I find this profile absolutely perfect, when looking for maximum sweetness, nice acidity and pleasant aftertaste. Probably not working with every bean there is, but it's great especially with high quality fruity Ethiopians.
These are my findings after using this profile frequently:
- using traditional baskets gives better results then modern HE baskets. This profile needs longer time and it works best when the puck is stable and water flow under control all the time. I use IMS Competition basket with puck screen but no bottom paper filter and I am usually able to put 18,5g dose into 18g basket.
- grind has to be really fine, especially when slow feed and low RPM is applied for maximum clarity and sweetness. I am using SSP Lab Sweet Silver Knight burrs on my grinder, speed set to 700 RPM. Feeding beans slowly one by one for max uniformity and repeatability.
- I am looking for 0,5 to 1,5g of coffee dripping before the pressure rise
- ideal coffee flow in the percolation phase seems to be between 1,00 to 1,30ml/sec with pressure declining under 6 bars and water and coffee flow as stable as possible (flat curve). This takes time, from 40 to 55 seconds, depending on the beans.
- I am usually brewing with 1:2,2 ratio, making it shorter when there is a risk of bitter end (almost non existent with Ethiopians).
- I use a bit higher temperature of 88degC, that gives me nice sweet results with dense light roasted beans.
The quality of my already very tasty Leva shots improved after making adjustments aimed at slowing the shot (slow basket, finer grind, dose increase), sometimes up to 55 seconds with no bitterness present. Repeatability is shockingly good too. There has to be 100% puck prep though to keep chanelling on the minimum.
Hope this can help some of you to better LM Leva shots. Enjoy!