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.
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?
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.