Al's Rule extracted from Coffee by Espresso

Al Critzer's understanding of Espresso extraction has become the most common concept of Espresso in Europe and the United States.

The translation is as follows:

Start with the result that 30cc/ 30sec gets a perfect Espresso. These two values of course depend on beans, and the differences in baking method, baking degree and formula ratio will naturally lead to changes in the reference point.

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

The more the amount of extraction, the shorter the time for coffee powder to come into contact with hot water (to avoid excessive extraction).

On the contrary, when the amount of extraction is reduced, the contact time between coffee powder and water should be increased (to avoid insufficient extraction).

Al formula: when the extraction amount of 5cc is increased, the extraction time should be subtracted from 1sec. On the contrary, add 1sec.

For example, when the amount of extraction increases to 45cc, 30-(45-30) / 527, the extraction time is reduced to 27sec.

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

Within the reasonable limit of Espresso of 0.75-2.5oz, this formula can quickly and correctly hunt sweet spots (Sweet Spot), effectively catch satisfactory ingredients, and maintain the balance between over-extraction and under-extraction. The main means of control is to adjust the grinding thickness.

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

Ristretto is a very different drink from normal espresso.

If the grinding is constant and the extraction is finished early at the normal espresso flow rate, for example, at the original 30sec/ 30cc flow rate, only 25cc is taken, which is the result of insufficient cup extraction because it has not yet reached the sweet point (Sweet Spot).

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

All sensory sensations, including what the eyes see, what the nose smells, and what the tongue tastes, whether it's good or bad, are aggravated.

Ristretto is characterized by a particularly thin mouse tail and a darker brown crema, so it has to be adjusted by grinding.