Archive for the ‘videos’ Category

Videos from MG seminar in Belgium

Thursday, January 11th, 2007

Videos from the MG seminar in Belgium held on November 20th last year have generously been made available for free on the net. There are four videos to watch: presentations by Prof. Peter Barham (‘Molecular Gastronomy? The science of taste and flavour’) and Prof. Jorge Ruiz (‘Methods in the kitchen: the science behind’) plus demonstrations by Kobe Desramault and Sang Hoon Degeimbre.

Also, Bernard Lahousse (who is in charge of food for design and a co-organizer of the MG smeinar) has let me know that the next seminar will be held on March 16th with the title “A world of Pinot noir” – focus is on wine, but with live MG demos. Stay tuned!

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!

St. Lucia, saffron and turmeric

Thursday, December 14th, 2006

lussekatt-stor
Lussekatt (Photo by Jonas Bergsten)

The day of St. Lucia is celebrated in Scandinavia and some countries in southern Europe on December 13th. In Scandinavia a traditional kind of bun, lussekatt, is normally made and eaten on this day.

What is exciting about this from a chemical perspective is that they are made with saffron, the world’s most expensive spice (a recipe can be found here). Because of the high price, saffron is sometimes adulterated with turmeric. There is however a simple chemical test to check whether your saffron has been adulterated or not.

The color of saffron comes mainly from crocin, a carotenoid with a sugar attached that makes it water soluble (this is why the color is so easily extracted into water containing foods):

crocin

The aroma arises mainly from the degradation of picrocrocin to release the terpene safranal:

picrocrocin

The yellow color of turmeric comes from curcumin.

curcumin

Upon reaction with a base, curcumin turns bright red whereas crocin is unchanged. Because of this it should be possible to detect whether saffron has been adulterated with turmeric. In the picture below, strips of coffe filters where inserted into suspensions of saffron and turmeric in water (two of each), and those on the right where then held over a bottle of aqueous ammonia. An immediate reaction takes place between ammonia and curcumin, producing a bright red color. I should quickly admit that I haven’t had the opportunity to test this on an “authentic” adulterated sample!

saffron-turmeric-620px

BTW, the color change is very fast as is obvious from the video below (click here if it doesn’t play in the window below):

Video on alginates

Sunday, September 17th, 2006

My fellow blogger on molecular gastronomy, Göde Schüler (check out his German MG blog Gourmetrics) found a great video on YouTube. The video shows how a red beet paste mixed with alginate solidifies when dripped into a solution of calcium lactate (this solution is normally clear, the yellow colour comes from extensive use).

Chef Simon (French, click here for babelfish translation) has a nice page on alginates as well. Another french page here (with english translation by babelfish). You can find links to more technical information (free pdf’s) on alginates in the static pages of khymos.org.

The chemical principles put simply are as follows:
Sodium alginate is water soluble and can be mixed with many different fruit/vegetable juices and purés. When dripped into a solution containing calcium ions, each calcium ion (which holds a charge of +2) knocks away two sodium ions (each holding a charge of +1). The alginate molecule contains loads of hydroxyl groups (OH’s) that can be coordinated to cations (that’s ions with a positive charge such as sodium and calcium).

calcium alginate
Figure from Draget, K. I.; Smidsrød, O.; SkjÃ¥k-Bræk, G. “Alginates from Algae” in “Polysaccharides and Polyamides in the Food Industry. Properties, Production, and Patents”, Steinbüchel and Rhee (Ed.), Wiley 2005.

When alginate is coordinated to sodium, it’s a very flexible chain. When sodium is replaced by calcium however, each calcium ion (black dots in the image below) coordinates to two alginate chains, linking them together. The flexible chains become less flexible and form a huge network – a gel. The fun thing is that this happens within seconds after the alginate mixture is dripped into the water bath with the calcium ions.

Two alginate chains
Figure from Draget, K. I.; Smidsrød, O.; SkjÃ¥k-Bræk, G. “Alginates from Algae” in “Polysaccharides and Polyamides in the Food Industry. Properties, Production, and Patents”, Steinbüchel and Rhee (Ed.), Wiley 2005.

Approximate concentrations:

  • Fruit/vegetalbe juice/puré with 1-2% sodium alginte
  • 2% calcium chloride solution (approx. 10g in 1/2 L of water) – because calcium chloride has a slightly bitter taste, it is a good idea to rince these pearls with water before consumption. This is also the reason why calcium lactate is often used in stead (as shown in the video).

Update: The Frog Blog has nice posts with pictures showing how Jay Veregge and Joel Robuchon utilize alginate gels. Also, check out this “caviar” maker for dripping 96 drops of sodium alginate solutions into calcium chloride at once.