Physicists from the University of Pennsylvania in the United States have discovered a simple method to make pourover coffee stronger without using additional beans.
Co-Author Dr Arnold Mathijssen said pouring the hot water slowly from a goose-neck kettle increases the contact time between the water and the grounds, while pouring from a greater height increases mixing. Both of these methods are said to result in more coffee being extracted from the same volume of grounds.
In a paper published in Physics of Fluids, Dr Arnold and Co-Authors Ernest Park and Margot Young said that while coffee is one of the most consumed beverages in the world it was under threat due to climate change. They wanted to explore how to make it more efficient, using less coffee while still meeting the high demand for the beverage.
The research team undertook a series of experiments, first using transparent silica gel particles to represent ground coffee, which were illuminated with a laser sheet and recorded with a high-speed camera. They then performed the experiments with real coffee to measure the extraction yield of the dissolved solids.
“Together, these results indicate that the extraction of the coffee can be tuned by prolonging the mixing time with slower but more effective pours using avalanche dynamics. This suggests that instead of increasing the amount of beans, the sensory profile and the strength of the beverage can be adjusted by varying the flow rate and the pour height. In this way, the extraction efficiency could be better controlled to help alleviate the demand on coffee beans worldwide,” the team reported in the paper, ‘Pour-over coffee: Mixing by a water jet impinging on a granular bed with avalanche dynamics‘.
