What Is Golden Cup Coffee Extraction and Where Did It Come From?

Golden Cup extraction refers to the range most people find acceptable: an extraction yield of 18% to 22% and a concentration of 1.15% to 1.35%. It comes from a 20th-century United States preference survey run by the Brewing Committee, set up in 1952 by the American Coffee Association with Dr. Lockhart of MIT.

The committee reported in 1957 that roughly 30% of a coffee bean is soluble material and 70% is insoluble fiber, so only part of the solubles should be extracted. Because the range came from taste testing rather than a fixed rule, it works as a reference point rather than an absolute standard.

The Golden Cup extraction is a widely circulated concept in the coffee world, defining an extraction range that most people find acceptable. This concept originated from a large-scale preference survey in the United States in the 20th century, driven by the Brewing Committee established by the American Coffee Association in collaboration with Dr. Lockhart of MIT. The survey found that about 30% of coffee beans are soluble substances, while the remaining 70% are insoluble fibers. After two rounds of testing with ordinary people and coffee experts, the Golden Cup range was determined as an extraction yield of 18%–22% and a concentration of 1.15%–1.35%. This article will sort out the origins and development of the Golden Cup standard, the calculation methods for extraction yield and concentration, and explain why the Golden Cup range can only serve as a reference rather than an absolute standard, helping you view coffee extraction more rationally.

What exactly is Golden Cup extraction?

Front Street Coffee has mentioned many times that Golden Cup extraction is essentially a concept, aiming to express that there is an extraction range most favored by the general public, and as long as the brewing result falls within this range, the flavor of the coffee is acceptable or even preferred by most people. The birth of this concept can be traced back to a survey conducted in the United States in the 20th century.

In 1952, the American Coffee Association and Dr. Lockhart (a chemistry professor at MIT) jointly established the Brewing Committee, with the goal of promoting in-depth research and knowledge dissemination in the coffee industry. The conclusion that 'a coffee bean contains 30% soluble substances,' which Front Street Coffee frequently mentions, was released by this committee in 1957.

Dr. Lockhart's team conducted a detailed analysis of the internal structure of coffee beans and found that about 30% of the components in coffee beans are soluble substances, while the remaining 70% are insoluble fibrous materials.

Soluble substances are the parts that can be extracted by water; insoluble fibrous materials, in simple terms, are 'coffee grounds' that cannot be dissolved or extracted and can only be discarded or used for other purposes (such as fertilizer or deodorizer).

However, the team soon realized that not all 30% of the soluble substances should be extracted. Different degrees of extraction lead to changes in the taste of coffee. So they designed a special preference survey, having randomly selected American passersby taste coffees with varying degrees of extraction and then choose their favorite cup.

After the survey, the team immediately summarized and analyzed the data, and the results showed that the most preferred coffee had an extraction yield between 17.5% and 21.2%, and a concentration between 1.04% and 1.39%. These parameters, most welcomed by American passersby, formed the initial version of the 'Golden Cup standard.'

Front Street Coffee will briefly explain extraction yield and concentration here: extraction yield refers to how much of the soluble substances in coffee beans have been extracted; concentration refers to the amount of coffee substances in the liquid.

But this range was still too broad, so the committee later restarted the experiment. This time, they changed the survey subjects to coffee professionals, and after more rigorous tasting and analysis, the Golden Cup range was revised to: extraction yield increased to 18%–22%; concentration narrowed to 1.15%–1.35%. This set of data is the final version.

The Golden Cup extraction chart below shows how a cup of coffee presents flavor trends under different combinations of concentration and extraction yield.

In the chart, the horizontal axis represents extraction yield, the vertical axis represents concentration, and the diagonal lines indicate the coffee-to-water ratio.

Calculating the extraction yield is actually not complicated; you can calculate the extraction yield of a cup of coffee using the formula below. (Note that the measurement of concentration must be done with a concentration meter.)

The extraction yield formula is: coffee liquid weight (ml) ✖️ coffee concentration (TDS) ➗ coffee powder weight (g)

From the chart, you can see color blocks of different shades distributed within. The darkest block in the center of the chart is the Golden Cup extraction range. Exceeding this area is classified as over-extraction, showing varying degrees of bitterness depending on the concentration; falling below this area is classified as under-extraction, also with varying degrees of sourness depending on the concentration.

Therefore, many friends strive to control their coffee within this Golden Cup range. Whether it's extraction yield or concentration, if it deviates from the Golden Cup range, they feel the coffee is not good enough.

However, Front Street Coffee wants to emphasize that Golden Cup extraction is, after all, just a concept—a standard set by a group of people's taste preferences. You should know that each country has its own dietary habits, and we cannot guarantee that everyone agrees with the same standard.

So, Golden Cup extraction can only serve as a reference tool; with it, we can better understand the principles of coffee extraction, but we should not rigidly apply this theory to every cup of coffee. Coffee falling within the Golden Cup range is not necessarily delicious, and coffee outside the Golden Cup range is not necessarily bad. As long as you are satisfied with the coffee you brew, it is your 'Golden Cup coffee.'

Even if it is not within the Golden Cup range!

The above content is compiled by CoffeeHunters, a coffee news website.