Reducing (reduction)
Also searched as: reduce, reduction, concentrating, syrupy
In short: When reducing, water evaporates. Flavour, salt and gelatine stay behind and become more concentrated.
Like a closing-down sale in a shop: the shelves empty (water), but the best pieces (flavour) stay and stand out all the more.
Simplified model
What happens
If you boil a liquid uncovered, mainly water evaporates. Everything else stays in the pot: aromas, sugar, salt and, in stocks, the gelatine from the bones. That is why a jus turns stronger and silkier as it reduces, without any flour or starch.
Why it matters
Gives sauces depth and natural body. But salt concentrates too: salt at the start and you end up with an oversalted sauce.
Rules of thumb
- Salt only at the end: concentrates the salt too.
- Wide pot or pan: more surface, faster reduction.
- A stock with lots of gelatine thickens by itself as it reduces.
Levers
3
In practice
2
Sauces
Red wine sauce: reduce wine and stock to a third, then with cold butter.
Desserts and sweets
Reducing fruit juice to a syrup concentrates sugar and acid.
Sources · 1
- Harold McGee: On Food and Cooking (2004), Kapitel Saucen, Eier