Archive for the ‘fun with food’ Category

Dyeing eggs for the easter holiday

Thursday, April 5th, 2007

About.com has a nice guide on how to color eggs, and the list of colors is quite impressive (click for instructions):

Lavender
Small Quantity of Purple Grape Juice
Violet Blossoms plus 2 tsp Lemon Juice

Violet Blue
Violet Blossoms
Small Quantity of Red Onions Skins (boiled)

Blue
Canned Blueberries
Red Cabbage Leaves (boiled)
Purple Grape Juice

Green
Spinach Leaves (boiled)
Liquid Chlorophyll

Greenish Yellow
Yellow Delicious Apple Peels (boiled)

Yellow
Orange or Lemon Peels (boiled)
Carrot Tops (boiled)
Celery Seed (boiled)
Ground Cumin (boiled)
Ground Turmeric (boiled)

Brown
Strong Coffee
Instant Coffee
Black Walnut Shells (boiled)

Orange
Yellow Onion Skins (boiled)

Pink
Beets
Cranberries or Juice
Raspberries
Red Grape Juice
Juice from Pickled Beets

Red
Lots of Red Onions Skins (boiled)

More information about the chemistry behind can be found in the article “Chemistry in the dyeing of eggs” (Journal of Chemical Education, 1987, 291). The article discusses anionic dyes with sulfonate groups. These bond to the cuticle (protein) covering the egg shell forming salt linkages as shown (illustrated using FD&C yellow no. 6):

egg-colouring.jpg

By lowering the pH (for example by adding vinegar), more amino groups in the proteins covering the egg shell are protonated and thus available for formation of the salt linkages with the anionic dyes.

TGIF: Fed up with foam?

Thursday, March 29th, 2007

When many people hear molecular gastronomy, they think of culinary foams, originally introduced by Ferran Adria at El Bulli. In case you’re fed up with the foams, here’s a T-shirt to express your feelings:

foam-tshirt.jpg

Personally, I can’t even say I’ve taste any of these foams yet… Guess I’ll wait a little with the T-shirt then 😉

[Thanks to Chef John over at foodwishes]

TGIF: Molecular chocolate

Thursday, March 1st, 2007

chocolate-theobromine.jpg

When eating this chocolate, you eat a molecular model of what you are eating (well, at least one of it’s components) – theobromine!

It’s the brainchild of two Belgians, chocolatier Pierre Marcolini and furniture designer Dirk Meylaerts. More info on the Belgian and US website.

The taste scheme used for the different elements does not seem to be quite consistent (i.e. each element represented by a unique color):

  • Carbon: matte brown (crunchy shell)
  • Nitrogen: golden (mixture of caramel, roasted pineapple and praline) + bronze (bitter ganache with gingerbread notes)
  • Hydrogen: white (milk chocolate ganache flavoured with raz-el-hanout, sheathed in white chocolate) + bronze (bitter ganache with gingerbread notes)
  • Oxygen: shiny dark brown (blend of chocolate and caramel ganache with a touch of tonka bean)
  • chocolate-theobromine-assigned.jpg

    [Via Inkling Magazine]

    Scientific chocolate tasting kits

    Monday, February 19th, 2007

    Dominique & Cindy Duby, chocolatiers based in Canada, have put together two “scientific chocolate tasting kits” (one, two). Some of the science behind is explained in their “tasting notes” (copy the text into a wordprocessor to read it). For a review of the first kit, check out Rob and Rachel’s blogpost over at Hungry in Hogtown.

    The kits illustrate the use of various hydrocolloids to produce foams, gels, dispersions, emulsions and pearls. The principle of flavor pairing is illustrated and binary taste interactions are explored. They also include experiments to explore crunchy vs. soft textures. Each kit comes with four different experiments and enough ingredients to make 8 servings. Furthermore they let you serve every experiment at two different tempereatures. This is neat because is allows you to explore the great influence temperature has on texture and aroma. Each kit sells for $125 – expensive yes, but from the presentation it seems like a good bundle.

    Science tasting kit no. 1
    skv05.jpg

    The following is illustrated in kit no. 1:

      Experiment 1: foaming of pectin and gelatin gels, spherification of a fruit juice/chocolate emulsion (there’s no info on this, but I guess the spherification is alginate based)
      Experiment 2: explore how temperature influences sweet and bitter tastes, make a chocolate emulsion (with cream, strawberry juice, wine, cocoa butter and oil) and serve it at two different temperatures
      Experiment 3: explore the fact that “taste” is 80% smell, illustrate how salt can suppress bitterness, use a special powder made from an aromatic liquid and maltodextrin which is then dried under vacuum with microwaves (sort of like freeze drying, only this uses microwaves in stead)
      Experiment 4: Hervé This’ double dispersion chocolate “cake” made with chocolate and egg white foam which is set in a microwave oven (described in his Angewante Chemie article on molecular gastronomy), short lived crunchy texture, flavor pairing is illustrated by combining cumin and coffe with chocolate

    Science tasting kit no. 2
    skv06.jpg

    Kit no. 2 starts of by exploring culinary “equations” which are remarkably similar to (yet somewhat less comprehensive than) the CDS formalism described by Hervé This elsewhere. The following is illustrated in the second kit:

      Experiment no. 1: a “whisky” is constructed from ethanol lignin, aromatic aldehydes, sugars, acetic acid, oak flavor, vanilin, malt etc.
      Experiment no. 2: ice cream is made without churning using foamed egg whites to incorporate air (is this what Italians refer to as a frozen parfait?)
      Experiment no. 4: meringues floating on a pool of custard sauce drizzled with caramel

    If you’d rather reverse engineer the dishes, my list of hydrocolloid suppliers might come handy. The “tasting notes” also gives you some hints if you want to have a go on your own.

    TGIF: Levitating strawberry

    Thursday, February 8th, 2007

    The video is from the High Field Magnetic Laboratory in Nijmegen. Read more about levitation and check out their other movies (includes a levitating tomatoe!).

    A short explanation of how this works:

    An object does not need to be superconducting to levitate. Normal things, even humans, can do it as well, if placed in a strong magnetic field. Although the majority of ordinary materials, such as wood or plastic, seem to be non-magnetic, they, too, expel a very small portion (0.00001) of an applied magnetic field, i.e. exhibit very weak diamagnetism. The molecular magnetism is very weak (millions times weaker than ferromagnetism) and usually remains unnoticed in everyday life, thereby producing the wrong impression that materials around us are mainly nonmagnetic. But they are all magnetic. It is just that magnetic fields required to levitate all these “nonmagnetic” materials have to be approximately 100 times larger than for the case of, say, superconductors. This experiment was conducted at the Nijmegen High Field Magnet Laboratory.

    (Via food for design)

    TGIF: Achewood on molecular gastronomy

    Friday, January 26th, 2007


    achewood.jpg

    Click to see the complete comic.

    TGIF: Mechanical gastronomy!

    Friday, January 5th, 2007

    This is slightly off-topic, but take a look at these two videos on mechanical gastronomy. First one is a lego-machine that opens a bottle of beer. The second one is a Rube Goldberg (homepage, Wikipedia) machine that pours a beer (jump to 2:10 if you want to skip the intro and just watch the action). Rube Goldberg described his cartoons as “symbols of man’s capacity for exerting maximum effort to accomplish minimal results”, but has since given name to complicated machines that perform simple tasks!

    Happy New Year with the Science of Champagne!

    Sunday, December 31st, 2006

    Have you ever though about how far you can shoot a champagne cork? The swedish physicist Hans-Uno Bengtsson has actually done the necessary calculations in the wonderful Swedish book “Kring flaskor och fysik” (which translates to something like “Among bottles and physics”, it was written together with sommelier Mischa Billing). Assuming a bottle pressure of 6 atmospheres, a cork length of 25 mm (the part in contact with the bottle), a radius of 9 mm and a mass of 7.5 g, this gives an initial cork velocity of approximately 20 meters per second or 70 km/h! This translates into a maximum shot length of around 40 m (if we neglect air resistance). In case you prefer not to shoot the cork, you could of coarse turn to a saber or a heavy kitchen knife instead to open the bottle.

    When opening a bottle of champagne, you might have noticed the cloud forming right above the bottle neck (see picture below). This is due to a significant temperature drop, caused by gas expansion when we open the bottle. Assuming an adiabatic expansion (meaning no heat exchange with the surroundings), Hans-Uno Bengtsson has calculated a temperature drop of 112 °C! No wonder the vapor around the bottle neck immediately freezes forming a small cloud.

    cloud at neck of champagne bottle
    (picture by polarunner at flickr.com)

    If this doesn’t satisfy your craving for champagne science, there’s a whole book on the subject: “Uncorked – The Science of Champagne” by Gérard Liger-Belair. He’s an associate professor of physical sciences at the University of Reims Champagne-Ardenne and probably knows more about champagne bubbles than anyone else! In addition to many fascinating pictures of bubbles, the book has many interesting facts. Did you know that:

  • 0.1 liters of champagne (the contets of an average flute) contains approximately 0.7 liters of carbon dioxide which must escape to restore equillibrium – assuming an average bubble size of 500 micrometers in diameter this corresponds to 11 million bubbles!
  • Contrary to popular belief, nucleation sites for bubbles are not found on scratches or irregularities on the glass itself, but on impurites stuck on the glass wall. These impurities are typically fibres from paper or fabrics.
  • From the point when a bubble leaves the nucleation site till it reaches the surface, the volume increases by a factor of 1 million. This is due to diffusion of carbon dioxide from the solution and into the bubble.
  • Surfactant molecules in champagne form a protective shield around the rising bubbles. This stiffens the bubbles and significantly increases the drag on the bubble as it rises (which gives us more time to admire the trail of bubbles!).
  • The surfactant coating of the bubbles helps keeping them in line as they rise. In pure water, the bubbles would jostle around.
  • The bursting bubbles play an imporant role in flavor release as they collect and concentrate surface active molecules which are thrown against your nose once the bubble bursts, creating a cloud of droplets.
  • (these facts should be perfect conversation starters!)

    trail of champagne bubbles
    (photo by Gérard Liger-Belair)

    An interesting article by Gérard Liger-Belair, “Effervescence in a glass of champagne: A bubble story” is available from Europhysics news.

    Happy New Year!

    Wolke with column: Food 101

    Thursday, December 28th, 2006

    This is not exactly breaking news, but I just recently discovered that Robert L. Wolke, a retired chemistry professor and author of “What Einstein told his Cook” (volume one and two), writes a food/science column in the Washington Post entitled Food 101. Readers post questions which are then answered. One reader asks:

    Why does a pot roast brown in a crockpot? It seems to be steaming in the pot, which one would think would create a blanched and pale cut of meat, but it comes out as browned as if we had seared it on the stovetop (not that I’m complaining).

    […]
    Now, did I say the Maillard browning reaction involves parts of sugar molecules?

    Yes, I did.

    Does that mean there are sugars in the meat?

    Absolutely not.

    Then what the. . . .

    Easy, now. Let me explain.
    A carbonyl group is indeed a certain grouping of atoms found in sugar molecules. But it also is found in many other kinds of molecules, including the meat’s very own fats and proteins. The Maillard browning process can use the carbonyl groups that are inherent in the meat; it does not require sugars. And that’s fortunate, because there are no sugars in meat, beyond perhaps traces of glycogen, a source of glucose that fades away following the animal’s death.
    […]

    Check out the other posts – there’s a lot to pick up for anyone interested in the food and science (especially if you like Wolke’s anti “tech speak” jargon – otherwise I would suggest reading McGee instead)!

    McGee with column in NY Times

    Thursday, December 14th, 2006

    Under the heading “The Curious Cook” Harold McGee recently started an occasional column on food and chemistry and everything in between in the New York Times. It’s definitely worth reading as Harold McGee has time and opportunity to really dig into these matters. Also, don’t forget to check out his blog. The latest post on his blog provides more detail on the blue-green colors in garlic and onion, discussed in the NY Times column.

    the curious cook