"Does acidic marinade actually tenderize meat?"

"Only the surface. Acids denature proteins by disrupting the hydrogen bonds and electrostatic interactions that hold protein structures together. But acid diffuses slowly through muscle tissue — research consistently shows penetration depth of 1-3mm in typical marinating times. Beyond that depth, the interior of the meat is essentially unchanged. What you get from an acid marinade is a texture change on the outer layers (sometimes pleasantly softer, sometimes unpleasantly squishy if left too long) and surface flavor."

"How long should you marinate chicken?"

"For acid-based marinades, 30-60 minutes is effective for thin cuts. For thicker pieces (bone-in thighs, breasts), up to 4 hours adds marginal additional surface flavor without degrading texture. Beyond 8 hours in a strongly acidic marinade, proteins on the outer surface begin to denature to a mushy consistency. For whole chicken, a salt-forward marinade (essentially a brine) overnight gives better results than an acid-forward one."

"Can you use marinade that raw meat soaked in?"

"Not without cooking it first. Raw meat marinade contains raw meat juices, which can carry Salmonella, Campylobacter, and other pathogens. If you want to use it as a basting sauce or dipping sauce, bring it to a full boil first (above 165°F) and hold it there for at least one minute. Alternatively, set aside a separate portion of marinade before the meat goes in and use that for basting."

"Is a salt-based marinade the same as brining?"

"Functionally, yes. When salt concentration in the marinade is high enough to drive osmotic movement (typically 0.5-1% of meat weight in salt), the mechanism becomes brining. Salt draws moisture out initially, then a counter-flow occurs where the concentrated brine solution is absorbed into the meat, denaturing proteins in a way that actually improves moisture retention during cooking. This is categorically different from what acid or enzymes do and is the reason salt is uniquely effective."

Does Marinating Actually Tenderize Meat? The Science of What Marinades Do

Quick Answer

Acid marinades (citrus juice, vinegar, wine) denature proteins only in the outermost 1-3mm of meat — they don't tenderize deep tissue. Enzyme marinades (papain from papaya, bromelain from pineapple) work faster but turn the surface mushy if left too long. Salt is the one marinade ingredient that penetrates deeply through osmosis and protein interaction, genuinely improving moisture retention throughout the cut.

The Science

The 24-hour marinade is kitchen mythology for most purposes. The idea that a longer soak tenderizes meat more deeply is intuitive but mostly wrong. Understanding why takes about three minutes and will change how you plan your cooking.

What Acid Marinades Actually Do

Vinegar, citrus juice, wine, yogurt, buttermilk — all are acidic, and all denature surface proteins in meat. Denaturation means disrupting the protein’s three-dimensional structure. Muscle proteins are held in shape by a combination of chemical bonds. Low pH breaks some of those bonds, causing proteins to unfold.

This sounds like tenderization, and at the surface, it is. But the diffusion of hydrogen ions (acid) into muscle tissue is slow. Studies consistently show acid penetration of 1-3mm in typical marinating windows. For a chicken breast that’s 30-40mm thick, that means 93-97% of the meat’s interior never sees the marinade at all.

The outer layer doesn’t just get tender, either. It gets progressively denatured. An hour in citrus juice produces a pleasant texture change on the surface. Four hours in a strongly acidic marinade produces a mealy, squishy surface texture that most people don’t enjoy. The meat is “tenderized” in the strictest sense, but in the wrong direction.

Enzyme Marinades: Faster, But Risky

Papain (from papaya) and bromelain (from pineapple) are proteolytic enzymes — proteins that cut other proteins apart. They don’t just denature the surface structure the way acids do. They physically sever peptide bonds.

This makes them faster-acting and more aggressive than acid marinades. They’re also surface-limited by diffusion (they’re large molecules and penetrate even less deeply than hydrogen ions), but within that thin surface layer, they work fast. A 30-minute marinade with fresh papaya pulp or fresh pineapple juice on chicken produces measurable tenderization. An 8-hour soak can turn the surface into something that falls apart unpleasantly and won’t hold together on a grill.

Canned pineapple and canned papaya won’t produce this effect. Heat during canning denatures the enzymes. Only fresh or freshly frozen fruit has active protease activity. This is a useful shortcut: if you need a recipe to use canned pineapple without turning the chicken to mush, you’re safe.

The bottom line on enzyme marinades: short contact times (15-45 minutes) on thin cuts can produce good results. They work best as commercial tenderizers (kiwi fruit is another source) for tough cuts that will be cooked quickly and served thinly sliced. They’re not a solution for whole-muscle cooking.

Salt Is Different

Salt is the odd one out among marinade components. It doesn’t just work at the surface.

When dissolved in water, sodium chloride creates an osmotic gradient across the meat surface. Initially, this draws moisture out — you’ll see liquid pool around meat in a salty marinade. But over time, the process continues and the concentrated salt solution is absorbed into the meat. As it penetrates, sodium and chloride ions interact with muscle protein filaments, causing them to partially denature and expand.

This expanded protein network retains more water during cooking. The meat isn’t just salty; it’s structurally changed in a way that reduces moisture loss when you cook it. A 4% salt brine on a chicken breast overnight produces measurably juicier meat after cooking compared to an unsalted control. No acid marinade does this.

This is why a marinade with significant salt content (soy sauce, Worcestershire sauce, fish sauce, or added table salt) produces noticeably better results than the same marinade without. The surface flavoring from aromatic compounds is real, but the moisture benefit is salt’s contribution alone.

Flavor Penetration Is Also Mostly Surface-Level

Flavor molecules in a marinade — garlic compounds, herb oils, spices, citrus zest — are mostly too large to penetrate deep muscle tissue in typical marinating windows. Like acid, they work on the surface.

This isn’t a flaw. Surface flavor concentration is real and noticeable. A piece of chicken marinated in garlic, lemon, and olive oil for two hours tastes meaningfully different from an unmarinated one. The flavor isn’t evenly distributed through the meat, but it doesn’t need to be. The surface is what you taste on each bite.

The practical implication is that 30-60 minutes is enough for most of the surface flavoring to occur. At 4 hours, you’ve captured most of the available surface flavor. At 24 hours, you’ve captured marginally more and risked surface texture degradation from acid.

When Overnight Marinating Makes Sense

There are real reasons to marinate overnight — but they’re not about deeper penetration of acid or flavor.

Salt needs time to migrate into thicker cuts and do its protein-modifying work. A dry brine (salt rubbed directly onto meat) on a thick pork chop or steak is better at 12-24 hours than at 2 hours because the ion exchange needs time to reach deeper tissue layers. This is a real overnight benefit, but it’s the salt acting alone.

Yogurt and buttermilk marinades benefit from extended time not because of their acidity (which is relatively mild) but because the fat and protein components coat the meat and carry fat-soluble aromatic compounds. Southern fried chicken brined in buttermilk overnight tastes better primarily because of the salt in the buttermilk doing its work.

The takeaway is not “don’t marinate overnight” — it’s “understand what the overnight time is actually buying you.” If it’s salt doing the work, overnight is worth it. If it’s acid or aromatic flavor, you’ve mostly captured the benefit within the first hour.

What This Means for You

Use acid and aromatics for surface flavor, but don't expect them to tenderize a tough cut. For real tenderization, dry brine with salt (1% of meat weight) overnight. If you marinate with acid, 30-60 minutes is usually as effective as overnight for most proteins — beyond that, surface texture degrades without additional tenderization benefit. Never use fresh pineapple or papaya juice on chicken breasts you plan to grill whole; the enzyme action turns the outside slimy before the inside is done.