Keep the lid closed and your hands behind your back like the pitmaster at legendary Cooper's in Llano, TX.

Mythbusting: Basting, Mopping, And Spritzing

Part of the ritual of working the grill is standing with the brush and periodically, like the great artists we are, painting the food with a magical liquid.

It allows us to inhale the aromas (ahhh it smells sooooo good), check on the progress (almost done, honey), look at the hypnotic flames (Meathead like fire!), and act like we know what we are doing.

I wondered if this is a good idea and if it helps or hurts the food, so I asked my science advisor, Dr. Greg Blonder, to conduct some tests to enlighten us. "Spritzing a fraction of an ounce of liquid onto meat is more or less like spitting into a hurricane. It can hardly be expected make a dent in the humidity. And, a water spray is more likely to drip off the oily, crispy surface than be absorbed. On the other hand, small amounts of moisture evaporating from within the meat, while baking at low temperatures, can be a remarkably effective coolant."

In previous experiments Blonder explained that moisture evaporating from the surface of meat cooked at low temps, at or below 225°F, cooled the surface so effectively that the meat would heat up to a point somewhere about 150°F in the center, and then it would stop warming for hours. This phenomenon is well known to people cooking beef brisket and pulled pork, and is called "The Stall". The meat temp stalls sometimes for many hours until the surface began to dry out and form a crust (sometimes called "Bark"), before continuing to cook up to the target temps of 190 to 200°F at which the connective tissues made of collagen combine with moisture in the meat to form gelatin producing the succulent rich flavors prized in pulled pork, ribs, and beef brisket.

Blonder took pork tenderloins and bundled them into 3" thick cylinders because they are fairly uniform in texture and moisture content. He put one in a kitchen oven and cooked it at 225°F and with a recording thermocouple digital thermometer logged its progress. It is the solid red line in the chart at right. As you can see it warmed rapidly to about 140°F and then began to stall as the moisture on the surface began to evaporate and cool the meat the same way sweat cools an athlete.

He then put another section of loin in the oven and quickly opened the door every 30 minutes, spritzed the meat with a mix of apple juice and apple cider vinegar (the dotted red line). In previous experiments on whether opening and closing a smoker will slow cooking, Blonder showed that the impact is minimal on the meat, especially on cookers with a thermostat such as an indoor oven, pellet smokers, or a charcoal grill with a thermostat blower. That's because meat cooks by the heat built up in the outer layers of the slab being transmitted to the center of the slab, and although opening the cooker cools the air slightly, it has little effect on the meat, and the air rapidly returns to cooking temps.

As you can see, from Blonder's chart, spritzing had little or not impact on cooling and cooking time needed to hit the optimum temp of 145°F for the tender and lean pork loin. If he took it up to 180°F, a temp more common for pork shoulder, the cut used for making pulled pork or the temp common for ribs, the unspritzed meat hit 180°F in about eight hours (the bumps in the lines are due to the oven cycling on and off in response to its thermostat). Spraying extended the time needed to reach 180°F to nine or 10 hours. A small percentage of that is due to opening the door, but most of it is due to the cooling effect of the mist. Still, the impact on cooking time is not huge, probably about 10 to 20%, adding perhaps one or two hours to the cook.

Then he cranked up the temp and cooked one hunk at 250°F without misting (solid blue line), and one with (dashed blue line), and both finished in a dead heat. Notice that they both hit 180°F in about five hours, much faster than when cooked at 225°F. Finally, for the fun of it, he cranked the oven to 325°F and cooked two more loins. You can only see one line in the chart, the black line, because the dashed line is hidden behind it. The results were identical.

Blonder used a kitchen oven because there is much less airflow than an outdoor oven (around 5 air exchanges per hour). "However," he explains, "as any athlete knows, evaporative cooling is more effective in a breeze" and outdoor cookers tend to have a lot more airflow to vent the combustion gases and smoke (more than 100 air exchanges per hour).

This time he placed both hunks of meat into a MAK 1 Star pellet smoker which has a thermostat control. They went in together in order to minimize the differences caused by opening the lid to spritz one. There was no difference in cooking time and weight loss! He explains that "Although high air flow rates rapidly cool, they also dry out the sprayed surface layer just as quickly."

Tireless and tirelessly curious, the hungry scientist took small hunks of brisket and coated one with just a barbecue rub, another with a sticky barbecue glaze, and spritzed another. They cooked at 260°F and all three finished in a dead heat (pun intended). Weight loss and tenderness were also similar, with a slight edge to the glazed meat.

What about weight loss? In a similar experiment on chicken thighs, thighs just lightly seasoned with a spice rub lost 33% of their initial weight, while thighs sprayed lost 29%, and thighs with sauce lost only 22%. So the difference between plain and sprayed is minimal and probably not worth the effort. But thighs with a saucy glaze have less loss because the sauce can help seal the moisture in.

What about flavor? Remember, apple juice and vinegar are mostly water. If you mist meat multiple times you are putting down a fraction of a teaspoon of liquid per bite of which flavor molecules are probably less than 2%. The flavor in the meat, in your spice rub, in the smoke, and in the sauce will obliterate the impact of the mist.

So what is the take home? Spritzing, mopping, and basting have no effect on cooking at temps of 250°F and up, or on short cook times to internal temps around 150°F or less. On low and slow cooks to 180°F and up internal temp, the extra moisture can add 10 to 20% to the cooking time. On one more front, wet surfaces do help create more of a smokering, but as we will show in future articles, the smokering has little or no impact on flavor. There is one more effect: Wet surfaces attract and hold more smoke.

When we mop, baste, or spritz, there are other things that we are doing:

We are adding flavor. Depending on what is in your mop, the flavorings stick to the surface. They don't penetrate much at all, but they build up in layers. Now a thin mop of apple juice, beer, vinegar, or wine isn't going to contribute any noticeable flavor boost compared to spices, meat, and sauces. The flavor molecules in thes liquids are few and far between. But if you use a thicker mop, like a Texas mop, there can be some flavo addedr. The time to baste is immediately after flipping the meat while the top surface is still hot and bubbly, and so the mop can mix with the juices of the meat. While sitting on the surface the water can evaporate, so when you flip again you are not steaming the meat and so the flavor can cook on. If you baste and flip immediately, can retard the formation of the crust. For more on these processes, read my article on meat science.

We are removing flavor. One of the problems with mopping and spritzing is that they can wash off spices and marinades. Do it repeatedly, and you can remove a significant amount.

We are softening the skin. A lot of the flavor of chicken, turkey, and duck is in the fatty skin. The skin is best when dark and crispy. This happens as dry heat drives off moisture in the skin and melts fats that baste the meat underneath it. Painting the skin with water-based bastes, even pan drippings or butter (which has water in it), just wets the skin and keeps fowl skin foul and rubbery. Sometimes, if the cooker is hot, painting the skin with oil-based bastes can help browning and crisping, especially if the oil is really hot.

We might be contaminating the meat. Most meat has potentially toxic microbes on its surface. They are killed rapidly in the grill (most are zapped when the temp gets over 155°F). If the marinade has had meat soaking in it, it has microbes from the surface of the meat. So when we baste or mop, we are putting live microbes back on the surface of the pasteurized meat. They will die pretty quickly if we leave the meat alone under a closed lid for a few minutes, but if the lid is open, or if the meat is removed soon after basting, we could be serving our guests a tummy ache. Or worse. Click here for more info on food, grill, and knife safety.

Click here to see more complete data on Blonder's experiments in spraying.

This page was revised 4/7/2010