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M3-Kitchen-chemistry-EN-2.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21
1
Chemistry for cooks - the alliteration
Leo Gros, Noreen Klein, Sascha KleinHochschule Fresenius
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 2
Szent-Györgyi (1925) - observation:
patient brown skin(adrenalopathy)
apple apple (just cut) (brown)
apple apple (just cut) acids (brown)
1. Chemists are observers
citrus fruit juice
polyphenoloxidase
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 3
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!
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 4
http://www.gartendatenbank.de/photo/2004012583
http://www.fao.org/ag/Ags/agsi/ENZYMEFINAL/Enzymatic%20Browning.html#ASCORB
Ascorbic acid prevents polyphenoloxidase
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 6
To observe something means,
to see something,that has already been seen by many,
and to think somethingthat nobody has thought about before.
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 7
www.schule-bw.de/unterricht/faecher/biologie/archiv/tiere/voegel/Huhn2.jpg/view
2. Chemists know how to help themselves. A strange salt in the soup.
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 8
The revealing indicator
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 9
This way chemists see red light:
http://www.ieap.uni-kiel.de/plasma/ag-stroth/lehre/physik/HTML/f40_08.html
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 10
http://lims.uni-duisburg.de/Lehre/Material/PMAll/vorproben.pdf
Based on this phenomenon, Bunsen and Kirchhoff developed an analysis principle:
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 11
Today: Atomic emission is used in quantitative analysis
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 12
http://www.uni-essen.de/chemiedidaktik/S+WM/NachteileSeife/Wasserh.htm
3. Chemists have to remove dirt from the bathtub like anyone else –but they know where it comes from
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 13
http://de.wikipedia.org/wiki/Tenside
That's what surfactants look like:
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 14
--
Ca 2+
This is how chemists see calcium-surfactant precipitates
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 15
NaHCO3 + C6H8O7 → NaC6H7O7 + H2O + CO2
H3O+ + HCO3- → H2CO3 + H2O → CO2 + 2 H2O
• Brause (sherbet)• Schorle (spritzer)• Baking powder
http://de.wikipedia.org/wiki/Brausepulver
4. Chemists recognise the „underlying principles“: Three examples of effervescence – one principle
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 16
http://www.gartendatenbank.de/photo/2004012583
5. Chemists know the tricks:How garlic destroys „poison“
(A story taking place at the Auer Dult near Munich)
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 17
http://www.uni-bayreuth.de/departments/ddchemie/umat/knoblauch/knoblauch.htm#1
That’s only one part of the „chemistry“ of garlic
Alliin ((+)-(S)-Allyl-L-cysteinsulfoxid)
Alliin Allylsulfensäure alpha-Aminoacrylsäure
Allylsulfensäure Allicin
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 18
http://www.chemie.uni-greifswald.de/~analytik/Lehre/Schr%F6der/Quanti/Wasserg%FCte.pdf
(Determination of oxalic acid)
An example of a chemical reaction using permanganate:
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 19
http://www.springerlink.com/content/k85400x365p3q37h/fulltext.pdf
Water pollution in the Elbe river at the beginning of the 20th century.
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 20
http://www.xlab-goettingen.de/pics/medien/1_1097848861/Wasseruntersuchungen.pdf
Procedure:
The following determination is accomplished simultaneously with the water sample and distilled water
1. Prepare in a 400 mL beaker boiling water for a water bath2. 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.
3. 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
4. Afterwards the colourless, hot fluid with potassium permanganate is titrated until a light pink colouration persists for about 30 seconds
Today in the labs it’s practiced like this:
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 21
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
A recent publication tells us more:
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 22
Angew. Chem. 2009, S. 121, 163-166
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http://www.physics.ubc.ca/~stm/news0229.pdf
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What does that teach us?
M3-Kitchen-chemistry-EN-0.0 CITIES Project N. 129193-CP-1-2006-1-DE–COMENIUS–C21 25
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