Explanation of the nouns related to coffee extraction

30% of the ingredients in coffee beans are soluble, and these 30% contain organic substances that provide aroma and taste. These organic substances contain all the good and bad properties, so it is not that the higher the extraction rate, the better the taste and aroma. In addition, a moderate concentration is an important factor that can not be ignored for the overall taste.

(1) the method of concentration determination:

1. The refractometer (vst meter) measures the change of the refraction angle of the air in the liquid and converts it to get the tds reading in'%'.

Usage: 0.1% for water, 1.3% for coffee, 1.2% for tds (relatively convenient)

2. Conductive pen (tds pen) the measurement of the electrical conductivity of the electrolyte in the soluble matter in the liquid shows that the bound electrolyte accounts for about 10% of the total soluble matter, and the tds reading in units of 'ppm' is converted.

Usage: 100ppm for water, 1300ppm for coffee, and tds 12000ppm for coffee, 1.2% (relatively cumbersome)

3. Evaporation drying: after the coffee liquid is dried, the weight of the soluble matter can be obtained. Combined with the total weight of the liquid, the concentration can be obtained (relatively accurate).

Note: with regard to the concentration recommendation, that is, the concentration recommendation of Gold Cup, SCAA recommends 1.15% SCAA and SCAE 1.45%.

(2) conversion of extraction rate:

1. Refractometer or conductive pen reading * Coffee liquid total weight / solid weight

2. The weight of dissolved matter / solid weight obtained after drying the coffee liquid.

Remarks: 1. Ppm is the abbreviation of parts per million, translated as part of per million, that is, parts per million (parts per million), or parts per million. 1ppm, for example, contains 1kg of solute in a solution of one million kilograms. Ppm is the same as the percentage (%), except that the percentage is larger than the percentage.

2. Among the three methods, the natural drying method is the most accurate, but the drying method requires high experimental environment; the other two conversion methods, because of the uncontrollable variables caused by different production methods, actually ignore the factor of coffee water absorption.

(3) the method of calculating the extraction rate by combining the specific coffee utensils.

For the convenience of calculation, it is assumed that the TDS of water is 0, of course, it is usually necessary to subtract the value of TDS of water.

1. Immersion type (French kettle, smart cup, Cupping, etc.)

Amount of water used * TSD (concentration) / coffee powder

For example: 240g (water) * 1.2% Universe 15g 19.2%

2, follicular type (such as hand flushing, CHEMEX, Philharmonic pressure, flannel, etc.)

Weight of coffee liquid * TSD (concentration) / amount of coffee powder (e.g.: 240g (coffee liquid) * 1.2% 15g coffee 19.2%)

Or (amount of water used-coffee powder absorbs water) * TSD (concentration) / coffee powder quantity

Note: coffee powder absorbs water, and the theoretical value is twice the weight of coffee powder.

For example, [280g (water)-30g (coffee powder absorbs water)] * 1.2% Coffee 15g 20%

3. Espresso

Before testing TDS, espresso needs to filter the suspended particles insoluble in water in the liquid. (if there is no special filter equipped with VST concentration meter, filter paper can be used instead)

Weight of coffee liquid * TSD (concentration) / amount of coffee powder (e. G.: 36g / 10g / 18g / 20g)