Cooking Issues

The International Culinary Center's Tech 'N Stuff Blog

Cooking Issues header image 1

Delicious, Defective Cured Olive Oil

March 30th, 2010 · Uncategorized

posted by Dave Arnold 

We think olive oil from cured olives is delicious. A professional olive oil taster would disagree. Let me explain: 

We’ve been using our centrifuge to make cured olive oil.  First we blend pitted olives (kalamata’s been our choice) in a Vita-Prep until they form a smooth paste; then we load the paste into centrifuge buckets and spin them at 4000 times the force of gravity for 20 minutes.  While the olives are spinning they separate into 3 layers by density: a layer of olive oil at the top, followed by a solid layer of olive paste, sitting on a  liquid layer of dense olive brine at the bottom. To separate the olive oil from the brine we use a piece of lab-glass called a separatory funnel. Don’t be without one. The olive brine would make a fantastic dirty martini.  The olive paste makes a very meaty tapenade.  Our favorite part, however, is the olive oil layer on top. 

Olives straight out of the centrifuge: oil, paste brine. The paste and the brine get muddled in the bag, so now we just spin the olives directly in the centrifuge buckets, which yields a nice puck of tapenade.

Using a separatory funnel to separate oil from brine.

The goodness of olives: oil, brine and paste.

We really, really, like the olive oil.  It tastes just like kalamata olives.  I was discussing this oil with Harold McGee (master blaster of the delicious science, see him here at the FCI April 22 and 23), who told me an interesting story: 

In 2006 Cook’s Illustrated published an article rating extra virgin olive oils.  Alexandra Kicenik Devarenne, an olive oil expert and instructor at UC Davis, read the article and was surprised by the results. She convened an expert olive oil tasting panel and re-tested the exact same oils.  The results were astounding.  The oils rated tops by Cook’s Illustrated were rated defective by the trained testers.  Oils that fared badly in the Cook’s test were highly rated by the trained panel (Read about it here). What the hell? 

Many of the oils that had done poorly in the Cook’s test, but were liked by professionals, were bitter.  McGee told me that bitterness is an indication of polyphenols, a mark of quality  — polyphenols prevent oxidation and rancidity.  On the flip-side, many of the oils rated highly by Cook’s showed some rancidity.  It turns out that we tend to like rancidity when we’re used to it.  To illustrate, here’s a story about rancidity that will probably get us sued: 

A packing company  approached a large manufacturer of peanut-butter cups with a proposal for an oxygen-absorbing insert that  prevented rancidity.  The company test-marketed their peanut butter cups with this  rancidity-reducing package. Customers balked.  Turns out, people expected their peanut butter cups to taste a little rancid, and didn’t like them when they didn’t.  Of course, those consumers didn’t know that they were selecting for rancidity, they were just choosing what they liked.  Back to olive oil: 

Another defect that the Cook’s panel liked was the taste of fermented olives.  Fermented olive taste (pros call is fustiness) indicates  that some olives had started to ferment before they were pressed.  Trained olive oil professionals see this trait as a defect, because oil from those olives won’t last as long and was made with sub-optimal olives.  Tasters who don’t know any better like the fermented taste, because it tastes more like olives than ‘good’ olive oils.  Our centrifuge olive oil, made with 100 percent cured olives, takes that defect to the extreme. 

Well, anyway, we like it.

→ 13 CommentsTags:

Pectinex Ultra SP-L For Sale

March 29th, 2010 · Uncategorized

Pectinex Ultra SP-L --makes your oranges smile.

Ahoy Readers!

You asked for it, you got it.  Pectinex Ultra SP-L is on its way. We’ve ordered a 25 Liter pail from Novozymes and we’d like to share it:  $20 for a 250 mL bag of the stuff.  

See last week’s post to read how we’ve been using Pectinex Ultra SP-L to maximize our flavedo.  

For every liter of enzyme solution we add 2 grams of Pectinex Ultra SP-L and 1 gram of Pectinex Smash XXL.  250 mL of Ultra SP-L is enough to de-albedo a whole citrus grove.  Keep in mind, for citrus fruit, Novozymes advised us that Pectinex Ultra SP-L works best when mixed with Pectinex Smash XXL. There’s still a good amount of the XXL left in our pail for those who haven’t already purchased some from us.

We’re using the same ordering procedure for both the XXL and the SP-L. Go to www.paypal.com and use my email address – nlopez@frenchculinary.com.  $20 per bag, plus $5 shipping.

Thanks for reading!

Love,

The Cooking Issues Team

→ 28 CommentsTags:

Enzymatic Peeling? Hell Yes!

March 23rd, 2010 · Uncategorized

posted by Dave Arnold

Some assorted citrus: Red pomelo with peel, grapefruit, lime, lemon peel, lemon.


A few years ago, a number of chefs got a hold of Peelzym, an enzyme that can dissolve the white part of citrus (the albedo) while leaving the fruit segments and the colored part of the peel (flavedo) intact.  It can be used to automatically peel and supreme any citrus fruit without cutting the segments with a knife.  Pretty cool. 

Aw yeah.


Unfortunately, Novozymes, the company that made Peelzym, stopped production and has no more to sell (in this country at least).  Luckily, they suggested a substitute: a mixture of Pectinex Smash XXL (the enzyme we use to clarify apple juice), and Pectinex Ultra SP-L, a new enzyme we had never tried. 

Dynamic Duo: Pectinex Ultra SP-L and Pectinex Smash XXL

Here, our tests:

Here is the citrus we tested clockwise from upper left: California pink pomelo, Florida pomelo, grapefruit, orange, lemon, lime (kumquat not pictured).

The Procedure:

Make an enzyme solution with 2 grams of Pectinex Ultra SP-L and 1 gram of Pectinex Smash XXL per liter of ice water. The water has to be cold because you are going to vacuum it.  If you don’t have a vacuum the water can be warm, around 40-45°C. Either pre-peel the fruit or puncture the flavedo to allow the enzyme to penetrate. Vacuum-bag the fruit with the enzyme mix at full vacuum.  If you don’t have a vacuum, you can just soak the fruit in a Ziploc bag, but you won’t be able to use unpeeled fruit—you’ll have to peel it first.  Put the bags in 40°C water and allow the enzyme to work at 40°C for 25 minutes to 2 hours depending on results.  Rinse the fruits under cold water to remove the dissolved pectin. Enjoy.

The Steps in Pictures:

Step 1: Peel your citrus or...


... stab holes in the flavedo with needles. One of the best words in the English language: Flavedo–the very outside of a fruit–the colored part–the part with the delicious oils.


Step 2: Bag whole citrus or...


... bag the peels and peeled fruit.


Gratuitous close up of bagged grapefruit


Step 3: Circulate citrus at 40 degrees C


Step 4: Rinse under water. Peels should be lightly scrubbed with a toothbrush.

Results and Notes:

Originally, we tried to puncture the flavedo using a dog brush.  We had high hopes for the dog brush. We purchased one after we saw Chris Young and Nathan Myhrvold using them to puncture the skin of duck breasts at their Starchefs demo.  The dog brush works great on duck breasts–it helps the fat to render without letting the meat overcook the way traditional scoring does, but it was a bust on citrus.  The needles were too soft.  Instead we used a floral frog, or kenzan, the spikey thing used for ikebana (Japanese flower arranging).  You can get them at many Asian housewares stores.  The kenzan worked great.

Pet brushes don't work on citrus like they do on ducks.


Floral frog or kenzan

To get fully supremed segments, it worked better to pre-peel the fruit and split it in half since the enzyme tended not to penetrate fully to the center of the fruits.  The whole fruits we tested peeled amazingly well; but the membranes on the interior of the fruit were largely intact.

The most amazing products we obtained weren’t necessarily the fruits themselves, but perfect sections of peel.  Pure flavedo, baby.  We pre-sectioned the peel in large pieces, vacuumed them with enzyme and incubated them like the fruit.  We then carefully cooled the peels down and gently scrubbed off the goopy dissolved albedo with a toothbrush under water.  These peels would make a great garnish.  We haven’t candied one yet but I bet they’d be pretty good.

Notes on Individual Fruits:

Oranges worked great.

Orange segments and super peel

Peeling an orange

Grapefruits worked well but the segments were fragile and had to be handled with care.

Peeling a grapefruit

Lemons worked well.

Peeling a lemon

Limes were tricky.  We could get limes to peel nicely but the inner membrane never dissolved as well as the membranes in other fruits.

Peeling a lime

Pomelos were great.  We tried a white pomelo from Florida and a pink one from California.  Check out those pomelo segments! Check out those peels!  Pomelo segments are extremely fragile because their fruit vesicles are not tightly bound to each other.  Be gentle with them.

Cleaning a pomelo peel


Pomelo segments are pretty messy.


Purdy pink pomelo


Peeled Florida Pomelo. The flesh is still a little raggy. This one didn't work as well as the pink pomelo.

Kumquats are fantastic.  We really love what happens to kumquats.  If you pre-peel the kumquat in a star pattern (see picture) and incubate it with the enzyme you get kumquat-flower garnishes.  If you vacuum infuse the whole kumquat (there is no need to puncture the kumquat peel, just make sure it is ripped a little at the top where the stem was) you can easily remove the peel and divide the kumquat into perfect individual segments.  They look like miniature mandarin segments and taste like sour orange.  If you have access to seedless kumquats these would be great.

Kumquat flower

Other Stuff We Tried:

The enzyme mix doesn’t work on grapes.  The enzymes dissolve the insides of bell peppers, turning them to mush.  Tomatoes get softer and mushier when exposed to the enzyme. Blueberries were unaffected.

Pepper turned to mush

A Note on the Enzymes:

The original Peelzym was a mixture of enzymes obtained from Aspergillus Aculeatus, a fungus that attacks plants.  The data sheet says it is a mix of pectolytic enzymes (enzymes that break down pectin) but then says the main enzyme is a beta-glucanase. Beta-glucanases should break down cellulose, not pectin. Pectin is made up  galacturonic acid, not glucose.  I’ll have to get more information on this.  Pectinex Smash XXL is a pectin lyase (breaks down pectin) from Aspergillus niger, another plant-attacking fungus. Pectinex Ultra SP-L is primarily a polygalacturonase (breaks up polymerized galacturonic acid, like pectin) from Aspergillus Aculeatus, the same organism that was used to make Peelzym.  It makes sense that the SP-L and the Peelzym would have similar functionalities since they come from the same fungus and aren’t pure enzymes but mixes of several different enzymes.  Peelzym and Pectinex SP-L are probably slightly different mixes of the same components.

By the way, polygalacturonase enzymes are responsible for the softening of tomatoes, so it makes sense that Pectinex Ultra SP-L would soften them up.

→ 40 CommentsTags:

Fake Fryable, Brûlée-able Salep Dondurma Ice Cream: A Legal Recipe

March 20th, 2010 · Uncategorized

posted by Dave Arnold  

While trying to make an ice cream that could be fried or brûléed, I accidentally produced a recipe that very closely resembles Salep Dondurma –the fabled Turkish stretchy ice cream.  

Salep dondurma. Stretchy Turkish ice cream made from orchid powder.

Fake salep dondurma.

Dondurma means ‘ice cream’ in Turkish. Salep dondurma is an ice cream made with flour from the ground tubers of wild Turkish orchids.  Some say the word Salep is derived from the word for fox testicles, which makes sense if you look at the picture below.  

Salep orchid (from wikimedia commons).

Salep flour contains a hydrocolloid that produces  a stretchy, chewy ice cream.  The ice cream has to be worked long and hard to make it stretchy –almost the way you would to make gluten develop in a bread dough.  Vendors in Turkey beat and pound the hell out of it with long rods to get the consistency right.  When the texture is right you can cut the ice cream with a knife and eat it with a fork.  

Harold McGee told me about Salep Dondurma in 2007.  He wanted to cover ice creams with alternative textures in a class he teaches with us at the FCI (the next one is in April, by the way). Nils and I decided to make some for the class, but we couldn’t –  turns out it is illegal to export Salep, which only grows in Turkey. The Turks love Salep so much that they are hoarding the world’s supply.  It takes something like a thousand salep orchids to make one kilo of flour. You can’t increase Salep production; it is wild, not farmed.  So McGee suggested we use guar gum as a substitute.  Guar made a very chewy ice cream, but it wasn’t like the pictures and descriptions of Salep Dondurma.  After the class, McGee wrote a piece on Salep and other non-standard ice creams for the New York Times, which includes a photo of the most amazing mustache I’ve ever seen.  

Mc Gee’s article piqued the interest of  our friend Professor Kent Kirshenbaum of NYU and the Experimental Cuisine Collective.   He and a Turkish graduate student wanted to find a way to reproduce  Salep Dondurma legally here in the US.  Under the auspices of scientific research they smuggled some Salep flour out of Turkey.  The ice cream they made at the FCI with that Salep,  flavored with gum mastic (Chios Mastic), was my first authentic Salep Dondurma.  Indeed, guar was not a substitute for Salep.  Guar, as Kent pointed out, is a galactomannan (a type of complex polysaccharide).  Salep, on the other hand, is a glucomannan –like Konjac flour.  We tried Konjac, but unfortunately it didn’t work.  We seemed to be out of luck. 

Fast forward to last week.  I wasn’t thinking about Salep.  I had a hydrocolloid class coming up, and I wanted to demonstrate a few new recipes: how about a fryable, brûlée-able ice cream using a fluid gel?  Fluid gels are made by blending a solid gel, usually agar or gellan (a type of hydrocolloid made by CP Kelco).  Once blended, the fluid gels have some properties of a liquid, and some of a solid.  When they are standing still they act like gels; when force is applied they give way like a fluid. Thick fluid gels look like purees, but have the mouth-feel of a sauce.  Thin fluid gels look like a liquid, but can suspend particles.  I chose gellan because I wanted a thick fluid gel that wouldn’t melt. There are two types of gellan: high-acyl and low-acyl.  High-acyl gellan is freeze-thaw stable –  great for ice cream. Unfortunately,  it melts at high temperatures, especially in milk. Bad for an ice cream that you intend to fry.  Low-acyl gellan won’t melt when fried, but it isn’t freeze-thaw stable; I decided to add Guar to increase freeze-thaw stability (thickeners like guar can do that).  Most Guar tastes pretty crappy, but we have some nice guar from TIC Gums with a dead neutral flavor. 

The result:  ice cream with a texture almost exactly the same as Salep Dondurma! I was surprised and excited.  It gets better: this same month my Turkish intern, after many botched attempts on our behalf,  made her first successful Salep smuggling run.  We whipped up some authentic Salep Dondurma to compare with our fake batch.   We were still impressed.  Real Salep is slightly more stretchy, but the mouth-feel of our imposter is almost exactly the same.  Plus, unlike Salep Dondurma, this stuff can be brûléed or deep-fried.  

Making fake salep part one: Left,the blended fluid gel; right, freezing with liquid nitrogen.

Making fake salep part 2: Beating in a Kitchen Aid, and the final product.

You can fry it (in a crust).

You can brulee it.

Making real salep dondurma at the FCI with salep smuggled in by our Turkish intern, Deniz. Unlike a traditional dondurma maker, we used liquid nitrogen.

Beating real Salep at the FCI, a multicultural extravaganza. The Salep is from our Turkish intern, the ice cream is being beaten by Cliff, our intern from Palau, and the whole thing is filmed by Wipop, our intern from Bangkok.

I called CP Kelco.  They said they were not aware of any strange Salep-like behavior when Gellan and Guar are combined. I had to figure out whether the Guar was needed for the Salep texture, or whether gellan would work alone. If gellan alone worked, was it necessary to use dairy to get the Salep texture? Many hydrocolloids have weird interactions with dairy, including gellan. If gellan alone didn’t work, would another thickener other than guar work in concert with gellan to give the Salep texture? Maybe Xanthan? CP Kelco had asked why the hell I used guar to help with freeze/thaw instead of Xanthan, which is what they would use.  I had some more experiments to do.  

We tested Heston Blumenthal’s flaming apple sorbet, a non-dairy gellan fluid gel, and confirmed that gellan alone in a non-dairy system does not yield a Salep feel.  I then made a milk-based ice cream with  gellan and no guar.  It was creamy and delicious; many people in our class loved it.  It could be brûléed and fried, but it didn’t have Salep-ness either. Gellan and dairy alone were not sufficient. Next I tried ice cream with gellan and xanthan –nope.  There is something special about gellan and guar together. Tests yet to run: Gellan and locust bean gum, gellan and Konjac flour, and gellan and guar in a non-dairy system.

As luck would have it, one of the students in our Hydrocolloids class was Turkish.  She gave us a two-thumbs up for authentic Salep texture!  

Class tested, Turkish approved!

Here is the recipe for our fake Salep.  This version is flavored with tea.  

Fake Fryable, Brûlée-able Salep Darjeeling Dondurma  

24 grams Singell Darjeeling tea leaves (A second flush Darjeeling from Harney and Sons with a fruity, muscatel note)  
500 grams cold milk  
500 grams cold cream  
5 grams KelcoGel  F Low Acyl Gellan Gum  
3 g salt  
5 grams TIC Flavor Free Guar (TIC is a company; they make a neutral tasting guar.  Most guar is “beany” tasting –not delicious borlatti bean tasting either, just guar bean tasting.)  
150 grams granulated sugar  
2 scraped vanilla beans  
3 egg yolks (beaten)  
2 grams Calcium Lactate Gluconate  

Combine the milk, cream, and tea leaves. Infuse the mixture in a vacuum bag at full vacuum plus 30 seconds. Allow to steep till flavor is developed (about 1 hour). Strain tea from milk/cream mixture and add gellan, salt, and guar. Whisk vigorously to combine (this step disperses the gellan and begins to hydrate the guar). Bring the mixture to a boil while stirring (to hydrate the gellan). Simmer for 1 minute (ensures the gellan is hydrated). Remove from heat.  Add sugar and vanilla and stir (drops the temperature a bit). When mixture drops to 83 or 82C add the egg yolks and stir (if you go higher you might curdle the eggs.  The yolks increase the creaminess of the recipe). When the temperature drops to 70C mix in the calcium and stir (I read a reference that calcium added to milk/gellan systems might cause problems if added above this temperature.  Calcium added below this temperature will also cause problems).  Put mixture in an ice bath to set. When mixture is completely set, blend in a high-speed mixer till creamy.  Freeze with liquid nitrogen in a Kitchen-Aid mixer fixed with a paddle attachment.  Beat until the ice cream gets stringy and stretchy.  

To make creamy ice cream without the Salep feel omit the guar gum and increase the gellan to 7 grams.

→ 40 CommentsTags:

Ka-Boom: Liquid Nitrogen Safety Rules are There for a Reason!

March 12th, 2010 · liquid nitrogen, Uncategorized

posted by Dave Arnold

Last week we had our first liquid nitrogen *incident.* No one was hurt, but it emphasizes how important safety rules are.

For more information on liquid nitrogen safety, see our LN primer.

The damaged dewar

While moving our 160 liter LN dewar from the 4th floor to the second floor of our building the dewar got knocked over—don’t ask how.  One of our interns pulled a Hercules and righted the many-hundred pound monster single handedly.  Seconds later, the dewar vented with a thundering ka-boom, blowing the cap off the top, and punching out a ceiling tile.  The hallway filled with nitrogen.  We were okay because we followed the rules.  Everyone cleared the area. I opened the window and monitored oxygen levels on our oxygen meter.  We put the dewar in the elevator without anyone in it (that is one of our standard safety rules), and took it down and outside where we chained it up.

Close-up of dewar top

The ceiling

Imagine if we didn’t have the “no people riding in the elevator with the dewar” rule.  If the dewar had vented 20 seconds later and it was in an elevator with people, they most likely would have been asphyxiated. Some of the safety rules we follow with liquid nitrogen seem to guard against far-fetched scenarios that will never happen.

Looks like they can happen.  Stay safe.

→ 14 CommentsTags:

Pet Peeves put to the Test: Refrigerating Fresh Mozzarella

March 10th, 2010 · Uncategorized

posted by Dave Arnold

Some things I never refrigerate:

Tomatoes –they go mealy.

Potatoes –they develop sugar and brown too much when fried.

Fresh Mozzarella –It doesn’t taste the same after it has been in the fridge. It loses its milky characteristics. I buy it the day I need it and leave it on the counter. Left- overs go in the fridge, destined for pizza or grilled cheese sandwiches.

I was recently challenged on my mozzarella habits, so I decided to settle the matter with a blind tasting. I ran two tests. The first test was my dinner Saturday night, and served as preliminary fact-finding. The second test was a more rigorous one at the FCI.

DiPalos: my favorite cheese shop.

Test One:
For the first test I purchased two identical 4.5 inch balls of fresh mozzarella from DiPalos cheese shop here in New York. Both balls were still warm and both had come from the same batch of curd, made by the same person. (DiPalos is one of my favorite shops in the whole world. Unless I’m in Italy, I won’t buy Italian cheese from anyone else.) One I left on the counter and one I put in the fridge. Three hours later the one in the fridge had only reached 11ºC (52ºF) at the core. It was taking a lot longer to chill than I had anticipated. In the interest of getting dinner on the table before my kids went to bed I cut the test short and pulled the cheese out of the fridge. The non-refrigerated cheese was 23ºC (74ºF) at the core. I didn’t have time for the refrigerated cheese to come back to room temperature so I put both cheeses in Ziploc bags and circulated them at 26.5ºC (80ºF). After an hour the non refrigerated cheese was 25ºC (77ºF) at the core and the refrigerated cheese was at 20ºC (68ºF) –still way off! Unfortunately, it was dinner time and the tasting couldn’t wait. I figured we’d taste from the outside of the cheeses –unlike the cores of the cheeses, the outsides were almost the same temperature.

How to do a blind tasting with only two people:
With a sharpie I labeled the refrigerated cheese as 1 and the counter cheese as 2, and I made sure that the holes from probing the temperatures were identical in both balls. I handed the cheese to my wife, who had no idea what the difference between 1 and 2 was, and had her unwrap the cheeses and put them on plates she randomly labeled A and B. She only knew which letter corresponded to which number, and I only knew which number corresponded to which temperature treatment. We were both tasting blind.

The First Taste Test

Results:
There was a large difference between the cheeses. The refrigerated one was decidedly less milky, and oozed far less on the plate. I liked it a lot better. My wife, however, noted that the unrefrigerated cheese had a squeaky characteristic she didn’t like. I didn’t mind it, but she was definitely right – squeakiness was a result I hadn’t expected. Because the cheeses were still not exactly the same temperature, all we had shown is that mozzarella shouldn’t be served cool. The crucial fact I learned is that it takes a long time to bring a cheese back to room temperature. My guess is that most people don’t allow enough time for cheeses to warm up. I still had to investigate the squeak phenomenon.

Squeakiness, and what’s going on in a ball of mozzarella:
I frequently visit the dairy science page at the University of Guelph, maintained by Professor Douglas Goff. I called him up. He said mozzarella was not his specialty, so he passed me to his cheese specialist colleague, Professor Arthur Hill. Dr. Hill explained several important points: The springiness of a cheese actually increases with increasing temperature. Springiness and elasticity is the result of hydrophobic reactions between casein micelles in the coagulated cheese curd. Those hydrophobic interactions are strongly temperature dependent and get stronger as the temperature increases. At the same time, however, as the temperature goes up, the milk fat provides more lubrication and the water in the system become more motile so the cheese gets softer. Cold cheese, therefore, is hard but not springy, while warm cheese is soft and elastic. Dr. Hill said that some of the original elasticity of the cheese that is lost on chilling might not be fully recovered when the cheese is brought back to room temperature. The elasticity of the unrefrigerated cheese that was actually slightly warmer than normal was perceived by my wife as squeaky.

The second question I asked Dr Hill was why the refrigerated ball didn’t taste as milky. He said that unlike most cheeses, fresh mozzarella has a lot of unbound water in it. Over time that water is reabsorbed into the protein and fat matrix that makes up the curd, and the mozzarella appears progressively drier (even if no moisture is leaving the cheese) because the water becomes bound. This is why you normally would not use today’s mozzarella to make a pizza; it has too much free water available to leak out and make your crust floppy – and it also won’t melt as well. Dr. Hill said it was possible that refrigeration enhanced water re-absorption into the cheese.
According to Louis DiPalo (of cheese shop fame), water re-absorption is why you store mozzarella that won’t to be eaten right away in liquid. The extra liquid supplies water to take the place of the water that is absorbed by the cheese. Moral: If you must keep mozzarella more than a day, make sure you store it in the liquid it was made in.

By the way, the absorption of water, which tends to make mozzarella firmer over time, is counterbalanced by protein breakdown, which tends to make it softer. That is why some liquid-stored mozzarella can actually get softer with time (but more mushy to my taste).

For more information, see these papers by mozzarella specialist Dr Paul Kindstedt at the University of Vermont’s Insititue for Artisan Cheese.

Test Two:
We purchased two 4.5 inch balls of mozzarella made at 9am from DiPalos. At 11:30AM, one was placed in our walk in refrigerator (4ºC, 39ºF), while the other was left at ambient temperature (23ºC, 73.5ºF). It took 4.5 hours for the center of the refrigerated cheese to reach (4.5ºC, 40ºF). We purchased a third 4.5 inch ball of mozzarella that had been made at 2pm by the same cheesemaker that made our 9am batch. All three cheeses were put in Ziploc bags and circulated at 23ºC (73.5ºF). It took 2.5 hours for the refrigerated cheese to get to 22ºC (71.5ºF) at the core. We tasted all three cheeses blind.

Taste Test Two

Results:
Not surprisingly, the 2pm cheese was the milkiest of all. It was too milky for one of the six tasters. The 2pm was the milkiest because it was the youngest. The two 9am cheeses were far closer in taste and texture than I thought they’d be. The refrigerated cheese was a little drier than the unrefrigerated cheese, but not by a lot. Everyone liked the flavor of the unrefrigerated cheese a little more than the refrigerated one, but the unrefrigerated cheese didn’t blow the refrigerator cheese out of the water like I thought it would.

Taste Test Two: aftermath and answers

Upshot:

Most of the damage of refrigeration can be undone by careful re-warming, but bringing cheeses back to room temperature takes a long, long time. Longer than you think and probably longer than you have time for.

You are better off never refrigerating mozzarella than serving it a little too cool.

If you’re not going to eat the mozzarella right away, store in the liquid it was made in.

For the freshest, milkiest taste, eat soon after it’s made.

→ 22 CommentsTags:

Nut Milk.

March 2nd, 2010 · Uncategorized

by Dave Arnold, with Nastassia Lopez

Our favorite new centrifuge application is making nut milks.

Recently, a pastry student complained that her almond milk was too grainy. She wanted to know if we could do a better job. Damn skippy we could –and we started down a fruitful path of exploration.

Almond milk is typically made by blending almonds with hot water and straining the resulting glop through cheesecloth; most of the solids are retained in the cheesecloth and most of the liquid and fat passes through (coconut milk is made in a similar fashion). We do things a bit differently: we blend the almonds with hot water and put the resulting sludge into a centrifuge at 4000 g’s for 20 minutes. The centrifuge separates the mixture into 3 parts based on density. At the bottom are the grainy solids (which we discard), in the middle is the watery stuff, and the fat floats on top. Almond milk made this way is incomparably smooth and delicious.

Then we got to thinking. If almond milk is good, how about peanut milk, pistachio milk and pecan milk? They are all fantastic. What if we replaced the water with chicken stock, dashi, or orange juice? The orange pecan milk was a dud, but the dashi and chicken milks we made with peanuts and pistachios were amazing.

The ground peanut paste and stock being loaded into the centrifuge bottles.

In the bottles on the left are the solids, the pans on the right hold the fats and milks.

Initially, we had problems with the pistachio milks because the 3 pound vacuum packed cans of pistachios we buy have too many bad and oxidized pistachios. A couple of bad pistachios will ruin the whole batch of milk. It is now our standard procedure to dump all of the pistachios on a sheet tray and visually check for crappy pistachios.

Application: Soups

For our first application, we wanted to do a riff on Tom Kha Gai, Thai chicken and coconut milk soup. Luckily we have a Thai intern to get the flavors right.

Pistachio and Peanut Milk Tom Kha Gai

Nut Milk:
300 grams of pistachios (or peanuts)
900 ml chicken stock

Blend and spin in centrifuge at 4000g’s for 15-20 minutes.

Soup (per 500 ml nut milk):
20 grams of lemongrass
20 grams of ginger
8 grams of galangal
1 gram coriander seeds
1.5 limes squeezed
5 kafir lime leaves ripped
Pinch of salt
20 grams Tiparos fish sauce
50 g honshemeji mushrooms
2 grams Thai bird chilies (chopped)
10 grams scallions for garnish
25 grams of ginger
Pistachio Oil for garnish
Pinch pepper

Bring nut milk, mushrooms, garlic, fish sauce, peppers, lime leaves, coriander seeds, white pepper and salt to a boil. Simmer 5 minutes. Add galangal, ginger, lemongrass and cilantro. Simmer another three to five minutes. Strain it. Add lime a little at a time to balance acidity.

The pistachio soup being strained.

We garnished the pistachio soup with crushed toasted pistachios, and our centrifuge spun pistachio oil. The peanut soup was garnished with scallions and red Thai chilies.

Pistachio milk soup on the left; peanut milk soup on the right.

Pistachio-Dashi Milk Soup

Dashi Nut Milk:
900 ml dashi (20 g/liter ma kombu vacuum packed and circulated at 70 C for 1 hour infused with a bunch of bonito flakes and strained).
300 grams toasted pistachios

Blend and spin in centrifuge at 4000g’s for 15-20 minutes.

Soup:
red miso paste
Ayu fish sauce (this is an amazing new fish sauce being brought in from Japan. It smells like country ham. It is crazy good. Get it from True World Foods).
Chopped scallions
Bacon bits
Pistachio oil
Coconut-milk/lime fluid-gel
Rice vinegar

Bring nut milk and miso paste to a boil. Add fish sauce and miso, blend. Correct acidity with rice vinegar. Garnish with bacon, fluid gel, scallions, and pistachio oil.

Dashi-Pistachio Soup garnished with bacon bits, chives, coconut-lime fluid gel, and pistachio oil.

→ 13 CommentsTags:

Pectinex Smash XXL For Sale

February 18th, 2010 · Uncategorized

Our 25 Liter Pail of Pectinex Smash up for grabs in 250 mL quantities.

Howdy Readers!

We use a lot of Pectinex Smash XXL, the enzyme that clarifies apple juice, orange juice, etc. We have always gotten samples from the company. The well ran dry –now they are making us buy it.

Turns out Pectinex Smash XXL is only sold in 25 Liter pails. 25 liters is enough to clarify at least 17,000 liters of juice. Even we don’t need that much, so we are selling 250 ml bags (not vacuumed) of the stuff for $20 each + $5 shipping (USPS priority) via Paypal. 250 ml will clarify about 170 liters of product. That’s only 8.5 cents per mililiter!  We’re not sure about the shelf life, but we’ve had ours for about a year.  I think we can only ship domestic (If you live somewhere else we’ll try to work it out). First come, first serve.

To find out about how we’ve used Pectinex Smash XXL, click here, here, and here.

Contact me at nlopez@frenchculinary.com and I’ll give you our PayPal details.

Happy Clarifying!

Cooking Issues Team

PS: We are privately selling this; the French Culinary Institute is not involved.

→ 10 CommentsTags:

Heavy Metal: the Science of Cast Iron Cooking

February 16th, 2010 · Uncategorized

posted by Dave Arnold

I originally wrote this piece for a print publication, but they said the tone was too dry and axed it. They said they wanted something more like the blog. Here it is on the blog.

Heavy Metal

Cast Iron Intro:

While cast-iron cookware has been available for centuries, the advent of industrialized factory production in the mid 1800’s allowed cast iron to become widely available. The cast-iron skillet quickly became an icon of American cooking. Cast iron could be cheaply produced with minimum tooling in a wide variety of shapes –waffle irons, corn-shaped muffin pans, dutch ovens (dutch meaning “fake”, not “from Holland”), and skillets of every size. While many of these manufacturing advantages have since been supplanted, cast iron’s characteristic properties make it an excellent cookware choice in the modern kitchen. Corn bread made the classic way, in a pre-heated cast iron skillet, highlights cast iron’s cooking advantages: its temperature delivery power generates a good crust, and its temperature-regulating power provides even, constant heat –leveling out the temperature variations of your oven. The science of cast iron shows how these advantages work.

Cast Iron as a Pan Material:

The popular wisdom that cast iron cookware provides even heat is misleading. A cast iron skillet placed on a gas burner will develop distinct hot spots where the flame touches the pan. If you heat the center of a cast iron pan you will find that the heat travels slowly towards the pan’s edge, with a significant temperature gradient between the center and the edge. The pan will heat very unevenly, because cast iron is a relatively poor heat conductor compared to materials like aluminum and copper. An aluminum pan will heat more evenly because heat travels quickly across aluminum. Because of poor heat conduction, undersized burners are incompatible with cast iron cooking. The edges of a large cast iron pan will never get hot on a tiny burner. On properly sized burners you can minimize hot spots by heating slowly, but the best way to evenly heat cast iron is in the oven.

Sprinkling flour onto pans allows us to check their heating patterns. Just sprinkle with flour and heat. This is a variation on the technique Harold McGee uses. He puts paper in the bottom of a pan, covers the paper with beans, turns on the heat and makes a permanent print of the pan's heating pattern.

A flour-dusted cast-iron pan being heated on a high output burner. Notice the intensity of the hot spot and how uneven the browning is.

The mainly aluminum All-Clad has a much more even heat pattern on the same burner.

The cast-iron pan also shows some serious un-evenness on our induction burner.

The aluminum is more even than the cast-iron, but still not great. The induction burner's element is too small. Even a good conductor can't make up for a burner that is too small.

Cast iron has a higher heat capacity than copper, so it takes  more energy to heat a pound of cast iron to a given temperature than a pound of copper. More energy is stored in each pound of the cast iron.  Aluminum has a higher heat capacity than iron (it stores more heat per pound) but is much less dense than iron. For a given volume, therefore, cast iron stores more heat than aluminum.  Because cast iron pans typically weigh much more and are thicker than the same size pan in another material, they tend to store more energy when heated. This combination of high heat capacity and weight means that cast iron takes a long time to get hot. Once hot, however, a cast iron pan usually contains more thermal energy than other pans at the same temperature — a significant cooking advantage. Cast iron has unparalleled searing power because it has a lot of available thermal energy – and unlike almost any other type of pan, cast iron pans won’t warp when left dry on a burner to heat up. Thick and heavy cast iron will remain flat and true.

Cast iron is slow to heat up, so it’s also slow to cool down. It is a good regulator. It retains its temperature longer than other materials and won’t produce temperature spikes. This behavior can be disconcerting to the uninitiated. Cooking with cast iron is more akin to driving a boat than a car: the pan doesn’t respond instantly to changes in the applied heat.

Cast Iron – the OG Non-Stick Material:

Cast iron is naturally non-stick when seasoned properly. New cast iron is anything but non-stick, and it can easily rust. Seasoning — rubbing oil or fat into the cast iron and subsequently heating it — fixes both problems. Unsaturated fats work best (unsaturated means that some of the carbons in the fatty acid chains contain reactive double bonds). Nineteenth century American cooks typically used lard because it was readily available and unsaturated enough to polymerize well, but almost any oil will work. When an unsaturated fat is heated to high temperatures, especially in the presence of a good catalyst like iron, it is broken down and oxidized, after which it polymerizes –joins into larger mega molecules the same way plastics do – and mixes with bits of carbon and other impurities. This tough, impermeable surface adheres to the pores and crevices in the cast iron as it is forming. The surface is non-stick because it is hydrophobic – it hates water. Water soluble proteins make foods stick to their pan; a hydrophobic surface prevents sticking. The bits of carbon in the seasoning may also act as an additional release agent.

Cast iron isn't the only cookware with a burnt-oil based non-stick surface. This is a Korean dolsot --hot stone bowl. I routinely heat this thing to 615 F. I love dolsots. I have 8. I did not say anything about them in this post, but I could not resist putting in a picture. Maybe I'll do a post.

There is no quick way to fully season a cast iron pan; the surface of cast iron becomes slicker and blacker the more it is used. Though most cast iron today is sold “pre-seasoned,” this cursory seasoning protects against rust, but not against sticking. A good non-stick surface forms over time, with use. The oil polymer on a well-used piece of cast iron is built of many thin layers deposited over time. Thick layers can flake off in large pieces. Thin layers will remain adhered to the pan and will slough off microscopically. A true seasoned surface will only form properly at temperatures well in excess of the 350-375 degree F temperature that some manufacturers recommend for seasoning cast iron. Low temperatures do not completely polymerize and break down oil and will leave a brown, somewhat sticky pan instead of a black, non-stick one. 400-500 degrees F is the effective range for seasoning.

Good seasoning is good protection. Both these pans received the same amount of abuse and neglect. The one on the left was newly seasoned, the one on the right is 50 years old.

Early cast iron was sold either polished or unpolished. Polished cast iron isn’t polished the way silver is, it merely has a surface that was sanded or machined to make it smoother. The polishing process reveals more of the internal pore structure of the iron, and these pores make the seasoning adhere better to the pan. Polished cast iron is slick like glass when properly seasoned. Most modern cast iron is unpolished, meaning its surface has a pebbly appearance from the grain of the mold in which it was cast. Eventually, through years of seasoning, unpolished cast iron can become extremely smooth, but never as smooth as polished cast iron. New, unpolished pans can be sanded with rough sandpaper to approximate polishing.

The bumpy, non-polished surface on the left is now standard for cast iron, older pans also came polished, like the one on the right --a much better surface.

Caring For Cast Iron:

Many cooks are unnecessarily worried about maintaining their cast iron cookware. The seasoning on a good piece of cast iron is very durable. Modern soap will not harm seasoned cast iron. Old, lye based cleaners will hurt seasoned cast iron because lye dissolves the oil-polymer. Seasoned cast iron can also tolerate gentle scrubbing with non-metallic abrasives. Vigorous washing is not recommended on new, weakly seasoned pans.

Sometimes, the surface of a cast iron pan can become damaged through abuse or neglect. In this case the pan has to be stripped down to metal and re-seasoned. The best way to remove an old or bad seasoning job is to use a fireplace or the self-clean cycle of your oven to reduce the seasoning layer to ashes. This happens around 800 degrees F.

Another good maintenance technique with cast iron is to use metal cooking implements. The gentle scraping of metal along the bottom of the pan while cooking helps to even out the surface of the seasoning and make it more durable, not less.

Cast Iron Nutrition:

Studies show that cooking in cast iron can leach iron into food. Foods that are high in moisture, very acidic, or are long-cooked leach the most. For many people the extra iron is beneficial, but for a small minority of people who are sensitive to iron it can be harmful. The most quoted study on the effects of cast iron cookware on iron levels is the July 1986 study in the Journal of the American Dietetic Association. The pan used in that study had only been seasoned by daily usage for a couple of weeks prior to the study. As the study pointed out, better seasoned pans leach less iron. There are no data on iron leaching in decades-old pans.

→ 142 CommentsTags:

Sous-Vide and Low-Temp Primer Part I

February 12th, 2010 · sous vide

posted by Dave Arnold 

We have had a lot of requests to make last week’s low-temp charts available for download. Here you go: 

Click here to download the sous vide charts.

We are often accused of being long-winded. Guilty. When we looked at the sous-vide primer, however, even we thought it was too long—so we decided to break it into parts. We hope to put out a new section every week (or so). This is how we plan on breaking it down:

  • I . Introduction to Low-Temperature Cooking and Sous-Vide (Today’s Installment)
  • II. Use and Abuse of the Vacuum Machine and Packing for Low-Temp Without the Vac
  • III. Vacuum Tricks
  • IV. Temperature Control and Safety
  • V. Cooking Meats and Poultry
  • VI. Cooking Fish
  • VII. Cooking Everything Else

Today we have the introduction. It provides an overview for everything else. There won’t be any specific applications or how-to’s in this section. That is for later.

Part I. Introduction to Low-Temperature Cooking and Sous-Vide

I. Getting the Terms Right:
Sous-vide and low-temperature cooking are just two of the many techniques and processes that are revolutionizing modern cooking. Despite their growing popularity, many remain confused about the difference between low-temperature cooking and sous-vide—including equipment manufacturers. Between the two, low-temperature cooking is undoubtedly the more important.

Low-Temperature Cooking Defined:
Cooking low temperature does not mean cooking food to a lower internal temperature than is traditional. Low-temperature cooking refers to the temperature of the cooking medium, not the final temperature of the food being cooked. A rare steak has the same internal temperature whether cooked low-temperature or traditionally. Low temperature cooking is defined as any cooking procedure where the cooking temperature is at or close to the desired final internal temperature. There are two basic requirements for low-temperature cooking:

  • precise and accurate temperature control;
  • a cooking medium which conducts heat more efficiently and accurately than dry air. Water and water vapor are typical, but oil, stock, or any other liquid will work.

By way of example: to cook a steak to an internal temperature of 55°C (131°F), you could either sear it and put it in a 205°C (400°F) finishing oven till it reaches 55°C (131°F) (not low temperature cooking), or quickly sear it and throw it into an oil bath maintained at 55°C (131°F) (low temperature cooking but not sous-vide).

In traditional high-temperature cooking, the temperature of the cooking medium is almost never the same as the desired temperature of the food. That is, while your oven may be heated to 205°C (400°F), your fry oil can to 190°C (375°F), and poaching water to 100°C (212°F), a steak cooked in those mediums can only be considered rare when it reaches an internal temperature of 54°C (129°F). The difference between the desired final food temperature and the temperature of the cooking medium is referred to as temperature delta, or ΔT (pronounced “delta t,” the triangle is the Greek letter delta). You should just get used to referring to ΔT’s –like, “hey, you want that squab cooked to 56°C? Do you want to use a ΔT?”

Sous-Vide Defined:

In contrast, the simplest way to define sous-vide may be to refer to its French meaning, “under vacuum.” Anything associated with a vacuum machine is sous-vide. In restaurants, the sous-vide process usually (but not always) consists of:

  • placing products into impervious plastic bags
  • putting those bags under vacuum
  • heat sealing those bags
  • releasing the vacuum
  • further manipulating, processing, or storing

This is where it gets confusing: sous-vide techniques are often used for low temperature cooking, but not all sous-vide cooking is low-temperature cooking. The classic example of this is boil-in-bag meals. The cooking medium is boiling water—not low temperature. Yet, because there is a vacuum process involved, it is sous-vide. That said, sous-vide is very effective for low-temp cooking because food inside the bags neither dries out nor loses flavor during prolonged cooking if proper temperature is maintained. The vacuum bags also eliminate evaporation and evaporative cooling. The temperature of the food’s surface becomes identical to the cooking temperature after a short time.

Chefs and diners alike often confuse sous-vide and low-temperature cooking. Sous-vide must involve a vacuum process; but the food may be cooked at high or low temperatures. About 90% of what cooks want to achieve with low temperature cooking can be achieved without a vacuum.

II. Some Uses and Advantages of Low Temperature Cooking:

Uniform Cooking, Increased Consistency, and Shifting Control to the Chef:

Traditional steak vs. low-temp steak.

Traditional cooking typically uses a high ΔT. Foods cooked in this manner display an overcooked portion on the exterior. Meat cooked at high temperatures does not have one level of doneness—it is tasted as an average, from the well-done exterior to the less cooked center. Low-temperature cooking is less forgiving, because there is no way to average out errors. In a steak cooked at a low ΔT, the steak retains the same temperature throughout. The difference of 2°C can make a large difference in texture when there is no averaging effect—you need good temperature control (The entire range of steak doneness, from rare to well-done, is only a matter of 14°C (25°F). Luckily, modern equipment easily gives us temperature control accurate down to a tenth of a degree, which means we can cook products extremely uniformly and get them right 100% of the time.

Uniformity can be a disadvantage—no one wants a giant piece of roast beef that is one color all the way across—but most of the time uniformity is an advantage because it leads to increases consistency. Your steaks will never be over or under –always just right. This advantage cannot be overstated, and it applies to restaurants or home cooks. Additionally, because the hard work of reaching the correct internal temperature is being regulated by an accurate piece of equipment, the responsibility for getting the product right is shifted away from the line cook towards the chef who is choosing the temperature and setting the machine.

Shifting Work from Service to Prep (or from Party to Prep at Home):

We can always make more prep time. Service is what service is. Any time we can shift work away from service towards prep we win. Many low temp techniques require more prep time than their traditional counterparts; but are blindingly fast to finish off at service time. The high speed finish derives from the fact that the food is pre-cooked and can be held warm and ready to go, only needing a few seconds of finishing time. Speed finishing is a boon to the home cook as well. Parties are a lot more fun when you can hang out with your guests and all your food is in perfect finish at the same time.

Low-Temp for Insurance:
Low-temp cooking can provide a type of cooking insurance by guaranteeing a minimum doneness. Here’s how:

    1. Low temp your food to the rarest you want it. The food is now uniformly rare.
    2. Cool the product completely.
    3. Cook the product traditionally, but focus only on obtaining the perfect exterior because the middle is already cooked. You have insured that the inside is done.

Here are some examples of low-temp for insurance:

  • Roasts can be challenging. Often you get a good crust before the middle is done and then overcook the whole piece to bring up the center. Other times, you focus on getting the middle perfect but end up with a poor crust. Low-temp insurance fixes that. Low temp the roast till it is rare and cool it down. Put the roast in a high oven and pull it when the crust is perfect—you have already insured that the middle is done.
  • On a beef Wellington it is very difficult to insure that the puff pastry and the beef come out nicely at the same time. Usually the meat is overcooked or the pastry is too blond. With low-temp insurance you sear and pre-cook and cool your tenderloin and then wrap it in puff pastry. Now, you can turn your oven up and just focus on getting the pastry nice and brown since your meat is already cooked.
  • Sausages are often poached before being finished in a pan on the grill. This is high-temp cooking insurance. Instead, low temp-cook the sausages (60-62°C is usually good), then finish them on a grill or in the pan. The low-temp pre-cook doesn’t overcook the meat and rely on fat alone to provide juiciness.
  • Duck breast is best cooked with low-temp insurance. Pre-cook the breast to 57°C and cool it down. Then just focus on crispy skin.

Low-temp for insurance tends to produce items that have textures and appearances very close to traditionally cooked items, just better and more consistent. Because the products have a traditional feel, many cooks like this technique.

Low-Temp for New and Novel Textures:
Low-temperature cooking also allows for the production of some textures that were traditionally unattainable. Three examples:

  • Super-low temp fish: Fish heated at extremely low temperatures, around 50°C or (122°F) to an internal temperature of 42°C (107°F), has a dense, fudge-like or custard quality unattainable with high ΔT cooking. This type of cooking is controversial; many chefs dislike the texture attained with these methods, and some scientists believe the techniques are unsafe. Other chefs believe that the traditional cooking method overcooks fish and that the low-temperature method is best.
  • Low temperature braises: In a typical braise, meat with a lot of connective tissue is cooked at a high temperature for several hours. The high temperature and several hours is what is needed to break down the collagen into gelatin. This process overcooks the muscle and dries it out. Luckily, the gelatin re-moistens the overcooked meat and produces a delicious braise. When a meat is under-braised, it seems tough and dry because the collagen hasn’t melted into juicy, water holding gelatin. With low temperature cooking, however, we can hold a tough piece of meat at a very precise temperature for a very long time. If a short rib is held at 6o°C (140°F) it will maintain a lightly pink, medium-cooked color for days. The texture of the muscle fiber itself will also remain somewhat static. The connective tissue, on the other hand, won’t break down over the course of 3 or 4 hours at this temperature—you need to cook it for two full days. At the end of these two days, however, you will have a completely pink, completely tender short rib that is a dream to slice and portion.
  • Creamy egg yolks: When you heat a whole in-shell egg in water to 63°C (145°F), the yolk becomes creamy—not runny, not set. One degree lower is a runny yolk. One degree higher is a set yolk. The 63°C egg is a delight and completely impossible to make traditionally. More on eggs later.

Low-Temp for Increased Tenderness:

Low-temperature cooking can also produce meats that are more tender than normal. Enzymes responsible for some of the benefits of dry-aging meat increase activity as the temperature rises. These enzymes are most active right before they denature, between 49°C and 54.4°C (120°F and 129.9°F). Because low-temperature cooking allows meat to stay in this zone longer than traditional cooking, meat is more tender than normal. Traditionally, a large piece of meat heated for a long period of time, such as a roast, remains tender. Low-temperature cooking makes it possible for smaller pieces of meat to be held at these low temperatures for longer periods of time.

III. Low Temperature Cooking Disadvantages

Surface Browning, the Maillard Reaction, and the Challenges of Low-Temperature Cooking:

Low-temperature cooking does not produce crisp, flavorful, brown exteriors, which are usually obtained by cooking at high temperatures. Much of the artistry of low-temp cooking involves getting around this limitation. Some techniques include:

  • Using meaty, savory flavors like soy sauce and miso (both are high in umami).
  • Quick-searing meats for flavor either before they are cooked, right before they are served, or both. Quick-searing in low-temperature cooking is performed at a higher than normal temperature to develop a brown crust without overcooking the interior of the meat.
  • Browning bones, fat, inexpensive pieces of meat, or vegetables and putting them into the vacuum bag along with the main food before cooking. The savory notes of the added pieces permeate the food over time. Roasted fat is especially useful, as many of the characteristic flavors of different meats are generated by the taste of cooked and broken down fats.

Uniformity of Texture:

The biggest gripe people have with low-temp cooking is that the uniformity of texture. Some people say that all low temp food is “mushy.” While it is true that bad-low temp food is mushy, good low-temp food doesn’t have to be. One of the ways to guard against uniformity is to provide texture in the finishing step—usually by searing. Adding crunchy garnishes or cooking portions of the food separately to compensate for the lack of textural variety is another option. A chicken breast cooked sous-vide, for example, might be served with a piece of crispy fried chicken skin (although we have had good chicken this way, we find the skin served this way not as satisfying as good-old crispy skin that is still stuck to the chicken). Lastly, European chefs often cook with a moderate ΔT (usually 10-15 C) to “overcook” the outside of the food and provide some textural variation. Most Americans don’t cook this way because it require precise temperature measurement, precise timing, or both. Most Americans cook with 0 ΔT and add texture in the finishing step.

IV. Why do Chefs Use Sous-Vide? Sous-Vide for Economy and Sous-Vide for Effect
Chefs may use sous-vide techniques and processes for a variety of reasons which roughly break down into two categories: sous-vide for economy and sous-vide for effect. The two approaches are not mutually exclusive, therefore it’s important to thoroughly understand both.

Sous-Vide For Economy:

Storage:

Traditionally, vacuum-packing has been used to enhance the storage life of cooked products. The bacteria that cause food spoilage need oxygen to survive. Since vacuum packaging removes all air (and therefore oxygen) from food, spoilage is slowed drastically if the proper steps are taken. Oxidation is also greatly reduced by utilizing vacuum-packing. Foods like cut apples and artichokes do not turn brown quickly in vacuum pouches. In long-term storage, vacuum bags can prevent the oxygen-produced rancidity of unsaturated fats. Low-moisture products like dehydrated fruit chips tend to stay crispy indefinitely in the low-moisture vacuum environment.

Unfortunately, some bacteria that cause illness (pathogens) are not inhibited by a lack of oxygen. In fact, some of the most dangerous bacteria thrive only in the absence of oxygen. If sous-vide products are kept in unsafe conditions, these pathogens can grow to dangerous levels without the simultaneous spoilage that would normally signal their presence. This is why it is important to adhere to safety rules when using sous-vide.

Organization:

Vacuum-packed pre-portioned foods are neat, sanitary, and easy to organize. Many portions of the same product can be fabricated at the same time and then sealed, which minimizes cross-contamination. The food is handled minimally before being placed in a sterile environment. Retrieving food is easy, and each portion is individually protected from spills and other dangers, such as a raw product dripping onto a cooked product.

Sous-Vide for Effect:

Recently, the unique properties of the sous-vide process have inspired a cooking movement that aims solely to increase the quality of food and achieve special culinary effects. Think of this as sous-vide for effect.

Texture Modification (aka Compression):

The key to this technique is long vacuuming to get all the air out of the inside of the food. After the food is sealed and the vacuum released, there is an immediate observable change in the product as the voids that used to contain air are compressed. On some products, the effects of compression are accentuated over time (pears become more translucent after several hours). This process can be accelerated by re-vacuuming the sealed bag until the bag inflates with water vapor and then releasing the vacuum.

Porous foods can have their texture and appearance radically modified by vacuum-packaging. Watermelon, for instance, becomes denser, changing from a mealy to a candy-like texture. Pears, cucumbers, and tomatoes become translucent.

Flash Pickling and Vacuum Marination:

Vacuum-packaging foods increases the uptake of flavorful liquids, brines, and colors. The more porous the item, the more dramatic the end results are. For example, a pear can be colored with port in an hour under vacuum. Cucumbers and other vegetables can be flash pickled in seconds. Meats can be brined in much less time than at atmospheric pressure.

Forming :

The pressure exerted by the atmosphere can be used to form dishes. Layers of food can be pressed extremely flat. Once removed from the bag, these compressed layers become easy to slice into beautiful portions. Food can be arranged as in a terrine, vacuumed, solidified, and sliced for decorative effects. Some effects formerly achieved with a simple mold and a weight can be achieved more easily with a vacuum machine.

De-airing :

When thick sauces and purées are blended, they often have large amounts of air whipped into them. Sometimes this air is undesirable. When chefs use modern thickeners and gelling agents, like xanthan gum, trapped air becomes a problem, as it affects the body of the sauce and its appearance (liquids with many air bubbles appear white and opaque). The thicker the sauce, the more difficult it is to remove air. Sauces that contain too much air can be made crystal clear by removing the air bubbles in a vacuum machine.

Any liquid can have all their bubbles removed in a vacuum machine. Place the liquid in an appropriately wide container (not a bag) inside the vacuum machine. If there is too much liquid in the container, the mixture will boil over and create a mess during the process. Close the chamber and introduce a vacuum; the liquid will start to rise and bubble. Soon after, the initial bubbles will break and the liquid will enter a rolling boil. At this point the vacuum can be released and the liquid will have cleared. This procedure is one scenario where there is no need to pre-chill the product being vacuumed because the desired outcome is to have the product boil.

→ 86 CommentsTags: