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Front Street noticed that many friends fell in love with the golden espresso coffee and wanted to make it at home. Compared with hand brewing, espresso is made by using steam pressure to pass boiling hot water through coffee powder to brew a small amount of coffee liquid with a rich texture and strong flavor. Although the operation seems very simple, changes in the details of the parameters will affect the quality of the coffee produced, so every link needs to be strictly controlled and every parameter needs to be considered.
Before the advent of espresso, coffee was brewed by immersion, which not only required fine grinding of coffee beans, but also slow extraction and a long wait. In order to speed up the brewing process, the Italians thought of using steam pressure to pass high-temperature and high-pressure water through the coffee powder to speed up the extraction rate of the original drip filter. With continuous improvements and updates, our common semi-automatic/fully-automatic espresso machines have been derived.
Common commercial espresso machines can provide more than nine stable atmospheric pressures and hot water above 90 degrees Celsius. The high pressure forces the hot water to quickly pass through the finely ground coffee powder, extracting coffee liquid with rich oil, rich aroma and thick taste. In order to extract an ideal cup of espresso, the barista's job is to master the various parameters that affect the flavor of the coffee and then adjust the optimal extraction range.
There are many factors that affect the flavor of a coffee bean to a cup of coffee liquid, including grinding degree, coffee machine boiler pressure, water temperature, powder filling pressure, powder amount, extraction time, extraction liquid weight and other factors and details. Normally, the pressure and water temperature of the coffee machine are set and cannot be changed easily. The powder distribution and filling pressure will be controlled according to the barista's habits. The four major factors used to adjust extraction in daily life are powder volume, time, liquid weight, and grinding degree.
The thickness and uniformity of the grind are the most important factors affecting the change in flow rate from cup to cup of espresso. With just a 1 gram difference in powder volume, the drain time required to extract the same amount of espresso liquid will differ by several seconds. When the size of the coffee powder particles is uneven, the resistance to water passing through the high-density areas after packing will be greater, and the extraction distribution will become inconsistent. The grinding method will directly affect the flow rate, time and flavor of the coffee liquid.
The ratio of the amount of powder to the weight of the extraction liquid is what we often call the powder-to-liquid ratio, which is a relatively intuitive extraction parameter. The amount of powder depends on the capacity of the powder bowl model in the handle, which is divided into double portion and single portion. For example, the Front Street store coffee machine uses a double portion of 20 grams of coffee powder. Adjust it up or down based on this parameter (accurate to 0.1 grams). Since the ratio of powder to liquid is not fixed, the amount of coffee liquid output depends on the expression of coffee flavor.
In the past, baristas did not have accurate weights and would directly observe the color change of the oil to determine the amount of liquid. When the liquid first came out, it was dark brown and relatively rich. Over time, the color slowly turned to golden yellow, and then to light yellow. Generally, when the oil turns white, it means that the extraction needs to be completed. The current espresso extraction standards are more stringent, more stable data are summarized, and the powder-to-liquid ratio also tends to a fixed reference value of 1:2. For example, the Front Street store uses 20 grams of coffee powder and the extract weighs 40 grams.
The extraction time will be affected by the above key factors. Generally, the extraction time of espresso coffee is between 25 and 30 seconds. When determining the powder-to-liquid ratio, the shorter the extraction time, the less coffee substances will be dissolved, and the longer the extraction time, the more coffee substances will be dissolved. For the same powder-to-liquid ratio, if you want to change the extraction time, you can only adjust the grinding degree and amount of coffee.
Once we have mastered the correlation between various influencing factors, we can debug it based on the state of the coffee liquid and the feeling after tasting. The expression of coffee flavor depends on the espresso beans we use. The one we use here is the home-roasted "Front Street Sunflower Warm Blend", which is a combination of sun-dried Yirgacheffe red cherry coffee beans and Honduran sherry coffee beans. Ideally, espresso will have whiskey aromas, vanilla, cream, and berry acidity.
For those who like mellow coffee, we recommend the Front Street Classic Italian Blend Coffee. This is a formula made from a combination of Brazil, Indonesia and Vietnam. It uses deep roasting to maximize the mellow aroma of the coffee. The extracted concentrate is not only rich and dense with golden oil, but also has the aroma of dark chocolate, caramel, butter and roasted almonds. It is very rich in layers and can be purchased at the Front Street Taobao store or Front Street Tmall flagship store.
For example, the extraction parameters for the first cup of espresso on Front Street are: 19.8 grams of coffee powder, 40 grams of coffee liquid, 26 seconds, and the flow rate is too fast. When tasting the coffee, the taste is light, the wine aroma and fruity aroma are not obvious, and the astringency remains in the finish, which may be due to insufficient extraction or too much extraction in the later stage. The front street will increase the amount of powder and reduce the liquid weight to make the coffee flavor more concentrated. When the coffee has no astringency and the wine aroma becomes stronger, it means the adjustment direction is correct.
If the flow rate is still too fast and the aroma is not enough, it may be that the extraction is insufficient, and you need to adjust the grinding degree and extend the extraction time. If the flow rate is slow and the taste is bitter or sharp, it is probably over-extraction and the extraction rate needs to be reduced. You can reduce the amount of powder and coarsen the grinding to achieve more liquid weight in the same extraction time.
Front Street believes that as long as we straighten out the relationship between extraction parameters, it is not difficult to make a delicious cup of espresso. But we need to be clear that the functions of most home espresso machines are not as stable as commercial machines, and the cup output is also very small, which also tests our grasp of the parameters. Front Street suggests that we can record the parameters and flavor performance of daily extraction to achieve delicious results. Comparing and summarizing more will help improve the efficiency of our adjustments.
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
