Coffee brewing technology Personal understanding of coffee extraction

1.slayer pre-immersion system and three-stage extraction theoretical system

two。 The latest concept of grinding and extraction

1. Theoretical system of slayer pre-immersion system + three-stage extraction

1. Double-end boiler system with 1 / 2 / 2 / 1

That is, 1 large boiler installed steam + hot water + 2 small boiler installed brewing head to extract the water used for coffee, independent PID temperature control, 9mm water pipe outlet to ensure uniform water output + 1 pre-soaked boiler temperature control boiler through 1-6mm outlet pipe to accurately control the water output and water temperature of pre-immersion.

2. Theoretical system of three-stage extraction

They believe that in the process of coffee extraction, with the Mena reaction and caramelization reaction of coffee during roasting, the aroma of coffee can be summarized into three chemical polymers in terms of aroma:

That is, small molecular polymers, in terms of aroma, refer to the lighter aroma, that is, the uppermost aroma on the flavor wheel is the "fermentation product"-from top to bottom: flower type, fruit type, vanilla type.

Middle molecular polymer: in terms of aroma, it refers to the similar sweet aroma, that is, the "sugar browning reaction products" in the middle of the flavor wheel aroma-nuts, caramels and chocolates from top to bottom.

Macromolecular polymers,: in aroma refers to the thick and heavy aroma, that is, the flavor wheel aroma part depends on the lowest "coking process products"-from top to bottom: resins, spices, charcoal.

I believe we have all done such an experiment, we divided the extraction of espresso into three stages to extract, the first stage is often very strong, very sour taste. The second taste obviously lightens, a little sweetness appears, the third concentration continues to decrease, and accompanied by some bitter taste, because the concentration is too low, there is no other flavor at all. So in terms of taste, we can be divided into:

1. Substances that are very easy to dissolve. Through experiments, we know that the first paragraph is very, very sour. In the flavor wheel, it is also divided into heavy sour taste and wine-like sour taste by the top "sour taste".

2. For the substances that are easy to dissolve, there will be a significant decrease in the concentration of the substances that are easy to dissolve in the second stage of the experiment, which means that the substances in the coffee that are most easily dissolved have been dissolved. Next, the substances that are relatively less soluble, that is, the "sweetness" on the flavor wheel is divided into high-quality sweetness and smooth sweetness.

3. For the substances that are not easily dissolved, coffee continues to be extracted backwards. After the first two substances that are easily soluble in water are extracted, the substances that are not easily soluble begin to be extracted. The taste of this part of the substance is in the middle of the flavor wheel, that is, "salty taste" is roughly divided into refreshing taste and sharp stimulation.

4. the substances that are more difficult to dissolve, as we continue to extract, most of the soluble substances in coffee have been extracted, and the rest of the substances that are more difficult to dissolve will continue to support the extraction. at this stage, we can see that the flow rate is getting faster and faster, and the water column is becoming more and more unstable, which is a prelude to reminding us that there are not many soluble substances in coffee and that we should stop. So at this stage, the taste of coffee is at the bottom of the flavor wheel, that is, "bitterness" is roughly divided into bitter taste and slightly spicy bitter taste.

So when we go back to the previous slayer pre-soaking system, we understand that the substances in coffee have three stages, namely, sour, sweet, bitter and salty + bitter. They are all extracted by the hot water in our pot or the hot water in the coffee machine, so I can control the amount of water coming out of the pot, and slayer can control the amount of water that is pre-soaked, which means we can control the sour, sweet, bitter and salty + bitter we want. So after understanding this theory, our extraction is very simple. If I want the acid to be less sharp and softer, then if I am flushing by hand, I will make his steaming fuller, and the front water injection will be softer, by prolonging the contact time between coffee and water to make it disperse some over-sour substances as soon as possible and gently transition from acid to sweet slayer. Similarly, this effect can be achieved through long-time pre-soaking under low pressure and small water output. Sweet! This taste is a taste that we all like, so if I want to be sweeter at this stage, I can immediately return to the normal extraction state and fully extract this section of soluble matter to get enough sweetness. at the end of the sweetness transition, there are usually two options:

1. Stop the extraction when the sweetness is finished, then our cup of coffee or espresso will cause the flavor imbalance concentration to be too high and too strong, which is what we often call Ristretto.

2. After the sweetness extraction, lengthen a short bitter front end, that is, the "salty taste" in the flavor wheel-the refreshing taste to make up for the lack of balance. This kind of extraction is the espresso we often drink.

The above two extraction methods are our more common conventional extraction methods, we can through segmented extraction through segmented extraction to determine the taste we want to achieve the cup of coffee we want.

Second, the latest concepts of grinding and extraction

1. A brief review of gold cup extraction

Extraction rate:

We know that the taste of the cup is caused by the soluble substance in the coffee dissolving in the water to turn the cup of water into coffee, and there is up to 30% soluble matter in the coffee, so the soluble matter is the best range at 18% Rue 21%. In this range, the rich and pleasant substances in the coffee are extracted in the cup, and the bad substances are left in the coffee grounds.

Concentration:

We know that the same coffee dissolves different soluble substances at the same extraction rate.

The concentration of it in the water is different, so if the concentration is too high, we will feel a strong and strong taste, that is, what we call body (mellow thickness), and if the concentration is too low, we will feel a relatively elegant taste, that is, what we often say is watery and a little thin. According to the data of SCAA in the United States, the coffee concentration range of 1.15% Murray 1.45% is relatively acceptable.

Uniform extraction:

If the above two points are met, my extraction rate is 20% and my concentration is 1.2%. But if our extraction is not uniform, the above data will become meaningless. Because the problems caused by uneven extraction will be directly reflected in the flavor and taste of the cup, to give a simple example:

We divide a pressed powder into two halves, left and right. Due to uneven extraction, pressed powder extraction on the left has a transitional extraction rate of 25%, and an underextraction rate of 15%. Then his overall extraction rate reached 20% through complementarity under the same coffee liquid weight. But the performance in the taste will be that the flavor is extracted but there is a certain bitterness, and the coffee will show an unclean taste.

The extraction rate, concentration and uniform extraction are all the same. This is the state we want for each extraction.

2. The latest concept of grinding and extraction of champions.

Grinder: DittingKR804 coffee beans: 90 + series grinding fineness: fine grinding

If you use chemex to extract coffee, never use more than 30g powder to extract coffee, if you use V60 to extract coffee, never use more than 18g powder for extraction, too much coffee powder will be more likely to bring out too much caffeine and bitter taste.

Always use the same weight of water to wet filter paper if you use 100g hot water or 200g hot water wet filter paper, the water absorbed by filter paper is different, in other words, the function of filter paper is filtration. Different water-wet filter paper will cause inconsistency in the filtration function of each filter paper, which will affect the extraction consistency of each cup of coffee. The gap in the connection of the filter paper will always exceed one direction. Similarly, in order to ensure consistency, our habit of water injection is consistent each time, ensuring that the joint is in a position on the side to ensure the consistency of each cup extraction.

The gouache ratio is always 1 1000ml 16.66667 Let's review the gold cup rule that the slash of 60g powder extraction per cup water is the most through the ideal range of extraction. The specific water injection rate and the dripping speed of water on the powder layer are as consistent as possible each time. Can be considered in the powder-to-water ratio, grinding degree, water temperature, uniform extraction …... In the case of keeping all kinds of variables consistent, to ensure the consistency of my extraction time can maximize the extraction efficiency of each extraction, no matter how much powder extraction time is as consistent as possible. Using the right water and the right water temperature to extract coffee, too much or too low TDS of water is not conducive to coffee extraction. TDS180 is a more suitable interval. Use a spoon to evenly drop coffee powder into the filter cup. If there is a small mountain cone, do not shoot, just like Italian style, piercing will cause fine powder to sink and also change the density of the powder layer. In addition, we need to weigh the weight of coffee powder rather than the weight of coffee beans, and try to ensure that the weight of coffee powder is the same as the water temperature affects the density of water. Too high water temperature will cause the water density to be too low, making it more difficult for the water to pass through the coffee powder layer and contact with the coffee powder for longer, and vice versa.

As long as we touch the coffee powder, then the extraction has already begun, and we need sufficient pre-soaking, so we must wet the whole coffee powder layer with enough water in the shortest possible time, that is, using twice the amount of water in 10 seconds to quickly wet the whole coffee powder layer from the outside to the inside, so that the water completely surround and permeate the whole coffee powder water is active. It will move in the powder layer and find its own water channel to infiltrate, so we need to reduce the influence of external forces on the activity of the water itself to ensure maximum uniform infiltration, that is, uniform extraction after the end of pre-immersion, when the horizontal plane submerged the coffee powder layer, it will return to the central point of the powder layer for water injection, which is no longer a conventional circle water injection.

So we do not have ditting grinder, the restriction of grinder in fine grinding precision and evenness is relatively large, we do not have 90 + series coffee beans, general boutique coffee beans are not as rich in flavor and flavor quality as 90 + series. If we copy it, it may not be suitable for our existing equipment and coffee beans.

Then first of all, let's analyze that the grinder baratza I use can only reflect relatively uniform grinding on the degree of grinding of medium thickness. That means I can't achieve that high extraction efficiency, so we have a relatively high powder-to-water ratio to make up for the lack of extraction efficiency at 1:15.

Therefore, my extraction method is to use 1:15 water-powder ratio, medium fine grinding fineness. In the previous step, as before, use a spoon to place the coffee powder evenly on the filter cup and shake it to make it smooth. Then steaming normally, depending on the degree of baking to determine the time of pre-soaking. Next, use fine water to evenly wet the whole powder layer, and if the acidity needed is softer, the water flow will be finer and the time will be relatively slower. After flooding the whole powder layer in about 40S-50S time, uniform water injection back to the center does not need to complete the extraction before 1.30. Try to keep the extraction time consistent with each time. In this way, on the existing basis, the variables produced by the winding are reduced, and the water is extracted naturally and evenly by making full use of the activity of water. The key variables are all in the front section, so the water injection around the front section needs to be more uniform and important.