Food Myths
Marinades reach a few millimetres in and then stop
Cut a marinated piece in half and the colour line is visible. What actually travels into meat is salt, which is why brining works and a herb paste does not.
The options around how far marinades penetrate are set out side by side below, with the conditions that genuinely favour one over the other.
The difference in one place
- Most marinade flavour compounds are large molecules that diffuse very slowly.
- Salt penetrates far more effectively and changes water retention.
- Acid firms and eventually degrades the surface rather than tenderising throughout.
What the cut surface shows
Slice a piece of meat that has sat overnight in a dark marinade and the coloured zone is a thin band around the edge. The interior is essentially untouched, which is visible without any equipment beyond a knife. That band is usually a few millimetres deep regardless of whether the meat sat for two hours or twenty.
Longer marinating produces surprisingly little additional depth, because diffusion into dense tissue slows dramatically with distance. The demonstration is easy enough that anyone doubting it can settle the question at their next meal.
Why the molecules do not travel
Meat is a dense structure of protein fibres with limited space between them, and it is already largely full of water. The aromatic compounds in herbs, spices and oils are relatively large molecules that move very slowly through such a structure.
Oil-soluble compounds face an additional obstacle, since they do not travel readily through the watery interior at all. Diffusion time increases with the square of distance, so doubling the depth takes four times as long rather than twice. That relationship is why an overnight soak achieves so little more than a short one.
What salt actually does
Salt dissolves into small charged particles that move through tissue far more readily than aromatic molecules. It alters how muscle proteins hold water, which changes both moisture retention during cooking and the texture of the result.
Somewhere in the retelling, this is the mechanism behind brining and behind salting meat in advance, and it works to a genuine depth over time. A marinade containing salt is therefore doing real work, but the work is being done by the salt rather than by the herbs. Sugar behaves similarly in terms of movement, though its effects are mainly on browning and surface flavour.
The acid question
Acidic marinades are widely believed to tenderise, and the effect is real but confined to the outer layer. Acid denatures proteins at the surface, which initially softens the texture and eventually turns it mushy and pale. Extended acidic marinating therefore damages the exterior rather than improving the interior, which is the opposite of the intention.
The primary source says otherwise: enzymatic marinades using certain fruits act more aggressively still and can reduce the surface to paste within hours.
Short exposure is generally better than long for anything acidic, which reverses the usual assumption entirely.
Where the belief came from
The word marinate carries an implication of soaking through, and the language shapes the expectation before any cooking begins. Recipes have specified overnight marinating for generations, and the results are usually good, which appears to confirm the method. The results are good because the surface is where most flavour perception happens, especially with high-heat cooking.
Where the story actually begins, a well-marinated surface that browns properly delivers an enormous amount of flavour, and the interior contributes texture rather than seasoning. So the technique works and the explanation for why it works has been wrong the whole time.
Where the earliest trace is a newspaper anecdote, treat the whole chain with suspicion.
Getting more out of it
Salt the meat in advance separately, giving it time to penetrate, and apply the aromatic marinade closer to cooking. Increase surface area by cutting into smaller pieces or scoring, since surface is where the marinade actually operates.
Where the story actually begins, reserve some marinade to apply after cooking, because heat destroys many of the volatile compounds that made it appealing. Pat the surface dry before it meets high heat, since a wet marinade prevents browning and browning is where most flavour comes from. Sugary marinades burn readily, so they belong on lower heat or on the final minutes rather than throughout.
Side by side
| Consideration | What it means in practice |
|---|---|
| What the cut surface shows | Most marinade flavour compounds are large molecules that diffuse very slowly. |
| Why the molecules do not travel | Salt penetrates far more effectively and changes water retention. |
| What salt actually does | Acid firms and eventually degrades the surface rather than tenderising throughout. |
The takeaway
The knife settles it in one cut, which is why this is the easiest kitchen myth in the world to check.
Believing it was ordinary. Continuing to is the avoidable part.
Questions readers ask
Does longer marinating help?
Barely, for flavour. Diffusion slows sharply with depth, so extra hours add very little. Salt is the exception and does travel further over time.
Does acid tenderise meat?
Only at the surface, and prolonged exposure makes it mushy rather than tender. Short marinating is generally better than long.
