Harvard engineering students devise BBQ smoker(bostonglobe.com)
bostonglobe.com
Harvard engineering students devise BBQ smoker
http://www.bostonglobe.com/metro/2015/05/05/harvard-class-cooks-ultimate-bbq-smoker/0O4fLQ0rbt9qMGsllPoTjK/story.html?p1=Article_Trending_Most_Viewed#
56 comments
Franklin uses pink butcher paper, not foil. While the cook will be shortened with the crutch it is done at the expense of the bark. Crutching makes for a softer less "barky" bark. This is, supposdaly, one of the benefits to using butcher paper as it permits the meat to continue to breath and therefore has less of an impact on the bark formation.
"right temperature for a brisket" --> to clarify, you mean the "right temperature to smoke a brisket", not the right temperature for the meat.
Brisket (whole, untrimmed) takes about 1.5 hours per pound at a cooking temp of 225-250F. You really get the maximum smoke up through the range of 125 through 150 or so as the smoke ring forms...it's all related to collagen breaking down. Past that, the smoke isn't doing much except producing a good bark.
Here are my tips if you're doing this:
* Use untrimmed whole brisket. Fat matters.
* Get a Weber bullet and learn to use it. Rock solid in terms of maintaining temperature once you learn it.
* Leave the brisket on until you get into the 185-195F range. This might take 1 to 1.5 hours per pound. I've taken 18 hours for a 12 pound brisket.
* Depending on the time you want to serve it, here's where you have to adapt to meet your crowd's needs. If you're ahead of schedule, let it slowly rise on the smoker to the 195-205 range. If you're still early, wrap in foil and pack in a cooler, hich can help you hold temp for a few hours. If you're behind then you'll want to foil wrap, oven finish (or just foil wrap and ramp up to 275 on the heat), but allow enough time for it to rest.
The briskets I've screwed up were pulled off too soon (internal temp in the 185 range). The better ones were the ones I let get up to 195-205 (usually oven finished because I went too slow) and rested before slicing.
The best part of a whole brisket is trimming off the point, cubing it up, foil-wrapping it with some sauce inside, putting it back on for burnt ends. It's often a pound or so of meat that makes for great sandwiches for a few days after on toasted Texas Toast.
There is nothing more delightful in the world than snarfing up the trimmings of a well-smoked brisket...
Brisket (whole, untrimmed) takes about 1.5 hours per pound at a cooking temp of 225-250F. You really get the maximum smoke up through the range of 125 through 150 or so as the smoke ring forms...it's all related to collagen breaking down. Past that, the smoke isn't doing much except producing a good bark.
Here are my tips if you're doing this:
* Use untrimmed whole brisket. Fat matters.
* Get a Weber bullet and learn to use it. Rock solid in terms of maintaining temperature once you learn it.
* Leave the brisket on until you get into the 185-195F range. This might take 1 to 1.5 hours per pound. I've taken 18 hours for a 12 pound brisket.
* Depending on the time you want to serve it, here's where you have to adapt to meet your crowd's needs. If you're ahead of schedule, let it slowly rise on the smoker to the 195-205 range. If you're still early, wrap in foil and pack in a cooler, hich can help you hold temp for a few hours. If you're behind then you'll want to foil wrap, oven finish (or just foil wrap and ramp up to 275 on the heat), but allow enough time for it to rest.
The briskets I've screwed up were pulled off too soon (internal temp in the 185 range). The better ones were the ones I let get up to 195-205 (usually oven finished because I went too slow) and rested before slicing.
The best part of a whole brisket is trimming off the point, cubing it up, foil-wrapping it with some sauce inside, putting it back on for burnt ends. It's often a pound or so of meat that makes for great sandwiches for a few days after on toasted Texas Toast.
There is nothing more delightful in the world than snarfing up the trimmings of a well-smoked brisket...
Nathan Myhrvold in Modernist Cusine writes about a similar technique. Sous vide first, followed by a brief time in the oven, and finished on a smoker. This seems to be the reverse of the crutch. (The oven is used to prime the meat for smoking and is apparently based on a German technique for making sausages.)
Of course if you cringe at wrapping your smoked food in foil you'll hate this way too. I'm also not sure if this is the technique he used to win his bbq medals, perhaps that's a secret.
Of course if you cringe at wrapping your smoked food in foil you'll hate this way too. I'm also not sure if this is the technique he used to win his bbq medals, perhaps that's a secret.
As soon as the meat reaches ~130f, it's not going to absorb any more smoke.
Interesting. There seem to be conflicting opinions here. Referring again to Blonder[0], it seems that one can improve smoke absorption by mopping consistently. Personally, I'm usually pretty aggressive with the mopping, that is, every 45 minutes to 1 hour.
[0] http://www.genuineideas.com/ArticlesIndex/srasmokeringmoist....
[0] http://www.genuineideas.com/ArticlesIndex/srasmokeringmoist....
Lookin' ain't cookin' are the words I live by. (Brisket is very, very forgiving if you go low and slow and just focus on the internal meat temperature. Maintain 225-250F with the smoker, don't worry about short spikes, focus mostly on the target temperature.)
Turn once 50% into the cook (pounds * 1.5 hours), again at 75%. Spray apple juice.
I learned a ton from the Virtual Weber Bullet forums. From the perspective of food hacking, the HN crowd would really love it--lots of overlap with the approach, even a lot of good "hardware" mods.
Turn once 50% into the cook (pounds * 1.5 hours), again at 75%. Spray apple juice.
I learned a ton from the Virtual Weber Bullet forums. From the perspective of food hacking, the HN crowd would really love it--lots of overlap with the approach, even a lot of good "hardware" mods.
Could you explain why? Is it a property of the meat?
I should be more careful in how I write comments. What I should have said was: a few Cooking Issues episodes ago, Dave Arnold talked to the head smoker guy at Underground Meats in Madison, who said something to the effect of: there's minimal penetration of smoke into meat after ~130f.
I was under the impression from his book and his videos[0] that Franklin's didn't use the crutch as "policy" unless it was necessary...but I've never been lucky enough to get down there to Austin yet so I can't say for sure.
[0] https://youtu.be/pGZ39yYxeBk?t=5m7s
[0] https://youtu.be/pGZ39yYxeBk?t=5m7s
Might want to hurry http://reason.com/archives/2015/05/09/will-austin-proposal-t...
If you've ever wondered what the real value of going to Harvard is, it's all in this sentence from the article:
> On a hike up Camelback Mountain in Arizona, he pitched the idea to executives from Williams-Sonoma, who agreed to be the client for his class.
Just casually pitched an exec and got a brisket sponsor, no big deal...
> On a hike up Camelback Mountain in Arizona, he pitched the idea to executives from Williams-Sonoma, who agreed to be the client for his class.
Just casually pitched an exec and got a brisket sponsor, no big deal...
I think the article exaggerates the lack of accessibility in BBQ. There sure is a fair amount of BBQ-broscience but resources like AmazingRibs.com, Aaron Franklin's YouTube videos, and Virtual Weber Bullet all have great recipes, guides, and forums. The challenge is that BBQ is true regional American cuisine, with a lot of variation. This is similar to authentic Chinese or Indian food where there are significant differences among the regional flavors, techniques and ingredients. The cooking tools aren't overly dissimilar, or don't really need to be, as traditional pits are pretty impractical... but you have to know what flavors and textures you're looking for.
I own a Big Green Egg (ceramic Kamado-style oven) and a Weber Smokey Mountain (a vertical water smoker) and I have a hunch right away as to the improvement with this device.
The Egg is quite versatile in that you can do direct grilling along with indirect slow roasting, by use of a "plate setter". This is a large ceramic plate with legs that is very similar to what is used to fire plates in a kiln, though in this case it acts as a heat sink and shield between the meat and the fire.
The hourglass shape enables a better blockage of direct heat from the main cooking chamber. BGE plate setters have gaps on the sides that in the case of large briskets can burn the ends, leading to a form of traditional "burnt ends" unless you're diligent about dousing hotspots with a water gun and mopping/spritzing regularly.
This is partly why I prefer the Weber smokey mountain for brisket. That said, Kamados are very easy to use - dump your lump, light a couple paraffin cubes, and you're up in 20 minutes.
I own a Big Green Egg (ceramic Kamado-style oven) and a Weber Smokey Mountain (a vertical water smoker) and I have a hunch right away as to the improvement with this device.
The Egg is quite versatile in that you can do direct grilling along with indirect slow roasting, by use of a "plate setter". This is a large ceramic plate with legs that is very similar to what is used to fire plates in a kiln, though in this case it acts as a heat sink and shield between the meat and the fire.
The hourglass shape enables a better blockage of direct heat from the main cooking chamber. BGE plate setters have gaps on the sides that in the case of large briskets can burn the ends, leading to a form of traditional "burnt ends" unless you're diligent about dousing hotspots with a water gun and mopping/spritzing regularly.
This is partly why I prefer the Weber smokey mountain for brisket. That said, Kamados are very easy to use - dump your lump, light a couple paraffin cubes, and you're up in 20 minutes.
I agree, there's plenty of good online resources, and brisket especially is pretty straightforward. When I was learning, I absorbed Aaron Franklin's videos and was delighted with the results even as a beginner. By the time I mustered the willpower to actually wait in line and try some BBQ at Franklin's, I was pleased to find that I really wasn't too far off.
This line from the article was a little silly: "In the end, the secret was to precisely control the temperature both in the smoker and in the meat over the “low and slow” smoke."
When really the importance of heat control is pretty well known. Something I use and that may be of interest to HN is a heatermeter:
https://github.com/CapnBry/HeaterMeter
which uses a fan to maintain a set temperature automatically and has a web interface to monitor it remotely. The article mentioned the students had built something similar too.
This line from the article was a little silly: "In the end, the secret was to precisely control the temperature both in the smoker and in the meat over the “low and slow” smoke."
When really the importance of heat control is pretty well known. Something I use and that may be of interest to HN is a heatermeter:
https://github.com/CapnBry/HeaterMeter
which uses a fan to maintain a set temperature automatically and has a web interface to monitor it remotely. The article mentioned the students had built something similar too.
I love kamados, but if one is really concerned with temperature control I don't see how one could beat a water bath for cooking with a separate smoking step.
Also, while interesting, that hyperboloid profile has significant disadvantages compared to the more traditional ovoid used by the BGE and clones: more difficult to manufacture, internal stresses, smaller cooking area, more weight, etc. Good engineering practice would need to account for those. I don't expect a news article to address any of this, but I would be interested to hear what was considered in class.
Also, while interesting, that hyperboloid profile has significant disadvantages compared to the more traditional ovoid used by the BGE and clones: more difficult to manufacture, internal stresses, smaller cooking area, more weight, etc. Good engineering practice would need to account for those. I don't expect a news article to address any of this, but I would be interested to hear what was considered in class.
When Nathan Myhrvold visited Google and spoke, I asked him what he thought the "best" way to make BBQ ribs was (with a stretched definition for "BBQ").
He said: sous vide, arrest via dipping in liquid nitrogen, deep fry, then smoke.
I'm so conflicted with Myhrvold: I hate Intellectual Ventures and what they do with the passion of a thousand suns, but Modernist Cuisine is an incredible and seminal work of art and science.
The modernist methods for BBQ do consistently produce a great que, but throwing a butt on an egg slow and low tastes just about as good and takes a lot less work.
The modernist methods for BBQ do consistently produce a great que, but throwing a butt on an egg slow and low tastes just about as good and takes a lot less work.
The other thing I asked him about was BBQ stall.
He had done some nice work providing evidence against the "it's just fat melting" theory (he prefers the idea there is water vapor around the meat, absorbing the heat). I suggested that one could wrap the butt in aluminum foil, which would eliminate the evaporation and cause much more of the low heat to stay within the body of the meat.
That would presumably affect the bark, which is why he suggested the deep fry, although I don't think that's really the same as a slow bark.
He had done some nice work providing evidence against the "it's just fat melting" theory (he prefers the idea there is water vapor around the meat, absorbing the heat). I suggested that one could wrap the butt in aluminum foil, which would eliminate the evaporation and cause much more of the low heat to stay within the body of the meat.
That would presumably affect the bark, which is why he suggested the deep fry, although I don't think that's really the same as a slow bark.
If you don't want to build your own, the green egg is a really solid ceramic smoker/oven. expensive but the results are consistently good.
You can build a really cheap smoker out of a ceramic flower pot. I built one after I saw Alton Brown talking about it.
Mine is almost exactly like this one, except that I replaced the top pot with a ceramic lid. https://www.youtube.com/watch?v=ZAydLWYGoJA
I've been thinking about building a PID controller for it (I already have the equipment from a project I did for an embedded systems lab in college), but I'm worried I'll end up eating way too much barbecue.
Mine is almost exactly like this one, except that I replaced the top pot with a ceramic lid. https://www.youtube.com/watch?v=ZAydLWYGoJA
I've been thinking about building a PID controller for it (I already have the equipment from a project I did for an embedded systems lab in college), but I'm worried I'll end up eating way too much barbecue.
I've built a couple of smokers out of cardboard boxes and they were fantastic.
I got a large box (like refrigerator might come in), cut the bottom out and cut a door leaving one side for the hinge. I then used a pencil to poke some hole and ran dowels through the box horizontally to put the racks on. An electric hotplate and a cast iron skillet full of apple wood chips provides the smoke. I put it on the concrete and put the box over the top of it. I put a meat thermometer in the top of the box. Warning: the first time I did this, the concrete under the box was also smoked and I had a large black square on my patio. Cover the concrete with tinfoil to avoid this.
This method produces a lot of smoke and not much heat. I've done salmon and a couple of turkeys like this. I let them smoke for 4 or 5 hours, then finish them off in the oven. Rave reviews on the turkey at thanksgiving. The whole thing cost like $10 to make (I already had the hotplate).
I got a large box (like refrigerator might come in), cut the bottom out and cut a door leaving one side for the hinge. I then used a pencil to poke some hole and ran dowels through the box horizontally to put the racks on. An electric hotplate and a cast iron skillet full of apple wood chips provides the smoke. I put it on the concrete and put the box over the top of it. I put a meat thermometer in the top of the box. Warning: the first time I did this, the concrete under the box was also smoked and I had a large black square on my patio. Cover the concrete with tinfoil to avoid this.
This method produces a lot of smoke and not much heat. I've done salmon and a couple of turkeys like this. I let them smoke for 4 or 5 hours, then finish them off in the oven. Rave reviews on the turkey at thanksgiving. The whole thing cost like $10 to make (I already had the hotplate).
The cheaper kamado-style/big green egg clones are pretty good these days. I recently picked up a Kamado Kooker with stand for ~$300 vs. >$1000 for the similar size Big Green Egg and stand, and have been quite happy with it.
It's actually in the background of the last photo. Looks like they were comparing to the competition.
Strangely the article doesn't mention it, even though there's one in the photo.
I have a related project that I've considered commercializing. I've built a temperature controller with an embedded linux board that serves a webpage and runs a python websocket server that updates the page. I've also got a daughterboard with a thermocouple amplifier and transistor to power a small fan that feeds the fire. The system logs and graphs temperature data. It's basically complete control from your phone.
http://imgur.com/a/aGr0H
http://imgur.com/a/aGr0H
This is awesome. The big issue for me when I've considered this is the operating conditions. You're hosting a linux board near a 250 degree source of heat that may be operating in ambient conditions that range from 35F and very rainy to 100F summer smoke.
The board doesn't have to be near the fire. Even the fan is separated. I 3d printed a fan mount that threads onto a pipe that runs into the firebox. The board' temperature range is 0-70C, so freezing temperatures would be a problem, but high temperatures. The rain would be an issue though.
If you're willing to throw it up on github, I'd love to see the code that you're running. I'd understand if you want to avoid that if you're planning on commercializing it, though.
I'm an embedded developer, so this has been my first experience in HTML/CSS/JS/Websockets. Here's a general overview:
The Python server periodically reads the thermocouple chip over SPI and sends a JSON object over the websocket with temperature and time data.
The javascript websocket handler is a switch statement to parse the incoming JSON, which is data updates, log info, and graph data.
Each button on the webpage has a jQuery callback that sends a JSON command over the websocket.
The Python websocket handler has a class for each command, which is set point control, hysteresis control, fan on/off/auto, start log, finish log, delete log, fetch log info, fetch graph data. Incoming JSON is deserialized into a command object, and command.parse() processes the command through polymorphism.
The application is working well. What's holding me back is the general logistics of joe consumer connecting to the device. The system can act as a wifi access point, or it can join a network. The access point will be easier for a user to connect to, and I can run mDNS to give it an address like smoker.local, but it seems cumbersome to have to change your wifi every time you want to open the app. On the other hand, if it's on a network, there's no easy way to discover it without going into your router settings. Then you're going to 192.168.1.149. Building native Android and iOS apps would solve that, but I'd really like to keep it as a webapp.
The Python server periodically reads the thermocouple chip over SPI and sends a JSON object over the websocket with temperature and time data.
The javascript websocket handler is a switch statement to parse the incoming JSON, which is data updates, log info, and graph data.
Each button on the webpage has a jQuery callback that sends a JSON command over the websocket.
The Python websocket handler has a class for each command, which is set point control, hysteresis control, fan on/off/auto, start log, finish log, delete log, fetch log info, fetch graph data. Incoming JSON is deserialized into a command object, and command.parse() processes the command through polymorphism.
The application is working well. What's holding me back is the general logistics of joe consumer connecting to the device. The system can act as a wifi access point, or it can join a network. The access point will be easier for a user to connect to, and I can run mDNS to give it an address like smoker.local, but it seems cumbersome to have to change your wifi every time you want to open the app. On the other hand, if it's on a network, there's no easy way to discover it without going into your router settings. Then you're going to 192.168.1.149. Building native Android and iOS apps would solve that, but I'd really like to keep it as a webapp.
This is an awesome project! Don't let this network issue hold you back. What do you think about joining the network and displaying the IP in a dirt cheap LED screen? You can even use this screen to add additional value, like for example alarms, status, etc.
The first time joe consumer will need to write 192.168.1.149, but then his browser will autocomplete the address.
Go ahead, and go big! :-)
Go ahead, and go big! :-)
why not bluetooth then and make a real app instead of a webpage?
For those in the Seattle area, Jacks in Sodo is where you can get your BBQ fix. Best brisket outside of Texas.
One thing that they don't talk about at all is meat quality. Whom you buy your brisket from can be much more important than optimizing every detail of the smoking process.
I wonder if they really used mesquite as their wood or if that was some artistic license on the author's part. If so it would be an interesting choice. Mesquite burns hot, produces a lot of smoke and can very easily impart a harsh bitter flavor. It's a tough wood to get right.
Mesquite is the traditional wood for Texas-style beef brisket. Pork and chicken may not be able to stand up to the stronger flavor of mesquite, but beef does well with it.
Or at least that's what I've read. My smoking experience is very limited, but I've done a lot of reading.
Or at least that's what I've read. My smoking experience is very limited, but I've done a lot of reading.
Maybe in West Texas. Hickory and oak are more traditional for central Texas. Pecan and apple are good too. Mesquite is too bitter for me, but I grew up cooking with oak.
Oak is the traditional wood, not mesquite.
Mesquite is best for grilling due to its flavor and strength. You can smoke with it, but you really need to like Mesquite.
Oak and/or Hickory is usually what I've seen and used. I also like Pecan. (smoking briskets for about 5 years)
Oak and/or Hickory is usually what I've seen and used. I also like Pecan. (smoking briskets for about 5 years)
Apple wood can make outstanding pork & lamb.
I prefer the hot and fast cooking method (smoking temperature around 275). Ribs can be smoked in an hour and 10 minutes. I compete in KCBS sanctioned bbq events and do well using the hot and fast method. I've tried many smokers out over the years and now solely use vertical drum smokers (specifically Hunsaker Vortex Smokers) as they do well with the hot and fast method.
This one is also a temperature-controlled, natural fuel BBQ and smoker: http://www.grilltender.com/
PID controller, fan, heater and SSR relay is all you need.
"Berkeley engineering students respond with automated bong."
Anyone hungry tonight? How about some delicious Boston-style BBQ? Harvard-style BBQ? Engineering student-style BBQ? Anyone?
Harvard is one of the world's great educational institutions, but perhaps it's spreading the branding a little thin to apply it to BBQ made by engineering students.
Now a BBQ smoker from Central TX A&M might be interesting.
Harvard is one of the world's great educational institutions, but perhaps it's spreading the branding a little thin to apply it to BBQ made by engineering students.
Now a BBQ smoker from Central TX A&M might be interesting.
You say "Boston-style BBQ", and I think of Redbones and shudder. I'll take a chance on the students' brisket.
Seems to be a popular We-put-a-chip-in-it subject: http://venturebeat.com/2015/03/14/at-sxsw-ge-shows-how-data-...
Seems to be a popular We-put-a-chip-in-it subject: http://venturebeat.com/2015/03/14/at-sxsw-ge-shows-how-data-...
While I agree with the sentiment.. I do think the resulting device is a better design than most home smokers I've seen... Though given the materials, and likely the weight... The cost will probably be relatively expensive for home use. Not to mention, too small for commercial use.
If they could build one that is about 6x the total size, but could handle 15x the amount of meat... that's something quite a few chains might be interested in. Not that I disapprove of what they've done at all... gives me a lot of ideas, but more like something I would make, and not necessarily buy.
If they could build one that is about 6x the total size, but could handle 15x the amount of meat... that's something quite a few chains might be interested in. Not that I disapprove of what they've done at all... gives me a lot of ideas, but more like something I would make, and not necessarily buy.
Yeah, it makes me think of the knockoff "New Jersey Fried Chicken" and "Wisconsin Fried Chicken" restaurants you see in other countries.
Edit: some examples
https://www.pinterest.com/rhysdgriffiths/not-quite-kentucky/
Edit: some examples
https://www.pinterest.com/rhysdgriffiths/not-quite-kentucky/
What's the difference between Austin and Boston when it comes to cooking brisket? Given the ubiquity of information and the ease of travel, I wouldn't place such a premium on location. Some of the best BBQ I've ever had was in Brooklyn (and I didn't have to wait 2 hours for it).
Experience and standards? It's like asking what's the difference between NY Style pizza in NY and NY style pizza in LA. Do you think they are the same? It's also like saying that TexMex in MN is the same as in TX or CA.
Anybody can open up an BBQ place in Anytown, USA, and it could be passable or even pretty good, but it'll not beat a moderately good place in a town known for BBQ. It's mostly because the low quality places get run out of town to those with exceptional BBQ, and maybe even thrive in places where BBQ joins are scarce. Making really good BBQ is an art, and takes many years of experience and practice, maybe even mentoring under a master. Some guy smoking a brisket following a recipe online isn't going to come near even low quality BBQ restaraunts. Not without a lot of experience, trial and error, and by that point they aren't even following the recipe any longer.
Anybody can open up an BBQ place in Anytown, USA, and it could be passable or even pretty good, but it'll not beat a moderately good place in a town known for BBQ. It's mostly because the low quality places get run out of town to those with exceptional BBQ, and maybe even thrive in places where BBQ joins are scarce. Making really good BBQ is an art, and takes many years of experience and practice, maybe even mentoring under a master. Some guy smoking a brisket following a recipe online isn't going to come near even low quality BBQ restaraunts. Not without a lot of experience, trial and error, and by that point they aren't even following the recipe any longer.
Aaron Franklin just got the James Beard stamp of approval, winning Best Chef: Southwest for 2015. I expect there'll be Franklin-Style BBQ "Just Like Austin" places opening up around the country as a result.
http://dining.blog.austin360.com/2015/05/04/aaron-franklin-w...
http://dining.blog.austin360.com/2015/05/04/aaron-franklin-w...
Somehow I suspect this would have turned out better if they were UT or A&M students. Oh wait... can we just put brisket Texas students make using tin foil and a crock pot up against the brisket made by the Harvard kids? I'm pretty sure talent and experience will triumph over technology.
[deleted]
The upshot of the Texas Crutch technique is: after about 2 hours on the smoke, the internal temperature of a brisket will plateau for 6-8 hours before climbing toward its final temperature. According to experiments by Greg Blonder[0], this stall is caused by evaporative cooling: once the internal temperature reaches a point where the energy lost to evaporation balances the energy gained from the (low---225-250 Fahrenheit is the "right" temperature for a brisket) ambient temperature, the internal temp of the meat will stay put until sufficient water has evaporated.
Some call this cheating, but in my experimentation the "crutch" produces significantly tastier results because of the difference in juiciness. As additional evidence here, I'll note that every BBQ place in Austin whose brisket is good to great---Franklin, La Barbecue, John Mueller Meat Co., and even Rudy's---wraps their briskets in foil. (Edited to add: I didn't mention Black's and Kreutz's because I'm not 100% sure that they do, but I vaguely recall that they do.)
One worry might be that the meat doesn't absorb as much smoke after the foil is applied, and this is indeed true. One can trade off additional time in the smoke for more evaporation. After about 4 hours, the meat isn't going to absorb much more flavor from the smoke, so that's a great time to wrap it.
In fact, at that point you may as well make your life easier by transferring the meat to an oven (ideally, a convection oven to avoid hot spots) and finishing it off. It may feel wrong, but in my experience the results are superb.
[0] http://www.genuineideas.com/ArticlesIndex/stallbbq.html