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.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Week 2

As I posted in my October 13th blog entry, I've enrolled in an on-line course about the relationship between science and cooking. Still haven't had the chance to try any of the recipes, still trying to a get a better grasp of the science portion of the lessons. Not enough hours in the week, but no one ever said taking a Harvard on-line course would be easy.

Here's what went down on the second week.

• This week's guest lecturer is Dave Arnold. Week 2's focus is on energy, temperature, and heat, so naturally we begin with a recipe to carbonate a cocktail to show what happens when you mix ethanol and water. I knew I signed up for this class for a reason.
• Because they're scientists, the instructors like to make things quantitative, in the belief that when we start to make ideas quantitative, then we'll start to understand qualitatively better.
• The benefits of sous-vide cooking is then demonstrated in an example using eggs cooked at various temperatures in a very small window between 57 Celsius and 70. Accurately controlling the temperature can make a great deal of difference - something to keep in mind when you're trying to make the perfect Eggs Benedict or eggs on toast.
• Equation of the week:  equals mc sub p delta t. (Or heat equals mass x specific heat capacity x change in temperature). You can use that equation to calculate how much energy you have to put into heating a cup of  water.
• Start with water that's at room temperature, in this case, about 23 degrees Celsius. One cup of water is 237 grams. We are going to heat it to the boiling point, 100 degrees Celsius. The specific heat (c sub p). for water is 4.18 joules per gram degree Kelvin.
• How much energy do I have to dump in? Using the equation Q is equal to mc sub p delta t, put in that m is equal to 237 grams, that c sub p is equal to 4.18 joules per degree Kelvin, and that delta T is 77 degrees Celsius (100 degrees Celsius - 23 degrees Celsius, the final temperature minus the initial temperature) If we multiply all of these things out, we got 237 times 4.18 times 77. So that's how much energy it takes to boil a cup of water -76 280 joules.
• What does that mean? Think about it like this, how much wood would you have to burn in order to make this much energy? If you take the energy density of wood, 14 megajoules per kilogram, then you can calculate for yourself that the amount of wood that it takes is 76 280 joules divided by 14 megajoules per kilogram, which is 5.4 grams of wood.
• Just for fun!: Go look at the power output of your microwave, calculate how long does it take for you to generate the 76 280 joules needed to boil water. If you put water in a cup in your microwave for that amount of time, does it actually boil? If not, why not?
• NOTE: Most microwaves have a power output of about 400 watts.
  The watts to joules calculation is the energy E in joules (J) is equal to the power P in watts (W), times the time period t in seconds (s): E(J) = P(W) × t(s).
• I got 190.7 seconds, feel free to let me know if my math is off (scroll over to see).
• You really see how much you don't know about a topic when you answer all the week's pre-questions.
• The liquid nitrogen lecture reminds me of an experiment I've been meaning to try, and of a cool food truck I saw on an episode of Eat St. recently.
• Think of heat as the most used and the most mysterious ingredient in your kitchen --> Harold McGee
• Heat: the total energy that results in the temperature of a system
  Temperature: the measure of energy in the motion of molecules in the material
• Want a quick way to calculate the number of calories in what you're eating? Use the 449 rule.
• We end with a demonstration of the coffee-infused rum cocktail the cafe Touba being made, and some more fun with equations involving latent heat.

Science and Cooking: From Haute Cuisine to Soft Matter Science - Week 1

As I posted in my October 13th blog entry, I've enrolled in an on-line course about the relationship between science and cooking. Here's what went down on the first week. I'm liking the course so far, I just wish I could manage my time better to get through all the labwork. Just like back at Algonquin - some things never change.

• The course starts with a welcome and an overview from some of the instructors Michael Brenne, Pia Sorensen, and Dave Weitz, an applied mathematician, a chemist, and a physicist, respectively. They talk about learning about the underlying scientific principles of food and cooking, and about some of the cooking labs we'll get a chance to do in the course.
• Ferran Adrià introduces himself in the next video, and talk about his background in cooking, and his new project, the El Bulli Foundation.
• The author of the textbook we're using, Harold McGee  talks for a bit about the place he did most of his research for the book, the Schlesinger Library for the study of women in history at Harvard. I was surprised to learn that people where interested in the science of cooking since the 17th century, and that the pressure cooker has existed since 1681 (thanks Denis Papin).
• In between the videos are a series of short-answer questions about what we've watch so far. Participation in the online exercises do not contribute to my grade, what counts are the homework assignments, the lab exercises, and the final project. I'm still not sure if I'm going to complete the course for the certificate, or if I'm just learning for the sake of learning yet...
• Next we see an example of spherification, a form of gelation first pioneered by Adria. 
• Lecture 2 get right into the science part of the course with a decision about the molecules that make the food we eat. We are then asked to calculate the number of molecules in a 250mL glass of water. Terms like grams per mole, atomic mass unit, and Avogadro's number are being thrown around. I now see why a knowledge of high school physics and chemistry was considered a useful prerequisite for this course. So if you thought this was going to be a bird course, you're either sadly mistaken, or a lot smarter than I am.
• I'm introduced to the practice of clapping when the Equation of the Week is introduced during the lectures as a way to get people excited about the science...sure. I'll just say I clapped while I watch the lectures.
• One of the tasks in the week 1 lab is calibrating your oven using sugar. Sugar melts at 366 F (186˚C). If sugar melts at 350 F (177˚C), your oven is running hot. I preheated my oven at 350 F for 10 minutes and placed in it half a teaspoon of sugar in an aluminum pan.
  
  Here's the result 15 minutes later.
  
  Looks like I'm running hot, I may choose to calibrate it better using a oven thermometer.
• The homework portion finally gets to some cooking, but I didn't get a chance to buy the required groceries. I'll keep you posted my efforts.