Science and Cooking: From Haute Cuisine to Soft Matter Science - Fermentation

As I posted way back when, I enrolled in an on-line course about the relationship between science and cooking. Here's what went on during Week 10.

• The star power is upped this week with guest lecturers Wylie Dufresne of wd~50 and David Chang of Momofuku making appearances. Ted Russin of The Culinary Institute of America also makes an appearance. 
• Harold McGee informs us that food fermentations are the work of living microbes; they're essentially invisibly small cooks that change foods for the better.
• Foods that owe their popularity to fermentation include dry cured sausages, pickles, breads, the vinegar in vinaigrette, cheeses, chocolates, wine and beer and ciders and the distilled beverages made from them. These are all thanks to bacteria and fungi like Saccharomyces cerevisiae and Leuconostoc mesenteroides.
• The most common food fermentations develop spontaneously. They're spontaneous because the microbes that are responsible are all over the place, in the air and in the soil and on surfaces of everything. And they thrive on the sugars in nutrient-rich materials like plant tissues and animal secretions like milk. 
• The second big group of food fermentations is produced by yeasts, usually Saccharomyces cerevisiae, but also others. They produce alcohols and carbon dioxide from fruit juices and other liquids that are rich in sugars. 
• There's a third group of fermentations is based on an Asian method for fermenting starchy foods, like the seeds of grains and legumes. Yeasts and lactic acid bacteria can't deal with starch directly. Sometime before the second century BC, Chinese brewers domesticated a species of mold, a kind of Aspergillus, which prepares starchy foods for the yeasts and the lactic acid bacteria by converting the starch into fermentable sugars. At the same time that it does that, the mold generates its own distinctive aromas. With the help of this Aspergillus, called koji in Japan, sake and other alcohols are made from rice in Asia. It's also how soy and tamari sauces and miso pastes are made. 
• We are told that the fermentation reactions in yeast, or in bacteria, are due to enzymes. An enzyme is a protein that is a type of catalyst; a catalyst is a molecule that increases the speed of a favourable reaction either by helping to break bonds, or by helping to make bonds form, without being used up.
• An example of a catalyst is baking soda or lye, which speeds up Maillard reactions that contribute to browning and flavour. 
• As magical as catalysts appear, they cannot make unfavorable reactions become favorable. 
• For more on fermentation, here's David Chang and one of his minions:
• In terms of the bond breaking, enzymes do this by either rearranging the molecule, or by affecting the atoms in the molecules in some way. In terms of making bonds form, enzymes do this by bonding to two molecules, or bringing them closer in proximity. The bond can then form more easily, because the molecules are positioned in a way that makes the bond happen more easily. Enzymes need to be very specially designed to fit the particular molecules they work on, so for each type of chemical reaction that an enzyme catalyzes, it is designed to help that reaction.
• The enzymes bromelain and papain are enzymes from pineapple and papaya. Because these are often found in meat tenderizers, they are used a lot in recipes because they break down the proteins in meats, making it tenderer.
• The browning of fruit or vegetables is also due to enzymes. Biting or cutting releases enzymes in special compartments of the cell, and they react with other compounds in the fruit or vegetable. 
• Thanks to one of Dufresne and Russin's collaborations, we can now glue one piece of meat or one protein to another, thanks to meat glue, an enzyme also known as transglutaminase.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Baking

As I posted in a previous blog entry, I've enrolled in an on-line course about the relationship between science and cooking.

Here's what went down week 9 .

• To coincide with all the holiday baking going on, this week's lesson explores the basic physics and chemistry involved in baking. Joanne Chang is this week's celebrity instructor.
• Baking involves a lot of the topics already covered in the course. Understanding these concepts won't make you a master baker, but hopefully, it will help you make better sense of the recipes you're using: 
• Elasticity -  the properties of gluten; the elastic network that occurs in proteins, starches, and sugars.
• Viscosity - any time something expands and rises, it involves the flowing of molecules by each other; without it, your breads wouldn't rise, and your cakes and cookies wouldn't expand.   
• Emulsions - baked goods tend to be made of bubbles that are packed together, and those bubbles are the result of gas expansion that occurs during baking.
• Heat transfer - obeys the laws of diffusion.
• Joanne Chang shows us some of the science behind making a birthday cake and a flaky pie dough:
  
  
• Though a birthday cake would work for Christmas baking (think about it), here's the recipe for another cake used in this lesson to try over the holidays, a Coca Cola cake:
  

  Ingredients

  1 cup cola
  1/2 cup buttermilk
  1 cup butter, softened
  1 3/4 cups sugar
  2 large eggs, lightly beaten
  2 teaspoons vanilla extract
  2 cups all-purpose flour
  1/4 cup cocoa
  1 teaspoon baking soda
  1 1/2 cups miniature marshmallows
  3/4 cup chopped pecans, toasted (optional garnish)

  
  
  1. Combine the cola and the buttermilk in a bowl, then set the mixture aside.
  2. Beat the butter at a low speed with an electric mixer until creamy. Gradually add sugar; beat until blended. Add the egg and vanilla, and again beat at low speed until blended.
  3. Combine the flour and cocoa to the cola mixture. Add to the butter mixture alternately with the cola mixture; begin and end with the flour mixture. Beat at low speed just until blended.
  4. Stir in the marshmallows. Pour the batter into a greased and floured pan. Bake at 350° for 30 to 35 minutes. Now is the time to make your frosting.

  1/2 cup butter
  1/3 cup cola
  3 tablespoons cocoa
  1 (16-ounce) package powdered sugar
  1 tablespoon vanilla extract
  2 teaspoons vanilla extract

  5. Combine the butter, cola, and cocoa and bring it to a boil in a large saucepan over medium heat, stirring until the butter melts. Remove from heat, and whisk in the sugar and vanilla.
  6. Remove the cake from the oven, and allow it cool 10 minutes. Pour the frosting over the warm cake. Garnish with the pecans, if desired.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Emulsions and Foams

As I posted in my October 13th blog entry, I've enrolled in an on-line course about the relationship between science and cooking. I'm still plugging away at this, good thing I decided to do this for the knowledge.

Here's what went down on the eighth week.

• The focus of this week's lecture was on emulsions and foams. Ever since seeing that Marcel guy from "Top Chef" using them as a crutch, I respect the science behind foams a lot more than I do his use of them - that preening prat makes them look as pretentious as he is.
• An emulsion is drops of a fluid in a second fluid. A foam is the same thing, except instead of a fluid in a fluid, it's drops of air in a fluid. Mayonnaise is an edible example of an emulsion (oil and water). An obvious example of a foam is the stuff on top of your fancy coffee at the coffeehouse - your whipped cream is also a foam.
• Aioli is like a garlic mayonnaise. Below, Nandu Jubany, chef and owner of restaurant Can Jubany in Vic, Spain, shows how to make some:
• You might be asking how can an emulsion exist since oil and water don't mix. Emulsifying is done by slowly adding one ingredient to another while simultaneously mixing rapidly. This disperses and suspends tiny droplets of one liquid through another.The two liquids would quickly separate again, however, if an emulsifier, a stabilizer between the two liquids, wasn't added. In mayonnaise, the emulsifier is egg yolk, which contains lecithin, a fat emulsifier. Another food that contain emulsifiers is gelatin.
• Chemically, emulsions are colloids, heterogeneous mixtures composed of tiny particles suspended in another unmixable material. Though less than one one-thousandth of a millimeter, these particles are larger than molecules, and do not settle out and will pass right through filter paper. The particles in a colloid can be solid, liquid or bubbles of gas, and can be suspended a solid, liquid or gas, although gas colloids cannot be suspended in a gas.
• It's the tiny air bubbles in foams like meringues, soufflés, and mousses their texture and mouth-feel. In most of these foods, proteins are the main surface active agents that help in the formation and stabilization of the dispersed gas phase. To create a protein-stabilized foam, it usually involves bubbling, whipping or shaking a protein solution and its foaming properties refers to its capacity to form a thin tenacious film at the gas-liquid interface for large amounts of gas bubbles to become incorporated and stabilized.
• When protein concentrations are increased to their maximum value the foaming powers and foam formation are generally increased. A protein will always have certain stresses that it must over come, such as gravitational and mechanical, it’s the proteins ability to stabilize foam against these stresses that determines the foams stability. The foams stability is usually expressed as the time required for 50% of the liquid to drain from foam (a 50% reduction in foam volume).
• Here once again is Nandu Jubany to demonstrate how he makes a carrot foam:
  
• Two of the recipes used in this week's lesson were for hollandaise sauce and for a chocolate soufflé, taken from Julia Child's "Julia and Jacques Cooking at Home", and the Food Network website, respectively. Try them out to conduct your own emulsion and foam experiments.

Ingredients - Hollandaise sauce

1 Tbsp. (15 mL) water
1 Tbsp. (15 mL) fresh lemon juice
3  large egg yolks
6-8 oz. (177-236 mL) very soft unsalted butter
1 dash cayenne pepper
salt and ground white pepper to taste

1. Whisk the yolks, water, and lemon juice in the saucepan until thick and pale.
2. Set the pan over moderately low heat and continue to whisk at reasonable speed, reaching all over the bottom and insides of the pan, where the eggs tend to overcook.
3. Frequently move the pan off the burner for a few seconds, and then back on. (If, by chance, the eggs seem to be cooking too fast, set the pan in the bowl of cold water to cool the bottom, then continue).
4. As they cook, the eggs will become frothy and increase in volume. When you can see the pan bottom through the streaks of the whisk, remove from the heat.
5. By spoonfuls, add the soft butter, whisking constantly to incorporate each addition. As the emulsion forms, you may add the butter in slightly larger amounts, always whisking until fully absorbed. Continue adding butter until the sauce has thickened to the desired consistency.
6. Season lightly with salt, pepper, and a dash of cayenne pepper, whisking in well. Taste and adjust the seasoning, adding droplets of lemon juice if needed. Serve lukewarm with fish or vegetables.

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Ingredients - Chocolate soufflé

7 oz. (198 g.) finely chopped bittersweet or semisweet chocolate
4 Tbsp. (59 g.) unsalted butter (+ extra for greasing the molds)
1.5 tsp. (7.4 mL) pure vanilla extract
3  large egg yolks
3 Tbsp. (45 mL)  warm water
1/2 cup  (65 g.) sugar (+ extra for lining the molds)
8  large egg whites
1/2 tsp.  (2.4 mL) fresh lemon juice
confectioners' sugar for garnish

1. Brush 6 (6-ounce (177 mL)) ramekins with butter and coat with sugar. Preheat oven to 400 degrees °F (204 °C).
2. Melt and combine chocolate and butter in a double-boiler until smooth. Remove from heat and stir in vanilla extract.
3. Beat egg yolks and warm water until frothy. Add 2 Tbsp. sugar and beat till ribbons form. Fold into chocolate mixture.
4. Beat egg whites and lemon juice on medium until frothy. Gradually add the sugar, beating until stiff (but not dry) peaks form.
5. Fold about 1/4 of the egg whites into the chocolate to lighten; then fold in remaining whites until blended. Gently ladle or spoon the soufflé mixture into the ramekins and place on a baking sheet.
6. Immediately bake until the souffle rises about 1.5 inches above the ramekins and the tops brown, approximately 18-20 minutes. Remove from oven, dust with confectioners' sugar and serve immediately.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Viscosity and Polymers

As I posted in my October 13th blog entry, I've enrolled in an on-line course about the relationship between science and cooking.  I'm still plugging away at this, good thing I decided to do this for the knowledge and not the class credit.

Here's what went down for Week 7.

• Viscosity measures how easy something is to pour. Water has a low viscosity and cold syrup has a high viscosity.
• The molecules that make a liquid up flow past and bump into each other. To thicken it, we need to add molecules or particles that will impede the motion of the liquid.
• Want to measure the viscosity of a fluid, but you don't have a rheometer? If you have some free time on your hands (and who doesn't?), take a container and put a little hole in the bottom, and measure how long it takes for the fluid to flow through the hole.
• How thick or how thin a sauce is can make or break a recipe. Some of the ways to thicken food are:

1. Reduction: This term you've heard on your favourite cooking show means you take the material you want to thicken, heat it on a stove in an open pan, and you reduce it by simmering it until about half of the water has left, through evaporation. 
• This works because they were already enough molecules in the material you want to thicken to cause a thickening, but because of all the water molecules in the liquid, they were just too far apart to thicken. It works well if you have a stock, because it has lots of gelatin molecules. But it won't work if you just have something with only very small molecules in it. This is why you can't thicken a brine by boiling it, and why can't thicken wine by boiling it, unless you boil it all the way down till it's a glaze and there's almost nothing left.

Here is guest lecturer Carme Ruscalleda in her native Spanish to demonstrate:


2. Emulsion: Another oft-heard cooking show word, this is the process of combining two liquids (usually fat and water) that will maintain their distinct characteristics after being mixed. Common fat in water emulsifications include hollandaise sauce and mayonnaise, and common water in fat emulsifications are vinaigrettes and whole butter.
• Adding oil is a good way to thicken, but it makes what you're making taste of the oil you're using.
3. Starch-based thickener: This is a classic French technique of mixing and cooking equal parts flour and fat into something called a roux.
• The starch in the flour is heated up to the point that it hydrates and gelatinizes, turning the starch molecules into sticky polymers that make a liquid thick.
• Note that you have to cook the roux properly, otherwise it will have a floury taste, and it won't thicken well. You can use cornstarch or arrowroot or other starches, but if you put too much in, your roux will get rubbery and have an unpleasant texture.
4. Modernist thickener: These are substances used by those who worship at the altar of molecular gastronomy. Xanthan gum, a natural product, is made by fermenting a kind of bacteria. Because of the polymer molecules, very small amounts can produce a large increase in the viscosity of a liquid- in most foods, it is used at 0.5%, and can be used in lower concentrations. Xanthan gum also helps thicken commercial egg substitutes made from egg whites, to replace the fat and emulsifiers found in yolks, and is also used in gluten-free baking, as it gives the dough or batter a "stickiness" that would otherwise be achieved with gluten.
• A polymer is a very long, but very flexible molecule, made up of many, many monomers. Polymers have to get out of the way of one another in order for the fluid to flow. This is why polymer thickeners are so effective at increasing the viscosity of a fluid.

• Gels can also be used in thickening, as their long polymer molecules stick to each other, in a random way, trapping both water molecules and all other molecules, into something that effectively becomes a solid, like Jell-o. When you break them up, by pureeing it for example, the gel will reform slightly, and create a fluid gel, which acts like a thick liquid.
• Agar agar (or just agar) is a natural gelatin product made from seaweed that's been used for more than 1000 years in Asian cooking. Like xanthan gum, only a small amount of agar is needed to thicken your soups and sauces.
• Food additives like agar agar and xantha gum can be ordered online at MOLECULE-R.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Heat Transfer

As I posted in my October 13th blog entry, I've enrolled in an on-line course about the relationship between science and cooking.  I'm still plugging away at this, good thing I decided to do this for the knowledge.

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• This week's session is about the transfer of heat in cooking food.
  • Heat is described as a difference in temperatures. Something feels hot because your hand is colder than the thing you touched. When you touch the hot object, energy in the form of heat is transferred from the object to your hand because of the difference in temperatures
• As any cook can tell you, it's tough to make things by applying heat in order to make it taste good. The reason is that in order to properly cook something, it is not sufficient to cook the inside of the thing you're trying to cook to a target temperature. It turns out you also have to have the outside hit another target temperature. And that target temperature for the outside is higher than the target temperature of the inside, higher even than the boiling point of water. So to perfectly cook a meatloaf, or vegetables, or whatever you want to eat, you need to get the outside of the food a temperature higher than the boiling point of water, while getting the inside to a temperature below the boiling point of water.
• Why is it necessary to cook the outside of a food to a temperature that's higher than the boiling point of water? It's because it's needed to make a very important set of chemical reactions, called the browning reactions. Not surprisingly, these are the reactions that tend to take food and make it have a brown colour. Called the Maillard reactions, after the chemist Louis Maillard who discovered and described them in the 19th century, the way these reactions work is that they are a reaction between carbohydrate molecules, like a sugar, and a protein, which could be a single amino acid. At high temperatures, the combination of a carbohydrate molecule and a protein will lead to hundreds of small molecule by-products. Some of these by-products are colour compounds. They tend to be brown, which is the reason food gets that brownish colour when it cooks.
• This is why when you take a piece of fish, seal it in plastic, and cook it sous-vide style (that is, cook it in a constant temperature heat bath), there won't be any flavour molecules produced because the temperature is well below that of the Maillard reactions. Your fish will have a perfect texture, but it would taste quite bland.
• If we put a piece of meat or a piece of fish into an oven at a temperature much higher than 100 degrees, the centre of it, where there's lots of water, can't get higher than 100 degrees, because it can't go above the boiling point of water. The only way that it can actually go above that temperature is if you actually boil off some of the water in whatever it is it you’re cooking, so there's a thin layer around the outside where it's actually dried out. Once it's dried out, in that dried out layer, in that thin layer which is dry, you could push the temperature above 100 degrees Celsius, and you can start to get close to the temperature that's needed for browning reactions. That's the reason really that there's a thin crust of brown around food when you cook it because these temperatures can only be hit in the part of the food where it's actually dried out.
• Carme Ruscalleda, chef and owner of restaurant Sant Pau, demonstrates her method of cooking a steak.
  
  
  
• Nathan Myhrvold shares his secret to cooking the perfect burger; he uses liquid nitrogen. For those of us who don't have access to such chemicals, Heston Blumenthal has a more accessible way to cook meat.
  
• Michael Brenner and Daniel Rosenburg ttalk about the physics of how heat is transferred to food.
• Microscopically, the air around the food being cooked is hot, meaning the molecules are whizzing around like mad, causing the molecules in the food to start whizzing around like mad, and eventually, they all get hot.
• Heat diffuses into food like a random walk, which brings us to the Equation of the Week, L=4Dt−−−−√or L is equal to the square root of 4 times D times t, where L is the length of the food, D is the diffusion constant that's governing the random walk and t is time. Scientists call it the heat diffusion concept.
• Different foods have different heat diffusion constants. Knowing this and the above equation allows you to estimate how long it takes to cook different foods. I would still recommend using a kitchen timer, however.
• The week's lecture ends with a demonstration of how to make a better French fry, a lab assignment consisting of making a molten chocolate cake, and a homework assignment of making fried ice cream balls. I'll post my attempts of making at least one of these recipes in the future.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Week 5

As I posted in my October 13th blog entry, I've enrolled in an on-line course about the relationship between science and cooking.  Yes, I'm still plugging away at this, luckily I decided to do this for the knowledge as opposed to the college credit.

• This week the focus is on gelation, diffusion and spherification. Appearances will be made by Nathan Myhrvold, José Andrés, and Ferran Adrià, who popularized spherification, the ability to create a small shell of gel around food.
• Spherification happens when sodium alginate, a polymer that comes from seaweed, reacts with a salt like calcium chloride. The polymers, when in solution, are negatively charged. Electrical charges that are negative repel each other. Calcium ions have two positive charges, which allows the calcium ions to stick to the alginate molecule, as one of the positive charges will cancel out the negative charge, but still leaves a positive charge left. That positive charge can then stick to another alginate molecule, thus allowing the two molecules to stick to each other. If the number of such cross-links becomes high enough, you then create a gel.
• Got some clementines laying around? This is what José Andrés would do with them:
  
• A common example of gelation - making jell-o, or cooking eggs. They consist of polymers with cross-links holding the polymers to each other.
• Polymers are long strands that are intermixed with each other.  Think of them as being like a bowl of spaghetti.  When you form a gel, you stabilize the cross-links between the strands, the cross-links being the places where the strands overlap. Only a tiny part of the material actually are the molecules that cause the solid to hang together. Most of it is actually liquid. That's why it's not as solid as your hand.
• The equation E equals kT over l cubed, can be used to find the elasticity of a gel.
• There are two categories of how cross-links can form. In the first category, the polymers come from some protein component of the food. This is what happens with eggs. The proteins unfold because of heating, and then they stick to each other forming cross-links.
• The second category involves some other binding agent being added, like a type of glue, that causes the polymers to stick to each other.
• Nathan Myhvold comes on to talk about modern thickeners, like agar, xanthan gum and gellan gum.
• A great practical use for all this knowledge of gels is make great scrambled eggs. Dan Souza demonstrates:
  
• Harold McGee talks about the history of gels and jellies, and mentions an imitation egg recipe used during the time of fasting during Lent in 1600.
• Ever wonder why your homemade coleslaw gets watery? A cabbage is about 93% water, and some of this water dilutes the dressing used on it.  It's the salty ingredients in the dressing that are drawing water out of the cabbage and ruining the coleslaw. When salt is applied to any vegetable, including cabbage, it creates a higher ion concentration at the surface than exists deep within the cells. The salt slowly diffuses into the vegetable while also drawing moisture out.  To equalize the concentration levels, the water within the cells is drawn out to the permeable cell walls. This process is called osmosis.
• To get rid of that moisture, toss your shredded cabbage with a teaspoon of salt in a colander, and let the cabbage sit for at least an hour or up to 4 hours until it wilts. Rinse the cabbage under cold running water, and press, but not squeeze, to drain, and then pat dry with paper towels. Then combine your dressing as normal.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Week 4

As I posted in my October 13th blog entry, I've enrolled in an on-line course about the relationship between science and cooking. It's been awhile since my last post about this course, for reasons that may or may not have to do with "Batman: Arkham Origins", and a neglected stack of laundry.

Here's what went down on the fourth week.

• This week the topic is elasticity, and one of the guest lecturers is White House Pastry Chef Bill Yosses.
• Who knew the White House had its own pastry chef? I wonder if either Barrack or Michelle has ever asked him to whip up a batch of cro-nuts for them.
• To measure elasticity, we are shown how it is measured with a spring. This principle of physics, called Hooke's law, states that the force needed to extend or compress a spring by some distance is proportional to that distance. That is, F = k x, where k is a constant factor characteristic of the spring, its stiffness.
• What does this have to do with food? Elasticity in food relates to how it feels in your mouth when you chew it. For example, the elasticity of a steak will increase as it becomes more difficult to chew the longer it is cooked.
• I had no idea there were different mouth feels for tofu, or that firm and soft tofu even existed.
• The mathematical description of an object or substance's tendency to be deformed elastically (i.e., non-permanently) when a force is applied to it is E = U over I³, where U is the interaction energy between the bonds in the material, and I is the distance between them. This is also the equation of the week in case you were wondering.
• We are treated to a scientific look at the making of strudel, which leads to a discussion about gluten, the protein that gives strudel dough its special characteristics.



• Did you know hearing plays a part in the enjoyment of food? Harold McGee talks about an experiment done at Oxford University where the subjects put on sound-blocking headphones, and  sat in front of a microphone, and bit into potato chips. The sound of the biting was picked up by the microphone and processed before the sound was passed back to the eaters' ears through the headphones. When the chewing sound was sent to the headphones unchanged, the eaters rated the chip as normally crisp. When the sound was amplified, they rated the chip as more crisp.
• McGee also mentions anthropologist Richard Wrangham's belief that because cooked food is often easier to chew, the invention of cooking has had a profound effect on the evolution of the human species.
• Dan Souza from America's Test Kitchen and Nathan Myhrvold of Modernist Cuisine fame both recommend slow-roasting tough cuts of meat, like an eye of round roast - who am I to argue?
• Poking your meat full of holes can make it be more juicy. This process is called jaccarding, and is done with a device not surprisingly called a Jaccard. A Jaccard has tiny blades that cuts little bits of the muscle fibers weakening the collagen fibres in them without cutting the meat totally. By poking the meat with holes, the collagen fibers do a less effective job squeezing the moisture out of the meat when it's being cooked.
• Note to self: Invest in a sous-vide machine so I can experience a short rib slow cooked for 72 hours.
• We end Week 4 with a summary of elasticity and another appearance by Bill Yosses, who demonstrates how, with a little sugar, water, and glucose, you can make a candy apple.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Week 3

As I posted in my October 13th blog entry, I've enrolled in an on-line course about the relationship between science and cooking. A very video heavy week this time out - food porn fans would really appreciate all the detail that went into the making of this course. 

Here's what went down on the third week.

• The guest presenters this time out are Joan Roca, who runs the world-famous restaurant El Celler de Can Roca in Girona, Spain with his two brothers; and Dan Souza, senior editor for Cook's Illustrated Magazine, and current cast member of the America's Test Kitchen television show, radio program and podcast.
• This week we learned about the various phase transitions foods can go through in the cooking process. While a change in temperature can cause a phase transition, a change in pressure can also make this happen.
• A pressure cooker works by trapping some steam as water inside it boils, thus increasing the pressure and raising the boiling point. When the boiling water reaches this higher boiling point, it transfers heat to the food more quickly than water at just 100 degrees Celsius. This is a much better way to explain how a pressure cooker works than the method used to describe what happened in Boston back in April of this year.
• Want to cook the perfect egg, one with a temperature of about 64 degrees Celsius, perfectly every time? As water boils at a lower temperature as you gain altitude, just climb a tall enough mountain. Unfortunately, the boiling point of water on the top of Mount Everest is about 71 degrees Celsius, so you're going to need a bigger mountain.
• Chef Roca then demonstrates some of his renowned sous-vide cooking techniques by cooking, among other things, eggs and a fillet of sole.
  
  
  
  
• Another method to cause a phase transition is to use a rotovap, which is used in laboratories for the removal of solvents from samples by evaporation, and in cooking for the preparation of distillates and extracts. Check eBay for one if you ever need to distill the essence of something in one of your dishes.
  
• The concept of entropy has been introduced; I don't recall ever hearing about entropy in either elementary or high school science class, but I'm learning about it as part of a course about cooking, go figure.
• To be fair, I don't recall getting as much background in the half semesters of elementary school home-ec class either. Maybe it's time it should...
• Still haven't clapped for the equation of the week. This time it's U = CkBT.
• A chemical breakdown of fats and a discussion about the science of supercooling follows, along with an explanation of why you can't make water as salty as you can sweet. Thanks to this course, I now know that the solubility of any compound, is similar to the phase transition between a solid and a gas. 
• I scream, you scream, this week's lab involves the making of ice cream - sweet.