There is just something about a smoked brisket, cooked low and slow, that has backyard cooks obsessing over the perfect cooking method and time. A 15-pound whole packer brisket is a large, tough cut of meat and getting it right can be a bit of a challenge. In this post, we will explore the complexities of cooking this delectable piece of heaven to get the best results.
So, how long does it take to cook a 15 lb brisket? Well, the answer is, it depends on a lot of things like temperature, cooking method, size of the brisket, thickness of the brisket, thickness of the fat cap and if the brisket is wrapped, to name just a few. Before we delve into those topics, let’s start by talking about meat quality.
The first step in creating the perfect brisket is to select a USDA Prime or Choice grade beef brisket. These grades will have good marbling which means the end result will be more tender and have more flavor. Prime is going to cost a bit more, but I think it’s worth it. I have cooked a Wagyu grade brisket a few times and it was a real treat, but it was also substantially more expensive, like four times more expensive than choice. I’m just not convinced the juice is worth the squeeze. If you want tender brisket, buy prime if you can find it, otherwise go with choice.
Also, buy a brisket that will fit comfortably inside your smoker. A brisket needs smoke and that translates into needing enough room for the smoke to circulate around the brisket. I have cooked briskets that were so big they barely fit inside my Big Green Egg and wish that I had bought something smaller. If it hits the lid, it’s too big. If you find yourself in this predicament, cutoff an inch or two from the small, thin end of the brisket. In a few hours you won’t miss it.
Cooking temperature, of course, plays a key role in the overall cooking time. While a higher temperature will result in a shorter cooking time, it will not necessarily yield the result that you’re looking for. A 15-pound brisket is a very large cut of beef with a lot of fat and connective tissue. If you want your brisket to be tender, it will take time for the cooking process to break down the tough connective tissue and meat fibers. The best brisket is going to be one that is cooked low and slow at a temperature of 225°F to 250°F. Some competition Pitmasters will cook their brisket at 275°F, but I have never had much success cooking at that higher temperature. Go low and go slow.
Smoking a brisket does not affect the overall cooking time. Smoke adds flavor and some nice color, but does nothing to increase or decrease the rate at which the brisket will cook.
Fat Side Up or Down
A whole packer brisket will have a fairly large fat cap on one side that, left untrimmed, will adversely affect cooking time. Trim the fat cap back to about ¼ inch thick across the entire brisket. Watch my YouTube video on How to Trim a Beef Brisket. Even after trimming, there will be a fair amount of fat left on the brisket, and that is good for flavor.
There has been much written about the best orientation for brisket while it cooks. Some prefer fat side up, while others prefer fat side down. My personal preference is to cook a brisket fat side up. I think it’s the best way to get a little more fat distributed throughout the meat. Some of that fat penetrates the meat as it melts and helps keep the brisket moist. I have tried both methods and did not see any appreciable difference in overall cooking time.
Thickness of the Brisket
OK, this is one of those situations where size does matter. A 3-inch thick brisket will cook faster than a 4-inch thick brisket of the same weight. A thicker brisket will simply take a long time to heat through at a low temperature. So, when you are looking at the cooking times below, plan on the higher side of the range for a thick brisket.
The cooking method (oven vs. smoker) should not affect the overall time that it takes to cook a brisket, but it will affect the variation in ambient temperature inside the cooker. For example, a typical home oven can easily have an internal ambient temperature variation of plus or minus 25°F. I owned a name brand high-end oven that would cycle on and cycle off exactly 25° above or below the temperature set. If I set the oven for 225°F, it would cycle on until the internal temperature reached 250°F, then cycle off until the temperature dropped to 200°F. It was annoying to say the least and my wife hated to bake in it.
The temperature variation is much easier to control in a Kamado Joe or a Big Green Egg when using a good temperature control device like a Fireboard. It’s just not practical to cook a brisket with an instant-read meat thermometer. Every time you open the lid you add 10 minutes to the cooking time. At the very least, invest in a thermometer that you can put in and leave in. Place it in the thickest part of the brisket and let it stay there. If you are not familiar temperature controllers, watch my YouTube video on How to Use a Fireboard with a Kamado Joe.
Internal Temperature of the Brisket Before Cooking
The internal temperature of the brisket before it goes into a smoker does make a difference in the overall cooking time. A brisket right out of the refrigerator that is 34°F is going to take a lot longer to cook than a brisket that has sat out for 90 minutes. Also, smoking a brisket right out of the refrigerator runs the risk of drying out the outside before the inside is done. Do yourself a favor and take let your brisket warm up to close to room temperature (about 90 minutes) before placing it in your smoker.
The First Stage of Cooking
Smoking a brisket involves two distinct stages of cooking. The best brisket is cooked over low heat for a long period of time. In the first stage, the brisket cooks over a pan of water and indirect heat at 225°F – 250°F. I don’t like using high temperatures because I think it is more difficult to control the process when the brisket is cooking faster. This stage is where the brisket picks up the smoke flavor and forms a nice crust. The internal temperature will climb steadily to about 165°F and then stop. The internal temperature will just sit there hovering around 165°F and not move, seemingly forever. Welcome to the infamous stall.
The stall is the mysterious point in the life of a brisket where the cooking temperature stops climbing until some moisture in the brisket burns off. The brisket will form moisture on the crust that cools the brisket as it evaporates. The evaporation keeps the internal temperature from rising. In fact, the internal temperature of the meat may actually fall a few degrees during the stall. The internal temperature of the brisket is simply not going to move until the evaporation stops.
Resist the temptation to open the lid and peek. Resist the temptation to add more wood. You will just lengthen the overall cooking time every time you do. Be patient. The stall will end, eventually. When it does and the temperature starts to climb, the first stage of cooking is done. It’s time to take the brisket out and wrap it up.
Remember the water pan mentioned above? A pan of water set in the smoker, preferably below the brisket if possible, helps maintain a bit of humidity inside the smoker. This, in turn, helps the brisket preserve some of its moisture resulting in a juicier brisket.
This first stage of smoking a brisket can take a while. A 15-pound whole packer brisket could easily take 7 – 9 hours to reach the stall and another hour or so to break through the stall.
Wrap the Brisket
Most every pit master in Texas wraps their brisket. It’s an essential part of the whole cooking process because it helps keep the brisket moist and prevents it from drying out. A brisket can be wrapped in aluminum foil, a technique called the Texas Crutch. The foil basically steams the brisket and produces an end product a bit like a pot roast. The taste will be fine, but the texture of the meat will be loose.
Many BBQ gurus, including Aaron Franklin and cookbook author Steve Raichlen, use pink butcher paper (aka peach butcher paper) exclusively. The pink butch paper allows the brisket to breathe, resulting in a moist brisket with a better texture. Peach butcher paper is easy to find online, I bought mine at webstaurant.com.
The Second Stage of Cooking
Once the stall is over, the internal temperature of the brisket will, once again, steadily climb. This is the second stage of cooking and it is where the connective tissue breaks down resulting in tender meat. It’s also the stage where a lot of the fat will finally be rendered. Continue to cook the brisket until the internal temperature reaches 203°F. This could easily take another 2 – 4 hours or more, depending on the size of the brisket.
Look at my post How to Know When a Brisket is Done for more details about the cooking process.
Let the Brisket Rest
Just because your brisket has reached the ideal temperature doesn’t mean it’s ready to eat. Slice the brisket now and all of the juice will literally run out and you will end up with dry brisket. To get a juicy brisket, just let the brisket rest. I wrap my brisket in plastic wrap then a few old bath towels before placing it inside a small insulated cooler for two hours. This allows the muscle fibers to relax and the juices to be reabsorbed. The brisket in the photo below was cut too soon. Look at how dry it is.
The brisket in the picture below rested for two hours before it was cut. Look at how juicy it is.
When it comes time, cut the brisket across the grain. Watch my video on Smoked Beef Brisket and Burnt Ends for tips on how to notch the brisket before cooking to make cutting across the grain easier.
So, how long does it take to cook the perfect brisket? A good rule of thumb is to allow for 1.25 - 1.5 hours per pound of meat at 225°F and 1.0 – 1.25 hours per pound of meat at 250°F. These numbers are for a trimmed brisket. Remember, to weigh your brisket after trimming or you will just be guessing.
If you are going to invest the time and money into making the perfect smoked brisket, then you should also consider making your own rub and BBQ sauce. Both are easy to make and taste great. Take a look at my Kansas City BBQ Dry Rub recipe and Bourbon Barbecue Sauce recipe for inspiration.
Smoking a 15-pound brisket to perfection is certainly an undertaking, but definitely worth the effort. Be patient, enjoy the process and savor the mouthwatering results. Happy smoking.
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