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Tuesday, March 19, 2013

The French (Gastronomic) Connection

Photo: Alexandra Boulat/AP
I begin now the arduous task of writing about food and beer in the book, easily the subject I'm least qualified to write.  I mean I eat, but food?  An ignorant fool.  So I've been boning up on some theory, and in a book called Molecular Gastronomy: Exploring the Science of Flavor by French food chemist Hervé This, I encountered this fascinating passage (shortened somewhat for brevity):
"In wines made from the Sauvignon Blanc grape an odorant molecule has been found whose effect is registered only when the enzymes in saliva have separated it from its precursor.  A few moments are needed, then, for the aroma to be perceived.   In 1995, Philippe Darriet and Denix Dubourdieu  discovered a molecule a boxwood or broom note.  Significantly, this simple moecule, whose skeleton is composed of only five carbon atoms, contains a sulfur atom.  Additionally, they observed that the frequency with which this precursor is transformed into an odorant molecule depends on the strains of yeast responsible for fermentation."
There's not a lot more detail to be found, so it's difficult to know how much (if at all) this might be applicable to beer.  But the idea that the perception of aroma or flavor (the two are strongly related) depends on chemical reactions that happen with the application of the taster's saliva--this is fascinating.  When I hold beer in my mouth, flavors and aromas do emerge, but this may well be from warmth, which volatilizes aroma.  It would be hard to tease the two effects apart from a sensory perspective.  But I love the idea.


Update.  The internet is like a little god.  You stand in its dim light and pose your question.  It is only a little god and therefore often remains mute.  But sometimes it answers, and this time it said to me, "hop glycosides."  I swear it spoke in the voice of Stan Hieronymus:
Looking beyond the lupulin gland, and compounds that mostly evaporate during a vigorous boil, led to the discovery of glycosidically bound flavor compounds in hops that contribute to the complex aroma and flavor matrix....  Unlike essential oils some of these glycosides survive the vigorous wort boiling process.  Combined their parts are odorless and nonvolatile, but various yeast strains cause individual cleavage of glycosides, freeing the aromatic component and adding to what is called kettle hop flavor....

[Miller chemist Pat] Ting explained that this flavor does not result simply from hydrolyzed glycosides but also from the subsequent bioconversion by yeast and perhaps even enzymes and microorganisms in the mouth.
(As with my Hervé This quotes, I streamlined this one a bit--you'll just go have to buy the book if you want the full quote.)

8 comments:

  1. I love it...immense complexity for something so simple...taste. Great post!

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  3. If you haven't read it yet, Stan Hieronymous' Four the Love of Hops contains a passage about this very thing in beer - specifically in hop oils, but yes very much the same. Certain flavors our characteristics only coffee out if the right precursors are created by fermentation, with only certain varieties creating these in conjunction with certain hops. It makes every bet that little bit more unique :-)

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  4. Oh God autocorrect butchered that post. Coffee, not coffee, beer not bet, or not out. You get the picture.

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  5. Jeff, this reminds me of something I read in an early beer-and-food book, it was about foods that go particularly well with beer. The author said that with some combinations, the beer makes the food taste better and the food makes the beer taste better. And this is very true in my experience. Of course the opposite can happen too, not that often really - I do feel beer can accompany most foods - but sometimes. Especially with cheese, sometimes they clash and produce odd flavours.

    I wonder if this results from some obscure chemical change in the mouth when saliva works on the solids and liquids.

    Gary

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  6. what's curious to me is that the "oderant molecule" is released in the mouth. I wonder if we are somehow perceiving/receiving that scent in the back of the mouth, closer towards our nasal passages? Or are scent and flavor so very connected that we are tasting a smell?

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  7. You know what just occurred to me? CHICHA! Chicha is that S. American brew where people chew corn and then spit it out and ferment it. Though I'd be curious if that molecule that's unlocked by saliva would survive brewing.

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  8. Niki, to the scent thing. You are exactly on target. There's this amazingly interesting book called Neurogastronomy that details how the fusing of scent and taste create flavor. It happens "retronasally"--that is, the scents go to the nose via the mouth. Our tongues are so crude that alone they detect very little. But add scent to their inputs and you get flavor. Gordon Shepherd, the author, says that the human brain has evolved in such a way as to process "flavor" that's far in advance of other creatures, even famously nose-based ones like dogs. We are literally born foodies.

    On chicha, what's actually going on there is the mouth is functioning as the mash. We add the enzymes that convert the starches. It's similar but slightly different use of enzymes. Fortunately, they boil the spittle-mashed wort, but I still find it unnerving.

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