Det finns flera fördelar med att använda en annan tryckkokare än hastighet, varav den första adresserar dina farhågor om skimming. Om det fungerar korrekt, kommer vattnet i en tryckkokare aldrig att koka, vilket resulterar i ett tydligare lager än en som görs med konventionella medel. Från modernistiska köket (2-291):
The liquid inside the pressure cooker will not boil, despite the elevated temperature, unless you let the heat get out of hand. A liquid boils when its vapor pressure exceeds the ambient pressure around it. Inside a sealed pressure cooker, as liquid water vaporizes, it raises the ambient pressure, which in turn increases the boiling point. So long as water vapor is not escaping the pressure cooker, the pressure inside will stay high enough to keep liquid water from boiling. Never reaching a boil is important because it keeps the stock clear. Turbulence from boiling emulsifies oils and small food particles from the ingredients into a stock, thereby making it murky.
A telltale sign that the stock is at a rolling boil inside a pressure cooker is a jet of steam or fog from the overextended pressure valve. This jet means that the pressure cooker is overpressurized, and for safety's sake the valve is relieving the pressure.
Du kan ytterligare öka tydligheten genom att lägga till lite rå kött till dina ingredienser för att fungera som filtreringsmedel. Från modernistiska köket (2-295):
Dispersing a small amount of raw ground meat along with the other ingredients when making a pressure-cooked stock yields a stock with the clarity of a traditional consommé. This works because protein extracted from the uncooked ground meat acts just like protein in egg white: it sponges up tiny light scattering fat globules and other small particles.
En annan fördel kommer från den förseglade naturen i matlagningsmiljön, vilket förhindrar att flyktiga dofter avdunstas i luften. Heston Blumenthal citerar detta som en av anledningarna till att The Fat Duck började använda tryckkokare för deras lager i detta artikeln :
Now, this may seem obvious, but when you smell those wonderful odours while you're cooking, it's a sign that you're losing flavours through those volatile elements that disappear in the air. A pressure cooker, however, keeps the aromas and flavour molecules sealed in the pot...In a normal stockpot, by contrast, water evaporates at boiling point, taking flavour with it.
Modernistiska köket (2-292) överensstämmer:
When the the pressure-cooking step is done, you must let the cooker cool before removing the lid...Cooling first means that volatile aromas in the vapor above the liquid will condense back into the liquid rather than escape into the kitchen.
Men inte alla tryckkokare skapas lika och vissa kommer att släppa ut ånga för att upprätthålla trycket vilket resulterar i ett sämre kvalitetslager. Dave Arnold och Nils Norén från Cooking Issues har gjort omfattande experiment i detta fenomen här : i blindprovningar utstängda tryckkokare producerade sämre resultat till både konventionellt kokta lager och de som gjordes med mer avancerade fjäderventiler. De icke-ventilerade kärlen producerade dock de bästa resultaten av alla tre metoder.
Slutligen ökar den förhöjda temperaturen mängden Maillard-reaktioner, vilket resulterar i ett mer smakfullt lager. I artikeln om matlagningsproblem ovan var den resulterande brunningen tillräckligt stor för att det var lätt att berätta vilket lager som var kokt och inte bara genom visuell inspektion:
The aroma of the pressure cooked stock was clearly superior. The color was deeper as well (because of this all future tests were done actually blind –with our eyes closed). Unfortunately the conventional stock tasted better. It had a stronger chicken flavor and was better balanced overall.
...
I took 4 liters of conventional chicken stock from the restaurant and pressure-cooked half while the other half simmered on the stove. This time, I didn’t use the school’s pressure cooker, I used my own. When I compared the two stocks side by side the pressure cooked one was far browner. I hadn’t thought the pressure cooker would change the color of a pre-made stock. When we tasted them the pressure-cooker won.