Remember the public cooking lectures at Harvard that I mentioned in September? According to the website they are *very popular* and the auditoriums are packed! This is good news, but the best thing is that the lectures are made available through YouTube and iTunes for free! So far 9 of the sessions are available, but I guess all will be available soon. If the picture is difficult to read, here’s the list of all the lectures:

Lecture 1: Science and Cooking: A Dialogue. Speakers: Harold McGee, Ferran Adria (elBulli), José Andrés (minibar by josé andrés, Jaleo, The Bazaar) with commentary/moderation from Professors David Weitz and Michael Brenner (Harvard).

Lecture 2: Sous-vide Cooking: a State of Matter. Speaker: Joan Roca (El Celler de Can Roca).

Lecture 3: Brain Candy: How Desserts Slow the Passage of Time. Speaker: Bill Yosses (White House Pastry Chef).

Lecture 4: Olive Oil & Viscosity. Speaker: Carles Tejedor (Via Veneto).

Lecture 5: Heat, Temperature, & Chocolate. Speaker: Enric Rovira.

Lecture 6: Reinventing Food Texture & Flavor. Speaker: Grant Achatz (Alinea).

Lecture 7: Emulsions: Concept of Stabilizing Oil &Water. Speaker: Nandu Jubany (Can Jubany).

Lecture 8: Gelation. José Andrés (ThinkFoodGroup, minibar, Jaleo).

Lecture 9: Browning & Oxidations. Carme Ruscalleda (Sant Pau, Sant Pau de Tòquio).

Lecture 10: Meat Glue Mania. Wylie Dufresne (wd~50).

Lecture 11: Cultivating Flavor: A Recipe for the Recipe. Dan Barber (Blue Hill).

Lecture 12: Creative Ceilings: How We Use Errors, Failure and Physical Limitations as Catalysts for Culinary Innovation. David Chang (momofuku).

Cheeseburger in hydrochloric acid

Do ice cubes made with heavy water float or sink?

Exotic ways to cut through butter

Spectacular ways of destroying pumpkins for Halloween

Tea chemistry

See Martyn Poliakoff boil an egg

(Martyn mentions that the yellow color of egg yolks is due to a sulfur containing compound, but I’m not really convinced he’s right about that. The yellow color is mainly due to a group of chemical compounds called xanthophylls which have long conjugated double bond systems that absorb light. And BTW – if you want to dissolve the egg shell in your own kitchen: skip the hydrochloric acid and use vinegar instead.)

Baking a cake in the lab with akward equipment…

… and then figuring out what to do with the cake
(it wasn’t eaten since it was made in a chemical lab)

Mirror images: Carraway and spearmint

Fun chemistry with Crispy creme eggs

Chocolate and roses for Valentines day

As the name suggests, the TGIF posts are a little less serious than what I otherwise post here at Khymos. I hope you enjoy it

If Richard Wiseman’s fork balancing trick is not challenging enough, why not try the fork balancing trick I did for part 8 (where I encourage experimentation in the kitchen) of my Ten tips for practical molecular gastronomy series. You only need two forks, two skewers, a wine cork and a little patience. If interested you can read more about the physics behind the balancing fork trick.

As the name suggests, the TGIF posts are a little less serious than what I otherwise post here at Khymos. I hope you enjoy it

Miss Silvia is full of surprises! She’s been around the house for a year, but only now did she reveal one of her hidden capabilities. Did you know that you can make scrambled eggs with the steam wand of your espresso machine? Me neither. It’s a brilliant idea and one can wonder why no one has done this before. I mean, espresso machines have been around for a while. And as it turns out – according to Kelly’s comment below this was done in San Francisco back in the 90′s. It seems as if the credits for rediscovering these scrambled eggs should go to Chef Jody Williams (and thanks to Jessica at FoodMayhem for posting this). I’ve tried it several times and it works very well. I’d even say that this gives you another reason to purchase an espresso machine with a proper steam wand! Many other reasons can be found in my first post about Miss Silvia.

This is how I make the scrambled eggs: I crack 3 eggs in a 600 mL pitcher (normally used for steaming milk) and press the steam button on my Rancilio. After approx. 10 seconds I empthy the wand of water and wait for another 30 seconds to allow pressure to build up before I start steaming the eggs. Notice that I didn’t even whisk the eggs with a fork – the whirling effect of the steam wand is strong enough to get the eggs properly mixed. With my Miss Silvia it takes about 50 seconds before the steam breaks through to the surface. The eggs actually set in the pitcher and I used a spoon to scoop the eggs out and put them on a plate. Scroll to the end of the post for a video illustrating the whole process.

Make sure you clean the steam wand very well after using it for eggs. The best way of softening the protein residues is to immerse the steam wand in cold water.

I have tried to add a little milk to 3 eggs before steaming, but interestingly I wasn’t able to get this mixture to set properly. I say interestingly, because even though the scrambled eggs failed I figured that steaming perhaps could be a good way of preparing custards. Holding the pitcher one has pretty good control of the temperature, and also very efficient aeration. It could even that this is a more robust way of preparing a custard? This needs experimenting – and you are more than welcome to join me! And why stop with custard? How about a sabayon? Basically any egg based sauce could be prepared with a steam wand.

Update (added on October 25th)
In the comments there was a question about what would happen with egg whites. I had 3 leftover eggwhites so I added some sugar and tried to steam them. They fluffed up very fast and I was not able to control the process. I spooned the result onto a plate and as you can see the result was quite regrettable. The whites lost a lot of liquid.

I also tried to make a simple sabayon using 1 egg yolk, 30 g sugar and 60 mL of white wine. I got a frothy texture, but when I poured into a glass it separated quite fast. I think the main problem here is scale – on such a small scale it’s really difficult to control the temperature. I presume that this could be easier to control by tripling the amounts.

[Found via the Norwegian food blog Ordentligmat]

The products of the Maillard reaction provide tastes, smells and colors that are much desired and lend their charachteristics to a variety of foods. In this post I will focus on the factors that influence how fast the Maillard reaction proceeds. And more specifically I’ll give examples on how the Maillard reaction can be speeded up. This is not about fast food, nor is it about saving time. It’s more about controlling the browning reaction by speeding it up or slowing it down in order to get a desired end result.

The Maillard reaction is, to put it simple, a reaction between an amino acid and a sugar (there’s more on the chemistry at the end of the post). To speed it up you can do one or more of the following:

Chances are you have already utilized this in the kitchen without knowing. When eggs or milk are used for glazing, they act as a protein source for the Maillard reaction, giving a nice brown color. Milk also provides lactose which is a reducing sugar. You’ve probably also observed that temperature does influence browning. Water content is indirectly related to temperature – as long as there is water present, temperature will stay below 100 °C. But once the bread crust dries out the conditions are just right to get the Maillard reaction running.

The same principles are applied to microwaveable pies. The microwaves primarily interact with water and hence only bring the temperature up to the boiling point of water. In order to get sufficient Maillard productcs at these temperatures reducing sugars and amino acids are added to the crust (as exemplified in this patent where dextrose and whey solids are used). Not so surprisingly there is also a patent on how to avoid excessive browning in cookies which calls for addition of a polycarboxylic acid ester to lower pH and hence slow down the Maillard reaction.

Pretzels are an extreme example of how the Maillard reaction can be tweaked. Before baking the pretzels are brushed with lye, a dilute solution of sodium hydroxide, which is very basic. The high pH speeds up the bottleneck of the Maillard reaction (see end of post for details).

A pinch of baking soda can bring out a new taste dimension when browning onions

Another basic ingredient found in most kitchens is baking soda (sodium bicarbonate, NaHCO₃). It’s used as a leavning agent which requires addition of an acid to function. Since it is a weak base, it can be used to increase the pH and hence the speed of the Maillard reaction, for instance when browning onions. This basic task, which isn’t always so easy after all, benefits greatly from a pinch of baking soda (and surprisingly it seems that this hasn’t been done before!). To illustrate this I’ve made a time lapse video of chopped onions being fried with and without baking soda. The frying took 11 min, but things are speeded up about 10x.

Samples taken throughout the experiment are shown in the picture below. Even after 4 min there is a visible difference. After 11 min, the small addition of baking soda has yielded onions which taste remarkably sweet with strong caramel notes, compared to the control which tastes like fried onions.

Another example of how baking soda is used to speed up the Maillard reaction is dulce de leche, a popular sauce/caramel candy in Latin America. It’s made by slowly boiling sweetened milk. Baking soda is not a required ingredient, but is often included. The baking soda gives dulce de leche a darker color and also contributes to the flavor.

Photo by audinou from flickr.com.

It should perhaps be added that baking soda is frequently used in Chinese cooking, for instance in tempura batters and marinades. Once there, the baking soda will certainly speed up the Maillard reaction, but it also affects the texture of meat – I’ll have to return to that topic later.

To round of this post I will briefly touch upon one of the reasons why pH influences the Maillard reaction. The first step involves a reaction between a reducing sugar (depicted as R(C=O)H) and an amino acid (depicted as R’NH2) followed by loss of water to yield a Schiff base. The Schiff base rearranges to the Amadori product (not shown). Of these first steps the formation of the Schiff base is the bottleneck (rate limiting step). The reactivity of the amino acid is influenced by the pH. A simplified reasoning goes like this: At low pH the amino group is protonated, yielding it less nucleophilic. At higher pH, the nitrogen becomes more nucleophilic and at very high pH the amino group can even be deprotonated. It should be noted that the fate of the Amadori product is also in large determined by pH and hence pH will affect more than just the rate, but this is far beyond the scope of this blog post.

For the following experiment I purposly left some lettuce (Lactuca sativa var. crispa, sold in Norway under the name “Rapid”, it’s a Summer Crisp/Batavian cultivar) to really dry out as you can see from the picture.

After approximately 4 hours in water the leaf looks like this. Notice that along the rim the leaf was so dry that the cells were damaged “beyond repair”.

To illustrate this relatively slow process I set my camera to take a picture every minute and left it for almost 4 hours. I then stiched it together and the resulting time lapse movie shows the process speeded up 720x (click if the embedded video won’t work).

The wonderful thing about this simple experiment is that it actually illustrates the essence of a recently rewarded Nobel prize (and I should thank Erik Fooladi for pointing this out to me)! The 2003 chemistry prize was awarded “for discoveries concerning channels in cell membranes”. The swedish Nobel foundation have excellent pages with further explanations for the public and for specialists alongside an illustrated presentation (recommended!). There are even two animations of which the first is also available on youtube (embedded below, poor resolution, download the original for higher resolution!). It shows how water molecules move through cell membranes: