Coffee knowledge: Al's Rule of Espresso extraction (Ayer's rule: sweet spot formula)

Al's Rule for Espresso Extraction: For every 5cc increase in extraction volume, the extraction time should be reduced by 1sec. Otherwise, add 1sec. Al Critzer's understanding of Espresso extraction has now become the most common Espresso concept in Europe and America.

The translation reads as follows:

Start with the result of getting a perfect cup of Espresso at 30cc/ 30sec. These two values depend on the beans, of course, and differences in baking methods, baking degrees, and recipe proportions naturally lead to changes in the reference point.

The amount of extraction is inversely proportional to the extraction time:

When the amount of extraction is higher, the coffee powder must be in contact with hot water for a shorter time (to avoid over-extraction).

Conversely, when the amount of extraction is reduced, the contact time between coffee powder and water should be increased (to avoid under-extraction).

Al formula: For every 5cc increase in extraction volume, the extraction time is subtracted by 1sec. Otherwise, add 1sec.

For example, when the extraction amount is increased to 45cc, 30-(45-30) divided by 5=27, the extraction time is reduced to 27sec.

When the extraction amount is 60cc, the extraction time becomes 24sec.

This formula, within reasonable limits of 0.75-2.5oz Espresso, quickly and correctly hunts for sweet spots, effectively captures desirable ingredients, and maintains a balance between over-extraction and under-extraction. The main method of control is to adjust the grinding thickness.

In addition, Al Critzer also explained the definition of Ristretto:

Ristretto is a drink that is very different from normal espresso.

If the grinding is unchanged, use the normal espresso flow rate and end the extraction early, for example, the original 30sec/ 30cc flow rate, only 25cc, this is a cup of insufficient extraction results, because it has not reached the sweet spot (Sweet Spot).

The so-called ristretto means restricted, and the customary practice is 25cc/ 30-35sec.

All sensory sensations, whether good or bad, are accentuated: what the eye sees, what the nose smells, what the tongue tastes.

Ristretto is characterized by a mouse tail that is extremely thin, plus a darker brown crema, so it is also adjusted by grinding.

Source: Guangzhou Misi. com