Can I use a leftover marinade as a sauce?

This comes up most often at a barbecue, where the same bowl and the same brush are used for raw and cooked meat within a few minutes of each other. It is one of the more common routes to food poisoning in a domestic kitchen, and it is completely avoidable with one habit.

Safety

Step by step

1. Understand what is in the used marinade.Whatever was on the surface of the raw meat is now in the liquid — campylobacter and salmonella from poultry, E. coli and others from red meat. Acid, salt and alcohol in a marinade slow bacteria down but do not sterilise it. The bowl, the brush and the tongs are in the same state.
2. Reserve a clean portion before the meat goes in.Mix the marinade, pour a third of it into a separate container, cover it and refrigerate it. Marinate the meat in the rest. The reserved portion has never touched raw meat and can be used as a dressing, dip or finishing sauce with no further treatment. This is the habit worth building.
3. If you did not reserve any, boil what you have.Pour the used marinade into a small pan and bring it to a full rolling boil for at least a couple of minutes, stirring. Boiling is comfortably above any pathogen's survival range and this genuinely makes it safe. Expect it to look unappealing — proteins from the meat coagulate into grey specks. Strain it if you want it presentable.
4. Reduce it into something worth eating.Once boiled, keep it going until it thickens slightly and concentrates. A soy, honey and garlic marinade reduces into a decent glaze. Add a knob of butter off the heat to finish it. Marinades that were mostly oil separate badly and are usually not worth rescuing.
5. Change the brush and the plate at the barbecue.The same rule applies to equipment. Never brush cooked meat with a brush that has been in raw marinade, and never put cooked meat back on the plate the raw meat came off. Use two plates, two brushes, and two sets of tongs, and keep them visibly different.
6. Do not re-marinate a second batch in used marinade.Marinating a fresh piece of meat in liquid that has held a previous one multiplies whatever was there and gives it more time. If you want to reuse the flavours, boil it first, cool it fully, and even then it is better to make it fresh.

Tips

• Marinade drips are a cross-contamination route in the fridge as much as anywhere else. Marinate in a sealed bag or a covered container on the bottom shelf, never in an open bowl above other food.
• Boiled and reduced marinade concentrates the salt in it. Taste before you serve — a soy-based one can end up far too salty once it has reduced by half.
• Marinade that has held fish behaves the same way and should be treated the same way, and it usually tastes strongly of fish once reduced, so it is rarely worth it.
• A brine used for wet brining is in the same category. It goes down the sink; it is not a stock base.

Common mistakes

• Brushing raw marinade onto meat in the last minutes on the grill — The outside of the meat is not hot enough for long enough to reliably deal with a fresh application of contaminated liquid at that stage, and the surface is what people are about to eat.
• Warming the marinade through rather than boiling it — Warm is the growth range, not the kill range. It needs a genuine rolling boil, not a gentle heating.
• Assuming acid or alcohol makes a marinade safe — Vinegar, citrus, wine and yoghurt slow bacterial growth. They do not eliminate the organisms, and pathogens survive comfortably in every marinade you are likely to make.

Questions people ask