Wed. Dec 7th, 2022
The secret to tasty brisket and ribs lies in food chemistry and phase transitions.
enlarge / The secret to tasty brisket and ribs lies in food chemistry and phase transitions.

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Imagine this nightmare scenario for Labor Day. You invited a large group of friends for pulled BBQ pork or a delicious beef brisket. That morning you confidently place your meat in the smoker, handy digital thermometer in place so you know only when the internal temperature reaches the perfect point. Everything seems fine for the first two hours, but suddenly the temperature stops rising. And the stays constantly for hours and hours as your friends get hungrier and hungrier, and you are forced to order pizza in desperation.

You’ve just come across the bane of aspiring pitmasters everywhere: the Stall (aka the Zone or the Plateau), a common phenomenon in low-temperature cooking. What exactly causes the stall is a perennial topic of debate among BBQ enthusiasts. Is it a protein called collagen in the meat which when combined with water converts to gelatin at the 160°F point? Or is it due to the breakdown of fat, which liquefies lipids?

Several years ago, Greg Blonder, a professor at Boston College, did the experiments and came up with a definitive answer: evaporative cooling. The meat sweats during cooking, releasing the moisture inside and that moisture evaporates and cools the meat, effectively eliminating the heat from the barbecue. Today, Blonder is the regular science advisor and myth-buster at the popular BBQ and grilling site Amazing Ribs. “I actually spend a lot of my time settling bar fights,” he joked.

A slowly cooked passion for ‘cue’

Blonder has been an avid, inventive cook since college, when the only tools he had to work with were a single hob and pan. When a friend from Hawaii came to visit, they roasted a whole pig on hot rocks in the backyard. Ever the scientist, Blonder inserted a few thermocouples into the carcass to monitor the changing temperature during cooking. So, of course, when he heard about the barn, he decided to test it experimentally.

First he mapped out the actual stall. For his experiments, he used brisket and pork fillet, as these are the most popular meats for slow roasting and smoking. He used a thermostatically controlled smoker for cooking and maintained a careful temperature of 225°f. [corrected] As expected, the barn started after the first two to three hours and it took about six hours for the internal temperature to start rising again. It is a useful example of a simple phase transition, with an initial rise and then a long smoothing, before rising again to reach the critical turning point.

Greg Blonder's backyard experiments yielded this graph that clearly shows the "stall."

Greg Blonder’s backyard experiments yielded this chart that clearly shows the “stall.”

Greg Blonder

Blonder found that collagen is probably not the culprit, as it only makes up about a quarter of the total protein in, say, a pork shoulder (18 percent, with 65 percent water and 15 percent fat). The basic hypothesis is that the collagen soaks up so much energy that it is chemically converted to gelatin, that there isn’t enough left to keep the meat rising in temperature, and you get the stall. Admittedly, the collagen starts to melt at about the same point as the stable starts, but according to Blonder’s calculations, that’s just a coincidence. There just isn’t enough collagen in the meat. He proved it by wrapping a six-pound pork butt in aluminum foil before cooking and using just a rub on the other six-pound butt. There was no stall in the foil-wrapped pork butt, and it should have been if collagen was the cause.

As for the melting fat hypothesis, Blonder tested that too. He placed a chunk of pure beef fat in a smoker, along with a sponge dipped in water, put thermocouples in both and cooked them at 225 degrees.°F. Again, there was no stall with the beef fat. But the sponge showed a noticeable hiccup after the first hour, and the temperature didn’t start to rise again until all the moisture had evaporated. Voila! The culprit is evaporative cooling.

That’s why today a growing number of competitive pit masters cut their meat after the first few hours (usually when the internal temperature is 170).°F), along with a splash of apple juice, beer, or even Mountain Dew. Blonder doesn’t, because the downside is you don’t get the crispy, flavorful “bark” on the surface of the meat — a product of the evaporative cooling that removes so much moisture from the surface — and he likes the added crunch and “flavor bomb.” when he shreds it with the rest of the meat before serving. But he recommends aluminum foil if you’re not an experienced pit master, especially if you’re using a large offset grill with a lot of airflow (compared to an egg or Kamado). The aluminum foil trick can cut cooking time in half if you cook on the standard 225°F. “It’s absolutely foolproof,” he said. Raising the cooking temperature to 250°F can shave another hour or two from that. Or you can just do it the old fashioned way and stick with it for the full 14 hours.

A lump of beef fat shows no stall;  a soaked sponge.

A lump of beef fat shows no stall; a soaked sponge.

Greg Blonder

If 2-15 hours just seems like too much like a day-long commitment for your Labor Day festivities, Blonder suggests trying something he calls pork-us interruptus: start the process the day before and when the pork belly or brisket hits the stall, remove it from the smoker, wrap in foil, put the foil wrapped meat in a plastic bag and dip in ice water to cool. Then keep the meat in the fridge overnight and bake it the next day. He insists that you can even finish it in your oven as you already have the smoke flavor in the meat. “It takes the stress out of the chef,” Blonder says. “Because the worst thing you can do is panic when you walk into the stall, and your guests show up and you’re out of meat.”

Another handy (scientific) tip: you should pre-salt your meat a few days in advance, because it takes so long for the salt to be absorbed into the meat. Salt is essential to the cooking process as it adds flavor and reduces moisture loss, preventing too much shrinking. But keep in mind that some cuts of meat are pre-injected with phosphates, and if you add salt on top, it will be too much. That’s also why Blonder doesn’t add salt to the spice mix he uses in his go-to rubs. (He says you can add the rub or a marinade a few hours before cooking, it won’t penetrate as deeply anyway.)

Blonder is adamant that these are just helpful tips, colored by his personal preferences, and that there’s plenty of room for adjustment if your tastes unexpectedly differ. “I’m never going to tell you there’s only one way to do it,” he said. “But if you want to achieve a certain goal, there are better ways to achieve that goal through science.”

By akfire1

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