New developments in tomato flavor, part 2: How about some lemon basil in that tomato?

The second of two recent studies of tomato flavor involves genetic engineering, and offers a scent of tomorrow's tomatoes. 

A group of plant scientists in Israel and at Rutgers and the University of Michigan reported their success in transferring a gene from the basil plant into tomato plants. This particular gene diverts molecules in the pathway toward becoming the red pigment lycopene, and sends them instead onto the pathway that generates aroma molecules. The engineered tomato plants produced fruits that were paler than usual, but also had a stronger aroma and smelled distinctly of perfume, rose, geranium, and lemongrass. More than half of a panel of taste testers preferred the engineered tomato to its unengineered parent. 

This experiment may be a harbinger of things to come, a new era of plant modification in which flavor combinations once created by cooks will be re-created--or precreated--by breeders in the plants themselves. 

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Davidovich-Rikanati, R. et al., Enrichment of tomato flavor by diversion of the early plastidial terpenoid pathway. Nature Biotechnology 2007, online publication 24 June.
doi:10.1038/nbt1312

Curious Cook in the New York Times: Potato chips

In today's Dining section of the Times I write about potato chips: the sounds they make, the music that has been made from them, and the forces that shape them.

My source for those shaping forces was Paul Green, a professor of plant biology at Stanford, and a friend. Paul died in 1998. In the column he became "Mr. Green." When I find a near-perfect chip and think of him, I don't think of Mr. Green, I think of Paul.

For helping me understand and explain the physics of chip shape, I thank two people who worked with Paul as postdoctoral fellows: Jacques Dumais of Harvard University and Sidney Shaw of Indiana University. Of course the simplifications and approximations are my doing, not theirs.

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Kim, S.-E. et al. Development of a method for the musical expression of cognitive food taste. Food Sci. Biotechnology 2005, 14, 738-42.

Zampini, M. and C. Spence. The role of auditory cues in modulating the perceived crispness and staleness of potato chips. Journal of Sensory Studies 2004, 19, 347-63.

Green, P. Transductions to generate plant form and pattern: An essay on cause and effect. Annals of Botany 1996, 78, 269-81.

New developments in tomato flavor, part 1: Save the seeds

Two interesting studies of tomato flavor have appeared in the last month. One originated in the kitchen and may immediately change the way you taste and use tomatoes. The other involves genetic engineering, and offers a scent of tomorrow's tomatoes. Here's the first; check back in a few days for the second.

In classic French cooking, it's only the fleshy walls of the tomato fruit that get used in any kind of prominent way. The skin is peeled off and the seeds and their jelly are scooped out, perhaps to be used in a stock.

I've grown a number of different tomato varieties in my garden over the years, and in the course of comparing them in detail, found that I really liked the jelly more than the flesh. It has a wonderful slippery consistency, and it has more flavor. I thought that it was especially acidic and helped balance the sweetness of the flesh.

A few years ago, Heston Blumenthal at The Fat Duck near London tasted the seedy jelly of a tomato and was struck by what seemed to him a surprisingly intense umami taste, that savory, mouth-filling sensation created by MSG (monosodium glutamate, the sodium salt of glutamic acid) and several compounds called nucleotides. Heston maintains both formal and informal collaborations with several food scientists, and he asked Donald Mottram of the University of Reading whether there is more glutamic acid and nucleotides in the jelly than in the flesh. No one had asked the question before. So Professor Mottram's group did the analysis. The report has just come out, with Chef Blumenthal as a co-author.

Heston was right. The Reading group analyzed 14 different tomato varieties grown in a half dozen countries, and found that all of them had significantly higher glutamate contents in the jelly than in the flesh. The average ratio was nearly 4 to 1, and in some varieties was more than 6 to 1. The same general trend was found for several nucleotides, and for other free amino acids, which may contribute to the fullness of flavor. Though the salt content and pH weren't significantly different between jelly and flesh, the tasting panels consistently rated the jelly higher in perceived saltiness and acidity.

So: tomato jelly is packed with flavor. Taste it and use it! Several years ago at El Bulli in Spain, well before the Reading analysis, Ferran Adrià served clusters of tomato seeds and their jelly intact, as the central elements of a dish, to be admired for their glistening translucence and savored on their own. Why not?

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Oruna-Concha, M.-J. et al. Differences in Glutamic Acid and 5'-Ribonucleotide Contents between Flesh and Pulp of Tomatoes and the Relationship with Umami Taste. J. Agric. Food Chem. 2007, 55, 5776-80.
doi: 10.1021/jf070791p

Search "On Food & Cooking" from here

In a post last February, I described how to use Google Book Search as a kind of electronic index to On Food & Cooking. And I mentioned that Google engineers were working on a search box for this site that would take you directly to the snippets. Well, they've done it, and it works wonderfully! Find the search box in the right-hand column on this page, type in your word(s) and hit search, and on the resulting page look at the fourth box down along the right edge.

It will give you snippets around the term, and page references. The entire text isn't viewable on Google Books, so you'll probably have to go back to your hard copy to see all the appearances of the term. And the search index may not be complete. But it's much more complete than the book's printed index.

My thanks to Eric Case of the Blogger team at Google for taking my wish to the right people and bringing this back!