MS 4.06 The Steam Wand - Barista Hustle

September 20,2024

The Effect of Steam Pressure on Bubble Size Are you looking for an efficient milk heating solution by increasing your steam temperature? Turning up the temperature of the steam boiler comes at the expense of milk foam quality. Regardless of steam wand type, bubbles get bigger when the espresso machine operates at higher pressures. Researchers have observed that for every 0.2-bar increase in boiler pressure, the average bubble diameter increased by 3 um (Jimenez-Junca et al 2015). This research showed that of all the commercial systems for heating milk, the foam from the plunging jet steam wand system (i.e., a normal steam wand) was the least affected by increases in pressure. Ejector-type steam wands, used on bean-to-cup machines, recorded a bubble diameter increase of 10 um per 0.2 bar increase in pressure.