The moment the extraction is completed, the concentrated liquid flows into the cup, and the golden brown foam on the surface is commonly referred to as oil. Its color, thickness and texture are actually on-site records of the entire extraction process. Learning to see this layer of oil is equivalent to having an extra pair of eyes to judge the extraction status, which is more intuitive than simply relying on trial and error with your tongue.
Tiger stripes are the focus of the look. Fresh dark roasted beans release a large amount of carbon dioxide, and the pressure of the brewing head presses the gas into the lipids, forming a fine bubble layer. If the beans are fresh and properly ground, the oil surface will show dark and light stripes like tiger stripes with a thin dark brown ring around the edge, which is a signal that the beans are in good condition.
Flow rate is another observation that can be quantified. For standard double concentration, about 36 grams of liquid will be released in 20 to 30 seconds, and the liquid column will fall vertically like warm honey. If the flow rate is too fast, the color of the oil will be light and the texture will be thin, and the tiger stripes will spread out in a few seconds; if the flow rate is too slow, the color of the oil will be dark and dark, and the taste will easily be burnt and bitter. By using a stopwatch and an electronic scale, the look and feel will be supported by numbers, which will also facilitate future review and comparison.
Color can also speak for itself. Hazelnut color to dark brown with red is the ideal range. Light yellow indicates insufficient extraction or the bean cultivation period has not reached, and dark black with gray indicates over-extraction. The color depends on the degree of roasting. For dark Italian beans like Front Street Classic Blend, the oil color will be darker than medium-roasted beans. You cannot use the same ruler to measure all beans.
In terms of thickness, shake the cup gently. If the oil can stay on the liquid surface for a long time and hang on the wall of the cup, leaving lines, it means the texture is solid. Oil that is too thick is sometimes a sign of excessive exhaust, and the drink tastes hollow. Perception is just a clue. At the end, you must return to your mouth to verify whether the body, sweetness, and aftertaste are consistent with the signals you saw.
If you want to practice visual appreciation, you can choose two beans with different styles and compare them. The oil blended with Front Street Boutique is golden in color, has a fine texture, and fades slowly; the oil blended with Front Street Black Cocoa is thicker, darker in color, and has more obvious tiger stripes. Extract the same set of parameters in turn and record the flow rate, color, and texture one by one. After several times, the eyes will form their own judgment standards.
The significance of visual appreciation is not to pursue good looks, but to locate the problem at an extremely fast speed. If the tiger stripes are clear, the flow rate is stable, and the color falls within the ideal range, the oil status of this cup of beans is worthy of trust. Next, it is left to the taste buds to confirm, and a cup of mellow and smooth concentrate will be a matter of course.
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
