Changes in the Concentrations of Free Amino Acids and Soluble Nucleotides in Attached and Detached Tomato Fruits during Ripening

Abstract

In order to investigate the differences in flavor quality of tomato fruit ripened on and off the plant, the concentrations of free amino acids and soluble nucleotides in the room ripened fruits were compared with those in the field ripened fruits, during ripening. Room ripened fruits were picked at the mature green, turning or pink stage, and ripened at 25°C.
Glutamic acid was the predominant free amino acid in the fruit and progressively increased in quantity with advancing ripeness in every fruit studied. However, the content in room ripened fruit picked at the mature green or turning stage increased more rapidly than that in field ripened fruit.
The major soluble nucleotide was identified as adenosine-5'-monophosphate (5'- AMP) by chemical and chromatographic analysis. The 5'-AMP concentration also increased with ripeness in every fruit studied. Again however, room ripened fruit picked at the mature green or turning stage had a higher 5'-AMP content relative to field ripened fruit throughout ripening process.
These results indicate that deteriorating flavor quality in room ripened tomatoes can not be explained well by considering only the concentration of flavor-potentiating (umami) substances.