Study on taste substances of tomato. 2. Analytical investigation into the free amino acid, peptide and protein contents
1989
Petro-Turza, M. | Szarfoldi-Szalma, I. | Fuzesi-Kardos, K. | Barath, A. (Central Food Research Inst., Budapest (Hungary))
A study of the distribution of the N content in 2 tomato varieties /K-549 and Mokka/ and their purees showed that in fresh tomatoes more than 70 o/o of the N content can be derived from the compounds present in the serum in dissolved form. The total amount of free amino acids and, within these, the percentage of the individual components showed characteristic differences in the 2 varieties, however, in both of them glutamic acid and glutamine occured in the highest quantities. The presence of peptides in the samples was detected, too. Among the amino acid components of these, aspartic and glumatic acids were dominant. The results obtained with the amino acid analyser for the fractions separated from the samples were in good agreement with the N content determined with the K jel-Foss apparatus. It was established that about 1.7 o/o of the soluble dry matter of the tomatoes considered of free amino acids and 8-11 o/o of peptides, while soluble proteins were found in minor amounts only. The considerable deviation of the obtained results from data of the literature may be due to the fact that, for tomatoes, the generally used multiplication factor of 6.25 cannot be applied for calculating the protein concentration from the N content. The amount of free amino acids decreased in purees by ca 20 o/o as related to the fresh fruits while the concentration of peptides increased as a result of the partial hydrolysis of insoluble proteins.
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