What Marinades Actually Do (and Do Not)

A marinade stays on the surface

Cut into meat marinated overnight and the colour reaches one to three millimetres in. Most aroma molecules are large and fat-soluble, and they do not travel between muscle fibres.

So "I marinated it for 24 hours, so it is seasoned through" is not true. What long marinating mostly buys is a stronger-flavoured surface, and past a point the extra time returns nothing.

There is one exception, and it is the point of this guide.

Salt is the thing that gets in

Salt is a small ion. It dissolves and diffuses into the muscle — and once inside it does real work, loosening protein structure so the meat holds on to water and loses less of it in cooking (salt and seasoning).

Which means a good marinade is effectively a brine with surface flavour on top. If you keep one ingredient, keep the salt; a marinade without it is little more than aroma painted on the outside.

It is why the sauce on bulgogi or jeyuk bokkeum works in thirty minutes: soy sauce is doing the salt's job.

Acid does not tenderise

This is the most widespread misconception. Vinegar, lemon and wine denature surface proteins, which can read as tender, but they do not reach the interior — and given time they:

• leave the surface dry and chalky;
• drive out moisture, so the meat browns poorly;
• firm up white fish and prawns as though cooked, within tens of minutes. Ceviche is built on exactly that, and it is cooking, not tenderising.

Acid has its own proper place — dishes like vindaloo, where vinegar is the preservative and the flavour axis. Adding acid for tenderness is aiming at the wrong thing.

Enzymes really do break protein down, but they are hard to stop

Pineapple (bromelain), kiwi (actinidin), pear and fig carry enzymes that genuinely cut protein. They work — the trouble is that they do not stop.

• Thirty minutes is enough; a few hours turns the surface to mush.
• They act unevenly, so parts stay intact while parts collapse.
• Grated pear in Korean galbijjim is this mechanism in use, which is why the quantity is small and the time short.

Canned pineapple has been heat-treated and its enzymes are dead, so it is useless for this.

Yoghurt works differently

Tandoori chicken and Indian marinades use yoghurt for more than its acidity. Yoghurt combines mild acid, calcium and milk protein, so it acts far more gently than vinegar, and its thickness keeps it clinging to the surface. Its lactose and protein also feed the Maillard reaction, so it colours well (browning and maillard).

A yoghurt marinade can therefore sit overnight without wrecking the surface. Do not put it on the same timetable as a vinegar one.

What oil and sugar are for

• Oil distributes fat-soluble aromas — chilli, spices, herbs — evenly across the surface and carries heat in the pan. It has nothing to do with penetration.
• Sugar colours fast but burns. A sweet marinade over high heat scorches before the inside is done. Something like jerk chicken wants medium heat and time, or the sugar brushed on at the end.

Times, and two rules

Set the time by thickness, since the action is at the surface.

• Thin-sliced meat, prawns: 15-30 minutes
• Chicken pieces, 2cm-thick cuts: 2-4 hours
• Whole legs, thick joints: overnight, if it is salt-based
• Strongly acidic marinades: under 2 hours, always
• Enzymatic (pear, kiwi, pineapple): 30 minutes

And two things without exception:

• Pat the surface dry before it hits the pan. A wet surface steams instead of browning.
• Do not serve the marinade raw as a sauce. Boil it first if you want to use it.