I don't think the article is accurate. It really isn't density that is directly responsible for the faster cooking (though the increased impingement is a contri

I don't think the article is accurate. It really isn't density that is directly responsible for the faster cooking (though the increased impingement is a contributing factor). The more direct cause is heat. Cooking is the result of heat transfer. When you raise the vaporization temperature (by raising the pressure), more heat is transferred in the process of getting to that temperature and vaporizing the steam. To verify this, we can do an enthalpy calculation. Specific enthalpy (h) for water at 25C, 1 atm is 104920 J/kg. At 1 atm, the enthalpy for gaseous steam at vaporization is 2.676e6 J/kg. For pressure cookers, at 2 atm, the enthalpy is 2.707e5 J/kg. That is an extra 31000 J/kg.