The concentrations of 44 of the major aroma components of tomato paste were determined. Comparison with studies for fresh tomatoes showed marked decreases in concentration for some compounds, particularly aliphatic aldehydes ((Z)-3-hexenal and hexanal >400 times lower) in the paste. Other compounds, however, such as the potent odorant β-damascenone (also 6-methyl-5-hepten-2- one, other ketones, linalool, and α-terpeneol) show severalfold increases in concentration in the paste. The observation by other workers of the formation of relatively large (0.5–10 ppm) concentrations of dimethyl sulfide in processed tomato was confirmed. Considerations of the odor thresholds of components and their determined concentrations indicated that the compounds most important to tomato paste aroma include dimethyl sulfide, β-damascenone, β-ionone, 3-methylbutanal, 1-nitro-2-phenylethane, eugenol, methional, 3-methylbutyric acid, 6-methyl-5-hepten-2-one, phenylacetaldehyde, and linalool. © 1990, American Chemical Society. All rights reserved.