Acids arrive in recipes at various points, but their effects depend heavily on timing. Late acid brightens; early acid transforms. Knowing which outcome you want settles every debate.
What acid does on contact:
Tightens vegetable fibres within minutes: beans stay firm, potatoes hold edges, chickpeas refuse softening once lemon lands.
Curdles dairy gradually: yoghurt-based gravies split when boiled post-acid without stabilising care.
Stops lentil and legume softening permanently; rajma added lemon too early stays stubbornly firm through hours.
Dulls green colours: mint and coriander turn olive under sustained acidity.
The timing patterns worth memorising:
Legumes: acid only after full tenderness, always. One squeeze at the end accomplishes what hours of early squeezing cannot force.
Tomato gravies: cook tomatoes thoroughly before adding dairy or delicate vegetables; raw-tomato sourness needs cooking out anyway.
Yoghurt curries: stabilise with besan or slow tempering introduction, then never boil hard again.
Finish-line brightness: chutneys, chaat masala, final lemon squeezes happen off-flame entirely, preserving volatile brightness cooking would destroy.
Vessel considerations:
Acid-heavy finishes clean up promptly regardless of lining confidence; overnight acid sitting taxes any surface.
Wooden spoons absorb acid aromas happily; dedicated sour-dish spoons prevent cross-transfer into sweets later.
Recipe translation skill:
When recipes say "add lemon juice", read the surrounding steps carefully: before simmering means flavour-mellowing intent, after heat-off means brightness intent. Same ingredient, opposite purposes.
Acid timing is invisible seasoning. Master it silently and guests credit everything except the real reason.
Lemon being squeezed over finished curry off flame beside simmering pot.