage. It is also used as a term of describing a roast colour – eg. Espresso Roast.
For an optimal extraction of espresso, the coffee beans must be finely ground. This allows a wider surface area of coffee bed for water to extract from and to work on. The final result of extraction is a moderately intense, rich, treacly beverage with a foam called crema.
What is crema? It is a light layer of foam found on the surface of a shot of espresso. Crema is formed when coffee bean oils and water emulsify.
When hot water strikes the coffee grounds with the high pressure of an espresso machine, the water emulsifies the oils in the coffee and then gets supersaturated with CO2, resulting in lots of tiny bubbles that make up the foamy layer.
Crema in espresso could be traced back to 1948, when Achilles Gaggia invented his lever-driven machine which procured the chain of modern espresso machines. These espresso machines not only come with high pressure capable of extracting essence of coffee, but also has the ability to create crema on top of a shot of espresso. This viscous layer was spurred by Gaggia, who believed that it is a precursor indicator of a high-quality espresso.
Hence, the craving for and the raving about crema existence not only originate from Gaggia’s stamped belief, but also the fact that crema does in its own way, reveals clues about the qualities of various parameters which go into a cup of espresso – such as coffee beans, age of roast, the duration of a shot etcetera.
In addition, crema can be either optimal or mediocre. An optimal crema should:
- have a right balance of colour – not too dark or too light.
- have a smooth, velvety texture.
- have a pronounced, clear layer.
- not consist of any big bubbles.
- make up 1/10 of the espresso.
To make it simple, the 3 main things to observe in a crema are as follows:
- Colour of Crema
If the resulting crema is extremely light coloured, this may be an indicator that the espresso is under-extracted. The crema may be displayed as a thinner layer which does not last long.
Under-extraction may be a consequence of a number of factors such as grinding (too coarse), insufficient tamping, short brewing time etc which leads to the lack of complexity in flavour extracted from coffee grounds.
On the other hand, a darker crema is a result of over-extraction. The components that produce over-extraction are the exact opposites of under-extraction.
- Amount of Crema
Freshly roasted beans contain oils and gases, of which contribute greatly to the desired foam layer on top of the espresso. Thus freshly or recently roasted beans used will result in an espresso with well-defined, clean crema.
Generally, darker roasted beans will produce less crema in espresso due to the fact that dark roast beans will go through second crack during roasting. At this stage, and from then, oils will begin to escape from the beans. The vital oils will further be eliminated during packaging and grinding.
As for light roasted beans, crema may be achieved, but this may be very pale, bubbly and disappear quickly. Hence it is not considered an ideal crema.
- Staying Power of Crema
This defines how long the crema will last, and one of the deciding elements of this is how freshly roasted the coffee beans are. The basic rule of thumb is to start using (grind and brew) the beans after the 4th to 5th day after roasting. Do finish the beans within a month’s time as after which, the beans will become void of freshenss.
A superlative crema will usually last about 1.5 to 2 minutes or so after extraction.
Many connoisseurs or coffee lovers have differing opinions on whether an espresso should be coupled with this rich, delectable looking foam (which many likens it to “Guinness Stout Effect”) in order to make a quality cup. Most of them would still be inclined towards seeing the existence of crema – to many, this means a high-calibre demitasse and is what makes an espresso complete.
All in all, crema does enhance the body of and leave a pleasant, lingering flavour to an espresso, but it is not the only deciding parameter of a good espresso.
Whether or not you achieve the “perfect, superlative” crema, it is of no great consequence. Just enjoy the process of exploring and experimenting. Do not let the pursuit of that ideal crema to engulf the other measurables of obtaining that great espresso, OR the failure of obtaining it to dampen the enthusiasm and spirit of having that relaxing cup. If you enjoy your own cup of creation and its resulting taste, that’s all that really matters. And with BrewRatio’s range of espresso machines, we strongly believe that you will be able to achieve the real cream of the crop – the crema that you desire in no time.