Towards a new Brewing control chart for the 21st century

• Published in: Journal of agricultural and food chemistry 2018-04
• Main Authors: Melrose, John, Roman-Corrochano, Borja, Montoya-Guerra, Marcela, Bakalis, Serafim
• Format: Article
• Language: English
• ISSN: 1520-5118

This paper describes new results from a base model of brewing from a bed of packed coffee grains. The model solves for the diffusion of soluble species out of a distribution of particles into the flow through the bed pore space. It requires a limited set of input parameters. It gives a simple picture of the basics physics of coffee brewing and sets out a set of reduced variables for this process. The importance of bed extraction efficiency is elucidated. A coffee brewing control chart has been widely used to describe the region of ideal coffee brewing for some 50 years. A new chart is needed, however, one that connects actual brewing conditions (weight, flow rate, brew time, grind….) to the yield and strength of brews. The paper shows a new approach to brewing control charts, including brew time and bed extraction efficiency as control parameters. Using the base model, an example chart will be given for a particular grind ratio of coarse to fine particles, and an 'espresso regime' will be picked out. From such a chart yield, volume and strength of a brew can be read off at will.