How come I haven't noticed this dryness in restaurants? Now that I think about it, the kind of restaurants that cook their meat sous-vide are the kind of restaurants that place their meat in a lovely red wine reduction, demi-glace or some other super meaty sauce. In that case, the lack of juiciness is generously compensated for. If you make demi-glace on regular basis, more power to you, but my saucing work horse is a humble pan sauce made by deglazing the pan after searing. Unfortunately, these pan sauces are not possible for sous-vide cooked meat since searing after a water bath doesn't produce enough brown bits.
Tenderness vs. Juiciness
When I encountered the dryness problem, I tried to google to see what other cooks report. Everyone was describing the meat as "most tender and juicy." In traditional cooking methods, those two often go hand in hand, but they are not the same thing. Tenderness is the amount of work your teeth have to do to break down the meat. Juiciness is how much juice is released during the breakdown.
Before trying to solve the dryness problem, I wanted to verify that it's not a figment of my imagination and I set up the following experiment. I decided to compare a steak cooked using sous-vide method with the steak cooked using Kenji Alt's slow roasting method (bring to 95F internal temp on a rack in 275F oven, then sear).
Here are the details of my experiment.
Steak cut and thickness: Sirloin cut 1.25 inches thick (the thickness varied slightly in parts)
Salting: Since I wasn't sure how salt would effect juicinesses, I salted some steaks 24 hours before cooking and left some steaks completely unsalted.
Searing: all steaks were seared for exactly 1 minute per side
Measuring juiciness: Since collecting quantitative data on juiciness by means of chewing a steak is not very practical, I decided to slice the done steaks 1/4 inch thick, pour off the juice that they released into a cup and weigh it. I have a tea scale that can weight very small amounts accurately.
To rest or not to rest: I followed the best practices for each cooking method -- slice immediately for sous-vide, rest 5 minutes for slow roasting to let the temperature even out.
Doneness: unfortunately, there was no way to get the same exact doneness on all these steaks, but I was close for 2 of them. Steaks A and C (the salted ones) came out at 130F and 133F. Steaks B and D (the unsalted ones) came out at 124F and 137F. This difference is too large to make a good comparison, so I'll base my conclusions on steaks A and C.
Steak A: salted 24 hours in advance, cooked sous-vide at 131F for 3.5 hours, then seared
Weight before cooking (24 hours after salting): 190g = 100%
Weight after water bath and thorough drying: 175g = 92%
Weight after sear: 166g = 87%
Internal temperature after sear = 130F
Weight of juice after slicing: 3.9g = 2.05%
Steak B: no salt added, cooked sous-vide at 131F for 3.5 hours, then seared
Weight before cooking: 169g = 100%
Weight after water bath and thorough drying: 147g = 87%
Weight after sear: 138g = 82%
Internal temperature after sear = 137F
Weight of juice after slicing: 3.27g = 1.93%
Steak C: salted 24 hours in advance, cooked in 275F oven, then seared
Weight before cooking (24 hours after salting): 187g = 100%
Weight after after oven: 178g = 95%
Steak D: no salt added, cooked in 275F oven, then seared
Weight after sear: 169g = 90%
Internal temperature after sear = 133F
Weight of juice after slicing: 7.38g = 3.95%
Steak D: no salt added, cooked in 275F oven, then seared
Weight before cooking: 183g = 100%
Weight after after oven: 175g = 96%
Weight after sear: 164g = 90%
Internal temperature after sear = 124F
Weight of juice after slicing: at least 6 g = at least 3.3%*
* I am not sure exactly how much juice I got from Steak D because a piece of steak fell into the cup into which I was pouring the juice and knocked it down. I remember the number got to at least 6g before the spill. I am guessing the juice percentage was roughly the same as Steak C.
The sous-vide steaks were more tender, but the oven steaks yielded twice as much juice as the steaks cooked using the sous-vide method at the time the measurement was taken (2-6 minutes after sear). As they continued to sit on a plate, the oven cooked steaks continued to release the juice and sous-vide steaks did not. Where was the juice from sous-vide steaks? In the bags. After the sous-vide steaks were removed from the water bath and dried off on paper towels, they were 92% and 87% of their original weight. After the oven steaks were removed from the oven, they were 95% and 96% of their original weight.
Salting didn't seem to effect the juiciness much, but I noticed that the sous-vide steak tasted saltier than the oven steak. It was the same piece of meat, seasoned evenly and rested 24 hours before being cut in half, so I doubt the salt amount was indeed different, but somehow it is more noticeable with the sous-vide method.
So, does sous-vide method really suck when it comes to meat? No. I just wanted to stir up the sous-vide pot a bit. I believe it might be possible to produce a juicy steak using the sous-vide method that does not rely on the sauce. Unfortunately, sous-vide best practices described in all the books and websites don't tell you how to do that.
I want to try cooking steak for a shorter period of time and at a lower temperature to see what happens. I am guessing the reason the official sous-vide cooking resources don't like to talk about it is safety. Holding indefinitely at 131 is safe, but at 120 possibly not. I don't want to hold it indefinitely. Only an hour or so.
Stay tuned for more experiments.