This month’s round of TGRWT is hosted by Pablo over at Medellitin, and the foods to pair this time are tomato and black tea. As always you can find instructions on how to participate in the announcement post. If you are new to TGRWT (which stands for They Go Really Well Together), check out the round-ups of the previous 18 rounds! And if you are chemically inclined, you may want to read on to learn more about the compounds behind this months pairing.

With a little help from Douglas Baldwin (whom I interviewed about sous vide recently) I’ve been able to pinpoint the compounds which occur naturally in both tomato and black tea, according to The Good Scents Company website:

(E)-2-hexen-1-al, (E)-2-hexen-1-ol, (E)-2-hexen-1-yl acetate, (E)-2-nonen-1-al, (E)-geranyl acetone, (Z)-2-hexen-1-ol, (Z)-3-hexen-1-al, (Z)-3-hexen-1-ol, (Z)-3-hexen-1-yl acetate, 1-octen-3-ol, 1-penten-3-ol, 2,4-decadien-1-al, 2-hexen-1-ol, 2-methyl furan, 5-methyl furfural, ammonia, butyl alcohol, butyraldehyde, butyric acid, citronellol, dihydroactinidolide, dimethyl sulfoxide, dimethyl trisulfide, ethyl hexanoate, gamma-hexalactone, gamma-valerolactone, geranic acid, hexanal, hydrogen sulfide, isoamyl alcohol, isovaleraldehyde, isovaleric acid, linalool oxide, methyl ethyl ketone, ortho-guaiacol, propionaldehyde, valeraldehyde

Now this might seem impressive, but as I’ve touched upon previously it is highly uncertain that all of these compounds actually contribute to the flavors of tomato and black tea. Many are probably present at concentrations well below the individual odor thresholds. To alleviate this one preferably needs odor activity values. The closest I came for tomatoes was the mention (free pdf) of a “model” tomato paste with the following compounds:

(E)-beta-damascenone, 2-phenylethanol, 3-methylbutanal, 3-methylbutyric acid, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 4-hydroxy-4,5-dimethyl-2(5H)-furanone, 4-vinylguaiacol, 5-ethyl-4-hydroxy-2-methyl-3(2H)-furanone, acetic acid, butyric acid, dimethyl sulphide, eugenol, linalool, methional, methylpropanal, vanillin

And for tea (both black and green) there is a complete PhD thesis available for download (in German). The following compounds in black teas had high FD (flavor dilution) values:

(E)-2-nonenal, (E)-beta-damascenone, (E,E)-2,4-decadienal, (E,E,Z)-2,4,6-nonatrienal, 2-phenylethanol, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 3-methyl-2,4-nonandion, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, beta-ionone, geraniol, linalool, phenylacetaldehyde, phenylacetic acid, vanillin

Comparing the two latter lists, we get the following shortlist for odorants present in tomato (paste) and black tea which contribute significantly to their aromas:
(E)-beta-damascenone, 2-phenylethanol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, linalool, vanillin (shown below). The fact that none of these are included in the data from The Good Scents Database illustrates my point about using OAVs to evaluate flavor pairing.

References:
Werner Grosch “Evaluation of the Key Odorants of Foods by Dilution Experiments, Aroma Models and Omission” Chem. Sens. 2001, 531.
Schuh, Christian “Wichtige Aromastoffe in schwarzem und grünem Tee (Camellia sinensis)”, PhD disseratation, TU München, 2004.

A recent article (found via Harold McGee’s News for curious cooks) featuring Heston Blumenthal as a co-author emphasizes the huge difference in glutamic acid contents between the flesh and pulp of tomatoes. Glutamic acid and it’s sodium salt (mono sodium glutamate or MSG) are responsible for the characteristic umami taste. On average the flesh contains 1.26 g/kg glutamic acid whereas the pulp on average contains 4.56 g/kg glutamic acid. Similar differences are found for several nucleotides which posess similar taste qualities. These differences can explain the perceived difference in umami taste between the flesh and pulp of tomatoes – and is worthwhile considering when cooking.

Those concerned about food with added MSG should read the chapter about MSG in John Emsley’s excellent book “Was it something you ate?”. First thing to note is that you can’t be allergic to MSG because our body needs glutamic acid to function properly. Emsley retraces the history of the Chinese restaurant syndrome (CRS) back to it’s roots in 1968 when a letter was published (R.H.M. Kwok, New Engl. J. Med. 1968, 278, 796) describing a series of symptoms experienced after having eaten at a Chinese restaurant. To make a long story short, in 1993 Tarasoff and Kelly reviewed previous studies and conducted a double blind test which led to the following conclusion:

… ‘Chinese Restaurant Syndrome’ is an anecdote applied to a variety of postprandial illnesses; rigorous and realistic scientific evidence linking the syndrome to MSG could not be found.

Following the publication, a critical reply was published by Adrianne Samuels, to which the authors have replied.

Anyway, it was in John Emsley’s book that I first read about the record levels of glutamic acid found in parmesan cheese: 12 g/kg! That’s nearly three times the amount found in tomato pulp. In some cheeses there is so much that it crystallises out in small white crystals visible to the naked eye. Think about this when you sprinkle your food with parmesan. And if you ever wondered why Italian food tastes so nice, now you know that MSG is one reason (but of course not the only one …).