Assessment of Changes in Organic Acid and Sugar Profiles of Tomato Fruits Induced by UV-C Hormesis.

Charles, M.T., Rolland, D., Roussel, D., Merisier, M.J., Yaganza, E.-S., Charlebois, D., and Arul, J. (2015). "Assessment of Changes in Organic Acid and Sugar Profiles of Tomato Fruits Induced by UV-C Hormesis.", Acta Horticulturae (ISHS), 1079, pp. 159-164.

Abstract

The beneficial effects of UV-C hormesis encompass increased resistance to pathogens, delay in ripening and senescence, enhancement of specific phytochemicals potentially advantageous to human health, improvement of microbiological safety of minimally-processed commodities. However, consumer acceptability is highly dependent on the extent to which the treatment affects critical quality attributes, such as taste. To our knowledge, there is only one report regarding the evaluation of the acceptability of UV-C treated tomato (Solanum lycopersicum) fruits using a sensory panel, where small differences in taste perception were observed. We report profiles of simple sugars and organic acids in tomato fruits 15 days after UV-C treatment. The pre-storage UV-C treatment was applied at 3.7 kJ m-2, and the storage temperature was 14°C. The fruits from four different cultivars (‘Balzamoth’, ‘Clermont’, ‘Lorenzo’ and ‘Makari’) were harvested at two ripening stages. In the UV-C-treated fruits, acid titers tended to be higher and sugar titers tended to be lower. Treatment with UV-C had no significant effect on citric acid content but did significantly affect all other parameters. In ‘Balzamoth’, significant increases in ascorbic acid and sucrose levels were observed at both ripening stages, and a higher fructose level was observed with treatment at the breaker stage, suggesting an enhancement in quality for this cultivar. It is likely that in most cultivars, UV-C caused a metabolic shift that slowed down the expected degradation of organic acids. This shift might be related to senescence delay. The data are discussed in terms of the possible metabolic cost of defense and the importance of varietal differences.

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