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Explore the fascinating world of chemistry through the eyes of cooks. Learn about the principles and applications of acids, indicators, surfactants, and chemical reactions. Discover how chemistry can help solve everyday problems in the kitchen and beyond.
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Chemistry for cooks - the alliteration Leo Gros, Noreen Klein, Sascha Klein Europa Fachhochschule Fresenius Abitur an der Rheingauschule 1970, 2006, 2005 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
1. Chemists are observers Szent-Györgyi (1925) - observation: patient brown skin (adrenalopathy) apple apple (just cut) (brown) apple apple (just cut) acids (brown) polyphenoloxidase citrus fruit juice CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
Szent-Györgyi (1925) isolated an active substance • „It had been an acid, it seemed to be descended from an unknown sugar, that I called „Ignose“ , the substance itself I called „Ignosinacid“. But the editor of the newspaper, to whom I send my publications, didn‘t like any jokes and rejected the name. „Godnose“ hadn‘t been anymore successful, therefore we agreed, the child ought to be called Hexuronacid. Later on, with advanced knowledge about the structure, it had to be renamed hastily and now it is called ascorbic acid (sometimes Vitamin-C-acid), since it is identical to Vitamin C and prevents scurvy. That's how I became a father without intending it, father of the Vitamin C.“ • Therefore: acid is good! CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
Ascorbic acid prevents polyphenoloxidase http://www.gartendatenbank.de/photo/2004012583 http://www.fao.org/ag/Ags/agsi/ENZYMEFINAL/Enzymatic%20Browning.html#ASCORB CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
To observe something means, to see something, that has already been seen by many, and to think something that nobody has thought about before. CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
2. Chemists know how to help themselves. A strange salt in the soup. www.schule-bw.de/unterricht/faecher/biologie/archiv/tiere/voegel/Huhn2.jpg/view CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
The revealing indicator CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
This way chemists see red light: http://www.ieap.uni-kiel.de/plasma/ag-stroth/lehre/physik/HTML/f40_08.html CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
Based on this phenomenon, Bunsen and Kirchhoff developed an analysis principle: http://lims.uni-duisburg.de/Lehre/Material/PMAll/vorproben.pdf CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
Today: Atomic emission is used in quantitative analysis CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
3. Chemists have to remove dirt from the bathtub like anyone else –but they know where it comes from http://www.uni-essen.de/chemiedidaktik/S+WM/NachteileSeife/Wasserh.htm CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
That's what surfactants look like: http://de.wikipedia.org/wiki/Tenside CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
This is how chemists see calcium-surfactant precipitates - Ca 2+ - CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
4. Chemists recognise the „underlying principles“: Three examples of effervescence – one principle NaHCO3 + C6H8O7 → NaC6H7O7 + H2O + CO2 H3O+ + HCO3- → H2CO3 + H2O → CO2 + 2 H2O • Brause (sherbet) • Schorle (spritzer) • Baking powder http://de.wikipedia.org/wiki/Brausepulver CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
5. Chemists know the tricks:How garlic destroys „poison“(A story taking place at the Auer Dult near Munich) http://www.gartendatenbank.de/photo/2004012583 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
Alliin Allylsulfensäure alpha-Aminoacrylsäure Allylsulfensäure Allicin Alliin ((+)-(S)-Allyl-L-cysteinsulfoxid) That’s only one part of the „chemistry“ of garlic http://www.uni-bayreuth.de/departments/ddchemie/umat/knoblauch/knoblauch.htm#1 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
An example of a chemical reaction using permanganate: (Determination of oxalic acid) http://www.chemie.uni-greifswald.de/~analytik/Lehre/Schr%F6der/Quanti/Wasserg%FCte.pdf CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
Water pollution in the Elbe river at the beginning of the 20th century. http://www.springerlink.com/content/k85400x365p3q37h/fulltext.pdf CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
Today in the labs it’s practiced like this: • Procedure: • The following determination is accomplished simultaneously with the water sample and distilled water • Prepare in a 400 mL beaker boiling water for a water bath • With a 25 mL pipette add of the water sample in a tall test tube and add 5 mL of a 2 mol sulphuric acid. Likewise 25 mL distilled water are mixed with 5 mL sulphuric acid. The test tubes are put in boiling water for ten minutes to adjust the temperature. • Add exactly 5 mL potassium permanganate in both test tubes and leave them for exactly 10 minutes in the water bath. After ten minutes constant boiling add to each test tube 5 mL oxalic acid • Afterwards the colourless, hot fluid with potassium permanganate is titrated until a light pink colouration persists for about 30 seconds http://www.xlab-goettingen.de/pics/medien/1_1097848861/Wasseruntersuchungen.pdf CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
A recent publication tells us more: Here we show that human RBCs convert garlic-derived organic polysulfides into hydrogen sulfide (H2S), an endogenous cardioprotective vascular cell signaling molecule…. The vasoactivity of garlic compounds is synchronous with H2S production, and their potency to mediate relaxation increases with H2S yield, strongly supporting our hypothesis that H2S mediates the vasoactivity of garlic. Gloria A. Benavides et al., http://www.pnas.org/cgi/content/abstract/0705710104v1 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
Angew. Chem. 2009, S. 121, 163-166 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
http://www.physics.ubc.ca/~stm/news0229.pdf CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
What does that teach us? CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
How chemists see the world … they see molecules dancing where other people see nothing …and our benefit We understand our world better – we can make substances, transfer and measure them – and we learn about dangers and benefits of our actions CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21