Physicists have discovered a way to make a stronger coffee using less coffee grounds when brewing it by hand.
This latter method is known as a manual pour-over, and it involves slowly pouring the hot water in a circular motion over the coffee grounds by hand. The method, invented in the early 1900s, has seen a resurgence in popularity in recent years.
Researchers writing in the journal Physics of Fluids explain that the key to maximising flavour lies in the height and flow of the water stream.
Using a swan-neck kettle, which allows for precise pouring, creates a strong, concentrated jet of water that stirs the coffee grounds.
This motion, described as an โavalanche effectโ, circulates the grounds and allows the water to penetrate deeper into the coffee bed, resulting in a stronger, more flavourful brew.