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What's the Relationship Between Espresso Extraction Yield and Extraction Time? What is Pre-infusion in Espresso Extraction?

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, Professional coffee knowledge exchange. For more coffee bean information, please follow Coffee Workshop (WeChat public account: cafe_style). FrontStreet Coffee briefly describes pre-infusion: The act of pre-wetting the coffee grounds inside the espresso machine before actually starting to extract the coffee. Some machines achieve this through the pump; the pump works for 1-2 seconds, then stops for 1-2 seconds, before starting again to continue.

Professional coffee knowledge exchange and more coffee bean information, please follow Coffee Workshop (WeChat official account: cafe_style)

Pre-infusion Overview

FrontStreet Coffee provides a brief overview of pre-infusion (also called pre-wetting): the act of pre-wetting coffee grounds inside an espresso machine before actually beginning coffee extraction. Some coffee machines implement this through a pump; the water pump works for 1-2 seconds, stops for 1-2 seconds, then restarts to continue extracting coffee. Fully automatic machines and some semi-automatic machines adopt this method. After the pump starts, the second chamber must be filled before pressure is fully applied to the coffee puck. This provides 3-7 seconds of wetting time for the coffee grounds before pressure builds. This pre-infusion method is more popular. There are numerous theories explaining how progressive pre-wetting can improve coffee extraction.

Visual Indicators of Good Extraction

Tiger stripes and mottling: the main visual cues of good extraction. Tiger stripes are formed by the contrast of dark and light coffee oils in the coffee flow; ideally, they should appear at the beginning of the coffee extraction and continue throughout to the end. "Mottling" is the manifestation of extraction in the cup; it refers to the dark brown spots and reddish-brown patterns formed on the surface of the coffee oils.

Proper Extraction

Clear fruit acidity, rounded and warm flavors from Maillard reaction compounds

Al's Rule for Espresso Extraction (The Sweet Spot Formula)

Al Critzer's understanding of espresso extraction has now become the most widely accepted espresso concept in Europe and America. The translation is as follows:

Starting with the goal of achieving a perfect espresso at 30cc/30sec. These two values, of course, depend on the beans - differences in roasting methods, roast levels, and blend ratios naturally lead to variations in the baseline.

Extraction volume and extraction time are inversely proportional: when the extraction volume increases, the contact time between coffee grounds and hot water must be shorter (to avoid over-extraction). Conversely, when the extraction volume decreases, the contact time between coffee grounds and water needs to increase (to avoid under-extraction).

Al's formula: for every 5cc increase in extraction volume, extraction time should be reduced by 1 second. Conversely, 1 second should be added.

For example, when the extraction volume increases to 45cc, the extraction time is reduced to 27 seconds: 30-(45-30)÷5=27.

When the extraction volume is 60cc, the extraction time becomes 24 seconds.

This formula can quickly and accurately capture the sweet spot within the reasonable range of 0.75-2.5oz espresso, effectively capturing satisfying components while maintaining the balance between over-extraction and under-extraction. The primary control method is adjusting the grind size.