Analysing extraction uniformity from porous coffee beds using mathematical modelling and computational fluid dynamics...

Area of Science:

• Food Science and Technology
• Chemical Engineering
• Separation Processes

Background:

• Uniform extraction of soluble material from porous matrices is a key challenge in food processing, chemical, and pharmaceutical industries.
• Coffee extraction involves soluble material diffusion from coffee particles into flowing fluid within a packed bed.
• Understanding fluid flow and transport phenomena is critical for optimizing extraction processes.

Purpose of the Study:

• To model and analyze fluid flow and soluble material transport during coffee extraction.
• To compare one-dimensional (1D) flow models with computational fluid dynamics (CFD) models for coffee extraction.
• To investigate the impact of coffee grind size and brewing geometry on extraction uniformity.

Main Methods:

• Development and comparison of 1D flow models and CFD models for coffee extraction.
• Simulation of fluid flow and soluble material diffusion for fine and coarse coffee grinds.
• Experimental validation using a packed cylindrical coffee bed and analysis of a truncated cone geometry.
• Utilizing extraction maps and coffee brewing control charts to quantify extraction variation.

Main Results:

• Non-uniform flow in a truncated cone geometry leads to significant variations in local extraction levels.
• Model results were compared against experimental data for packed coffee beds.
• Extraction variation was analyzed using industry-standard coffee brewing control charts.
• Fine and coarse coffee grinds were considered in the modeling.

Conclusions:

• Geometric variations, such as using a truncated cone, can cause significant non-uniformity in coffee extraction.
• High variation in extraction yield is linked to bitter flavors in coffee brews.
• Quantifying extraction variation is important for controlling coffee brew quality and flavor profile.