Cooking food with heat is a far more subtle process than simply applying heat. Beyond that doubling the temperature obviously doesn’t cook something twice as fast, there is a vast array of stunningly complex chemical reactions that occur as food is heated.
Even the seemingly simple act of hard boiling an egg will cause the yolk and white to pass through nearly a dozen different phases as different temperature thresholds are crossed and different proteins and nucleic within the white and yolk are denatured. For an egg, the difference between clear, runny, jelly-like, and hard boiled is only a matter of degrees!
And some reaction can take quite a while, too. Making pulled pork, something for which I have a bit of experience, involves heating the meat to a temperature such that the collagen and fat effectively changes from a tough, chewy, substance into liquid or a jello like cloud of delicious. Done right, this can take hours or, even, days.
With a stove, grill or — even — an oven, it is extremely difficult to both maintain a constant temperature and not dry the food out.
Enter sous vide.
Sous vide means, literally, “under vacuum”. That is, in sous vide cooking, the food is vacuum packed, often with spices or marinades. The actual process of cooking, though, is generally done in a water oven; a device that can maintain a bucket of water at a very precise temperature.
Precise as in the ability to cook an egg to exactly 144 degrees throughout, just hot enough that the white is semi-solid but still runny while the yolk is nearly, but not totally, liquid. I.e. the perfect poached egg. Or 72 hour pulled pork at 141 degrees that comes out fork tender, medium-rarish, but with the flavor of ham. Or the perfect rare, fork tender, short rib by cooking at 138 for 48 hours.
“But, wait!, pork at 141?!?! Beef @ 138? The FDA says we need to reach ~160 for them to be safe!! You are gonna kill someone!”
Those temperatures are actually the instant kill temperatures for food borne pathogens. If you get the inside of a steak to 166, all bad critters will be dead. However, said same critters cannot survive at ~135 or above and, thus, if you keep the meat at said temperature for long enough, the bad critters will generally be just as dead.
This isn’t the end of the story and I encourage you to both read Douglas Baldwin’s Sous Vide for the Home Cook and, covering much more than just sous vide and the single most accessible and entertaining science oriented cookbook around Jeff Potter’s Cooking for Geeks: Real Science, Great Hacks, and Good Food
(seriously — get this book — even if you have a moratorium on cookbooks, get this book!!).
I had the pleasure of hearing Jeff speak and having lunch with him. It was that conversation that convinced me to dive into Sous Vide cooking; it scratches all of the über-control penchant of my geekiness while promising to yield new potential heights to appease my chefiness.
At left is the SousVide Supreme, an appliance that quite conveniently maintains a bath of water at whatever temperature you want from less than 100 degrees up to just below boiling point.
There are also a number of homebrew solutions and lab quality circulators (no surprise, heating some live soup of pathogenic critters to ideal reproduction temperatures is a long solved problem in the lab). And you can go the PID controller route and whip up a hot water oven for ~$50 (link to an excellent write-up on doing exactly that).
I personally chose the SVS both because I didn’t have a crock pot and the good quality lab circulators are typically considerably more expensive. As well, the margin for error with Sous Vide can be pretty damned narrow when cooking at the border of pathogenic reproduction temperatures; best to have a dead accurate unit than one that is off by 5 degrees.
NOTE: Since writing this article, I sold my SVS to a friend and upgraded to the Polyscience Sous Vide Professional. While more expensive, it is both slightly more accurate and, the motivating factor, vastly more versatile. As an added benefit, there is no big, single purpose, metal tub. Storing the Polyscience circulator takes vastly less room and the device can maintain temperature on a truly huge tub of water (up to 30 liters). I have various sized Cambro food trays and, thus, I can choose a smaller container when doing a handful of eggs, a deep container when doing very veggies that like to stand up, or a really large 25L relatively shallow container when cooking 5 slabs of my now infamous 65 hour tropical BBQ pork ribs!
For vacuum sealing, I’m using a FoodSaver v3840 upright sealer. In hindsight, I would much rather have a clam shell vacuum sealer as they waste less bags and, though seemingly less convenient, are easier to align the bag for sealing purposes.
In the 2 weeks I’ve had the SVS, I’ve been able to produce some truly amazing foods (and one really bland bit of food). I’ve learned a lot and also come to realize that this is really an area of cooking for which there is no deep history or reference tome. A lot of times you are on your own. And as long as you follow the safety rules put forth in both Douglas’s and Jeff’s books, you’ll always be safe even if your meal turns out inedible (as Jeff likes to say, even the worst meal can be improved by a quick call to the local pizza delivery service).
So, what have I cooked?
In Shell Poached Eggs
Since I’ve discovered how easy it is to make excellent quality artisan bread, I figured I’d start with a dead simple poached egg, one of my wife’s favorites. A couple of hours at 145 degrees yielded eggs that were perfect; cracked out of the shell as a whole, yet were obviously barely held together by an outside layer of solidified proteins (there are actually about 6 layers to an egg). The yolk was runny, but not clear, and the white was almost solid.
Coincidentally, one of the folk working on our house brought by a dozen fresh eggs from his hens which were then poached. Oh, wow! Best. Eggs. Ever.
Next I made a basic steak. I thawed a nice, but unremarkable, cut of grass fed steak, lightly seasoned it with salt and pepper, sealed it away and dropped it in the sous vide for a few hours at 55 degrees Celsius. Once done, I unbagged the steak and seared it for about 15 seconds a side in a red-hot cast iron pan (used oil, don’t bother — just a dry pan is all that is needed) to put a little texture on the outside and add flavors from the Maillard reaction that occurs at higher temperatures.
End result? A perfect medium rare steak from edge to edge with a slightly crunchy crust. Very tender and delicious.
Overcooking is hard with sous vide. Since you are targeting a particular temperature to achieve a particular set of chemical reactions within the food, you can leave the food in the water bath at that temperature for a long time without adversely impacting the flavor or texture. To a point; there are still reactions occurring — collagen breaking down, for example — but they are pretty slow. Hence, I left the steak in for an extra hour without worry.
This was a lose and it was entirely my fault. First, I made the mistake of not adding a marinade to the meat. Secondly, I didn’t clean up the thighs enough, leaving behind tasty — but unappetizing to see — bits of fat. Finally, I cooked it at too low of a temperature to get away with; high enough to be perfectly safe, but low enough that the pinkish color and the bloody liquid near the fat wasn’t something the family could deal with. That, and lacking a searing step (or good sauce), yielded chicken that was akin to very firm boiled chicken.
It is critical to consider both the likely broken food norms of your audience & the total consistency of the meat can be off putting. For the latter problem, it is a matter of having a tasty sauce, a plating that involves pre-cutting with something that can provide texture, and/or a searing step to add color, crisp & maillard reaction byproducts to the food. For the former, you just need to know your audience. In the United States, we have been so trained to believe that any pink or bloody liquid in pork or chicken means you gonna die! die! die! That just isn’t true, but it’ll take a few meals before your audience might be comfortable with a big piece of delicious rare pork.
In January, I bought some whole salmon from the farmer’s market and cut it down to nice fillets that were then vacuum packed and deep frozen. I cooked it at 131 degrees for a couple of hours to fully pasteurize (remember those pasteurization tables?) and simply cut open the bag, threw it on a plate and ate it.
Amazing. Buttery tender, but still had texture. Interestingly, I cooked it with the skin on, but the skin was so tender it cut with a fork just like the rest of the fish. The flavor was divine, the texture perfect, and the convenience factor is extreme; just grab a pack o’ frozen fish from freezer, drop it in the sous vide bath and forget about it for a couple of hourse.
You can easily vacuum pack the courses of a meal, with all spices/ingredients in the bag, freeze it, and then just pull the bag and drop in the warm water bath. Three items of note. First, keep in mind that the spices will be in contact with the food for a long time and, thus, you might want to back off on pungent spices a bit because the flavor transfer may be significantly than you are used to. Secondly, the only danger here is ensuring that the food passes through the “danger zone” of temperatures (which is not 40 to 140 — read the books!) in less than 6 hours, which isn’t generally a problem. Finally, you can cook a full meal in a sous vide oven, even with items that differ in temperature requirements. Start with whatever needs the highest temperature and let it cook for the needed time, then drop the temperature to the next highest item and keep doing that all the way to the lowest temperature, leaving all previous items in the bath. At the end, you’ll have a full meal at serving temperature ready to go.
48 hour pork belly
I love pulled pork and have made many a batch on the Big Green Egg; 22 hours at ~ 210 degrees generally does the trick. The common thinking is that you need to hold the pork at ~165 degrees for several hours to render down the connective tissues to make this otherwise tough cut of meat unbelievable tender, but not even remotely rare. The reality, though, is that the pork can be held at a lower temperature for much longer and the same tenderizing reactions happen, just much slower.
Thus, I vacuum sealed a bunch of chunks of pork belly that had been soaked overnight in a light salt/sugar brine. In each bag, I placed a different set of spices or marinades; a dry rub that I usually use, some spicy barbeque sauce, and some sliced lime/rosemary in another.
These then went into the water bath for 48 hours at 141 degrees.
The result was amazingly tender — just like pulled pork should be — but was also fall apart pulled pork tender. Not only tender, but the fat was also largely reduced to nothing but juice with some slight, very tasty, remnants.
And the meat was still medium; still had just a bit of pink to it. Awesomely delicious.
This is where I learned that the flavor carry over is much more intense in a vacuum pack (duh!). Next time, I’ll probably skip the brine. As well, the parts of the pork that were in direct contact with the rosemary were a bit bitter.
72 hour pork belly
I threw three bags of pork belly into the sous vide bath, but only ate one at the 24 hour mark. Family plans came up that prevented us from having a true meal.
What the heck? Might as well see what it is like at the 72 hour mark.
Something very delicious happened in the interim. What was very much an awesome traditional pulled pork at 24 hours turned into a unique eating experience at 72 hours. The result was a pork that was still very much fork tender, but otherwise had a texture and a flavor much more akin to ham.
The dry rubbed pork was very distinctly ham like in nature. The rosemary/lime pork was closer to pulled pork while having a distinct citrus overtone.
Yes, yogurt. Yogurt, as it turns out, is remarkably easy to make it home. The problem, though, is getting a consistent result and that is largely because it is relatively difficult to precisely control the temperature.
Unlike everything else I’ve written about, Yogurt is the opposite. Instead of pasteurizing the milk, the whole point is to inoculate the milk with active cultures and give them an ideal growing environment to turn the milk into yogurt.
And this is where the line between sous vide water bath cooking and biology/chemistry blurs. A quick search for “yogurt making temperature” led me to this page written by Professor David B. Fankhauser, who specializes in Biology and Chemistry.
In particular, while most yogurt making recipes recommend an incubation temperature of 110℉ / 43℃, Fankhauser’s claim is that 122℉ / 50℃ is an optimal temperature in that the yogurt making critters can still reproduce effectively enough, but it is too hot for certain common pathogenic bacteria. By doing this, we can better guarantee the consistency of results.
In any case, it is dead simple;
- Heat 2%/skim/whole milk (do not use ultra-pasteurized for it is the work of the devil) in sterilized canning jars to 190℉ / 87℃ for an hour or so. Remove any crusty bits that might form on top. (Since having written this, I’m typically heating the milk for an hour or so at 75C. Honestly, if you are starting with pasteurized milk, it ought to come out of the container pretty sterile. This step does insure that any bugs in the jar or pouring process are dead, though.)
- Cool to 122℉ / 50℃. I find any water bath holds temperature very well and, thus, accelerated the process by removing a bunch of the hot water and replacing it with cool water.
- Stir a spoonful or two (spoonful for a pint, more for larger containers) of your favorite yogurt that contains live cultures. Put the lids back on the jar, but do not screw down tightly.
- Let sit in the water bath at 122℉ / 50℃ for anywhere from 5 hours to 24+ hours. The longer it sits, the more sour the yogurt.
- When done, screw the lids on tightly and then submerge the jars in ice cold water to stop the yogurt making process and seal the jars with a light vacuum. Refrigerate.
The yogurt is ready as soon as it effectively sets up. In my first run, the result was about 10x better than the starter I used, likely because I started with better quality milk? Or because it was fresher? I don’t know, but the result was creamy and totally delicious.
This will also produce quite a bit of whey, which is both very healthy and can be used as a liquid additive in doughs. In fact, I collect all the whey and use it as the liquid, adding beer and/or EVOO and/or melted butter to bring it up to volume, in my no-knead dough. Makes fantastic pizza dough or sandwich breads!
All in all, the first two weeks have been an adventure. Mostly quite successful, with one backup pizza failure, and a few discoveries.
I suspect this is just the beginning of a wonderful culinary adventure.