Wednesday, June 29, 2011

Does resting meat help reabsorb the juice?

There is no shortage of best practices when it comes to meat juiciness.  Sear the meat to seal in the juices was one advice considered to be sound for over 100 years.  19th century cooks including August Escoffier believed it to be true.  Most professional chefs and food writers now laugh at this myth.  There are plenty of wonderful reasons to sear meat.  It tastes much more complex and crisp when browned, but as far as juices go, searing doesn't help.  How about the second best practice to optimize juiciness -- let meat rest after cooking to minimize the amount of liquid the meat loses during carving?  You can read about it on page 165 of "On Food and Cooking" by Harold McGee.  Kenji Alt set up an experiment in 2009 to test this idea, which lead him to agree with McGee.  I realize that arguing with Harold McGee in the 21th century is like arguing with Escoffier in the 19th.  But I couldn't help wanting to test this juice theory for myself and decided to set up an experiment that was similar to Kenji's.

I cooked 4 steaks.  All 4 were 1 inch thick and cut from the sirloin.  No salt was used.

All steaks were cooked in a hot skillet.  This is not how I normally cook steak, but that's how Kenji cooked them for his experiment. I flipped the steaks 3 times to help them cook more evenly.  I cooked until the internal temperature registered 120F.   I weighed the steaks as they came out of the skillet and assigned them to trail 1 or 2 based on their shape.  Since steaks A and B had similar weight and shape, I assigned them to the first trial and steak C and D to the second trial.  

Steak A: 90g, rectangular in shape
Steak B: 100g, rectangular in shape
Steak C: 81g, triangular in shape (tapered end of sirloin)
Steak D: 73g, triangular in shape (tapered end of sirloin)

I cut one steak in each trial (A and C) immediately in half and let them rest 12 minutes.  I let steaks B and D rest for 12 minutes and then cut them in half.  All steaks were sitting on plates so that I could collect their juice.

I poured the juice off each plate and weighed it.  Here is a chart with the weight of the juice recorded as percentage of the weight of steak as it came out of the skillet.

Whether the steak was cut and then sat for 12 minutes or sat for 12 minutes and then was cut didn't seem to make a difference in the amount of juice it released.

Why did trial 2 steaks release more juice than trial 1?  My guess is that steaks C and D had a higher average temperature -- they looked more done.  The more the temperature of the meat exceeds 120F, the more juice muscle fibers release.  Although I was aiming for the same doneness in all steaks, and removed them off the skillet when the minimum internal temperature was about 120F, the tapered shape of the steaks C and D (trial 2) probably caused their average temperature to be higher than the average temperature of the steaks A and B (trial 1).  

Does this mean you don't need to rest your meat?  It depends on how you are cooking it.  With all traditional methods, you still need to rest it so that the temperature can come to equilibrium.  All proteins have their ideal doneness temperature (the point at which they are most tender and juicy).  When you remove your protein from the heat source, the temperature in the outer layers is higher than ideal and the temperature in the center is lower than ideal.  As the protein rests, the outer layer raises the temperature in the center to the ideal temperature (assuming you did everything correctly), and then the whole thing starts to cool off.  This is known as carry-over cooking or residual heat.  How much residual heat you'll get depends on many factors that I covered in this post (scroll to the end of it).

What if you cook your meat using the sous-vide method?  Should you still let your meat rest?  In theory, your center is already at a perfect temperature.   I found that searing might bring it up a few degrees depending on the shape of your steak, but this is small potatoes compared to carry-over cooking that happens using traditional methods.  So if you are really hungry, dig right in.  

Since the experiment I was trying to reproduce was Kenji's, it's worth to compare our findings.  According to Kenji, cutting a steak after 12 minutes of rest can keep 7%* more juice inside the steak than cutting it right away.  My results were very different.  I found that how long you waited before you cut the steak didn't matter.  Of course, our experimental set ups might have been different.  And neither one of us did enough trials to give our results any statistical significance.  If someone wants to sponsor a serious steak juiciness study, I'd be more than happy to undertake this project.

I also must disagree with Kenji's graph of internal temperature after cooking (see the end of this post).  According to his graph, the internal temperature holds at 125 and then goes down.  I've never been able to reproduce this.  Every time I cook meat via a high-heat method, I always observe an increase in internal temperature during resting.  For more details see the end of my Roast Chicken Legs post.

* Since Kenji used raw steak weight as 100% and I used cooked steak weight as 100%, his 7% juice release difference would be more like 6% juice release difference assuming steak loses 13% of its weight during cooking.  

Tuesday, June 14, 2011

Sous-vide experiment: temperature vs. duration

You didn't think my last post was the end of my sous-vide experiments, did you?  Sure, I sounded a tad too pessimistic about the world's latest and greatest cooking method.  But my testing is only starting.  I have since cooked 4 more steaks and have some findings about the temperature and duration variables.  

My goal is to analyse the factors that impact the juiciness of the meat cooked using the sous-vide method.  I repeated last weeks experiment of measuring the steaks' weight during all stages of cooking and measuring how much juice a steak releases during serving.  Here are the details of my experimental set up:

Steak cut and thickness: Rib-eye 1 - 1.5 inches thick.  I used only the "eye" muscle to eliminate variability due to the difference in the fat content (the flap of the rib-eye tends to be fattier and juicier and it was impossible to give each steak exactly the same amount of flap). I tied the steaks with butcher twine to keep their shape uniform (within each steak).  This worked great for vacuum sealing preventing the usual tapered edges.

Salting:  I skipped the salt completely for this experiment to simplify things.

Searing: all steaks were seared for exactly 50 sec 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 weigh very small amounts accurately.

To rest or not to rest: I didn't rest any steaks after searing since that's the best practice of sous-vide cooking.  I actually have some doubts about this practice and am planning to set up an experiment to test the effects resting has on meat cooked using the sous-vide method.

Doneness: Since I cooked the steaks at different temperatures (121F, 126F, and 131F), final doneness varied.

Cooking duration: I cooked 3 steaks for a relatively short time (50 - 100 minutes) and 1 steak for a long time (5 hours)

Steak A: 121F water bath for 50 minutes

Thickness: 1 inch
Weight before cooking: 114g = 100%
Weight after water bath and thorough drying: 108g = 94%
Temp after water bath = 119F*
Weight after sear: 102g = 89%
Internal temperature after sear = 119F
Weight of juice after slicing: 4.12g = 3.61%

Steak B: 126F water bath for 50 minutes

Thickness: 1.25 inch
Weight before cooking: 124g = 100%
Weight after water bath and thorough drying: 117g = 94%
Temp after water bath = 123F*
Weight after sear: 107g = 86%
Internal temperature after sear = 130F
Weight of juice after slicing: 9.3g = 7.5%

Steak C: 131F water bath for 100 minutes

Thickness: 1.5 inch
Weight before cooking: 156g = 100%
Weight after water bath and thorough drying: 141g = 90%
Temp after water bath = 130F
Weight after sear: 132g = 85%
Internal temperature after sear = 132F
Weight of juice after slicing: 9.44g = 

Steak D: 131F water bath for 5 hours

Thickness: 1.5 inch
Weight before cooking: 150g = 100%
Weight after water bath and thorough drying: 124g = 84%
Temp after water bath = 130F
Weight after sear: 114g = 76%
Internal temperature after sear = 135F
Weight of juice after slicing: 2.4g =

* Steaks A and B were a little short of the desired internal temperature, but 1 and 2 degrees respectively.

The findings from steak A, B, and C is not a surprise.  It can be explained by the fact that the juices start to release from the meat fibers around 120F.  But all steaks cooked relatively quickly by sous-vide standards (50-100 minutes) were juicy.  What made the biggest difference is not varying the temperature, but varying the cooking duration.  Steaks C and D were technically the same doneness, but the steak that was left in the water bath for 5 hours released 1.6% of juice instead of 6.1%.  This explains the lack of juiciness of sous-vide steaks in my last experiment.  They were cooked in the water bath for 3.5 hours.

What most sous-vide books and websites tell you is that you can't overcook using the sous-vide method.  It all depends on how you define "overcook."  The steak will not go above the desired temperature no matter how long you hold it in the water bath (well, dah!), but the longer you hold it, the more juice you lose.

How long is too long?
It depends on the thickness of meat of course, but here is some data for 1.25-1.5 inch steaks:
131F for 100 minutes -- 6.1% juice release during serving
131F for 3.5 hours -- 1.93% juice release during serving
131F for 5 hours -- 1.6% juice release during serving

I am sure half an hour doesn't make much difference, but 3 hours do.  If you are using the ghetto sous-vide set up, you'll probably never run into this problem.  Who wants to monitor the water temperature for an extra few hours?  But if you are using an immersion circulator, you might be tempted to put meat in the water bath whenever it's convenient (in the morning before going to work, during kids' nap, etc) and then have it ready for dinner.  It will surely be very tender, but you'd better have a lot of demi-glace handy because it will be dry.

So where does this leave us?  Do I still think sous-vide sucks?  The good news is that I was able to get a steak that is as juicy as Kenji's oven method.  The bad news is that it takes about 3 times longer with the sous-vide method.  It is not active time, of course, but I need to be home to put the steaks in the water bath 1.5 hours instead of 30 minutes before the meal.  

Here is a summary of sous-vide vs. oven method pros and cons

Sous-vide pros:
  • Oven is free to cook other dishes.
  • Meat can be held at desired temperature for close to an hour with no ill side effects.  It can even be held longer (juiciness will be reduced, but tenderness won't be compromised -- if anything it will get more tender).
  • No last minute monitoring with a thermometer, freeing you to work on other things.
Sous-vide cons:
  • Requires either a lot of baby-sitting or a lot of expensive equipment.
  • Takes way longer than the oven method (about 3 times as long).
  • Takes a lot of counter space.
  • All servings will have the same doneness.  I don't think it's a biggie.  Most people in my family now know to trust me on doneness :)
Oven pros:
  • A lot faster than the sous-vide method
  • No expensive equipment
  • If different donenesses are desired, some pieces can be started in the oven earlier.
Oven cons:
  • Need to keep the oven at a low temperature, so most vegetable side dishes would have to be done in advance.
  • When the meat reaches 95F (or some other desired temperature), it has to be seared and served.  Can't be held at a steady temperature.
  • A little last minute monitoring.
What next
I am tempted to test the theory that sous-vide cooked meats don't need resting.  It's true that the temperature doesn't need to come to equilibrium like it does for traditional methods (it already is at equilibrium).  But I am wondering if the steak would hold its juice better if it rested.

Roasted tomatoes (in any season)

These roasted tomatoes are inspired by Judy Rodgers' recipe from the Zuni Cafe cookbook.  I cooked them for the Cool Beans and Grains class last week to top our Mujaddara (lentils with bulgur and caramelized onions).  This was an improv topping that was not part of the handouts.  But the students made me promise that I'll post a recipe as soon as possible.

This is a similar dish to Tomatoes Confit -- the ultimate dish to make when you are bombarded with ripe and juicy tomatoes from your garden or CSA.  The rest of the year, the technique described in this post of roasting high quality canned tomatoes is a good alternative and way less work than peeling and seeding fresh tomatoes.

My favorite canned tomatoes are Muir Glen (available in Whole Foods and organic section of most supermarkets)

28 oz can whole peeled tomatoes
2 Tbsp olive oil
2 whole garlic cloves, peeled and halved (optional)
1/4 tsp sugar

  1. Preheat the oven to 500F.  
  2. Cover the bottom of an oven proof 10 inch skillet with 1 tsp olive oil (or use some other oven and broiler safe dish of equivalent size)   
  3. Remove tomatoes from juice and cut in half lengthwise.  Arrange them in a skillet cut side down in a tight single layer.  Tuck the garlic pieces under a tomatoes.  Sprinkle top with sugar and a pinch of salt.  Drizzle with remaining oil (1-2 Tbsp).  Place in the middle of the oven for 20 minutes.
  4. Tilt the pan and use a spoon to baste tomatoes with the oil from the pan.  Place the pan under the broiler until tomatoes get slightly charred, 4-8 minutes.
Before placing tomatoes in the skillet, you can spread a layer of caramelized onions or braised fennel underneath them.

Uses for roasted tomatoes:
  • side dish for fish and meats
  • topping for pizza, flat breads, and crostini
  • coarsely chopped and mixed with pasta, risotto, or any other grain

Monday, June 6, 2011

Why sous-vide sucks

As much as I enjoyed the charms of the ghetto sous-vide method, I finally gave in to peer pressure and bought the Sous-Vide Supreme.  This was supposed to be the post where I tell you how sous-vide cooking has revolutionized my life, how it turns every piece of protein into gold, and how you should buy one too.  But it's not that post.  This is a post about the juiciness analysis of sous-vide meats.  After cooking a number of proteins using this method (chicken, duck, beef, and lamb), I've noticed that while the meat comes out very tender, it is not nearly as juicy as I am used to.  It tastes a little -- dare I say it -- dry.  

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%
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 results
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.
What now
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.

Thursday, June 2, 2011

Sunny-side up

There are 3 secrets to perfect sunny-side up eggs: very low heat, cover, and padding.  The first two I have figured out a long time ago.  The lower the heat, the more tender the egg.  The cover helps the top and bottom cook more evenly.  But what about that padding?  By padding I mean the stuff you put under the eggs to make them into a more substantial and interesting meal: vegetables, grains, meats, etc.  I used to think those were nice additions, but didn't realize how much they impacted the texture of the eggs until I tried skipping them.  Without all that padding,  the white inevitably got tough and the bottom of the yolk got set.  Those tomatoes, asparagus, and lentils do much more than compliment your eggs, they insulate them from direct heat of the skillet, making the white tender and yolk runny.

The wonderful thing about this dish is that in only 4 minutes, you can turn your leftovers into a breakfast, lunch, or dinner.

Set a skillet over moderate heat and spread your leftovers evenly to form a layer 1/4-1/2 inch.  Cover and heat for a couple of minutes until warm.  Reduce the heat to low (if using electric stove, take the skillet off heat to let the burner cool off while you are adding the eggs).  Break the eggs on top of your leftovers, cover the skillet, and cook on low heat until the whites are almost opaque, 3-4 minutes (check at 3 minutes).  It is safer to remove the skillet off the heat when the whites are slightly translucent.  Leave it covered for 30-60 seconds, and they'll be done.  If you missed that moment and the whites got completely opaque, remove the eggs onto the plate immediately.  Sprinkle with salt and pepper and serve.

The eggs in the pictures are cooked over lentils braised in red wine.