Marinades, and what they actually do

Raw meat is marinated in the refrigerator, not at room temperature. A marinade is not a preservative and the food in it is raw meat sitting at whatever temperature the room is.

A marinade's acidity must not be relied on to kill bacteria, whatever it is made of and however long the food sits in it. This is the one that catches people out, because the folk reasoning is plausible: acid kills things, marinades are acidic, therefore the marinade has done some work. The University of Illinois Extension addresses it directly and says not to rely on it — in the same sentence in which it acknowledges that marinades are acidic.

The reuse rule is worth being precise about, because the source is precise and most repetitions of it are not. The instruction attaches to marinade that has touched raw meat. Liquid you set aside in a separate bowl before the meat went in is a different thing, and the source does not address it — so BBQHQ does not extend the rule to cover it, and does not tell you it is fine either.

A marinade is usually four things doing four different jobs, and separating them is most of what makes the difference between one that works and one that is just wet.

Salt is the component with the strongest evidence behind it and the one people think about least. The peer-reviewed review BBQHQ holds describes it drawing liquid out of the meat by osmosis, after which the marinade solution is absorbed and the muscle structure is broken down. That is a mechanism, stated by a source, and it is doing more than the flavourings are.

Oil is a carrier rather than a flavour. Oil in a marinade carries fat-soluble flavour compounds from seasonings such as chillies, herbs and spices. Which is why a marinade with chilli and herbs in it and no fat tastes thinner than the same ingredients with oil.

Acid — vinegar, citrus, wine, yoghurt — is the contested one, and it gets its own section below.

Aromatics are the part everybody concentrates on and the part that travels least far, because the molecules are large. BBQHQ holds no measurement of how far, which is also below.

Whether an acidic marinade tenderises meat is contested in the peer-reviewed literature. A 2023 review states that acid marination lowers the pH of meat and improves tenderness, and in the same passage reports a study in which 1.5% citric acid increased hardness instead.

That is one review reporting both findings, in the same passage, deliberately. It is not BBQHQ hedging: the second result is raised by the reviewers themselves as a counter to the first, at a stated concentration of 1.5% citric acid.

What follows practically is modest and worth having. “Acid tenderises” is not a reliable enough effect to build a plan on, and a long soak in a strongly acidic marinade is at least as likely to firm the surface as to soften it. If a cut is tough because of connective tissue, the thing that converts connective tissue is time at temperature — which is a cooking decision rather than a marinade one, and belongs to the indirect side of the barbecue.

BBQHQ publishes no marinating time. What it can report is what the extension service observed: some marinades sit for 15 to 30 minutes before the meat is cooked, and other recipes go up to 24 hours. That is a description of what recipes do — the source attaches no outcome to either end and does not recommend either, and neither does this page.

On depth, the honest answer is that BBQHQ does not have one. The widely repeated figure is that a marinade reaches only a millimetre or three, and that overnight changes little below that. It is probably about right. It appears in test-kitchen and hobbyist writing and in none of the institutional sources retrieved for this site, so it is not printed here as though it were established.

The open question: How far into meat does a marinade actually penetrate, and which publisher has measured it? What would close it

What the mechanism does support is that marination is substantially a surface treatment, with salt the component most able to travel. That has a practical consequence worth more than a number: surface area is the variable you control. Diced meat on a skewer takes far more from the same marinade in an hour than a whole joint takes overnight, because there is simply more surface for it to be a treatment of.

These are treated as one topic almost everywhere and they are five different operations, separated by when they go on and what they are for. BBQHQ files each one as its own kind rather than as flavourings that happen to have different consistencies.

• A marinade is a liquid the food sits in, before the cook. Mostly surface, salt travelling furthest.
• A paste or wet rub is the same chemistry with the water taken out, so it stays where you put it instead of running off. Useful on anything vertical or on a skewer.
• A dry rub goes on dry and draws moisture out to make its own brine on the surface. Whether it carries sugar decides whether it survives a long cook.
• A brine is salt and water and is about water retention rather than flavour.
• A glaze goes on at the end, and it is the only one of the five that does. Sugar caramelises and then burns, so a glaze applied at the start is charred by the time the food is done — which is a physical fact rather than a stylistic preference, and is why BBQHQ made it a separate kind rather than filing it as a wet rub.