Characterization of the key aroma compounds in tomato pastes as affected by hot and cold break process

The popular flavor of tomato and its products are primarily due to a complex mixture of acids, sugars, amino acids, minerals, and volatile compounds. Within this mixture, the aroma of tomato and its products is an important attribute that greatly influences consumer acceptability and preference. In the present study, tomato and its two types of pastes, produced from hot and cold break methods, were subject to sensory profiling, aroma, and aroma-active compounds analysis. The key aroma compounds in tomato and its two types of pastes were characterized by application of direct solvent extraction with dichloromethane/solvent assisted flavor evaporation (SAFE), gas chromatography-mass spectrometry-olfactometry (GC-MS-O) technique and aroma extract dilution analysis (AEDA). Fresh tomato and its paste volatiles were composed of alcohols, aldehydes, lactones, carboxylic acids, ketones, furans, esters, volatile phenols, 13-C norisoprenoid, terpene, and pyrrols. Via AEDA application, a total of 21 and 13 key odorants were detected in tomato and its pastes, respectively. In tomato pastes, lower numbers of aroma-active compounds than in fresh tomato were determined. The most important difference of aroma-active compounds in tomato and its pastes was hexanal, (Z)-3-hexenal, 2,3-butanediol, (Z)-3-hexenol, (E)-2-octenal, benzaldehyde, (E,Z)-2,6-nonadienal, methyl salicylate, -ionone, 5-penthyl-2-(5H)-furanone and eugenol was not detected in tomato paste samples. On the basis of flavor dilution (FD) factors obtained by AEDA, the most powerful aroma-active compounds were (Z)-3-hexenal (FD=512; green-grassy), 4-methyl-(5H)-furan-2-one (FD=512; fruity), -ionone (FD=512; floral-violet) in tomato; 6-methyl-5-hepten-2-one (FD=1024; green-leafy) in cold break tomato paste and furfural (FD=512; pungent) in hot break tomato paste. In the sensory analysis, the tomato paste produced with the cold processing method was more acclaimed in terms of color, smell, taste and fruity aroma than the paste produced via the hot processing method.