Search Results
Abstract
Differences in aroma have been examined in headspace samples of ripe tomato (Lycopersicon esculentum Mill.) fruit of ‘Rutgers’ and of yellowing fruit of the nonripening mutants rin and nor. Volatiles were trapped and separated by gas chromatography, and the intensity of the effluent aromas was rated by sniffing. Intense aroma compounds were identified by mass spectrometry. Sixty-nine intense compounds were found in ‘Rutgers’, of which 46 were present in one or both mutant strains. Fifteen compounds with odor intensities rated medium to very strong were identified that were deficient or absent in fruit of the mutants. The latter compounds included two aldehydes, seven alcohols, two ketones, three sulfur-containing compounds, and a phenol. A few compounds were intense odors in ‘Rutgers’ and in one or both mutants; hex-2-enal, linalool, phenylacetaldehyde, methyl salicylate, 2-phenylethanol, and eugenol. Some compounds were detected that were more intense in rin and nor than in ‘Rutgers’ (e.g., guaiacol). It is proposed that the “normal background aroma” in fresh tomatoes is caused by those intense odors, which are common to both normal and mutant strains, whereas the bland flavor of mutant fruit is caused by the absence of those intense aroma compounds found only in ‘Rutgers’. The intense aroma compounds found only in ‘Rutgers’ may be crucial determinants of acceptability in fresh tomato fruit.
Abstract
A range of tomato (Lycopersicon esculentum Mill.) cultivars was examined for changes during ripening in firmness, endopolygalacturonase (PG) activity and the molecular forms of polygalacturonase, Ca concentration, and the extractability of the Ca. Firm cultivars were firmer than the soft cultivars throughout ripening, and generally they contained less PG activity at each stage examined. In all cultivars, PG was predominately or entirely in the high molecular weight form (PG1) early in ripening, with the PG2 forms being increasingly prominent as ripening progressed. Differences in firmness were established while PG1 was the predominant PG. Uronic acid polymers in isolated cell walls were degraded rapidly by endogenous PG when citrate was present to complex Ca. In the presence of sufficient citrate, cell wall uronic acids of a firm and soft cultivar were equally susceptible to hydrolysis, suggesting that differences in the digestion of the walls by PG were dependent upon differences in Ca content or distribution. However, neither total, water, nor saline-extractable Ca showed consistent correlations with fruit firmness, and they also showed no progressive change during ripening.