Extraction depth analysis: How to improve coffee Flavor with different grinding degrees of coffee powder

2022-05-21 0 By

Coarse-ground coffee does not taste better the higher the brewing temperature, the faster the rotation frequency and the greater the water flow.I remember going to a friend’s shop to play when I first started learning coffee.Seeing new coffee beans in a friend’s shop, I was ready to brew them.Coffee beans are medium roasted and used medium ground.Soon after the coffee is made, there is only one word: light!By raising the water temperature to 96℃ and using large water flow and speeding up the circle frequency, the coffee is not weak but has a lot of mixed taste.I adjusted other brewing parameters repeatedly for several times, but I never got a satisfactory coffee.Later, on the advice of a friend, I just reduced the proportion and drank the coffee I was satisfied with.This is the “golden rule” for brewing coffee. It is essential to master the knowledge of hand brewing coffee.The grinding degree of coffee particles directly affects the length of extraction time, extraction rate and concentration.Law 1: The finer the coffee bean is ground, the denser the powder layer will be, the larger the overall surface area of the coffee powder will be, the longer the extraction time, the higher the extraction rate, and the stronger the taste of the extracted coffee will be.It is also easy to cause excessive extraction.Second law: the more coarse grinding coffee beans, the clearance between the powder layer is larger, the coffee and hot water contact surface area is less, less extraction resistance, shorten extraction time, extraction rate is reduced, coffee particles to release soluble substances, easy to cause the insufficiency of extraction, and to extract the coffee taste is thin and weak.Combined with the case at the beginning, coarse ground coffee powder improves water temperature, proportion and water flow. Why is the flavor of coffee not good?This is because the coarse-ground coffee is easier to extract unevenly!In his book “The Science of Coffee Brewing”, Scott Rao, the godfather of coffee, describes the “particle size distribution of coffee powder” : Due to the irregular structure of coffee beans and uneven distribution of forces on the whole structure during the grinding process, coffee particles are not ground to the same size or shape.In the general coffee particle size distribution, the vast majority of coffee particle size will be concentrated in the grinder “set scale” within a small range, that is, the ideal degree of grinding.In addition, there are a small number of large particles, accounting for a small amount of total weight, known as “coarse powder”;And a large but very small number of fine particles called “fine powder”.The most suitable coffee extraction rate is 18%-22%.In other words, not all coffee powder can be completely involved in extraction, and the part involved in extraction can be called “effective extraction mass”.1. The finer the coffee ground, the more effective the extract.When the particles are relatively fine (small), the difference between the surface and the center part of the extraction will be reduced, and the surface of coffee particles is not easy to over-extraction;As a result, the more finely ground coffee is, the higher the extraction efficiency is required to match it, which means changing other brewing factors, such as higher water temperature, ratio and flow.In a cup of finely ground coffee, there is a bitter and astringent feeling caused by excessive extraction.– If the coffee is bitter but not bitter, but has a good flavor, it is probably caused by a high concentration of coffee, which can be solved by adding water.– If there is a very clear sense of astringency, mixed taste, is basically caused by uneven extraction.In many cases, uneven extraction of coffee powder will appear on the side of the cup. Try shaking the filter at the back to solve the problem.2. The coarser the coffee ground, the less effective the extract is.When the particles are relatively thick (large), the extraction difference between the surface of the particles and the central part will increase, and the surface of coffee particles is easy to be over-extracted.Therefore, the coarser the coffee ground, the lower the extraction efficiency, such as lower water temperature, ratio and flow.In a cup of coarse-ground coffee, just as in the beginning of the article, when the water temperature and the proportion are increased, the flavor is still very light and bad, in fact, the root is: too little effective extraction quality and excessive surface extraction.If you don’t change the degree of grinding, you can try to reduce the ratio.Coffee particles are fine, brewing hot water contact with the particles, in a short time can reach the deepest part of the extraction, extraction uniformity is higher.The over-extracted surface, fully extracted part and partially extracted part are more consistent and uniform, and the part that cannot be extracted is very few, which is easier to form a concentrated flavor style.The coffee is coarse, the hot water takes longer to reach the deepest part of the extraction, and in some cases the center part may also be difficult to participate in the extraction.It is easier to create layers of coffee by extracting a large portion of overextracted surface, a small portion of fully extracted surface, a small portion of partially extracted surface, and an unextractable center.It is not without reason that European and American coffee circles advocate the brewing method of “fine grinding, high water temperature and large water flow”.When I first started, I always thought how could this kind of cooking, especially the fine grinding, not overextract?But when tested, it tasted good!Coarsely ground coffee, in order to improve the extraction uniformity principle, can try to reduce the proportion or water temperature, may open up a new world!Very complex, not a hundred and eighty times to go back and forth of exercise, may not find feel, such as me, now also shake, water column intermittently, uneven thickness, very difficult!So you need my espresso, 10g/ slice, medium dark roast, medium ground, ripped off and hung on a cup with water at 85-92 degrees.No matter how bad it is, it won’t be too bad!