Many people judge an espresso by its crema. It is not a rigorous method, but experience tells us that crema really does reveal a thing or two. At Front Street, we think a good crema is golden, moderately thick, fine-textured and even in colour; shake the cup and it moves like cream, clinging visibly to the wall of the glass; if it is too thin or too sparse, the beans may not be fresh enough, or the roast may be too light; if it is pale or almost white, the shot is probably under-extracted, and in that case you should look at the machine's pressure, the water temperature and the grind size.
Yet some friends apply this trick to pour-over coffee and ask us: “Why can't this bag of coffee produce any crema? Has it gone stale?” Before answering that, let's talk about what coffee crema really is.
First, what exactly is the “crema” in espresso?
What we call “crema” is the golden foam on top of a freshly pulled espresso, though its proper name is crema. Its appearance is inseparable from the 9 bar of pressure: under high temperature and pressure, water extracts the soluble substances in the coffee grounds and emulsifies the fats and oils naturally present in the coffee, which then carry carbon dioxide out together with the coffee liquid. Because oils and gas are lighter than water, the extracted coffee gradually separates into layers, so the crema floats on the surface and looks very tempting.
Crema doesn't just make an espresso look good. It adds body and aroma to the cup, protects the flavours of the coffee, and when you make hot milk drinks it helps the milk and coffee blend and supports latte art. Perhaps that is why people go to such lengths in pursuit of an espresso with perfect crema.
Getting a generous crema is actually easy. When buying beans, choose ones rich in oils with plenty of carbon dioxide, ideally medium-dark roasted and fresh, within their best-tasting window (7 to 50 days). Front Street's Classic Blend, for example, is an espresso recipe made for people who want a beautiful crema and a full body: it pulls a generous crema easily and delivers thick notes of caramel, dark chocolate and buttered hazelnut.
Once you have the right beans, you also need freshly ground coffee, a stable high temperature, more than 9 bar of pressure and sensible extraction parameters. Only when all these key factors come together will you get an espresso rich in dense crema. In short: the fresher the beans, the darker the roast, and the greater and more stable the machine's pressure, the better the crema will be.
Which other coffees show oils?
We now know that crema comes from the fats in coffee beans; the espresso machine simply magnifies it enough for us to recognise easily. Besides pressurised extraction, ordinary infusion methods also produce oils; they are just less abundant and finer than in espresso, and you have to look carefully to see them.
One feature of French press coffee is that it keeps most of the oils, which raises the body. The brew looks slightly cloudy, with a faint sheen floating on the surface. The French press extracts much like cupping: the grounds are steeped, then the plunger is pressed down to filter them out; because the metal mesh has wide openings, it preserves the oils to the greatest extent possible.
Apart from the French press, the traditional siphon also gives coffee a thin layer of oils, thanks to its cloth filter. Lipids and very fine particles pass through the cloth into the cup, bringing a richer aroma and a solid mouthfeel, and making the coffee smoother and fuller.
In sensory terms, coffee oils do two good things: they make the body fuller and richer, and they extend the length of the finish.
Why can't you see oils in pour-over coffee?
Compared with the coffees above, pour-over coffee has virtually no oils. Served in a clear server, it looks perfectly clear, with nothing suspended in it at all.
Pour-over coffee appears to have no oils partly because the grounds are never extracted under high pressure, so fatty compounds are hard to squeeze out, but the main reason is the paper filter.
Paper blocks the vast majority of suspended solids; fines and oils find it very hard to get through, so coffee filtered through paper is clean and bright. This doesn't mean pour-over coffee has no oils at all: brewing through paper filters them out, and paper is precisely what pour-over brewing uses most widely.
That said, keeping the oils in pour-over coffee is not impossible. Besides paper, there are two other filter materials on the market: metal filters and cloth filters. A metal filter is shaped like paper but uses countless tiny holes to hold back the grounds while letting the liquid through; the best-known cloth filter is the flannel one. Both retain some of the coffee's oils and can be reused. They work even better with a medium-dark bean such as Front Street's PWN Golden Mandheling or Front Street Colombia Huila.
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You can now buy the above coffee beans online at the Taobao store “FrontStreet Coffee” (前街咖啡). FrontStreet Coffee is a long-established specialty coffee roaster in Guangzhou, China, and its Guangzhou retail shop sells coffee beans only. The shop carries dozens of coffee beans from different origins around the world, including carefully selected single-origin beans for V60 pour-over and espresso. Guangzhou’s FrontStreet Coffee shop is recommended by many coffee lovers.
The FrontStreet 2013 Yunnan coffee beans sold in the store come from the Typica variety grown at FrontStreet Coffee’s own plantation in Yunnan. The name comes from the year the brand and the plantation were founded. You can buy these beans from China’s Yunnan origin at the Guangzhou shop and at FrontStreet’s Taobao store.
FrontStreet coffee beans are freshly roasted within 5 days and deliver consistently excellent quality and great value. Orders placed before 17:00 are shipped the same day, and most areas within Guangdong Province receive them the next day.
FrontStreet Coffee Taobao store: https://qianjiecoffee.taobao.com
Or search for “前街咖啡” (FrontStreet Coffee) on Taobao
Important Notice: FrontStreet Coffee has moved to a new address: 315, Donghua East Road, Guangzhou (coffee beans only)
Tel: 020 38364473
