Web Release Date: June 14,
Differences in Glutamic Acid and 5'-Ribonucleotide Contents between Flesh and Pulp of Tomatoes and the Relationship with Umami Taste
and
Department of Food Biosciences, University of Reading, Whiteknights, Reading RG6 6AP, United Kingdom, and The Fat Duck Restaurant, Bray, Berkshire SL6 2AQ, United Kingdom
Received for review March 16, 2007. Revised manuscript received May 4, 2007. Accepted May 5, 2007.
Abstract:
A difference in taste characteristics between the outer flesh and the inner pulp of tomatoes has been observed; in particular the pulp, which contains the seeds, had more umami taste. Analysis of the free amino acids and 5'-ribonucleotides in the different parts of 13 varieties of tomatoes showed that in all cases the pulp contained higher levels of glutamic acid, 5'-adenosine monophosphate (AMP), 5'-guanosine monophosphate, 5'-uridine monophosphate, and 5'-cytidine monophosphate. The mean concentration of glutamic acid in the flesh was 1.26 g/kg and that in the pulp 4.56 g/kg but in some varieties the difference between pulp and flesh was more than 6-fold. For AMP, the mean concentration in the flesh was 80 mg/kg and that in the pulp was 295 mg/kg with one variety showing an 11-fold difference between pulp and flesh. These differences in concentration of these compounds, which are known to possess umami characteristics, provide an explanation for the perceived difference in umami taste between the flesh and pulp of tomatoes.
Keywords: Tomato; glutamic acid; 5'-ribonucleotides; umami.
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